I'm having an issue with what I think is a standard high-side PWM LED dimmer circuit.
It uses a P-channel FET ATP304-TL-H and gets an input voltage of anywhere from 9 V to 16 V.
The Zener diode across the gate and source is 16 V to prevent exceeding VGS(max) and the two diodes across drain-source are actually one clamp: SMBJ24CA.
The BJT has the gate and pull-down resistor internally, the emitter resistor is there in case I want to mess with the values.
The LED strip is not power hungry, it's internally limited at 30 mA.
What is happening is that at rest with no control the light is fully off. Scoping the output shows about 600 mV, about a diode drop, which I expect. When it is run however, at minimum duty cycle (1/256) the output off state is around 2 V. This causes the LEDs to stay relatively bright at their lowest dim setting. Normally I would consider the BJT is not fast enough to drain the current but the PWM frequency is only 400 Hz, so I really can't believe it can't drain whatever is in the FET residually.
Any help is appreciated I really am stumped.
simulate this circuit – Schematic created using CircuitLab