TPS61289: 2V input to 10-15V Boosted output that will support 48W

Additionally the minimum turn on voltage for the input seems to be around 4.6V and it would be great to lower that down to around 2V as well.

Hi Haiden,

Thank you for reaching out.

The EVM is for BTS test and if you'd like to do pure boost test, some parts need to be modified.

1. for the efficiency test, it is like below:

Power up VHIGH to 15V. yes, 15V for VHIGH is a bi-direction power for the device.(OR using power supply paralleled with a load)

Power up VLOW to 2V.

EN pulled high. MODE choose to be LOW(Boost MODE)

give the current reference to be 8A.

Then test the input/output voltage/current of the converter to get its efficiency.

2. As it said before, the vout set point is not 15V, it will be 18V.

The set point is higher than VHIGH power supply to ensure comp source current.

3. If you only supply the input voltage, the start voltage will be VHIGH UVLO point, 3.4V+ 0.7V(body diode voltage)

As a result,

The EVM cannot support pure boost mode.

Please tell me your application and I can recommend other suitable device for you or modify the TPS61289 circuit for you.

Best Regards,

Fergus

I cannot share specifics about the application but in a general explanation, we are looking to take a 2V output of a circuit and boost it up to the highest voltage possible while maintaining an efficiency above 85%. This boost will also have to support up to 40W or be capable of external synchronization for putting it in parallel with a second boost. Thank you.

I get a rough picture of your application.

Here is the conclusion:

1. 2V to highest with max 40W

2. eff about 85%

3.capable of external sync

The most difficult one is the 2V requirement.

Do you need the device start at 2V or just start at a higher voltage than still keep working at 2V?
if 2V start is needed, we need to consider connecting an external voltage to device's Vin pin to disable its UVLO function and just enable device with EN pin.

Please see below:

slvaf89-Using External Bias to Broaden the Input Voltage Range.pdf

Please feel free to comment.

Best Regards,

Fergus

The input of the boost circuit can run up to 4V at startup but it is crucial that it can maintain operation indefinitely at a 2V input after initial startup.

Hi Haiden,

Please see if LM5155 is the device you are looking for.

LM5155x 2.2-MHz Wide Input Nonsynchronous Boost, SEPIC, Flyback Controller datasheet (Rev. E) (ti.com)

The Bias pin can connected to Vout to ensure working at 2V input.

I will forward this thread to LM5155's expert for more information if you are interested.

Best Regards,

Fergus

I believe with an asynchronous design as shown above we would see significant power loss through the shottcky  diode on the output. I believe I would be looking for a synchronous boost controller with both switching FETs external.