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TPS92692: LED ON/OFF control

T Kishi
Genius 4425 points
Part Number: TPS92692

Hi

My customer as question.
The customer wishes to control lighting on / off in TPS92692.
Also, the control signal is assumed to be PWM.
Is it possible to turn off the LED with TPS92692 so that the FLT terminal does not fall to Low?

Best Regard

T Kishi

  • 0
    TI__Mastermind 18890 points
    Kishi-San,

    The proper way to enable and disable the TPS92692 is to pull down the Soft-Start pin (pin5) with an open collector or drain transistor. This way, when the TPS92692 is enable it goes thru the normal soft-start cycle and will not get an over-current condition and Fault trigger. This is in the data sheet on the last sentence in Section 8.1 page 13 (Overview).

    If you use the PWM as an enable and disable pin then when PWM is low (disable) for a long time the output caps will droop in voltage and can totally dis-charge. Then when PWM goes high there is no soft-start and it will re-quire on the compensation to limit the PWM duty cycle and you can get an over current condition to trigger a Fault.

    Thanks Tuan
  • 0 in reply to Tuan Tran74
    Genius 4425 points
    Hi Tuan

    Thank you for reply.
    Please tell me one more.

    Will the FLT also go low when the PWM pin = low?
    If the PWM terminal is set to Low, I think that the switch will stop.
    In this state, the output voltage drops, I think that FLT goes low because "VOV <100 mV" and "VIMON> VIADJ".
    Is my recognition correct?

    Regard
    T Kishi
  • 0 in reply to T Kishi
    TI__Mastermind 18890 points
    Hi Kishi,

    When you put PWM pin to low...We suspend switching and monitoring circuit for ouput so FLT will not automatically go Low.

    Thnaks Tuan