kanonka
Member level 1
Hi,
I need help with design of PS with following specs:
Input - 19.5V (regular laptop PS);
Outputs -
+43V / 0.8A, precision and load regulation within 0.2% or better; load sharply switches from 10mA to 0.8 A;
+36V/ 50mA, precision within 1% or better; load is constant;
+5V / 2A, precision and load regulation within 1% or better; load can vary from 50mA to 2A, sometimes sharply (user inserts USB device; but mostly this is MCU and precision DACs supply);
-0.04V / 1mA, precision within 1% or better; load is constant;
-1.25V/ 50mA, precision within 1% or better; load is constant;
I don't care about PCB space (well, within reasonable limits, of course )
I don't care much about efficiency, as long as total power draw is less than 65W; but I also don't want to have heatsinks, unless absolutely necessary (because this adds cost).
I do care about cost and minimum components possible (well, cost is the main consideration; if there is a solution with more components but overall cheaper, I'm all for it!)
Right now I have straight, dumb design - one buck, one boost and one inverting convertor; 4 LDOs (3 positive, one negative); supply for -0.04V/1mA is just a resistor divider from shunt reference. Simulated this thing successfully in LTSpice, used cheapest components that fit specs.
But, the whole design is ... ugly. For example, to get 0.2% for load regulation on +43V rail, I beefed up output capacitor to 1200uF (!). (It's dumb, but it works). I think that this could be done simpler and more elegant. I don't know, may be some existing 4 or 5-output chip, or something. Or SEPIC with some off-the shelf transformer. I'm not a PS designer at all, so may be someone can give me a hint?
Thanks in advance!
I need help with design of PS with following specs:
Input - 19.5V (regular laptop PS);
Outputs -
+43V / 0.8A, precision and load regulation within 0.2% or better; load sharply switches from 10mA to 0.8 A;
+36V/ 50mA, precision within 1% or better; load is constant;
+5V / 2A, precision and load regulation within 1% or better; load can vary from 50mA to 2A, sometimes sharply (user inserts USB device; but mostly this is MCU and precision DACs supply);
-0.04V / 1mA, precision within 1% or better; load is constant;
-1.25V/ 50mA, precision within 1% or better; load is constant;
I don't care about PCB space (well, within reasonable limits, of course )
I don't care much about efficiency, as long as total power draw is less than 65W; but I also don't want to have heatsinks, unless absolutely necessary (because this adds cost).
I do care about cost and minimum components possible (well, cost is the main consideration; if there is a solution with more components but overall cheaper, I'm all for it!)
Right now I have straight, dumb design - one buck, one boost and one inverting convertor; 4 LDOs (3 positive, one negative); supply for -0.04V/1mA is just a resistor divider from shunt reference. Simulated this thing successfully in LTSpice, used cheapest components that fit specs.
But, the whole design is ... ugly. For example, to get 0.2% for load regulation on +43V rail, I beefed up output capacitor to 1200uF (!). (It's dumb, but it works). I think that this could be done simpler and more elegant. I don't know, may be some existing 4 or 5-output chip, or something. Or SEPIC with some off-the shelf transformer. I'm not a PS designer at all, so may be someone can give me a hint?
Thanks in advance!