Hi,
I am designing a low voltage high current traction inverter (72V, 150A) switching at 20kHz using UCC21755-Q1 driver ICs. I am planning to use bootstrap circuitry for all the top switches and split the bootstrap voltage thereafter using back to back zener connection and coupling capacitors as shown in one of the Ti documents. Can you please verify the schematic (1-leg drivre circuit of the inverter) I attach below for the correct operation.
Hi Shishir,
Please see my comments below:
1. 10k pullup for FLT & RDY is required. Tying the LS and HS signal together would make it hard to isolate which part has the FLT.
2. HS AIN when should not be floating should be tied to GND.
3. Gate pull down resistor and capacitor should be placed as shown in the
UCC21750_Schematic_Layout Recommendation(1).pdf
The bootstrap circuit looks fine to me. You can also refer to the post below for more details on bootstrap circuitry:
Best,
Pratik
Hi Shishir,
The implementation doesn't seem to be creating a negative bias but rather looks like clamps the gate voltage. Please refer to the circuit below for generating negative bias with bootstrap circuitry:
Page (31-33) of the datasheet below:
UCC21551x-Q1 Automotive 4-A, 6-A, Reinforced Isolation Dual-Channel Gate Driver datasheet (Rev. D)
You can also refer to the below e2e post for more details on its implementation:
Hope this helps.
Best,
Pratik
