There are another 11 LEDs in series (12 toral - set to 50mA max wire 3R9)
The LIGHTS net is direct from a 1.8V CPU, and voltage goes rail to rail (checked on scope). When we run the PWM at around 500Hz (way below the spec) , the LEDs work and it appears to function ok.
HOwever winding up PWM to 1000Hz its starts only working at the lower PWMs, going to max output at around 50%
Winding up PWM to 5KHz and abive as recommended in datasheet and the device doesn't appear to respond at all.
This trace shows the PWM when runnig at around 800Hz