I'm on my third laptop right now. Every time I plugged my Dell's "fat
snake" into the wall, I drew quite an arc. The Lenovo's arc was not
noticeable, but now I get a noticeable arc with my new HP -- not as
big as the Dell's, however.
I know FA about switch mode power supplies, obviously, so I wonder
1. What produces the arc?
2. Why would different power supplies produce different arcs (does it
just depend on output power capability)?
3. Why is there no arc when I pull the plug from the outlet?
> I'm on my third laptop right now. Every time I plugged my Dell's "fat
> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
> noticeable, but now I get a noticeable arc with my new HP -- not as
> big as the Dell's, however.
> I know FA about switch mode power supplies, obviously, so I wonder
> 1. What produces the arc?
The input filters are discharged and draw high current for a cycle or
two..
> 2. Why would different power supplies produce different arcs (does it
> just depend on output power capability)?
Variations in design. Some have a thermistor to limit the rush
current.
> 3. Why is there no arc when I pull the plug from the outlet?
> I'm on my third laptop right now. Every time I plugged my Dell's "fat
> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
> noticeable, but now I get a noticeable arc with my new HP -- not as
> big as the Dell's, however.
> I know FA about switch mode power supplies, obviously, so I wonder
> 1. What produces the arc?
> 2. Why would different power supplies produce different arcs (does it
> just depend on output power capability)?
> 3. Why is there no arc when I pull the plug from the outlet?
It is caused by very poor and cheap design.
Be careful where you plug in as fumes and dust ignite with a bang.
Devices like this are not allowed in certain areas.
On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
<spamtrap1...@gmail.com> wrote:
>If someone has a free moment, I'd like to know:
>I'm on my third laptop right now. Every time I plugged my Dell's "fat
>snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>noticeable, but now I get a noticeable arc with my new HP -- not as
>big as the Dell's, however.
>I know FA about switch mode power supplies, obviously, so I wonder
>1. What produces the arc?
>2. Why would different power supplies produce different arcs (does it
>just depend on output power capability)?
>3. Why is there no arc when I pull the plug from the outlet?
Dumb switching power supplies have a bridge rectifier and a big
electrolytic filter capacitor. If you plug them in near the peak of
the AC line waveform, the charging current will spark.
Better supplies, with inrush limiters, or PFC (power factor corrected)
front-ends, have much less inrush charge.
Ask Jim for details. He is *so good* at designing switching power
supplies.
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
>>I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>noticeable, but now I get a noticeable arc with my new HP -- not as
>>big as the Dell's, however.
>>I know FA about switch mode power supplies, obviously, so I wonder
>>1. What produces the arc?
>>2. Why would different power supplies produce different arcs (does it
>>just depend on output power capability)?
>>3. Why is there no arc when I pull the plug from the outlet?
>Dumb switching power supplies have a bridge rectifier and a big
>electrolytic filter capacitor. If you plug them in near the peak of
>the AC line waveform, the charging current will spark.
>Better supplies, with inrush limiters, or PFC (power factor corrected)
>front-ends, have much less inrush charge.
>Ask Jim for details. He is *so good* at designing switching power
>supplies.
Indeed I am >:-)
...Jim Thompson
-- | James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
>>>If someone has a free moment, I'd like to know:
>>>I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>noticeable, but now I get a noticeable arc with my new HP -- not as
>>>big as the Dell's, however.
>>>I know FA about switch mode power supplies, obviously, so I wonder
>>>1. What produces the arc?
>>>2. Why would different power supplies produce different arcs (does it
>>>just depend on output power capability)?
>>>3. Why is there no arc when I pull the plug from the outlet?
>>Dumb switching power supplies have a bridge rectifier and a big
>>electrolytic filter capacitor. If you plug them in near the peak of
>>the AC line waveform, the charging current will spark.
>>Better supplies, with inrush limiters, or PFC (power factor corrected)
>>front-ends, have much less inrush charge.
>>Ask Jim for details. He is *so good* at designing switching power
>>supplies.
>>>>If someone has a free moment, I'd like to know:
>>>>I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>big as the Dell's, however.
>>>>I know FA about switch mode power supplies, obviously, so I wonder
>>>>1. What produces the arc?
>>>>2. Why would different power supplies produce different arcs (does it
>>>>just depend on output power capability)?
>>>>3. Why is there no arc when I pull the plug from the outlet?
>>>Dumb switching power supplies have a bridge rectifier and a big
>>>electrolytic filter capacitor. If you plug them in near the peak of
>>>the AC line waveform, the charging current will spark.
>>>Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>front-ends, have much less inrush charge.
>>>Ask Jim for details. He is *so good* at designing switching power
>>>supplies.
>>>If someone has a free moment, I'd like to know:
>>>I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>noticeable, but now I get a noticeable arc with my new HP -- not as
>>>big as the Dell's, however.
>>>I know FA about switch mode power supplies, obviously, so I wonder
>>>1. What produces the arc?
>>>2. Why would different power supplies produce different arcs (does it
>>>just depend on output power capability)?
>>>3. Why is there no arc when I pull the plug from the outlet?
>>Dumb switching power supplies have a bridge rectifier and a big
>>electrolytic filter capacitor. If you plug them in near the peak of
>>the AC line waveform, the charging current will spark.
>>Better supplies, with inrush limiters, or PFC (power factor corrected)
>>front-ends, have much less inrush charge.
>>Ask Jim for details. He is *so good* at designing switching power
>>supplies.
> Indeed I am >:-)
I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
>>>>If someone has a free moment, I'd like to know:
>>>>I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>big as the Dell's, however.
>>>>I know FA about switch mode power supplies, obviously, so I wonder
>>>>1. What produces the arc?
