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LMZ21701: +5V/-5V using LMZ21701

Murat_
Prodigy 150 points
Part Number: LMZ21701

Dear all,

I need a converter from +5V to -5V and 0.3A output current. I want to use LMZ21701 which is already used in our design as a buck converter. 

But in my application I will use it as negative buck boost.  In some application notes I have seen that it is possible to use synchronous buck converters to generate negative output by connecting the output voltage to ground and ground terminal of the device to negative output. But in LMZ21701 datasheet I haven't seen anything about negative buck boost operation.

My question is that is it possible to use it as negative output buck boost ? Is there something important to take into consideration when we use it as buck boost?

  • 0
    TI__Mastermind 47060 points

    Hi Murat,

    There is nothing gating the LMZ21701 from being modified into an inverting buck boost(IBB) configuration. As you might have read already, in order to generate a negative output the output voltage must be connected to ground and the ground terminal will now be the negative output and IC return path. 

    Something to keep in mind is that a ceramic bypass capacitor and schottky diode are two additional external components that is recommended for the IBB configuration. The input voltage range and output current will be lower than the LMZ21701's original operating specs. If you need to use the EN and PG pins, a level-shifter circuitry must also be taken into consideration. 

    Regards,

    Jimmy Hua