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LM5122: Dual Phase Boost or boost-bypass

Hugo Lee
Intellectual 540 points
Part Number: LM5122
Other Parts Discussed in Thread: TPS62180, LM5175

Tool/software:

Hi,

I am looking for dual phase boost or boost-bypass for 6.4A peak output current while peak input current could be limited < 3A or lower.

My application is described as below.

*******************************
16ps of vibrator of 5V output with duration as square wave as ON 10ms/400mA, OFF 11ms/0mA, ON 10ms/400mA, OFF 11ms/0mA.....repeatdly.

16pcs vibrator turn on at the same time, thus it will take 16 * 400mA = 6.4A peak, average = 6.4A * 10ms / ( 10ms + 11ms) = ~3A

The input power source will be Power Bank with 5V Vout. So I am tring to limit input current of boost to below < 3A or lower.

*******************************

LM5122 (external FET) seems to be a good candidate, right?
However, I am looking for more effective proposal, and I have listed my ideas as below, please help advise, thank you.

1. Is there any similar part as LM5122, but it has integrated FET?

2. TPS62180 is a dual-phase buck. Is there boost (integrated FET) part like TPS62180 with dual pase with single Vout or dual Vout?

  • 0
    TI__Mastermind 26070 points

    Hello Hugo,

    Thanks for using the e2e forum.
    Can you clarify your input/output specs once more for me?

    - Input power bank 5V
    - Output: 5V, 0A - 6.4A alternating

    You need a boost controller if the output voltage is higher than the input voltage, or if the input voltage drop but the output voltage needs to stay constant.
    If input and output voltage are both constant at the same level and only the load changes, I am not sure if a boost or buck controller is even necessary here.

    Best regards,
    Niklas

  • 0
    Intellectual 540 points

    Hi Niklas,

    Input Power : it is 5V from Power Bank, thus it will drop some voltage due to cable loss ( assume 0.2 ohm )
    Output Power needs to be constant as 5V

    Only 5V output load changes with the range of 0~6.4A with the square wave duration 10ms ON/11ms OFF....

    Its open to use boost or buck-boost for any chance to reduce the input current within 3A peak.

  • 0 in reply to Hugo Lee
    TI__Mastermind 26070 points

    Hi Hugo,

    Thanks for the confirmation.
    LM5122 could be used for this application, but this device is not able to buck down the voltage. It may jump back and forth between bypass mode and boost operation, so voltage peaks/overshoots can be higher.

    To achieve a very stable output voltage, I would recommend a Buck-Boost design.
    LM5175 should be a suitable device for this.
    However, this would require four external switches in comparison to two switches with LM5122.

    Best regards,
    Niklas