>>>>2. Why would different power supplies produce different arcs (does it
>>>>just depend on output power capability)?
>>>>3. Why is there no arc when I pull the plug from the outlet?
>>>Dumb switching power supplies have a bridge rectifier and a big
>>>electrolytic filter capacitor. If you plug them in near the peak of
>>>the AC line waveform, the charging current will spark.
>>>Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>front-ends, have much less inrush charge.
>>>Ask Jim for details. He is *so good* at designing switching power
>>>supplies.
>>Indeed I am >:-)
>> ...Jim Thompson
>---
>Wow!!!
>A compliment from Larkin???
>How unusual.
Sarcasm. He's screwed up everything he's posted so far.
He did apologize for calling me a fraud, when he'd messed up.
I wonder why he's designing a discrete SMPS for a Chinese company.
That's clearly not his skill set.
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
>>>>>If someone has a free moment, I'd like to know:
>>>>>I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>>snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>>noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>>big as the Dell's, however.
>>>>>I know FA about switch mode power supplies, obviously, so I wonder
>>>>>1. What produces the arc?
>>>>>2. Why would different power supplies produce different arcs (does it
>>>>>just depend on output power capability)?
>>>>>3. Why is there no arc when I pull the plug from the outlet?
>>>>Dumb switching power supplies have a bridge rectifier and a big
>>>>electrolytic filter capacitor. If you plug them in near the peak of
>>>>the AC line waveform, the charging current will spark.
>>>>Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>>front-ends, have much less inrush charge.
>>>>Ask Jim for details. He is *so good* at designing switching power
>>>>supplies.
>>>Indeed I am >:-)
>>> ...Jim Thompson
>>---
>>Wow!!!
>>A compliment from Larkin???
>>How unusual.
>Sarcasm. He's screwed up everything he's posted so far.
>He did apologize for calling me a fraud, when he'd messed up.
>I wonder why he's designing a discrete SMPS for a Chinese company.
>That's clearly not his skill set.
Not my normal task for them. It's been chips. Their power supply
designer went AWOL and I was asked to fix a flaky start-up... just a
"patch" in a BIG design :-( Just about there, in spite of what you
might think... had to remember stuff I haven't done since about 1985.
...Jim Thompson
-- | James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
>"Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote >in message news:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
>> <jlar...@highlandtechnology.com> wrote:
>>>>If someone has a free moment, I'd like to know:
>>>>I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>big as the Dell's, however.
>>>>I know FA about switch mode power supplies, obviously, so I wonder
>>>>1. What produces the arc?
>>>>2. Why would different power supplies produce different arcs (does it
>>>>just depend on output power capability)?
>>>>3. Why is there no arc when I pull the plug from the outlet?
>>>Dumb switching power supplies have a bridge rectifier and a big
>>>electrolytic filter capacitor. If you plug them in near the peak of
>>>the AC line waveform, the charging current will spark.
>>>Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>front-ends, have much less inrush charge.
>>>Ask Jim for details. He is *so good* at designing switching power
>>>supplies.
>> Indeed I am >:-)
>I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
>Cheers
So does the L6561. But poorly documented and no model; and ST ignores
my pounding on their door >:-)
If I could make major changes I'd design ST out _forever_!
...Jim Thompson
-- | James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Jim Thompson wrote:
> On Mon, 8 Oct 2012 20:21:35 -0400, "Martin Riddle"
> <martin_...@verizon.net> wrote:
>> "Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote >> in message news:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
>>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
>>> <jlar...@highlandtechnology.com> wrote:
>>>> On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
>>>> <spamtrap1...@gmail.com> wrote:
>>>>> If someone has a free moment, I'd like to know:
>>>>> I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>> noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>> big as the Dell's, however.
>>>>> I know FA about switch mode power supplies, obviously, so I wonder
>>>>> 1. What produces the arc?
>>>>> 2. Why would different power supplies produce different arcs (does it
>>>>> just depend on output power capability)?
>>>>> 3. Why is there no arc when I pull the plug from the outlet?
>>>> Dumb switching power supplies have a bridge rectifier and a big
>>>> electrolytic filter capacitor. If you plug them in near the peak of
>>>> the AC line waveform, the charging current will spark.
>>>> Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>> front-ends, have much less inrush charge.
>>>> Ask Jim for details. He is *so good* at designing switching power
>>>> supplies.
>>> Indeed I am >:-)
>> I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
>> Cheers
> So does the L6561. But poorly documented and no model; and ST ignores
> my pounding on their door >:-)
> If I could make major changes I'd design ST out _forever_!
Might be the new normal. I want to design in a National video driver,
LMH6722. Has a thermal pad under its belly. In the datasheet they forgot
to mention where its s'posed to be connected to. Probably V- but I'd
rather make sure. Filed a support ticket with the new owner TI on 10/2.
Got a service request number.
Today is 10/8 and (finally! ... or so I thought) there was a message in
the inbox this morning. A form letter, merely saying that, tada, a
service request number has been issued. New number: Same as the old number.
So I responded politely as to when I might be expecting an answer. No
response all day.
>>>>>>If someone has a free moment, I'd like to know:
>>>>>>I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>>>snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>>>noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>>>big as the Dell's, however.
>>>>>>I know FA about switch mode power supplies, obviously, so I wonder
>>>>>>1. What produces the arc?
>>>>>>2. Why would different power supplies produce different arcs (does it
>>>>>>just depend on output power capability)?
>>>>>>3. Why is there no arc when I pull the plug from the outlet?
>>>>>Dumb switching power supplies have a bridge rectifier and a big
>>>>>electrolytic filter capacitor. If you plug them in near the peak of
>>>>>the AC line waveform, the charging current will spark.
