Other Parts Discussed in Thread: TPS923652
Tool/software:
Hello,
I'm having trouble getting the TPS61165 to power a 35 V 0.33 A LED.
I believe it's the boost converter reaching it's natural limit?
VIN = 12 V
CTRL = 12 V
Target current 0.323 A (= 0.2 V / 0.62 R)
I've simplified my prototype down to this:
The issue is that the driver is only outputting 0.28 A.
I started with 10 uH inductor (VLCF5020T-100M1R1-1 as per datasheet recommendation)
Increased inductance to ~19.4uH (with parts I had spare), this increased my current marginally to 0.285 A, still 15% lower than I need.
Using the SLVC366 design tool's graphs, I recorded the current with different PWM duty cycles and you can clearly see the SMPS topping out.
(Although my final design is based on analog dimming using the SLVC366 technique, I have made a simplified version to narrow down this issue. My requirements include PWM dimming at a few possible frequencies including 250 Hz, 500 Hz, 3kHz etc. so analog seems to be more sensible than digital when working with your chips to avoid putting them into the wrong mode accidentally)
If I increase my input voltage, the output current rises along with it, until it stops at 0.323 A, when VIN is ~13.8 V
If I try a lower forward voltage LED, the correct current also flows.
My next idea is to try a larger, lower resistance 22 uH inductor, but I wanted to see if this was even a suitable application for this IC?
I appreciate that while 35 V is below the 38 V recommended maximum output voltage, it's still cutting it close.
Thanks in advance
