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help: pre-regulator for high-voltage power ICs

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jianjing526

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help: pre-regulator

In high-voltage power ICs, always a low voltage bandgap is necessary, so a pre-regulator is needed. Always there are two solutions:
1. resistor series with a zener diode. need a zener implantation mask
2. cascoded devices(nmos,pnps,resistors) voltage clamp, always need a high volatege current source with a start-up circuit. always consumes a lot of area!

Are there any other solutions？
Thanks in advance!
 

help: pre-regulator

Vbe (or Vt) multiplier used as a "zener".

Also, you may be able to use the reverse Vbe breakdown as a zener. While that may not be strong enough, you can sometimes use it as a reference voltage for an active zener like clamp.

Keith.
 

help: pre-regulator

In a power IC the bandgap and any cascoding is unlikely to
be significant in the end, area-wise. It's the power devices' area.
The current for a reference and housekeeping analog should
not need much device width.

Stacked MOS diodes and a resistor make a good enough shunt
regulator, a pass follower (high voltage capable) makes
a series regulator out of that. If you need fancier, then
make the thing cut over to closed loop, bandgap-referenced
when that is up. Making sure that you don't have undesirable
self-feedback going on.
 
Re: help: pre-regulator

dick_freebird said:
In a power IC the bandgap and any cascoding is unlikely to
be significant in the end, area-wise. It's the power devices' area.
The current for a reference and housekeeping analog should
not need much device width.

Stacked MOS diodes and a resistor make a good enough shunt
regulator, a pass follower (high voltage capable) makes
a series regulator out of that. If you need fancier, then
make the thing cut over to closed loop, bandgap-referenced
when that is up. Making sure that you don't have undesirable
self-feedback going on.
Click to expand...

Thanks keith and dick,
Obviously, pre-regulator is a high-voltage circuit. Compared with zener, it needs large area though it's small compared with power devices. My project is a cost-down one, i'm just trying to acquire all possible solutions to reduce the chip area no matter it's a pre-regulator or power devices. Thank you guys!
 

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