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LM27761: 5V input and -5V output

Aditya Teja Damera1
Prodigy 120 points
Part Number: LM27761
Other Parts Discussed in Thread: TPS63700, TPS6735

Hi,

Can we generate precise -5V output from 5V input in LM27761?, As I am getting only -4.85V instead of -5V when Vin=5V. Please suggest how to generate -5V from Vin=5V.

Thanks,

Aditya Teja

  • 0
    TI__Expert 3645 points

    Hello,

    please consider the attached values in the electrical characteristics of the d/s. You should increase your Vin to obtain Vout= -5V.

  • 0
    Guru 284060 points

    The charge pump has an equivalent resistance of about 2 Ω (specified as RNEG; you can measure this at the CPOUT pin), and the LDO adds its own voltage drop (VDO).

    To get exactly −5 V even with a load, you need a DC/DC converter like the TPS6735. If you need an LDO, you have to use an adjustable inverter like the TPS63700 to get a lower voltage and then add a separate LDO.