TPS43336-Q1 Boost Controller is unused

Hello Tateo,

I'd suggest to the customer to use the TPS43351-Q1, which is footprint-compatible with TPS43336-Q1 and comes without the boost.

Using the part with boost enabled requires some external components and can cause issues if the boost is accidentally enabled.

Best regards,

Frank

Thank you for your reply.

I suggested TPS43351-Q1 for my customer.
My customer should design 3 type of PCB board. And these PCB board should be same layout.

 Board 1. Boost + 2 Buck -> TPS43336-Q1
 Board 2. 2 Buck -> TPS43351-Q1
 Board 3. 1 Buck -> TPS43351-Q1

My customer considers to use TPS43351-Q1 one side Buck controller is unused.
If one side Buck controller is unused what is the each unused terminal processing method?

Best Regards,
tateo

Hi Tateo,
please make sure that the unused buck is disabled. Since ENA and ENB have an internal pull-up and such are enabled per default, the respective ENx needs to be pulled hard to GND.
PGNDx should also be connected to GND.
The remaining pins (FBx, CBx, Gx1, Gx2, PHx, Sx1, Sx2, COMPx, SSx, PGx) of this regulator should be left floating.
Best regards,
Frank

I'm sorry for late in my reply.
Thank you for your support.

My customer has other question about TPS43336-Q1. Could you answer this question?

- When device is external synchronization mode, how much is the boost controller switching frequency?
  Datasheet says boost switching frequency is fsw_buck/2. If device is set RT=400kHz and input 500kHz external clock, does the boost switching frequency be 250kHz?

Best Regards,
tateo

Tateo,

yes, you are correct: the Boost-frequency is ALWAYS half of the buck-frequency, independent if buck-frequency is default, set by RT-resistor or applied externally, so in your case with 500kHz external clock, it will be 250kHz.

Best regards,

Frank

Hi, We got an additional qurstion about TPS43351-Q1.
Could you help us?

- If High side PMOS control is unused, what is GC2 pin processing method?

Best Regards,
tateo

Hello Tateo,

please see design checklist in the product folder, under Technical documents:

GC2 should be left open/not connected/floating if unused.

Best regards,

Frank

Tateo,
please note, I added the link in above response, but it only shows if you log in to the forum, bot in the eMail-notification.
Best regards,
Frank