I'm considering using a tps61165 led driver for an LCD backlight. While I know it is far from recommended, I quickly breadboarded the typical application circuit using TH components that match the recommended SMD parts as much as possible, and used a SOT to DIP adapter for the IC.
In my case I have to go from 5V to 12.8V @ 40mA. (2x4 LEDs). For some reason the circuit works fine when I take out the C4 4.7uF input cap. When I do use it, I only get a really low output current, barely enough to light up the LEDs.
Why could this be the case?
-- edit --
- C4 is on the far right in this picture where I put it.
- R4 and R5 are not in this picture.
- R1 is 2x10R
- L1 is a Bourns RLB0712-100K
- D1 is an 1N5817
While I was editting the post to add the breakout picture, I noticed something new: When I enable power without C4 present, it will start up and light the LEDs at the desired power. Then I can add C4 while it is running and it will keep running and light the LEDs even brighter. But when I power up the circuit with C4 already there, it will get stuck in a low power output.
The location of adding C4 (after the circuit is running) also seems to matter. When I put it far away from the IC, it will increase brightness, but when I add it close to the IC when the system runs, it will shut down the cicruit.
Also when I power up the circuit with C4 present, I will get a weak constant output current when C4 is far away from the IC, but I'll only get a short blink once when I put it as close to the IC as the breadboard permits.