TPS56637: Suitability as a peltier driver?

Hi

   The TPS56637 has a reverse current limit of -2.3Amin which will allow you to sink current in FCCM mode. If you are looking for Buck Boost converters, have you looked at the TPS55288?

https://www.ti.com/product/TPS55288

regards,

Gerold

Hi Gerold

My supply voltage will be much higher than required voltage output of the driver, so buck generally makes more sense. The TPS55288 does look like an impressive converter though.

A buck-boost would work if it were on one side of the load and a fixed voltage supply on the other, but both would have to both source and sink current as the boost-buck went above and below the voltage on the other supply. I'm not sure of a way to do that as yet.

Thanks

Lucas

Hi Lucas,

You have mentioned that the spec for your application is 6A, 8.6V output. So is the bidirectional power which you need are same? For TPS56637, it can't sink 6A reversed current from output side due to the reversed current limit.

In addition, I'm afraid that I didn't get your meaning for the application. For the buck converter like TPS56637, it has ability for the bidirectional power transmission. But it can't consume the reversed power, which means that you need to use a power source with sink ability at input side. And the reversed power transmission normally happens when a source with higher voltage than Vout is forced on the output side of buck. (Or sometimes output voltage is higher than set Vout in load transient dynamic state.) It can't be triggered by adjusting the input voltage. I don't know if that accords with your demands for the application. 

Regards,

Andrew

Andrew Xiong said:

You have mentioned that the spec for your application is 6A, 8.6V output. So is the bidirectional power which you need are same? For TPS56637, it can't sink 6A reversed current from output side due to the reversed current limit.

In addition, I'm afraid that I didn't get your meaning for the application. For the buck converter like TPS56637, it has ability for the bidirectional power transmission. But it can't consume the reversed power, which means that you need to use a power source with sink ability at input side. And the reversed power transmission normally happens when a source with higher voltage than Vout is forced on the output side of buck. (Or sometimes output voltage is higher than set Vout in load transient dynamic state.) It can't be triggered by adjusting the input voltage. I don't know if that accords with your demands for the application. 

Right. The previous prototype had two buck converters and two FETs, one on each side of the load. GPIO enabled a buck converter and the FET on the opposite side of the load, enabling a ground path. PWM controlled the output voltage of the buck. Not good as far as parts count, but it worked.

Fundamentally, I'd like to find a buck converter that can supply at least 6A (maybe a bit more to allow for some margin), but isn't so "smart" as to have problems when I'm steering the feedback voltage with PWM. If I can't manage 6 or 8 Amps with a buck converter with integrated switching, then the next step would be a controller that drove external transistors, but I'm not 100% sure if they could be driven to 0V output (important in this application).