right Ty, but I'm having two problems: On this clock, I want the digit cross fading to work, and the HV5622 appears not to respect the BLANK pin as I expected. I'm not sure if it only reads it when the latch is toggled, and in that case I won't be able to use the PWM as I wanted to.
Maybe I'll take a break for a bit and have another look at it when I have a fresh head.
EDIT: Ooops. Typing at the same time as Ian was posting above. Guess this isn't relevant now.
Hard for me to contribute much without seeing the schematic. But I will say this: I've used plenty of 5530s but never 5622s. I have the data sheets side by side and the block diagrams are identical. So I think I'm safe thinking blanking works the same on 5622 as it does on 5530.
In my clock circuits I have /POL pin tied high. That matters because the state of /POL affects the action of /BL. I pwm /BL to control overall display brightness.For blanking I pull /BL low and the outputs turn off immediately. Clocking and latching have no effect on blanking behavior which is how it should be.
Look into it later when the dust is clearing off the crater.