>>>>>Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>>>front-ends, have much less inrush charge.
>>>>>Ask Jim for details. He is *so good* at designing switching power
>>>>>supplies.
>>>>Indeed I am >:-)
>>>> ...Jim Thompson
>>>---
>>>Wow!!!
>>>A compliment from Larkin???
>>>How unusual.
>>Sarcasm. He's screwed up everything he's posted so far.
>>He did apologize for calling me a fraud, when he'd messed up.
>>I wonder why he's designing a discrete SMPS for a Chinese company.
>>That's clearly not his skill set.
>Not my normal task for them. It's been chips. Their power supply
>designer went AWOL and I was asked to fix a flaky start-up... just a
>"patch" in a BIG design :-( Just about there, in spite of what you
>might think... had to remember stuff I haven't done since about 1985.
> ...Jim Thompson
Well, I'm not going to get you out of trouble on your next pass. Twice
is enough.
>Jim Thompson wrote:
>> On Mon, 8 Oct 2012 20:21:35 -0400, "Martin Riddle"
>> <martin_...@verizon.net> wrote:
>>> "Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote >>> in message news:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
>>>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
>>>> <jlar...@highlandtechnology.com> wrote:
>>>>> On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
>>>>> <spamtrap1...@gmail.com> wrote:
>>>>>> If someone has a free moment, I'd like to know:
>>>>>> I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>>> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>>> noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>>> big as the Dell's, however.
>>>>>> I know FA about switch mode power supplies, obviously, so I wonder
>>>>>> 1. What produces the arc?
>>>>>> 2. Why would different power supplies produce different arcs (does it
>>>>>> just depend on output power capability)?
>>>>>> 3. Why is there no arc when I pull the plug from the outlet?
>>>>> Dumb switching power supplies have a bridge rectifier and a big
>>>>> electrolytic filter capacitor. If you plug them in near the peak of
>>>>> the AC line waveform, the charging current will spark.
>>>>> Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>>> front-ends, have much less inrush charge.
>>>>> Ask Jim for details. He is *so good* at designing switching power
>>>>> supplies.
>>>> Indeed I am >:-)
>>> I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
>>> Cheers
>> So does the L6561. But poorly documented and no model; and ST ignores
>> my pounding on their door >:-)
>> If I could make major changes I'd design ST out _forever_!
>Might be the new normal. I want to design in a National video driver,
>LMH6722. Has a thermal pad under its belly. In the datasheet they forgot
>to mention where its s'posed to be connected to. Probably V- but I'd
>rather make sure. Filed a support ticket with the new owner TI on 10/2.
>Got a service request number.
>Today is 10/8 and (finally! ... or so I thought) there was a message in
>the inbox this morning. A form letter, merely saying that, tada, a
>service request number has been issued. New number: Same as the old number.
>So I responded politely as to when I might be expecting an answer. No
>response all day.
John Larkin wrote:
> On Mon, 08 Oct 2012 18:59:46 -0700, Joerg <inva...@invalid.invalid>
> wrote:
>> Jim Thompson wrote:
>>> On Mon, 8 Oct 2012 20:21:35 -0400, "Martin Riddle"
>>> <martin_...@verizon.net> wrote:
>>>> "Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote >>>> in message news:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
>>>>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
>>>>> <jlar...@highlandtechnology.com> wrote:
>>>>>> On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
>>>>>> <spamtrap1...@gmail.com> wrote:
>>>>>>> If someone has a free moment, I'd like to know:
>>>>>>> I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>>>> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>>>> noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>>>> big as the Dell's, however.
>>>>>>> I know FA about switch mode power supplies, obviously, so I wonder
>>>>>>> 1. What produces the arc?
>>>>>>> 2. Why would different power supplies produce different arcs (does it
>>>>>>> just depend on output power capability)?
>>>>>>> 3. Why is there no arc when I pull the plug from the outlet?
>>>>>> Dumb switching power supplies have a bridge rectifier and a big
>>>>>> electrolytic filter capacitor. If you plug them in near the peak of
>>>>>> the AC line waveform, the charging current will spark.
>>>>>> Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>>>> front-ends, have much less inrush charge.
>>>>>> Ask Jim for details. He is *so good* at designing switching power
>>>>>> supplies.
>>>>> Indeed I am >:-)
>>>> I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
>>>> Cheers
>>> So does the L6561. But poorly documented and no model; and ST ignores
>>> my pounding on their door >:-)
>>> If I could make major changes I'd design ST out _forever_!
>> Might be the new normal. I want to design in a National video driver,
>> LMH6722. Has a thermal pad under its belly. In the datasheet they forgot
>> to mention where its s'posed to be connected to. Probably V- but I'd
>> rather make sure. Filed a support ticket with the new owner TI on 10/2.
>> Got a service request number.
>> Today is 10/8 and (finally! ... or so I thought) there was a message in
>> the inbox this morning. A form letter, merely saying that, tada, a
>> service request number has been issued. New number: Same as the old number.
>> So I responded politely as to when I might be expecting an answer. No
>> response all day.
>> Hurumph!
> Get one and ohm it out.
No kidding, that may be the only way :-(
Just made a CAD model for a 100-TQFP processor. Now I know why I chose
to become an analog guy and not a digital one.
> Jim Thompson wrote:
> > On Mon, 8 Oct 2012 20:21:35 -0400, "Martin Riddle"
> > <martin_...@verizon.net> wrote:
> >> "Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote
> >> in messagenews:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
> >>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
> >>> <jlar...@highlandtechnology.com> wrote:
> >>>> On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
> >>>> <spamtrap1...@gmail.com> wrote:
> >>>>> If someone has a free moment, I'd like to know:
> >>>>> I'm on my third laptop right now. Every time I plugged my Dell's "fat
> >>>>> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
> >>>>> noticeable, but now I get a noticeable arc with my new HP -- not as
> >>>>> big as the Dell's, however.
