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TPS61197: Can't work on Boost mode for 12Vin to 18V/400mA

Eric Chen4
Expert 2370 points
Part Number: TPS61197
Other Parts Discussed in Thread: TPS61107

Hi,

Now we test TPS61107 PCB and find can't boost to 18V output then also can't find Switching wavefrom.

May we have your suggestion to check which pin voltage and schematic is below for your check again.

Inquiry is below.

1. Vin 12V

2. Vo 18V/400mA

Measure Result:

Pin1 UVLO is 2V

Pin2 EN is 3V

Pin3 PWM 10KHz signal

Pin5 REF is 0V 

Pin6 Comp is 0V

Pin7 IFB is 0V

Pin8 IDRV is 0V

Pin9 ISNS is 0V

Pin10 OVP is 1.8V

Pin12 GDRV is 0V

Pin13 VDD is 6.4V

Pin14 FSW is 1.8V

Pin15 Fault is 0V

Pin16 VIN is 12V

NMOS use 60V/10A

Regards,

Eric

  • 0
    TI__Prodigy 600 points
    This Thread was assigned, Someone will respond in an short period of time. We appreciate your inquiry .
  • 0
    TI__Expert 4550 points
    Please check R18 and R19, they decide the startup voltage of the device. As for your setting now, the start voltage is 20V, but your input voltage is only 12V, that doesn't make sense. the start voltage should be lower than min input voltage.
  • 0 in reply to Caryss Li
    Expert 2370 points

    Hi Caryss,

    Yes, I already change R18/ R19 and UVLO is 2V on 3/2 E2E Report.

    So should be start up from 12V input and if have another voltage setting define wrong,

    Please kindly provide your suggestion for our check again.

    Thanks.

    Regards,

    Eric

  • 0 in reply to Eric Chen4
    TI__Expert 4550 points
    A few things could be checked:
    1. the input capacitor maybe too small, there is possible the input voltage is pulled lower than UVLO then the device could not start. please try to add an electrolytic capacitor such as 100uF and see if the input voltage is too low.
    2. please add a small resistor from GDRV pin to gate of MOSFET, this is to limit peak current during mosfet on/off
    3. please short output LC filter inductor L2, the LC filter may have impact of output voltage sensing.
    Another suggestion is please keep PWM always high, don't dim during debug.