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I have a linear range control signal from 1.75 V (0%) to 3.22 V (100%) .

How can I convert this to a 0-5V signal (0-100%)?

I have a single +5V supply with same 0V as control signal.

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  • \$\begingroup\$ Surely this must meet the "no research effort" criteria? \$\endgroup\$
    – pipe
    Commented Mar 22, 2020 at 16:14

1 Answer 1

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As a starting point, see Bruce Carter's application report titled Designing Gain and Offset in Thirty Seconds (Texas Instruments, document number SLOA097, Feb. 2002).

For what it's worth, if your power supply voltage is +5 VDC, the task of designing a signal conditioning circuit whose output voltage is precisely 0 V – 5 V is not a straightforward task. The reason is this: an op amp cannot output a voltage that is equal to the voltages at the op amp's power input pins. For example, for an op amp whose power pins are connected to +5 VDC and ground, the op amp's output voltage range does not include +5 VDC nor ground:

$$ 0\,\mathrm{VDC} \lt V_{out} \lt +5\,\mathrm{VDC} $$

So you might find it easier to design a signal conditioning circuit whose output voltage range is, for example, 0.2 V – 4.8 V.

See also:

  1. Single-Supply Op Amp Design Techniques (Texas Instruments application report, document number SLOA030A, March 2001).

  2. J. Heath, "Amplifiers: What do rail-to-rail and single supply mean?" Analog IC Tips: An EE World Online Resource, Oct. 10, 2017 [Online]. Available: https://www.analogictips.com/amplifiers-rail-to-rail-single-supply-mean/

  3. J. Fischer, "Op Amp in buffer configuration is decreasing output voltage", Electrical Engineering Stack Exchange, June 19, 2016 [Online]. Available: https://electronics.stackexchange.com/a/241540/79842

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  • \$\begingroup\$ Regarding your second paragraph, what about rail-to-rail opamps? \$\endgroup\$ Commented Mar 22, 2020 at 16:52
  • \$\begingroup\$ I edited my answer and added two additional references (#2 and #3). In Heath's article, with regard to rail-to-rail op amps she states, "The term 'rail-to-rail' is marketing speak for 'darn close' [to the power supply voltages.] Some advertisements state that they go 'beyond the rails,' but going beyond the rails usually means clipping the signal. The maximum peak-to-peak voltage output swing is one where the waveform is not clipped with reference to a specified level." So rail-to-rail op amps are not exempt from the laws of physics: they also cannot achieve Vout = voltage @ op amp power pin. \$\endgroup\$ Commented Mar 22, 2020 at 18:00

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