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Bench CC/CV PSU Based on Daves uSupply (Not Anymore)
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KC0PPH:
Not having the best of luck with the breadboard, decided Ill go ahead and order some boards. Before I do Ill post all the info and see if anyone has any final comments. Ill be using JLCPCB and total cost is $8 including shipping for like 10 of these.

I determined i need a beefier diode in the GND return and also a heat sink on the pass element. A bit difficult to fit a 1n54xx in the board :) Since I dont have a pre-reg set up its all on that transistor.

So Ill be ordering the few items i dont have tonight and hopefully the boards tomorrow.

I am missing a few 3D models so that is not 100% accurate.


Thanks in advance.

iMo:
Is the R22=0.1ohm something you inserted in with an intention to do some experiments?
Otherwise it is the capacitor's internal ESR.

Also your Vset and Iset trimmers are wired wrong, imho.

The trimmers, afaik, shall be wired such that their cold side is wired to GND, and their hot side to a STABLE REFERENCE VOLTAGE, for example +4.096V or +5V or +10V, etc.

PS: You may also use a single 78L05/06/08/09 to provide the Ref Voltage, decouple its output with a 10uF cap and do wire it to both Vset and Iset trimmers hot sides. The cold sides of the trimmers to the gnd.

You may use a spare opamp to buffer an external stable Ref Voltage, or, create the stable Ref Voltage from a zener and buffer it with an opamp -> see the PSU schematics in different threads.

Mind the relationship between the voltage on the trim's wipers and the Vout and SlowCC is given by the ratio of the resistors in the voltage divider for Vset (Vsense node) and ratio of resistors in the differential amplifier for Iset (Isense node) and the Rshunt value.. Therefore you have to adjust the values of those resistors based on max wiper voltage such you get the desired Vout and SlowCC range.

Also the opamps shall get a good decoupling close to their package (ie 10u tantalum/elyt in parallel w/ 100nF ceramic).
PS2: in harsh environments it helps to place a small resistor, ie 10ohm in the positive and negative opapm power rails - it creates, together with the 10u+100n decoupling a lowpass.
Better use a separate voltage regulator(s) to feed the opapms.
Mind in this schematics the max Vout depends on max opamp's output voltage.


I would connect the cold side of the constant load to your "-1V" voltage.

"-1V" source - that voltage will float a few hundreds mV up/dwn based on the Iout.

Mind the grounds and power tracks have to be beefy, short as possible and best in a "star" configuration.

Note: LTspice simulation neglects some obvious things which have to be provided in a real HW. LTSpice simulation is usually NOT a schematics directly applicable for a pcb design.

PS1: doublecheck your Voltage assignments in the schematics, ie. your main power voltage calls V-.. I would call it V+.

Kleinstein:
If only 2 OPs of the LM324 are needed, there is the LM358 as an equivalent dual OP.

Unused OPs should be wired differently, e.g. as a follower (connect out to the inverting in).  With the LM324 just leaving the inputs open may work, but is not good with others.

The 3rd OP of the LM324 could be used for an LED to indicate CC or CV mode - it may help to have 2 LEDs as one can better see short pulses of light than short dark periods.

I don't think an extra voltage regulation for the OPs is needed here, unless the voltage may come close to the maximum ratings.

For the voltage reference the 78L05 or similar are an option. Other cheap ones would be TL431 and if low noise is wanted an LM329.
iMo:
Added hints from Kleinstein.
There are other ref diodes/ zeners you may use too.
You may wire any suitable zener in the feedback of a free opapm and multiply its voltage by ratio of the feedback resistors, as you may find in other PSU schematics recently posted.

PS: I would also add a large value resistors (ie 560k) from the pots wipers to GND (in case the wiper loses its contact the voltage/current jumps somewhere, the resistor should maintain a "zero").
Also add 100nF ceramics from the wipers to GND.

And you would certainly need to play with the setting's ranges - therefore I would add the Ris and Rvs resistors there - see below.

PS1: mind the pass transistor has to be an npn power darlington.
jaycee:
My comments on the PCB layout are:

Dont use tiny tracks if you dont have to, you can do this with 0.8128 I would guess
Use bigger thermal reliefs on the pads to ground
Stitch both top and bottom groundplanes together with plenty of via stitching. Ideally, keep one side as an unbroken ground plane.

Oh, and what others have said about the reference voltages too. A TL431 makes a good reference and you're bound to have at least one in a dead switchmode supply :)
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