>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).