TPS61185: Reducing Power Consumption

hello Jejomar

        It is possible to lower power consumption by sequencing the LEDs, how will you sequence the LEDs, by shunt dimming?

Hello Mason,

Thank you for your response. I would like to ask for your advise on how to use TPS61185 in sequencing the outputs to lower power consumption but still keeping the LEDs' brightness the same. I'm quite not sure what shunt dimming is. Can you give us more information about or any design guideline or app note that might help for this?


Kind Regards,

Jejomar

hello Jejomar

       shunt dimming is to add a shunt FET in parallel with the LED, and can bypass the LED according to the sequencing timing. So shunt dimming requires extra shunt FETs and I double check the TPS61185, it adopts PWM dimming by turning on/off current sinks, so it is not suitable to use shunt dimming here.   

Hello Mason,

Thanks for the clarification. If shunt dimming won't be possible with TPS61185 can you advise some other procedures or implementations with the device that we can use for sequencing and to achieve lower power consumption?


Kind Regards,

Jejomar

hello Jejomar

        Sorry for the late reply. Can I ask about the background for this? right now we have limit shunt dimming backlight products and there is no suitable choice for this.

Hello Mason,

No worries. I completely understand the delay. What our customer is trying to achieve is to have a lower power consumption but still keeping the brightness to LEDs the same. I understand if the shunt dimming won't be suitable for TPS61185. But can you advise on some other LED sequencing procedures that can be considered to achieve lower power consumption?


Kind Regards,

Jejomar

Hello Mason,

A gentle follow-up on this please? Thank you!


Kind Regards,

Jejomar

hello Jejomar

        Just want to confirm: the concern of customer is the power loss of LED at 25mA.

        For LED sequencing, the overall brightness of this should be less than that with all eight LEDs working all the time. Decreasing power loss by this, I am wondering if it can meet the requirement "still keeping the brightness to LEDs the same".

      Should it be an option to just simply find LEDs with smaller forward voltage.