Hi

I removed a small PCB from a bathroom led light which has this MT7865 led driver IC. I tried to google it or look for examples to understand how does it work or what kind of configuration available, but the only thing I can find is a single page "datasheet".

https://www.alldatasheet.com/datasheet-pdf/view/1134573/MAXIC/MT7865.html

Any idea on this? Btw, the leds are gone in the light, so its just for fun / to learn.

Thank you

 

What is it you want to know? The datasheet fully describes its operation and shows a typical circuit using rectified AC mains to drive a local switch-mode constant-current power supply for the LED, which can use a pulse-width modulated signal (PWM) to dim the LEDs (from a separate controller, may not be used in a bathroom light).

 

What is it you want to know? The datasheet fully describes its operation and shows a typical circuit using rectified AC mains to drive a local switch-mode constant-current power supply for the LED, which can use a pulse-width modulated signal (PWM) to dim the LEDs (from a separate controller, may not be used in a bathroom light).

Hm, okay.. but for example how do I know what is the current its going to supply? Can it be changed? Can it drive a single led for example?

I kinda start to get your point given its a constant current power supply so measuring voltage on the output without load doesnt make much sense.

 

Sad data sheet. data sheet
MAXIC
Rs measures the LED current indirectly. There is a MOSFET from DRAIN to CS. When a PWM cycle starts current flows from C7 through the LED, L2, MOSFET and Rs. The on-time stops when the voltage across Rs reaches some (unknown) voltage. Maybe 1V.
The on-time is set by how long it takes to charge up L2 to the desired current. I do not know the frequency maybe 60khz to 200khz. (internal oscillator)
Note the PWM pin, has a frequency set by an external computer. Probably 100 to 1000hz. This is for dimming, not current control.