> >>>>> I know FA about switch mode power supplies, obviously, so I wonder
> >>>>> 1. What produces the arc?
> >>>>> 2. Why would different power supplies produce different arcs (does it
> >>>>> just depend on output power capability)?
> >>>>> 3. Why is there no arc when I pull the plug from the outlet?
> >>>> Dumb switching power supplies have a bridge rectifier and a big
> >>>> electrolytic filter capacitor. If you plug them in near the peak of
> >>>> the AC line waveform, the charging current will spark.
> >>>> Better supplies, with inrush limiters, or PFC (power factor corrected)
> >>>> front-ends, have much less inrush charge.
> >>>> Ask Jim for details. He is *so good* at designing switching power
> >>>> supplies.
> >>> Indeed I am >:-)
> >> I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
> >> Cheers
> > So does the L6561. But poorly documented and no model; and ST ignores
> > my pounding on their door >:-)
> > If I could make major changes I'd design ST out _forever_!
> Might be the new normal. I want to design in a National video driver,
> LMH6722. Has a thermal pad under its belly. In the datasheet they forgot
> to mention where its s'posed to be connected to. Probably V- but I'd
> rather make sure. Filed a support ticket with the new owner TI on 10/2.
> Got a service request number.
> Today is 10/8 and (finally! ... or so I thought) there was a message in
> the inbox this morning. A form letter, merely saying that, tada, a
> service request number has been issued. New number: Same as the old number.
> So I responded politely as to when I might be expecting an answer. No
> response all day.
> Hurumph!
They're either overworked or lazy, so they punted. Probably the
responders are graded based on how fast they turn around responses,
and on yours they already hit infinity.
spamtrap1888 wrote:
> On Oct 8, 6:59 pm, Joerg <inva...@invalid.invalid> wrote:
>> Jim Thompson wrote:
>>> On Mon, 8 Oct 2012 20:21:35 -0400, "Martin Riddle"
>>> <martin_...@verizon.net> wrote:
>>>> "Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote
>>>> in messagenews:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
>>>>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
>>>>> <jlar...@highlandtechnology.com> wrote:
>>>>>> On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
>>>>>> <spamtrap1...@gmail.com> wrote:
>>>>>>> If someone has a free moment, I'd like to know:
>>>>>>> I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>>>> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>>>> noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>>>> big as the Dell's, however.
>>>>>>> I know FA about switch mode power supplies, obviously, so I wonder
>>>>>>> 1. What produces the arc?
>>>>>>> 2. Why would different power supplies produce different arcs (does it
>>>>>>> just depend on output power capability)?
>>>>>>> 3. Why is there no arc when I pull the plug from the outlet?
>>>>>> Dumb switching power supplies have a bridge rectifier and a big
>>>>>> electrolytic filter capacitor. If you plug them in near the peak of
>>>>>> the AC line waveform, the charging current will spark.
>>>>>> Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>>>> front-ends, have much less inrush charge.
>>>>>> Ask Jim for details. He is *so good* at designing switching power
>>>>>> supplies.
>>>>> Indeed I am >:-)
>>>> I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
>>>> Cheers
>>> So does the L6561. But poorly documented and no model; and ST ignores
>>> my pounding on their door >:-)
>>> If I could make major changes I'd design ST out _forever_!
>> Might be the new normal. I want to design in a National video driver,
>> LMH6722. Has a thermal pad under its belly. In the datasheet they forgot
>> to mention where its s'posed to be connected to. Probably V- but I'd
>> rather make sure. Filed a support ticket with the new owner TI on 10/2.
>> Got a service request number.
>> Today is 10/8 and (finally! ... or so I thought) there was a message in
>> the inbox this morning. A form letter, merely saying that, tada, a
>> service request number has been issued. New number: Same as the old number.
>> So I responded politely as to when I might be expecting an answer. No
>> response all day.
>> Hurumph!
> They're either overworked or lazy, so they punted. Probably the
> responders are graded based on how fast they turn around responses,
> and on yours they already hit infinity.
Lo and behold, just as I wanted to order samples I finally had a "You've
got mail" event. TI support said the pad is not connected to anything.
It can be left floating (which I'd never do, of course), connected to
V-, or connected to GND (which I'll do).
>John Larkin wrote:
>> On Mon, 08 Oct 2012 18:59:46 -0700, Joerg <inva...@invalid.invalid>
>> wrote:
>>> Jim Thompson wrote:
>>>> On Mon, 8 Oct 2012 20:21:35 -0400, "Martin Riddle"
>>>> <martin_...@verizon.net> wrote:
>>>>> "Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote >>>>> in message news:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
>>>>>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
>>>>>> <jlar...@highlandtechnology.com> wrote:
>>>>>>> On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
>>>>>>> <spamtrap1...@gmail.com> wrote:
>>>>>>>> If someone has a free moment, I'd like to know:
>>>>>>>> I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>>>>> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>>>>> noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>>>>> big as the Dell's, however.
>>>>>>>> I know FA about switch mode power supplies, obviously, so I wonder
>>>>>>>> 1. What produces the arc?
>>>>>>>> 2. Why would different power supplies produce different arcs (does it
>>>>>>>> just depend on output power capability)?
>>>>>>>> 3. Why is there no arc when I pull the plug from the outlet?
>>>>>>> Dumb switching power supplies have a bridge rectifier and a big
>>>>>>> electrolytic filter capacitor. If you plug them in near the peak of
>>>>>>> the AC line waveform, the charging current will spark.
