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LM3409: Analog + PWM dimming

Part Number: LM3409

Hello all,

Working on a constant current LED driver application where I would like to do PWM dimming (~20kHz) using EN pin as well as using IADJ to:

a) Set the current limit for different light fixtures (some want 300 mA, others 750 mA, etc.

b) Do analog dimming in some cases at the lower end to avoid low duty cycles.

Essentially, I'm looking for maximum flexibility with a single hardware design where possible.

I've built the following circuit based on the data sheet's "EN PIN PWM Dimming Application for 10 LEDs" example in 9.2.1 except with Rsns of 200 mOhm which I believe was a simple mistake on my part. What I'm seeing is that the chip seems to be always on, and I can't get it turn off the output via:

a) Grounding IADJ pin.

b) Grounding EN pin.

c) Sending various PWM duty cycles into EN doesn't make a difference either.

I'm measuring 24v input, 22.7v output, about 1.7A to an LED string.

Anything obviously wrong with the circuit or my understanding of the capabilities of the chip?