Another question:
I notice the LEDs for the high-current MOSFETS are driven by +5V instead of +V_POWER, and I'm wondering why.
Typcical LEDs have very low reverse voltage ratings (it's 5V for the OSRAM LH R974-LP-1 pulled up by the DigiKey part number in the BOM), and typically don't include specifications for zener or avalanch mode. If +V_POWER is 24V, that puts 19V of reverse bias across the LED, well outside it's specs. Even at 12V the LED is seeing 7V reverse bias...outside it's specification, but not as likely to cause damage as the 19V probably would. I've seen LEDs that begin to conduct under reverse voltages of 7V or less, so this seems marginal even when running on 12V.
Am I missing something that makes this OK?
I notice the LEDs for the high-current MOSFETS are driven by +5V instead of +V_POWER, and I'm wondering why.
Typcical LEDs have very low reverse voltage ratings (it's 5V for the OSRAM LH R974-LP-1 pulled up by the DigiKey part number in the BOM), and typically don't include specifications for zener or avalanch mode. If +V_POWER is 24V, that puts 19V of reverse bias across the LED, well outside it's specs. Even at 12V the LED is seeing 7V reverse bias...outside it's specification, but not as likely to cause damage as the 19V probably would. I've seen LEDs that begin to conduct under reverse voltages of 7V or less, so this seems marginal even when running on 12V.
Am I missing something that makes this OK?