>>>>>>> Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>>>>> front-ends, have much less inrush charge.
>>>>>>> Ask Jim for details. He is *so good* at designing switching power
>>>>>>> supplies.
>>>>>> Indeed I am >:-)
>>>>> I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
>>>>> Cheers
>>>> So does the L6561. But poorly documented and no model; and ST ignores
>>>> my pounding on their door >:-)
>>>> If I could make major changes I'd design ST out _forever_!
>>> Might be the new normal. I want to design in a National video driver,
>>> LMH6722. Has a thermal pad under its belly. In the datasheet they forgot
>>> to mention where its s'posed to be connected to. Probably V- but I'd
>>> rather make sure. Filed a support ticket with the new owner TI on 10/2.
>>> Got a service request number.
>>> Today is 10/8 and (finally! ... or so I thought) there was a message in
>>> the inbox this morning. A form letter, merely saying that, tada, a
>>> service request number has been issued. New number: Same as the old number.
>>> So I responded politely as to when I might be expecting an answer. No
>>> response all day.
>>> Hurumph!
>> Get one and ohm it out.
>No kidding, that may be the only way :-(
>Just made a CAD model for a 100-TQFP processor. Now I know why I chose
>to become an analog guy and not a digital one.
Do you mean a PCB decal, or an actual Autocad sort of thing?
PADS makes IC decals really fast, for sort of standard things with
rows of numbered pins.
Are you doing 3D Solidworks sort of physical modeling? It is fun to
finally spin that stuff around in space, or take a virtual walk under
the IC pins.
>spamtrap1888 wrote:
>> On Oct 8, 6:59 pm, Joerg <inva...@invalid.invalid> wrote:
>>> Jim Thompson wrote:
>>>> On Mon, 8 Oct 2012 20:21:35 -0400, "Martin Riddle"
>>>> <martin_...@verizon.net> wrote:
>>>>> "Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote
>>>>> in messagenews:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
>>>>>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
>>>>>> <jlar...@highlandtechnology.com> wrote:
>>>>>>> On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
>>>>>>> <spamtrap1...@gmail.com> wrote:
>>>>>>>> If someone has a free moment, I'd like to know:
>>>>>>>> I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>>>>> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>>>>> noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>>>>> big as the Dell's, however.
>>>>>>>> I know FA about switch mode power supplies, obviously, so I wonder
>>>>>>>> 1. What produces the arc?
>>>>>>>> 2. Why would different power supplies produce different arcs (does it
>>>>>>>> just depend on output power capability)?
>>>>>>>> 3. Why is there no arc when I pull the plug from the outlet?
>>>>>>> Dumb switching power supplies have a bridge rectifier and a big
>>>>>>> electrolytic filter capacitor. If you plug them in near the peak of
>>>>>>> the AC line waveform, the charging current will spark.
>>>>>>> Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>>>>> front-ends, have much less inrush charge.
>>>>>>> Ask Jim for details. He is *so good* at designing switching power
>>>>>>> supplies.
>>>>>> Indeed I am >:-)
>>>>> I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
>>>>> Cheers
>>>> So does the L6561. But poorly documented and no model; and ST ignores
>>>> my pounding on their door >:-)
>>>> If I could make major changes I'd design ST out _forever_!
>>> Might be the new normal. I want to design in a National video driver,
>>> LMH6722. Has a thermal pad under its belly. In the datasheet they forgot
>>> to mention where its s'posed to be connected to. Probably V- but I'd
>>> rather make sure. Filed a support ticket with the new owner TI on 10/2.
>>> Got a service request number.
>>> Today is 10/8 and (finally! ... or so I thought) there was a message in
>>> the inbox this morning. A form letter, merely saying that, tada, a
>>> service request number has been issued. New number: Same as the old number.
>>> So I responded politely as to when I might be expecting an answer. No
>>> response all day.
>>> Hurumph!
>> They're either overworked or lazy, so they punted. Probably the
>> responders are graded based on how fast they turn around responses,
>> and on yours they already hit infinity.
>Lo and behold, just as I wanted to order samples I finally had a "You've
>got mail" event. TI support said the pad is not connected to anything.
>It can be left floating (which I'd never do, of course), connected to
>V-, or connected to GND (which I'll do).
The ground plane is a good place to dump heat, plus some additional
heat spreader patterns on other layers, when possible. The optimum via
pattern to do that isn't obvious. We've had debates around that issue.
I wish I had some software to help with that. We just sort of guess.
Data sheets should state the power pad electrical connection. Often
it's missing, or obscure.
> spamtrap1888 wrote:
> > On Oct 8, 6:59 pm, Joerg <inva...@invalid.invalid> wrote:
> >> Jim Thompson wrote:
> >>> On Mon, 8 Oct 2012 20:21:35 -0400, "Martin Riddle"
> >>> <martin_...@verizon.net> wrote:
> >>>> "Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote
> >>>> in messagenews:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
> >>>>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
> >>>>> <jlar...@highlandtechnology.com> wrote:
> >>>>>> On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
> >>>>>> <spamtrap1...@gmail.com> wrote:
> >>>>>>> If someone has a free moment, I'd like to know:
> >>>>>>> I'm on my third laptop right now. Every time I plugged my Dell's "fat
> >>>>>>> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
> >>>>>>> noticeable, but now I get a noticeable arc with my new HP -- not as
> >>>>>>> big as the Dell's, however.
> >>>>>>> I know FA about switch mode power supplies, obviously, so I wonder
> >>>>>>> 1. What produces the arc?
> >>>>>>> 2. Why would different power supplies produce different arcs (does it
> >>>>>>> just depend on output power capability)?
