controlCARD circuit

Markus Tamas

Other Parts Discussed in Thread: ULN2003A

Hello,

I would have a question in terms of the F28M36x controlCARD circuit. I have seen that some LEDs are driven by SN74LVC2G07DBVR buffer instead of directly by the GPIOs of F28M36 microcontroller. I also want to drive some LEDs and MOSFETs, but I would just connect them directly to the GPIOs.

So my question is why the buffer is used?

Thanks in advance!

Best Regards,

Tamas

over 11 years ago

0 Gautam Iyer over 11 years ago

Guru 192875 points

Hi Tamas,

I also want to drive some LEDs and MOSFETs, but I would just connect them directly to the GPIOs.

Please don't do that , GPIO's maximum sourcing current is only 4mA. Using a buffer is a must!

Atleast use ULN2003A buffer IC if cost is an issue.

Regards,

Gautam

0 Markus Tamas over 11 years ago in reply to Gautam Iyer

Intellectual 620 points

Hi Gautam,

I know that, but in the controlCard circuit the LEDs forward current is limited at 2mA by a 680Ohm resistor. Even though the buffer is used. And I would place in my circuit 2kOhms series gate resistor to limit the gate charge current. Do you think that it is not a good idea?

Thanks,

Tamas

0 Gautam Iyer over 11 years ago in reply to Markus Tamas

Guru 192875 points

Do you think that it is not a good idea?

True true, I agree with the facts but that's not recommended, Tamas.

Regards,

Gautam

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controlCARD circuit