Voltage supply circuit with current sinking capability

[DanioIO]

Hi,
How can i make a LDO voltage power supply, which can also work as constant current sink if the connected device voltage exceeds the power supply output?

[void_error]

If you provide more details (input voltage, output voltage, output current) I might be able to give you a solution.

[DanioIO]

I need something working from 30V and the output voltage should be min. 15V, output current isnt very important i will be happy with 1A.

[Zero999]

Then it's relatively simple. You need a voltage reference connected to a push-pull amplifier.

[macboy]

More explicitly, look at using a power op-amp such as LM1875 (3875 for more power), amplifying a voltage reference like TL431. You don't need symmetric supplies for the op-amp, -5V is enough for the negative supply, our use single supply (neg supply is ground) if the output never needs to go below about 5V.