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| Another uSupply style power supply |
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| Xenoamor:
Hi Guys Here's another uSupply inspired power supply. (also inspired by SmartSupply). The main aim is to keep cost low and to have a pretty good current resolution for use with microcontrollers. I haven't tested this yet as I'm going to wait and see what the latest uSupply Dave is working on turns out like. Features: output voltage: 0…15V output current: 0…1A voltage resolution: 3mV current resolutions: < 5mA : 1.2uA < 10mA : 2.4uA < 20mA : 4.8uA < 40mA : 9.8uA > 40mA : 245uA cost ~$20 (without housing) operation modes: CV, CC USB QC3.0 pre-regulator. (Expansion header for USB-PD experimentation) interface: Isolated UART 1-2MBaud (only method of control currently) Any feedback, good or bad is definitely appreciated as I'm primarily a software guy! I also have two spare op amps to use, any ideas? |
| JuanGg:
You could maybe do away with U2A, as it is buffering a low impedance source into 10K. And U4D could go as well. You can compensate the current the VOUT_MON divider draws in software (as you'll have to do anyway, because you are measuring current before the regulator). That way you can use just a quad op amp for the whole power supply. Take it with a pinch of salt though. Also, aiming for that current resolution, you'd have to take the stability of the CC load into account. Juan |
| minion:
Instead of using LT3080, I would sudgest you use LT3081. With LT3080, this current limiting that you decided on using is not that great, to say the least. I also played a bit with it few years ago, but then went with LT3081. The good thing about Lt3081 is, that it has Imonitor pin and Ilimit pin. You can play with this pins, to achieve much better over current detection and CC mode. |
| thm_w:
I am working on a similar project. Sadly QC3 was a partial dead end for me. The most I was able to get out of it was 12V. I'm now attempting to add USBPD. If you can find a reasonable cost 20V capable supply, I would like to see it. However, the two I have tried, even though they have a 20V capable IC, were unable to output 20V. I asked RuiDeng and they also seemed to have trouble locating one. Its possible there is more complexity to the protocol, but I think its no the case as QC 2 20V output is very simple (D+/D- = 3.3V). Honestly though even with 12V in most cases this is a nice design. Agree with Juan on U2A and U4D. Especially U2A, as input common mode range is V+ - 2V, so it could produce some unusual results. You can add a small cap across R10. You may also consider an RC filter on IMON_Course, either input or output, as it will likely be quite noisy. But not really an issue if you filter for DC levels. The drop across 2.5R is somewhat significant at 1A, but may be worth it for that low current resolution. Are Vset and Iset DAC or PWM outputs? |
| ggchab:
You measure current before the current sink. Do you think you will obtain 1.2µA resolution ? The current sink will have to be very stable. What will happen when the output will be closed to 0V ? Don't you need a negative supply ? |
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