> >>>>>>> 3. Why is there no arc when I pull the plug from the outlet?
> >>>>>> Dumb switching power supplies have a bridge rectifier and a big
> >>>>>> electrolytic filter capacitor. If you plug them in near the peak of
> >>>>>> the AC line waveform, the charging current will spark.
> >>>>>> Better supplies, with inrush limiters, or PFC (power factor corrected)
> >>>>>> front-ends, have much less inrush charge.
> >>>>>> Ask Jim for details. He is *so good* at designing switching power
> >>>>>> supplies.
> >>>>> Indeed I am >:-)
> >>>> I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
> >>>> Cheers
> >>> So does the L6561. But poorly documented and no model; and ST ignores
> >>> my pounding on their door >:-)
> >>> If I could make major changes I'd design ST out _forever_!
> >> Might be the new normal. I want to design in a National video driver,
> >> LMH6722. Has a thermal pad under its belly. In the datasheet they forgot
> >> to mention where its s'posed to be connected to. Probably V- but I'd
> >> rather make sure. Filed a support ticket with the new owner TI on 10/2.
> >> Got a service request number.
> >> Today is 10/8 and (finally! ... or so I thought) there was a message in
> >> the inbox this morning. A form letter, merely saying that, tada, a
> >> service request number has been issued. New number: Same as the old number.
> >> So I responded politely as to when I might be expecting an answer. No
> >> response all day.
> >> Hurumph!
> > They're either overworked or lazy, so they punted. Probably the
> > responders are graded based on how fast they turn around responses,
> > and on yours they already hit infinity.
> Lo and behold, just as I wanted to order samples I finally had a "You've
> got mail" event. TI support said the pad is not connected to anything.
> It can be left floating (which I'd never do, of course), connected to
> V-, or connected to GND (which I'll do).
I was curious so I looked at the pdf with the pcb for the evaluation
board,
it doesn't even have a pad on the pcb for the thermal pad
V+ and V- goes under theat part from each end to the center pins
John Larkin wrote:
> On Tue, 09 Oct 2012 07:37:25 -0700, Joerg <inva...@invalid.invalid>
> wrote:
>> spamtrap1888 wrote:
>>> On Oct 8, 6:59 pm, Joerg <inva...@invalid.invalid> wrote:
>>>> Jim Thompson wrote:
>>>>> On Mon, 8 Oct 2012 20:21:35 -0400, "Martin Riddle"
>>>>> <martin_...@verizon.net> wrote:
>>>>>> "Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote
>>>>>> in messagenews:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
>>>>>>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
>>>>>>> <jlar...@highlandtechnology.com> wrote:
>>>>>>>> On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
>>>>>>>> <spamtrap1...@gmail.com> wrote:
>>>>>>>>> If someone has a free moment, I'd like to know:
>>>>>>>>> I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>>>>>> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>>>>>> noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>>>>>> big as the Dell's, however.
>>>>>>>>> I know FA about switch mode power supplies, obviously, so I wonder
>>>>>>>>> 1. What produces the arc?
>>>>>>>>> 2. Why would different power supplies produce different arcs (does it
>>>>>>>>> just depend on output power capability)?
>>>>>>>>> 3. Why is there no arc when I pull the plug from the outlet?
>>>>>>>> Dumb switching power supplies have a bridge rectifier and a big
>>>>>>>> electrolytic filter capacitor. If you plug them in near the peak of
>>>>>>>> the AC line waveform, the charging current will spark.
>>>>>>>> Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>>>>>> front-ends, have much less inrush charge.
>>>>>>>> Ask Jim for details. He is *so good* at designing switching power
>>>>>>>> supplies.
>>>>>>> Indeed I am >:-)
>>>>>> I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
>>>>>> Cheers
>>>>> So does the L6561. But poorly documented and no model; and ST ignores
>>>>> my pounding on their door >:-)
>>>>> If I could make major changes I'd design ST out _forever_!
>>>> Might be the new normal. I want to design in a National video driver,
>>>> LMH6722. Has a thermal pad under its belly. In the datasheet they forgot
>>>> to mention where its s'posed to be connected to. Probably V- but I'd
>>>> rather make sure. Filed a support ticket with the new owner TI on 10/2.
>>>> Got a service request number.
>>>> Today is 10/8 and (finally! ... or so I thought) there was a message in
>>>> the inbox this morning. A form letter, merely saying that, tada, a
>>>> service request number has been issued. New number: Same as the old number.
>>>> So I responded politely as to when I might be expecting an answer. No
>>>> response all day.
>>>> Hurumph!
>>> They're either overworked or lazy, so they punted. Probably the
>>> responders are graded based on how fast they turn around responses,
>>> and on yours they already hit infinity.
>> Lo and behold, just as I wanted to order samples I finally had a "You've
>> got mail" event. TI support said the pad is not connected to anything.
>> It can be left floating (which I'd never do, of course), connected to
>> V-, or connected to GND (which I'll do).
> The ground plane is a good place to dump heat, plus some additional
> heat spreader patterns on other layers, when possible. The optimum via
> pattern to do that isn't obvious. We've had debates around that issue.
> I wish I had some software to help with that. We just sort of guess.
The challenge is always with switchers. The upper FETs of a bridge or
sync-buck are easy, I just use a V+ plane. The lower ones hang on the
switched node with their heat-carrying drain tabs. That is a real pain
because normally you don't want to make that very capacitive.
> Data sheets should state the power pad electrical connection. Often
> it's missing, or obscure.
Modern datasheets are notoriously incomplete. Even uC with their
hundreds of pages. They discuss the logic stuff ad nauseam and then, if
you are lucky, you find one or too sparsely populated pages on the ADC.
