Liu's RIOT expansion gadgets 4 in 1 Kit -LED current draw?

[Kande Laber]

Hello,

Question regarding RIOT expansion gadgets 4 in 1 Kit:

How much current draws an individual LED of the "simple I/O gadget" when on?

Best regards

[Ronny Ribeiro]

The LEDs in the gadget are connected directly (?) to the output of the RIOT chip. The chip is able to source around 2 mA of current and sink around 3 mA. Providing the chip is sourcing current for the LEDs, the current should be around 2 mA.

Ronny

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[Kande Laber]

" ... the current should be around 2 mA."

Yes, but what would happen if the real value would be more than that?

This could eventually drastically shorten the life expectancy of the RIOT.

This I would like to avoid given the sparcity of these chips.

Therefore I would like to have a value based measurement or supplier specification.
I could measure it my own, but I do not want to reinvent the whhel if it is not necessary.

[Ronny Ribeiro]

Go check the datasheet. I remembered this values from there

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[Kande Laber]

Go check the datasheet".

Data sheet of which component? 

"

[Ronny Ribeiro]

The RIOT chip: MOS6532, UM6532...

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[Kande Laber]

OK, this shows e.g.

Output High Current (Sourcing);
...
~ 1.5V Available for direct transistor drive (PB0-PB7)

Min. 3.0 mA, Typ. 5.0 mA

But what would happen if the circuit exceeds this current (for whatever reason).

Is there a chip protection? Or would the chip just somehow burn out?

[Ronny Ribeiro]

If you exceed that current, the output voltage is going to drop so to keep the dissipated power at bay. These IO adapters are fairly robust. If you short their outputs for a while they're gonna get through it.
But as you said, excessive current draw may shorten their life.

Liu did connect the LEDs directly to the output and I've used it a lot with my RIOT and it's there strong, pumping out electrons.

But indeed I've made a LED board for the RIOT using a network resistor of 2K2 ohms, which limits the output current to 1.3 mA maximum.

To view this discussion visit https://groups.google.com/d/msgid/pal6502/37846779-8365-41d3-983a-545f906812a5n%40googlegroups.com.

[Kande Laber]

Thanks.

Nice LED board design. Congrats! I have one of these LED light bar units in my drawer, but with 10 LEDs.
Where did you get it with 8 LEDs each?

[Ronny Ribeiro]

Thanks :)
You can find them at AliExpress.

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[Kande Laber]

Yesterday, I soldered and added Liu's I/O unit (see picture).
Everything works OK: Including the beeper, wich I tested with the clock from the "First Book of KIM-1".

What I stll would like to know are the exact specifications of the LED that are used in this kit.

@Liu: Do you have a datasheet of these LEDs? Or the exact type of LED that is shipped in your kit?

Best regards

"

[GN Liu]

There are two types of LEDs used on the simple I/O board, and the model supplied may vary between different batches.
Here are the datasheets:

https://en.everlight.com/wp-content/plugins/ItemRelationship/product_files/pdf/313-2SURD-S530-A3.pdf 

or

https://en.everlight.com/wp-content/plugins/ItemRelationship/product_files/pdf/333-2SURD-S530-A3.pdf

[Kande Laber]

Thank you very much, Liu.

That is very useful. When I look at the LEDs that are in the kit that was delivered to me, I see the typical collar at the bottom of the LED body (see attached picture). I conclude that I received the type 333-2SURD/S530-A3 in my kit.

I don't see that collar on the picture of type 313-2SURD/S530-A3 in the data sheet.

Is my reasoning correct?

With best regards

[Kande Laber]

Hello,

According to Liu's information, I assume that my I/O gadget works with the 333-2SURD/S530-A3  LED type.

I have measured voltage and current of the LED in on state:

Voltage: 1.905 V

Current: 7.16 mA (see attached picture).

This is more or less what the "Forward Current vs. Forward Voltage" curve in the data sheet (" https://en.everlight.com/wp-content/plugins/ItemRelationship/product_files/pdf/333-2SURD-S530-A3.pdf") states.

According to the UM6532 data sheet ("https://datasheet4u.com/pdf-down/U/M/6/UM6532_UMC.pdf") the typical current for the port B would be 5 mA.
With 7.16 mA the measured LED current draw of my I/O gadget  is 43% above the typical current according to the data sheet.

Any comments are welcome.

Best regards