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TPS54331: Not getting 3.3v output using 4.2v full charged li ion battery

Visakh VL
Prodigy 10 points
Part Number: TPS54331

Tool/software:

we are trying to get 3.3v output from a 3.6-4.2v lithium ion battery using TPS54331 dc-dc converter. the circuit is working fine with input voltage greater than 7v. Is there any modification has to be made for working with single cell lithium ion battery.

  • 0
    TI__Mastermind 22006 points

    Hi Visakh

    What's the Vin range you expect the circuit to operate at?

    Please configure R34 and R37 refer to Section 7.3.4 in TPS54331 datasheet. The circuit enable when VEN> threshold voltage of 1.25V.

    Thanks and best regards.

  • 0 in reply to Gui He
    Prodigy 10 points

    thanks for you reply.

    What's the Vin range you expect the circuit to operate at?

         Vin range : with smps 12v

         Vin range: without smps , 3.7v to 4.2v from a li ion battery.

    I tried by changing the input resisters also.That time the voltage at the EN pin was 1.37v and still the output voltage fluctuates between 1.2v to 1.9 v. After that i had left the EN pin floating, then also the same thing happens.

    what is the minimum input voltage that requires to get a 3.3v output from TPS54331.

  • 0 in reply to Visakh VL
    TI__Mastermind 22006 points

    Hi Visakh

    I tried by changing the input resisters also.That time the voltage at the EN pin was 1.37v and still the output voltage fluctuates between 1.2v to 1.9 v. After that i had left the EN pin floating, then also the same thing happens.

    ---What's the Vin voltage? Can you please share waveform of SW and Vo? can you share the layout image also?

    Thank you

  • 0 in reply to Gui He
    TI__Mastermind 22006 points

    Hi Visakh

    I will close this thread for now since no response. Please let me know if there are other questions.

    Thank you