NCP5901 mosfet driver problem!

[step_s]

Hi EEVblog.

I have wanted to do a project with a PIC controlled buck converter, and for this project the easiest solution is a mosfet driver.
I ordered the NPC5901, since this a synchronous mosfet buck driver, and am now testing it.
Datasheet:
http://www.onsemi.com/pub_link/Collateral/NCP5901-D.PDF

The driver works, even when connected to the gates of the 2 N channel mosfets. The high side out will turn on when the PWM goes high, and the low side out will turn on when the PWM goes low. The tri-state option works aswell, when giving the PWM a steady 2v, keeping both outputs low. (Reading datasheet might shead some light on this).

The problem occurs as soon as I connect source of the lowside mosfet to ground. When this is connected, it will no longer accept going from a PWM pulse, to the tri-state mid section.
When I try this, the driver will go into a "fault mode" of sorts, where the high side output is low, and the low side output is high. It will be stuck here until the power is disconnected. Not even pulling "Enable" pin down, will shut it off.

I'm driving it from 5.4V, and the PWM is supplied from a PIC. The driver works when everything is connected fully, and the PWM is going before the power is turned on, but again, changing the PWM input to 2v will put it into fault mode.
I noticed a cap between the SW pin and GND, in the datasheet, but connecting one seems to mess up the driver aswell.

What is going on here?

[ee_man2571]

Hello,

Were you able to solve this issue?

[Terry Bites]

See section of data sheet on power on reset.
The chip will latch off under some fault condtions.