Timeline for Inexpensive circuit architecture for power supply voltage adjustment?
Current License: CC BY-SA 3.0
13 events
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| Jul 28, 2016 at 23:45 | history | edited | Russell McMahon♦ | CC BY-SA 3.0 |
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| Jul 28, 2016 at 16:02 | history | edited | Russell McMahon♦ | CC BY-SA 3.0 |
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| Jul 27, 2016 at 17:02 | comment | added | Russell McMahon♦ | @AliChen I've addressed your various points in an addition to my answer. In summary: It works well in many cases, cost can be very low - it can use a spare OA if available OR just a <= 1 cent transistor & 3 x R, 3 x C (as in answer). Extra OA and components are most unlikely to be needed. See details in answer. | |
| Jul 27, 2016 at 11:32 | history | edited | Russell McMahon♦ | CC BY-SA 3.0 |
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| Jul 27, 2016 at 9:03 | history | edited | Russell McMahon♦ | CC BY-SA 3.0 |
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| Jul 27, 2016 at 8:50 | history | edited | Russell McMahon♦ | CC BY-SA 3.0 |
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| Jul 27, 2016 at 0:08 | comment | added | Ale..chenski | So what do we have here? You are suggesting (a) a continuously-running PWM controller; (b) OPAmp to filter the PWM to DC, then I guess you will need another OPAmp to provide the level shift of new biased signal into feedback pin of PMIC, plus a dozen of passive components, likely two power rails (+V, -V). Plus all corresponding PCB space. Do you have any BOM estimation in mind, not speaking that extra OPA will change transfer function of PMIC feedback loop and potentially cause instability or alter dynamic properties of the voltage regulator? IMO, the suggested "solution" makes no sense. | |
| Jul 26, 2016 at 23:50 | comment | added | Russell McMahon♦ | @user4718 See additions to answer re filters. | I mentioned DAC meaning in-processor - usually not available or in short supply. What is the overall design doing, if I may ask? | |
| Jul 26, 2016 at 23:50 | history | edited | Russell McMahon♦ | CC BY-SA 3.0 |
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| Jul 26, 2016 at 23:27 | history | edited | Russell McMahon♦ | CC BY-SA 3.0 |
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| Jul 26, 2016 at 23:21 | comment | added | user4718 | Hi Russell, thanks for your comment. Regarding PWMs, are you proposing something other than a capacitor as an integrating element? If so, see the noise concerns I raise in comment above. Regarding DACs, this would be great, but aren't DAC chips even more expensive than digital rheostats? The opamp suggestion is intriguing, we're already buying those in massive quantities and get great prices (and might even have half of a dual opamp lying around unused for free). Can you point me to a schematic or a search term that would lead me to one? | |
| Jul 26, 2016 at 23:17 | history | edited | Russell McMahon♦ | CC BY-SA 3.0 |
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| Jul 26, 2016 at 23:06 | history | answered | Russell McMahon♦ | CC BY-SA 3.0 |