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Subject: Constant current sources to drive LEDs on long lines

Date: 02/25/03 at 3:02 AM
Posted by: David Ambry
E-mail: david.ambry@tele-ip.com
Message Posted:

Hi All,
I've a need to drive remote LED indicators over 'long' lines (say up to 10 metres max).
The LEDs are on a mimic panel driven from CMOS inverter outputs.
I think the best way in terms of cost, performance and robustness would be to run them from constant current sources.
I've used the BCV62C current mirror in the past, and this was my first choice as you certainly couldn't get any simpler,
but I need current gain to reduce overall dissipation.
The remote LEDs have grounded cathodes. The supply rail is 5V. Operating current (say) 20mA.
Don't really want to go down the opamp path, there must be something simpler.
Anyone got any suggestions?

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