2021-01-18 06:51 AM
Hi, as the title asks. On my STM32F767 Nucleo board, there is an Op Amp U7 (TSV631AILT) that buffers user LD1 connected to a pin (either PB0 or PA5). What is the purpose for this? I'm sure it's obvious but it's not standing out to me and there's no mention of it in the User manual aside from the electrical schematic:
2021-01-18 07:38 AM
Only reason I can see is that it lets the LED pull current from a different supply. But pulling 3mA from PB0 or PA5 shouldn't be an issue.
2021-01-18 07:54 AM
The other on-board user LEDS (LD2, LD3) are directly connected to a pin through a resistor as one would expect. Looking more in to it, PA5 is connected to the Arduino header on the dev board, so I guess if PA5 was connected to the LED rather than the default PB0 the op amp is there to prevent the LED drawing current away from the pin if the arduino output is used.