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LED Driver ICs Forum Discussions

Moderator 10 replies posted 5 replies posted 10 questions asked
The LED voltage is limited by the pins FBH and FBL (absolute maximum rating is 61 V). There are two options if higher voltages than 60V are required:

  • Place LED current sensing resistor (RFB) at low side with a 2.5V zener diode to ground. This zener diode avoids false short-to-ground (S2G) failure detections at start-up (S2G detection threshold V~FBL,FBH_S2G~ is max. 2V).

  • Place LED current sensing resistor (RFB) inside the LED string such that FBH/FBL pins will see voltage < 61V in all cases. This solution saves the extra zener diode and corresponding power losses, but requires additional wires for RFB.

A small signal diode across the LED string is required in both cases in order to enable S2G detection in case of the anode is getting short-circuited to ground.
Then the maximum LED voltage is defined as the ratio of the minimum input voltage to the maximum duty cycle (91%).

This also works for TLD5097EP and TLD5098EP. See also the LITIX Power page.
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