Driving a Led with a driver

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gokulpradeep010

Joined Jun 2, 2021
28
Hi,
I have a simple question. I have power supply( as a part of a circuit) of 175V and I want to drive an LED with it. Is it possible for me to use a driver with Input voltage range of -0.3 to 400V and current 50mA max to drive an LED of Vf 2V and maximum current of 50mA.
 

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Lo_volt

Joined Apr 3, 2014
189
Sound reasonable to me. 400 volts is the maximum the AL5890 can handle. The spec says it turns on at 7 volts. 175 volts is within the device operating range.
 

BobTPH

Joined Jun 5, 2013
3,316
This is a linear device. If you have an input of 175V and the LED is 2V at 50mA it will be dissipating (175-2) *0.05 = 8.65 Watts. You would need a large heat sink.

Bob
 

BobTPH

Joined Jun 5, 2013
3,316
Actually, looking at the datasheet again, that exceeds the maximum dissipation on any package type, so no, you cannot do that.

The device may have those very high voltage capabilities, but practically, it is designed to drop a lot less voltage in operation. I.e. if you wanted to drive a string of 75 of those LEDs it would do it. But not a single one.

Bob
 

BobTPH

Joined Jun 5, 2013
3,316
What us the LED for? If it is just an indicator, a super bright LED at 1mA might be sufficient. That would be low enough power to just use a 1/4 W resistor to limit the current

Bob
 
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