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Last seen: 3 years 4 months ago
Joined: 2018-02-07 11:30
LED driving

Hi Dialog,
i need to drive some white LED's .
If i choose to have a fairly basic approach, and just use 1 external resistor to set the max current ( Vin - Vdrop)/R , what is the approx max current i can sink with an output configured as open drain - and what is the equiv on on resistance of the FET output approx ? like in AN10-52 (and use PWM to modulate the brightness) ?
If i want to check out something more sophisitcated : are there any apps notes for constant current sinks ? and what would the max current be ?
Thank you Vincent.

Device Number: 
Any Small GreenPAK
Last seen: 2 years 8 months ago
Joined: 2018-01-31 12:50
Hi Vincent_P,

Hi Vincent_P,

There are few apps notes dedicated to constant current LED driving. E.g. AN-1026, AN-1053, AN-1209. The maximum current depends on chip PN and supply voltage. You can expect 10-20mA or more for 1x open drain. For exact information please see your device base datasheet.