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TPS92410 fast turn-off

Other Parts Discussed in Thread: TPS92410EVM-001, TPS92410

I'm working with the TPS92410EVM-001, and have the ADIM pin/test point connected to a GPIO on my micro.  I need to turn on/off the LEDs very fast (30-60-Hz) but have noticed that they are very slow to turn-off.  The decay time for the light is nearly 1 second, after ADIM goes to GND, which is not compatible with my application. 

Would removing C10 help? 

Any other ideas to get a faster LED off time? 

  • Hello,

    C10 is not the issue, it's C3, C4 and C13. They are there to filter the 120 Hz ripple from the AC line to give low percent flicker or flicker index. By PWMing the ADIM the MOSFET is turning on and off but those electrolytic capacitors keep the current flowing to the LEDs. The TPS92410 and TPS92411s operate independent of each other. Pulling ADIM low would be the same as turning off the power to the lamp, the light decay would look the same. You can reduce those values to much lower values but have to watch for multiple switching issues meaning the hysteresis for the TPS92411s may need to increase.