H I need these rails
AVDD 11.6V @150mA max
VGH 22.0V @ 0.6mA max
VGL -9.0V @ 0.6mA max
I have a question though: VGL and VGH are generated by charge-pump networks from the ‘VSUP’ supply rail (11.6V in our case).
The datasheet examples typically show 1 charge-pump stage, but this won’t give much voltage headroom.
e.g. For VGH: 2x 11.6V = 23.2V, but after allowing for 2 schottky diode drops = 22.4V max (needs to be regulated at 22.0V).
e.g. For VGL: Inverted 11.6V = -11.6V, but after allowing for 2 schottky diode drops = -10.8V max (needs to be regulated at -9.0V).
I think I’ll need to use 2 charge pump stages for both VGL and VGH, to provide decent headroom for proper regulation:
For VGH: 2 stages = 3x 11.6V = 34.8V, but after allowing for 4 schottky diode drops = 33.2V max (regulated to 22.0V)
For VGL: 2 stages = -2x 11.6V = -23.2V, but after allowing for 4 schottky diode drops = -21.6V max (regulated to -9.0V)
would you agree?
