Part Number:TPS5420
I am using an open drain mosfet to control en (pin 5) on controller. Sometimes the chip doesn't start - no output. The mosfet I am using is a ROHM SM6K2. It is maximum leakage of 1uA at 60v. I am turning him off with another SM6K2 pulled to ground.
I have 4 of these supply circuits and only 2 are giving me a problem. The good units measure (enable pin) about 5v to ground, while the units with no output hang round 1.3v.
I am thinking to put a pull-up to the input voltage to try and help the enable pin go high. Maybe a MEG ohm resistor to the 28V supply.
Any thoughts this?