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TPS61221 / Battery decreasing voltage

Kuramochi Tadahiko
Guru 28715 points
Other Parts Discussed in Thread: TPS61221

Hi, 

The problem is occurred on my customer's circuit. 

The problem is what large current flows when inserting the battery decreasing voltage.

The occurrence frequency is several percent.

I attach waveform below.

TPS61221.xlsx

I have following question.

A) What is cause of this phenomenon ? Cause which I guess is mentioned below.

B) Is there any countermeasure for this phenomenon?

C) Has this phenomenon occurred on another circuit?

[Guessed cause]

1. The TPS61221 starts to work because there is spike when inserting battery.

   And the output voltage rises.

2. Battery voltage decreases, the device stop work by EN or UVLO. 

3. Battery voltage rises little by little and the device start to work again.

4. The high side switch turns-on, and battery voltage rises steeply by reverse current.

5. Back to No.2

Best Regards,

Kuramochi

  • 0
    TI__Mastermind 46905 points
    please help to confirm the problem: Insert a alkaline battery to the TPS61221, the device fail to startup, and stay at 1.5V?
    From Battery waveform, the UVLO should trigger because the battery voltage drops down to 0.5V. it may be caused by the startup current of the device, or the load connected to the TPS61221 output.
    1. please share the schematic and PCB layout.
    2. disconnect the load of the TPS61221, check if the device startup normally.
    3. used a external power supply to power the TPS61221, check if the device startup normally.
  • 0 in reply to Jasper Li
    Guru 28715 points
    Li-san,

    Thank you for your response.

    > Insert a alkaline battery to the TPS61221, the device fail to startup, and stay at 1.5V?

    Yes, correct.

    > or the load connected to the TPS61221 output.

    The load is not connected.

    >1. please share the schematic and PCB layout.

    Could you send email to "kuramochi@fujiele.co.jp"?

    >2. disconnect the load of the TPS61221, check if the device startup normally.

    The load is not connected.

    >3. used a external power supply to power the TPS61221, check if the device startup normally.

    I request my customer.

    Best Regards,
    Kuramochi