Complex multi-voltage regulator circuit

[caoquyen164]

hi guys, I want to design a multi-voltage regulator with from 18 to 30 outputs, from 0V-15V, to control varactors. would you have any ideals for this circuit ?
supply voltage should be 15V. tks all.

 

[E-design]

Please clarify; do you want 15 V in and 18 and 30 V out?

 

[KlausST]

Hi,

Like so often: a simple drawing could avoid guessing.

Klaus

 

[crutschow]

Please clarify; do you want 15 V in and 18 and 30 V out?

I believe he wants 18 to 30 different outputs, each of them separately adjustable from 0-15V with a 15V input.

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What is the varacter current?

 

[caoquyen164]

tks for your replies. yes, my ideal is exactly like what crutschow said. My design is in the receiver, so the current is not problem, let's say about under 20mA. and if I want to apply in transmitter with 3A-current, can it be possible ? 'cause due to what I searched, there's no varactor with 3A current.

 

[crutschow]

tks for your replies. yes, my ideal is exactly like what crutschow said. My design is in the receiver, so the current is not problem, let's say about under 20mA. and if I want to apply in transmitter with 3A-current, can it be possible ? 'cause due to what I searched, there's no varactor with 3A current.

That's a huge jump between 20mA and 3A.
The transmitter current is not the varactor current.

For the 20mA load you could use a single voltage reference connected to a bunch of high output current quad rail-rail op amps such as the LT1639.
Configure the op-amps as non-inverting amps and use a 100kΩ pot at each input for voltage adjustment (one pot end to ground, the other end to Vref, and the wiper to the op amp (+) input.
The voltage reference you use will determine the op amp gain needed.
Thus for a 5V reference, the op amp gain should be +3 to give a maximum output of 15V.