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TPS61094: Facing issue with boost mode operation

Miteshkumar Dalabhai Patel
Intellectual 2330 points
Part Number: TPS61094

Hi..

One of my cusotmer is working on TPS61094 & facing starne issue while device operating in boost mode of operation.

Problem statement

Input voltage  = 5V

Output voltage = bypass mode when input is present

Super cap = Single Cell (2.7V)

Charging function is working ok when input is present.

When input is not present then output voltage should be 4.2V as per normal operation.

Issue:-

1). When supercap is charged above 2.0V then device  is drawing more than 2A current from super cap & output is almost a 1V. (load current is very negligible so where these 2A current is consumed?)

2). After discharging below 2.0V, device start functioning normally and able to boost the voltage to 4.2V

Can you explain why such behaviour is observed?

Mitesh

  • 0
    TI__Genius 10545 points

    Hi Mitesh,

    Please check my several questions below,

    1.In the duration of charging super caps, there is always no load in VOUT pin?

    2.What's input source(5V) type? Is it a USB port or some other power supply? 

    3.how does customer measure the 2A current which is drawing from super cap?

    4.how does customer set the ICHG VCHG, could customer provide their schematic?

    And more, it'd  better if customer could provide VSUP VOUT SW node voltage waveforms when "device  is drawing more than 2A current from super cap".

    Thanks.

    Best Regards,

    Nathan

  • 0 in reply to Nathan Ding
    TI__Intellectual 2330 points

    Nathan,

    As I mentioned while input is present device is working fine, however pls. find my inputs.

    1.In the duration of charging super caps, there is always no load in VOUT pin?

    Response - Load is present, load is MCU & display.

    2.What's input source(5V) type? Is it a USB port or some other power supply? 

    Response - Power Supply

    3.how does customer measure the 2A current which is drawing from super cap?

    Response - Using multimeter placed in series.

    4.how does customer set the ICHG VCHG, could customer provide their schematic?

    Response - Kindly find the schematic.

    We have also requested for Switching node waveform, as soon as it is available to us I will share it with you.

    MiteshSUPCAP_MANAGEMENT_2.pdf

  • 0 in reply to Miteshkumar Dalabhai Patel
    TI__Genius 10545 points

    Hi Mitesh,

    Very thanks for your sharing. 

    Miteshkumar Dalabhai Patel said:
    while input is present device is working fine

          So the problem is only appeared when input is not present, there is only a super cap to power supply output. Is this right?

    And what is the state of SUPCAP_ENA_TGR signal during the 2A drawing current appeared? Is it logic high or low?

    And more, about the waveforms, could customer please add EN waveforms? Thanks.

    Regards,

    Nathan

  • 0 in reply to Nathan Ding
    TI__Intellectual 2330 points

    Nathan,

    Kindly find attached waveforms for switching node while working in boost mode.

  • 0 in reply to Miteshkumar Dalabhai Patel
    TI__Intellectual 2330 points

    First 2 waveforms are for boost mode operation & waveforms showing burst operation is in buck mode.

  • 0 in reply to Miteshkumar Dalabhai Patel
    TI__Genius 10545 points

    Hi Mitesh,

    Could you please provide the test condition in these 3 figure? And which one is the condition that "device  is drawing more than 2A current from super cap when super cap voltage > 2.0V" ? These three results is seemed to be normal.

    Regards,

    Nathan

  • 0 in reply to Nathan Ding
    TI__Intellectual 2330 points

    Nathan,

    Waveforms shown previously are with the lower voltage with which device is working fine but whenever voltage from super cap is above 2.0V device is start drawing  > 2A of current even if there is no load at output.

    customer has shared the waveform & you can see the duty cycle is very wide for no load condition.

    Mitesh

  • 0 in reply to Miteshkumar Dalabhai Patel
    TI__Genius 10545 points

    Hi Mitesh,

    It seems the device is triggered valley current limit (about 2A), so it can't regulate VOUT to target value. And this may because there is large load current although customer said there is no load but it would be better customer could double check this. 

    And more, did customer try another chip? Did this problem appear each time? Or customer could also have a try in our EVM to see if there is a same problem.

    Thanks.

    Regards,

    Nathan

  • 0 in reply to Nathan Ding
    TI__Intellectual 2330 points

    Nathan,

    We have doubled check with customer about the load & they confirmed that there is no load connected at output & voltage at output terminal is also not as per the set voltage & still device is drawing 2A. Once supercap voltage come down below 2V, device is operating normally & that is most baffling behaviour.

    On EVM device is working fine but then why device is not working in only boost mode operation & that too above 2V input?

    Mitesh

  • 0 in reply to Miteshkumar Dalabhai Patel
    TI__Genius 10545 points

    Hi Mitesh,

    It is not a expected behavior of TPS61094, and it is no problem in our EVM so I think it may be caused by some wrong setups of customer.

    Could customer try to test TPS61094 separately, I mean that try to disconnect or remove other unrelated components of their board and test again?

    And is the chip temperature very high? If the 2A is consumed by our chip, it will cause a big temperature rise.

    Nathan

  • 0 in reply to Nathan Ding
    TI__Guru 63025 points

    Hello Mitesh,

    As we did not hear back from you, I expect the problem is solved and will now close the thread. If you have further questions, please post below or start a new thread.

    Best regards,
    Brigitte