Yeah, it's also in series, but for any strange reason I still can't explain, the driver works perfect even where you might think that, with the diode and the resistor, it should provide about 5V for the LD + 1,235V from the ref, which would mean 6,235V, when the driver has an absolute maximum of 5,5V.
I did some simulations and saw that a design like that would work and yeah, the real one did work. I'll have to measure the voltage between the out and ground when working. I haven't measured it yet, that way I could see if it's 6,2 V or less.
I'm not saying that my design is the bestr or anithing like that, i'm just saying that it does work. It can perfectly be improved, and your design is a good improvement because it also provides a way so the diode has the same ground than the regulator.
I'll check your op amps later, but I have to say that there's not very much room for "solderable at home size" resistors in a design that must fit inside an aixiz module. In fact, a 0805 resistor uses almost the same space than the regulator IC. So, if we can find anything that just requires a single pot, it would be perfect.
Uh, yes is strange ..... being the FB pin kept at 1,235V, theorically it must fail, cause referred to GND it's 6,235V to keep ..... if the LD is 5V FV ..... ah, well, mysteries of electronics
I've seen at datasheets (still not get my samples, also if requested 2 weeks ago
), that LT6107 can be the better choice, anyway it need at least one sense resistor (ofcourse) and one current-to-voltage resistor (perhaps all these amplifiers have only open-collector current source outputs, so need at least a resistor for convert the out from current to voltage) ..... and, probably, for the use we need, is enough to use a 150 / 200 ohm trimmer for set the input ..... or, maybe also better, a fixed resistor at the input and a trimmer at the output ..... cause, after all, using it in the configuration we need, is not the use they are designed for
.....
I mean, all these ones are designed to be measure probes, giving an output that is proportional to the current passing through Rsense, so, a potentiometer can be used in 2 ways ..... or at the input, for vary the gain, so the output can read 1,235V at the desired current, or at the output, so the voltage can be set through the trimmer at 1,235V when the current is at the desired value ..... both the solutions have pro and con, imho, but considering the high impedance of the FB input of the MAX1723, probably the better solution is using a 10Kohm trimmer at the output of the amp, and drive directly the FB pin with the central of the trimmer ..... i know, it's not a professional design, but we're speaking about hobby level product, so i think it can be acceptable.
Also, must considerate that the maxixum output current of the amp is given at 1 mA, so, on 10Kohm, with 0,1ohm of Rsense and the gain set to 100 with Rin=100, must have an output of 1 V each 100 mA of load, at max ..... not too much to regulate ..... maybe better try with an Rin of 200 ohm, or also just 150, for 2V (1,5V) each 100 mA of current, so the trimmer can regulate it better in the full range of the MAX1723 .....
Something like this
@ john_lawson: don't be preoccupied, you also can learn how to speak in this language ..... all that you need to renounce, is your mental health ..... (J/K
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