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Power Design Inquiry

Other Parts Discussed in Thread: LM5158, TPS61376, LM5155, LM5156

Hi, TI support team

The customer wants to design a power supply with the block below.

In order to operate the 7MHz HIFU Transducer using the power of the lithium polymer battery, the intermediate power must be step-up.

Since 20V/2A is finally required, we are reviewing whether to apply it in 2 steps by adding a step-up in the middle.

If designing in 1 step, is it possible to design with TPS61376 or LM5158? When looking at the Efficiendy graph of the datasheet, I am concerned that the efficiency will drop a lot or the performance will drop at 1A or 2A, so

if there is a possible item, please recommend it.

If you are designing in 2 steps, try to review the design by configuring the circuit as shown below. Please examine whether it is an appropriate circuit.

Thanks.

Regards,

MJ

  • Hello MJ,

    Please excuse the late response.

    As you do not mention the minimum input voltage of your design, I can only guess that the minimum input voltage of 3.2V of LM5158 are ok for you.

    Based on this and the given output power, the estimated peak current in the switch is 40W*1.1/(3.2V*0.9)=15.3A. With 20% estimated ripple current and 90% efficiency.

    None of the named devices has such a high current capability.

    Please have a look at LM5155 or LM5156. These are controllers which need an external power MOSFET.

    Best regards,
    Brigitte