TPS54A20: SCAP and AB phase drivers.

gomi.ryota

Prodigy 140 points

Part Number: TPS54A20

Hello TI Expert,

I have a question about SCAP and AB phase drivers.

1. I would like to know how the SCAP charges 1/2 of Vin.

2. Do you agree that VGA and VG open the gate at 5V? Is it correct that VGA requires 5+VSCAP?

3. Is it okay to supply 5.3V to VG?

4. When supplying Vin, VG, EN, and SYNC externally, is the order Vin → EN → VG → SYNC correct?

best regards.

over 1 year ago

+1 Tahar Allag over 1 year ago

TI__Mastermind 29440 points

Hello,

It is a two series cap with VIN on one side the two caps in series. In steady state, the duty cycle is should be half. the voltage across both the inductor is equal. The voltage across La is LdIla/dt=Dvin-Dvt-Vo. and the voltate Lb is Ldilb/dt= Dvct-vo. this should give you the Vc voltage

https://www.ti.com/lit/an/slva750a/slva750a.pdf?ts=1686167949923
High side phase A gate driver supply pin that is 10V
5.0V is recommended to override the internal 4.8V LDO
yes, that is correct sequence

thanks

Tahar

0 gomi.ryota over 1 year ago in reply to Tahar Allag

Prodigy 140 points

Hello TI Expert,

4.　I think VG and SYNC are sequence free, but is it okay to apply voltage to VG and SYNC before Vin?

best regards.

0 Tahar Allag over 1 year ago in reply to gomi.ryota

TI__Mastermind 29440 points

Hello gomi.ryota,

Just make sure the SYNC is provided with the right voltage levels and within the expected range within ±10% of the nominal frequency set via SS/FSEL.

Thanks

Tahar

0 gomi.ryota over 1 year ago in reply to Tahar Allag

Prodigy 140 points

It's not about the SYNC frequency, it's about the timing sequence. In order, is it possible to supply SYNC and VG before EN and Vin? In other words, if I supply 5V externally to VG first, and then to Vin and EN, will it work properly?

+1 Tahar Allag over 1 year ago in reply to gomi.ryota

TI__Mastermind 29440 points

Hello,

Yes, but the SYNC has to be within the spec, you can just connect any voltage to SYN an expect the device to start up.

thanks!

Tahar

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TPS54A20: SCAP and AB phase drivers.