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Mon, 08 Oct 2012 21:06:21 -0700, Joerg <inva...@invalid.invalid>
> wrote:
> >John Larkin wrote:
> >> On Mon, 08 Oct 2012 18:59:46 -0700, Joerg <inva...@invalid.invalid>
> >> wrote:
> >>> Jim Thompson wrote:
> >>>> On Mon, 8 Oct 2012 20:21:35 -0400, "Martin Riddle"
> >>>> <martin_...@verizon.net> wrote:
> >>>>> "Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote
> >>>>> in messagenews:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
> >>>>>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
> >>>>>> <jlar...@highlandtechnology.com> wrote:
> >>>>>>> On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
> >>>>>>> <spamtrap1...@gmail.com> wrote:
> >>>>>>>> If someone has a free moment, I'd like to know:
> >>>>>>>> I'm on my third laptop right now. Every time I plugged my Dell's "fat
> >>>>>>>> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
> >>>>>>>> noticeable, but now I get a noticeable arc with my new HP -- not as
> >>>>>>>> big as the Dell's, however.
> >>>>>>>> I know FA about switch mode power supplies, obviously, so I wonder
> >>>>>>>> 1. What produces the arc?
> >>>>>>>> 2. Why would different power supplies produce different arcs (does it
> >>>>>>>> just depend on output power capability)?
> >>>>>>>> 3. Why is there no arc when I pull the plug from the outlet?
> >>>>>>> Dumb switching power supplies have a bridge rectifier and a big
> >>>>>>> electrolytic filter capacitor. If you plug them in near the peak of
> >>>>>>> the AC line waveform, the charging current will spark.
> >>>>>>> Better supplies, with inrush limiters, or PFC (power factor corrected)
> >>>>>>> front-ends, have much less inrush charge.
> >>>>>>> Ask Jim for details. He is *so good* at designing switching power
> >>>>>>> supplies.
> >>>>>> Indeed I am >:-)
> >>>>> I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
> >>>>> Cheers
> >>>> So does the L6561. But poorly documented and no model; and ST ignores
> >>>> my pounding on their door >:-)
> >>>> If I could make major changes I'd design ST out _forever_!
> >>> Might be the new normal. I want to design in a National video driver,
> >>> LMH6722. Has a thermal pad under its belly. In the datasheet they forgot
> >>> to mention where its s'posed to be connected to. Probably V- but I'd
> >>> rather make sure. Filed a support ticket with the new owner TI on 10/2.
> >>> Got a service request number.
> >>> Today is 10/8 and (finally! ... or so I thought) there was a message in
> >>> the inbox this morning. A form letter, merely saying that, tada, a
> >>> service request number has been issued. New number: Same as the old number.
> >>> So I responded politely as to when I might be expecting an answer. No
> >>> response all day.
> >>> Hurumph!
> >> Get one and ohm it out.
> >No kidding, that may be the only way :-(
> >Just made a CAD model for a 100-TQFP processor. Now I know why I chose
> >to become an analog guy and not a digital one.
> Do you mean a PCB decal, or an actual Autocad sort of thing?
> PADS makes IC decals really fast, for sort of standard things with
> rows of numbered pins.
> Are you doing 3D Solidworks sort of physical modeling? It is fun to
> finally spin that stuff around in space, or take a virtual walk under
> the IC pins.
we have everything modeled in inventor, pcb with components,
enclosure,
connectors etc.
so we know it will fit in the box, there's room for the connectors
etc.
John Larkin wrote:
> On Mon, 08 Oct 2012 21:06:21 -0700, Joerg <inva...@invalid.invalid>
> wrote:
>> John Larkin wrote:
>>> On Mon, 08 Oct 2012 18:59:46 -0700, Joerg <inva...@invalid.invalid>
>>> wrote:
>>>> Jim Thompson wrote:
>>>>> On Mon, 8 Oct 2012 20:21:35 -0400, "Martin Riddle"
>>>>> <martin_...@verizon.net> wrote:
>>>>>> "Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote >>>>>> in message news:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
>>>>>>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
>>>>>>> <jlar...@highlandtechnology.com> wrote:
>>>>>>>> On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
>>>>>>>> <spamtrap1...@gmail.com> wrote:
>>>>>>>>> If someone has a free moment, I'd like to know:
>>>>>>>>> I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>>>>>> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>>>>>> noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>>>>>> big as the Dell's, however.
>>>>>>>>> I know FA about switch mode power supplies, obviously, so I wonder
>>>>>>>>> 1. What produces the arc?
>>>>>>>>> 2. Why would different power supplies produce different arcs (does it
>>>>>>>>> just depend on output power capability)?
>>>>>>>>> 3. Why is there no arc when I pull the plug from the outlet?
>>>>>>>> Dumb switching power supplies have a bridge rectifier and a big
>>>>>>>> electrolytic filter capacitor. If you plug them in near the peak of
>>>>>>>> the AC line waveform, the charging current will spark.
>>>>>>>> Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>>>>>> front-ends, have much less inrush charge.
>>>>>>>> Ask Jim for details. He is *so good* at designing switching power
>>>>>>>> supplies.
>>>>>>> Indeed I am >:-)
>>>>>> I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
>>>>>> Cheers
>>>>> So does the L6561. But poorly documented and no model; and ST ignores
>>>>> my pounding on their door >:-)
>>>>> If I could make major changes I'd design ST out _forever_!
>>>> Might be the new normal. I want to design in a National video driver,
>>>> LMH6722. Has a thermal pad under its belly. In the datasheet they forgot
>>>> to mention where its s'posed to be connected to. Probably V- but I'd
>>>> rather make sure. Filed a support ticket with the new owner TI on 10/2.
