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LM5150-Q1: 7v BOOST design

user503335153
Intellectual 810 points
Part Number: LM5150-Q1
Other Parts Discussed in Thread: LM3478, TPS61222, TPS61088

A boost design ,Vin=1.5V ,Vout =7V,and Iout=1A,  Can  lm5150-Q1 use in this design? I have design the SCH with WEBENCH, but Vin is required 5V,Why?  Can you recommend a right design for me ?

  • 0
    TI__Guru 68495 points
    Not really. The LM5150 is specially designed for start-stop and e-call applications, it should not be used as a regular boost controller.

    Yes, it requires 5V at the boost output, so the input should be 5.7V if your diode drop is 0.7V.

    Current there is no device can directly support 7V@1A load from 1.5Vin. You can consider a two chip solution, one small boost converter like TPS61222 to produce 5V from the 1.5V input and feed the VIN pin of the LM3478, so it has enough bias supply to drive the MOSFET, and use the LM3478 to implement the boost to boost from 1.5V to 7V. Note that in this case the 1.5V input should not be connected to the LM3478 VIN pin.
  • 0 in reply to Youhao Xi
    Intellectual 810 points
    There is aDC/DC on my PCB,who provide 3.3V/30mA for MCU(<10mA), Can I use it as a start power supply for main DCDC(TPS61088) for 7v@1A solution？
  • 0 in reply to user503335153
    TI__Guru 68495 points
    Maybe not, because the LM5150 requires VOUT to be at least 5V to start up. Your 3.3V is not enough to let the LM5150 to start. Also, the TPS61088 can directly start up with 3.3V.