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using TPS61165 >700mA

Other Parts Discussed in Thread: TPS61165, TPS61165EVM-283


I have recently brought a TPS61165EVM-283 kit to evaluate the TPS61165 chip for a product I am developing.

I am a little unclear as to what the maximum LED current this device will drive. I am aware that it is dependent on many variables including Vin, Vout, Inductor values, etc.

Using this kit and the components loaded on-board I can not seem to drive my LED's much above 450mA.

I have changed the Feedback resistor from 0.56R down to 0.28R ( 2x0.56R in parallel ) which should give me a theoretical drive output of ~700mA

I have tried increasing the output capacitance by adding a 4.7uF tant to C4 but this didn't seem to help.

My current specs are as follows

Power supply 5V 3A bench regulated power supply ( only drawing about 1.0A )

Vout for LEDS, 9V and 12V ( 2 different types )

CTRL is tied to Vin so no PWM control, all other components are stock.

I was wondering should I change the inductor value or the schottky diode as it only has a continuous forward current rating of 0.5A

I was just wondering if anyone has used these chips to drive a 700mA output before.. I think the specs say it can switch upto 1.2A but all the graphs and ratings only seem to go to 350mA

Any design advise would be greatly appreciated.

Kind regards


  • Hello Adam,

    A number of the specs for the EVM that you are using are contained here in the EVM guide:

    The guide suggests that the max current it can handle is about 368mA and looking at the datasheet for various devices in the power path of the EVM such as the inductor and the Schotky diode they would have difficulty operating or would be damaged operating at those higher current levels. While you could change these parts to higher current version of themselves there are inherent limits in the TPS61165 itself.

    The internal switch has a current limit of 1.2A which should not be approached in operation since switching transients typically cause the switch current to spike above the desired load current which would damage this switch.

    Also looking at your input voltage of 5 volts and comparing that to the plots seen on Pg. 6 of the datasheet seen below if they are extrapolated out assuming that the decreasing efficiency slope increases at 700mA and greater you would be looking at around 50% efficiency or worse.

    I would recommend looking at one of our different LED drives that has is characterized for the output current you are hoping to have. This means that TI has tested the device at that load and determined that operating at that level it can be expected to have a normal operational life.