TPS40428: Questions about the TPS40428

Ohad Bonneh

Intellectual 1110 points

Part Number: TPS40428

I am using TPS40428 in a design and I have some questions.

I couldn't find anywhere in the datasheet that it's written explicitly what is the maximum current the converter can supply when operating in 2-phase mode (when using the recommended power stages).
The datasheet says the current limit default configuration is 40A but after testing it's seems like 30A.
What is the right way to make the converter work with 60A current. The maximum current limit that can be configured is 50A. I found the IOUT_CAL_GAIN that can be set higher to get a higher current limit.
Continuing the previous question, can the current limit just be cancelled? I don't need it and it's just disturbing.
Summary question- I want to work with TPS40428 in the next conditions:
a. Smart Power Mode
b. 60A output current
c. 0.85V output voltage
d. No current limit
e. I'd like not to have to configure the component digitally but only with hardware. If not possible I'd like to know the simplest way to configure it.

Note- The current design is attached.TPS40428_RAFAEL.pdf

over 2 years ago

+1 Ryan Chen over 2 years ago

TI__Genius 10427 points

Hi Ohad,

1,2) The maximum current that the TPS40428 can support with 2-phases with the recommended CSD95378B power stage is 60 A. Each of the power stages can support up to 30 A.

3) On page 17 of the datasheet, while in smart power mode/using a smart power stage, IOUT_CAL_GAIN must be set to 0.5 mOhm instead of 5 mOhms.

TPS40428 Dual Output, 2-Phase, Stackable PMBus Synchronous Buck Driverless Controller with Adaptive Voltage Scaling (AVS) Bus datasheet (Rev. A)\

4) Having current limit is important in case the output is too high and the device will shut down. It is recommended to set the overcurrent warning (OCW) to 100% of the max current (in this case 60 A) and have overcurrent protection (OCP) to be set to 120% of the maximum current (in this case 72 A) due to fluctuatiions and overshoots.

5) Smart Power Mode is the default mode of this device. Some of the components will need to be set digitally. Such as the phase set, phase configuration, protection (overvotlage/undervoltage,overcurrent).

Best,
Ryan

0 Ohad Bonneh over 2 years ago in reply to Ryan Chen

TI__Intellectual 1110 points

Hi Ryan,

Many thanks for your answer!

much appreciated.

0 Ohad Bonneh over 2 years ago in reply to Ohad Bonneh

TI__Intellectual 1110 points

Hi Ryan,

I'd like to configure the current limit and current warning as you say but it's impossible. I am configuring the TPS40428 with the "Fusion Digital Power Designer" software and the maximum current limit that can be configured is 50A. So it can't be configured to 72A as you say.

what do you suggest?

0 Ryan Chen over 2 years ago in reply to Ohad Bonneh

TI__Genius 10427 points

Hi Ohad,

Can you send an image of your GUI?

Are you having trouble setting the overcurrent warning (OCW) or overcurrent fault (OCF)?

Best,

Ryan

0 Ohad Bonneh over 2 years ago in reply to Ryan Chen

TI__Intellectual 1110 points

both problems with OCW and OCF

0 Ryan Chen over 2 years ago in reply to Ohad Bonneh

TI__Genius 10427 points

Hi Ohad,

Are you using CSD95378 power stage?

Best,

Ryan

0 Ohad Bonneh over 2 years ago in reply to Ryan Chen

TI__Intellectual 1110 points

HI Ryan,

yes, attached is the scheme.

Best regards. 7356.TPS40428_RAFAEL.pdf

0 Ryan Chen over 2 years ago in reply to Ohad Bonneh

TI__Genius 10427 points

Hi Ohad,

It looks like it the current OVW and OVF is being limited by the controller.

Best,
Ryan

0 Ohad Bonneh over 2 years ago in reply to Ryan Chen

TI__Intellectual 1110 points

So, the TPS40428 can't be programmed more then 50A?

is it just for the EVM or for the device itself?

0 Ryan Chen over 2 years ago in reply to Ohad Bonneh

TI__Genius 10427 points

Hi Ohad,
It is the device itself.
Best,

Ryan

0 Ohad Bonneh over 2 years ago in reply to Ryan Chen

TI__Intellectual 1110 points

Hi Ryan,

Understood, but is it for each rail or for total output current?

how dose it possible to have more than 50A while using multiphase?

Best regards.

+1 Ryan Chen over 2 years ago in reply to Ohad Bonneh

TI__Genius 10427 points

Hi Ohad,

This should be per rail. When the datasheet says stackable, one device can only go up to two phases. Three and four phases need two controllers, and so does the 120 A.

Best,
Ryan

0 Ohad Bonneh over 2 years ago in reply to Ryan Chen

TI__Intellectual 1110 points

Hi Ryan,

I am working with the 2 phase mode so it should be higher.

I can maximum configure it to 50A (tested) and the default is 30A (tested).

What should I do now?

0 Ryan Chen over 2 years ago in reply to Ohad Bonneh

TI__Genius 10427 points

Hi Ohad,
The controller is not able to output more than 50 A by itself. I would recommend using another controller that has a higher output capacity.
Best,
Ryan

0 Ohad Bonneh over 2 years ago in reply to Ryan Chen

TI__Intellectual 1110 points

isnt it says that it can support 60A using 2 phases?

0 Ryan Chen over 2 years ago in reply to Ohad Bonneh

TI__Genius 10427 points

Hi Ohad,

Were you able to test the configuration file and pull a load of 60 A? The OCF/OCP settings should be per phase, so in this case be able to have 60 A total output should be fine. Sorry for the confusion.

Best,

Ryan

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TPS40428: Questions about the TPS40428