>>>> Got a service request number.
>>>> Today is 10/8 and (finally! ... or so I thought) there was a message in
>>>> the inbox this morning. A form letter, merely saying that, tada, a
>>>> service request number has been issued. New number: Same as the old number.
>>>> So I responded politely as to when I might be expecting an answer. No
>>>> response all day.
>>>> Hurumph!
>>> Get one and ohm it out.
>> No kidding, that may be the only way :-(
>> Just made a CAD model for a 100-TQFP processor. Now I know why I chose
>> to become an analog guy and not a digital one.
> Do you mean a PCB decal, or an actual Autocad sort of thing?
> PADS makes IC decals really fast, for sort of standard things with
> rows of numbered pins.
> Are you doing 3D Solidworks sort of physical modeling? It is fun to
> finally spin that stuff around in space, or take a virtual walk under
> the IC pins.
No, just the schematic library part and footprint. A hundred pins, most
of which have names like this:
(OC0A/OC1C/PCINT7)PB7
One typo and all hell can break loose because the routing resources in
those uCs are sparse and can be unforgiving. Just had a major
re-shuffling in one of them on another project, not because of an error
but for a feature change. When those get maxed out in port pins the
design can slow down as much as Van Ness at rush hour, mainly because of
routing compromises.
langw...@fonz.dk wrote:
> On 9 Okt., 16:37, Joerg <inva...@invalid.invalid> wrote:
>> spamtrap1888 wrote:
>>> On Oct 8, 6:59 pm, Joerg <inva...@invalid.invalid> wrote:
>>>> Jim Thompson wrote:
>>>>> On Mon, 8 Oct 2012 20:21:35 -0400, "Martin Riddle"
>>>>> <martin_...@verizon.net> wrote:
>>>>>> "Jim Thompson" <To-Email-Use-The-Envelope-I...@On-My-Web-Site.com> wrote
>>>>>> in messagenews:5396789ln236d2okjpbcv2m1on9gmejtqn@4ax.com...
>>>>>>> On Mon, 08 Oct 2012 12:03:12 -0700, John Larkin
>>>>>>> <jlar...@highlandtechnology.com> wrote:
>>>>>>>> On Mon, 8 Oct 2012 09:52:15 -0700 (PDT), spamtrap1888
>>>>>>>> <spamtrap1...@gmail.com> wrote:
>>>>>>>>> If someone has a free moment, I'd like to know:
>>>>>>>>> I'm on my third laptop right now. Every time I plugged my Dell's "fat
>>>>>>>>> snake" into the wall, I drew quite an arc. The Lenovo's arc was not
>>>>>>>>> noticeable, but now I get a noticeable arc with my new HP -- not as
>>>>>>>>> big as the Dell's, however.
>>>>>>>>> I know FA about switch mode power supplies, obviously, so I wonder
>>>>>>>>> 1. What produces the arc?
>>>>>>>>> 2. Why would different power supplies produce different arcs (does it
>>>>>>>>> just depend on output power capability)?
>>>>>>>>> 3. Why is there no arc when I pull the plug from the outlet?
>>>>>>>> Dumb switching power supplies have a bridge rectifier and a big
>>>>>>>> electrolytic filter capacitor. If you plug them in near the peak of
>>>>>>>> the AC line waveform, the charging current will spark.
>>>>>>>> Better supplies, with inrush limiters, or PFC (power factor corrected)
>>>>>>>> front-ends, have much less inrush charge.
>>>>>>>> Ask Jim for details. He is *so good* at designing switching power
>>>>>>>> supplies.
>>>>>>> Indeed I am >:-)
>>>>>> I like the ucc28019a. works like a champ. Undervoltage lockout too ;)
>>>>>> Cheers
>>>>> So does the L6561. But poorly documented and no model; and ST ignores
>>>>> my pounding on their door >:-)
>>>>> If I could make major changes I'd design ST out _forever_!
>>>> Might be the new normal. I want to design in a National video driver,
>>>> LMH6722. Has a thermal pad under its belly. In the datasheet they forgot
>>>> to mention where its s'posed to be connected to. Probably V- but I'd
>>>> rather make sure. Filed a support ticket with the new owner TI on 10/2.
>>>> Got a service request number.
>>>> Today is 10/8 and (finally! ... or so I thought) there was a message in
>>>> the inbox this morning. A form letter, merely saying that, tada, a
>>>> service request number has been issued. New number: Same as the old number.
>>>> So I responded politely as to when I might be expecting an answer. No
>>>> response all day.
>>>> Hurumph!
>>> They're either overworked or lazy, so they punted. Probably the
>>> responders are graded based on how fast they turn around responses,
>>> and on yours they already hit infinity.
>> Lo and behold, just as I wanted to order samples I finally had a "You've
>> got mail" event. TI support said the pad is not connected to anything.
>> It can be left floating (which I'd never do, of course), connected to
>> V-, or connected to GND (which I'll do).
> I was curious so I looked at the pdf with the pcb for the evaluation
> board,
> it doesn't even have a pad on the pcb for the thermal pad
> V+ and V- goes under theat part from each end to the center pins
Yikes!
Don't know about this one but sometimes with eval boards I have the
feeling that they aren't always super great. I remember one where I
fired it up, ran it with standard load and then caught a whiff of an
"amperage smell". Followed by smoke. That was the snubber resistors
turning themselves into charcoal. Another board ... one minute, two
minutes, three ... *PHHHHUT* ... a diode had left its workplace without
prior authorization to do so. A quick calc revealed a 3x or so overload.
Luckily I found its pieces on the floor before a guide dog puppy we had
for a week.
