LM51561-Q1: Boost output is not working

Hi CHO SR,

Thank you for considering TI solutions. Could you clarify what is exactly the issue?  The Webench cannot create the design, or cannot simulate, or your customer has a hardware circuit which does not produce Vout?

Regarding your spec below, the LM51561 is not a suitable controller to support 48Vout at 10A, because you cannot easily find a diode that could process 10A load without excessive heatsink.  Instead, you should consider 4 phase LM5122 sync boot solution.

https://www.ti.com/tool/PMP7979 is a dual phase design for 250W, and you can expand it to a four phase design to support your 480W application.  A four phase refer design you can find at  https://www.ti.com/tool/PMP7944.

You may also consider the LM5170.  The standard LM5170EVM can support 700W: https://www.ti.com/tool/LM5170EVM-BIDIR?keyMatch=&tisearch=search-everything&usecase=partmatches.  It is a bidirectional circuit but you can just use it as a boost circuit.  You will need to remove the circuit breaker function.

Thanks,

Youhao Xi, Applications Engineering

Hi Youhao,

Two solutions were delivered to the customer.

LM51561-Q1 ISSUE

The output is 12V, as shown in the waveform.

Q1) 48V not output → Is there any problem with the circuit configuration I sent you?

Hi CHO SR,

the waveform indicate that the device detects an overcurrent condition and then tries to restart. This can be seen on Softstart waveform: Slowly increasing and then gets reset to zero and then after a short time the device starts again.

May you can try to do scope shot of the voltage over the sense resistor. The over current does trigger as soon as this voltage reaches a level of 100mV.

Are you still targeting an output current of 10A @ 48V ?

Best regards,

 Stefan

Hi Stefan,

The customer resolved the 48V output issue.

The cause is other connected circuits.

If LM51561 can operate according to the requirements, we would like to continue using it.

If you are not satisfied, please guide us on possible solutions.

Requirements:

DC-DC Converter Power Specifications:

- Max 2KW

- Continuous : 480W (10A@48V)

- Peak : 2KW@1ms