<Question> How to use FET driver TC4420 with over 20v+ supply ?

Hi everyone.

I need help about TC4420. As datasheet, they just carry 18-20v supply input. But im in buck converter project so i need them to work with 24v or 36v power. I know a diode zener is one of method but where will it wire to ? at VCC of TC4420 or at logic input ? .

TC4420 drive APM4015 PFET. Thank very much friends.

Choose a different driver. 20V is the absolute maximum according to the datasheet.

Thank for reply Sir. But if i connect VDD of TC4220 with a voltage divider ? what will come ? ( example: i have max input at 24v. So, give a voltage divider by 20ohm and 100ohm resistor => we have 20v , then if i give it 12vinput (minimal ) ==> we have 10v.) With 10v from 12v input by voltage divider, i think its enough to turn on TC4420 internal block and MOSFET gate.

Another, how if i connect VDD to a diode zener rated at 18v ???

  1. Do not attempt to power any device from a voltage divider.

  2. If the MOSFET driver is powered from 10V then it will not be able to drive a MOSFET powered from any higher voltage.

Select a different chip for your application. Follow the suggested circuit in the datasheet.

nhannguyen310:
Hi everyone.

I need help about TC4420. As datasheet, they just carry 18-20v supply input. But im in buck converter project so i need them to work with 24v or 36v power. I know a diode zener is one of method but where will it wire to ? at VCC of TC4420 or at logic input ? .

TC4420 drive APM4015 PFET. Thank very much friends.

You need to post a diagram of your converter topology - it may be you need a high side driver, not a low-side one like the MIC442x family

Sorry for very late reply on your help. Im still get stuck on this and near crazy level about fet driving.

For schematic, i doing prototype on 2 separate.

One is test Poorman’s Buck from Ledartist (instructable, link: https://www.instructables.com/id/Poormans-Buck/).

And one is based on HV9910B led driver.

I need mosfet driver because in my country, to find out exactly needed mosfet is very challenging especially logic level fet. So its better do somthing with fet driver and normal fet like IRF5xx series.

On Poormans Buck, i had change a little on original circuit to handle over 3A. And i found that with push pull gate driver (i use B772 and D882 transistor pair), i recieve ahalf voltage from power rail on mosfet gate. I dont know how or why but i know my mosfet reach 130*C. Bad situation.

On HV9910, the datasheet said i can directly drive a normal fet and just take care on Qgate (25nC for <100kHz, 15nC for over 100kHz). But gate voltage of HV9910 just have 7.5v (equal VDD pin, internal voltage regulator). What happen if a IRF 530 or 540 or everything like them will be drived at that voltage? I think they not fully turn on to out of ohmic region.

Thank all very much. Im keep coninue find my way to use mosfet, thank thank thank… T_T