Dear *
I want to drive LED with the PG pin form TPS62170-Q1 like this:
DCDC Device: TPS62170-Q1
LED Device: TLMS1000-GS08
1) In the datasheet the are two values for PG sink current, on page 4 Power good sink current MAX 10mA, on page 8 it says that PG pin can sink 2mA of current and maintain its specific low level.
2) For my led per DS i need 2mA @ 1.8V to lid the LED => Rpull-up=(Vout-1.8V)/2mA
For Vout=3.3V => Rpull-up = 749,85Ohm if we say ( ILKG_PG = 400nA from DS page 5)
For Vout=2.9V => Rpull-up = 549,89Ohm if we say ( ILKG_PG = 400nA from DS page 5)
For Vout=2.8V => Rpull-up = 499,9Ohm if we say ( ILKG_PG = 400nA from DS page 5)
3) When the PG mosfet is ON (connected to GND) it sinks current and the LED is OFF
Sink max current in short time for Vout and Rpull-up:
Vout=3.3V, Rpull-up = 749,85Ohm => Isink=3.3V/749,85Ohm=4.4mA
Vout=2.9V, Rpull-up = 549,89Ohm => Isink=2.9V/549,89Ohm=6mA
Vout=2.8V, Rpull-up = 499,9Ohm => Isink=2.8V/499,9Ohm=6.6mA
Will this work in short time where the Vout is near to the desired output voltage the PG pin has to sink current grater than 2mA?
Best Regards.
