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Flashing LEDs by enabling /disabling the TPS40211 is OK?

treez
Intellectual 970 points
Other Parts Discussed in Thread: TPS40211, TPS61196, LM3409HV

Hello,

I wish to do LED driver with TPS40211.

 Vin = 12V or 24V

Vout = 100V

ILED = 150Ma

Switching frequency >200KHz.

DCM Boost converter

 

I wish to be able to flash the LEDs on and off  at 25Hz (50% duty cycle).,

 I do not want any LED current or inductor current overshooting when the LEDs are  flashing back on again.

 I notice that TPS40211  has a disable pin……if the part is re-enabled, does the soft start happen again?...or does soft start only happen at initial application of input power?

 Also,  when re-enabled, how long does the chip take to start-up again,? Is it a long time.

 Also, is it OK to flash the LEDs on and off by repeatedly enabling/disabling the TPS40211?

 

  • 0
    TI__Mastermind 25786 points

    well, EN doesn't acts like a PWM/DIMM function...

    it is even true that because the very low freuqency, the SS time could be neglected (since the overall effect would be "averaged")

    if you need a real dimming feature then you could have a look at the TPS61196 (still in preview) at the link http://www.ti.com/product/tps61196

    another possibility would be to use an external fet for dimming the current into the led (have a look at EVM of LM3409HV, for details)

    Vincenzo