CFAF240400D-030T Leds drive secure limits

F

frnando

New member
Hi,

I'm projecting the LED drive part of a CFAF240400D-030T lcd display (I'm thinking in use PWM), but when I read the datasheet, it teaches the MINIMUM LED current is - 60 - mA and min forward voltage as 3.2 V. It's not clear if this values are for a single led or for the 4 in paralell.

What's the maximum current within secure limits to use on each led? For simplifying reasons, I'm thinking of using a 5VDC power supply with a (4) current limiting series resistor.


Fernando
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C

cosmicvoid

Master
frnando said:
... the MINIMUM LED current is - 60 - mA and min forward voltage as 3.2 V. It's not clear if this values are for a single led or for the 4 in paralell.
Click to expand...
I think the numbers in that table are misplaced, and should be in the "Typ." column. The forward voltage is typically 3.2 volts AT a current of 60 mA. The minimum current is zero. IMO, I would not use a current higher than 70 mA. These numbers are per-LED, so your backlight would use (typically) 240 mA total.

In my test jig, I have 4 of 33 ohm (.25 W) resistors to 5 V, so each LED uses about 54 mA, and the screen is bright enough (if not in direct sunlight).

You can see the resistors, just barely, on the left edge of this image.
 

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