Help for a led driver

[traus]

Hi to all,
i need help for a led driver...these are my features
1. current up to 250mA
2. 2 series led max
3. 24V
4. output linear current regulation with a pwm micro output (3.3V or
5V)
5. simple for hand soldering
i haven't found an IC able to do what i want...do you know one?

 

[enjunear]

Power LED's - simplest light with constant-current circuit

I saw this circuit some time ago. I haven't tried it, but it looks reasonable and could be adapted to suit your needs.

1) Adjust resistors to give you 250mA, instead of 350mA (as it's shown).

2) add a resistor between your 24V power source and the (+) input to drop some of the 24 volts (article shows 2-18V input range).

3) add an N-channel FET to allow you to power up the circuit using PWM to control the duty cycle... maybe from the gate of Q2 to ground, or from the minus (-) terminal of the circuit to ground.

Just ideas... probably should throw it into a simulation and check it out (or put pencil to paper), or just breadboard it and see what it does.

 

[omielectronics]

i could help you , plz call me 00-86-13719307273