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outside control voltage signal precesion

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scscsc

Junior Member level 2
outside control voltage signal precision

Hi, everybody,
I have a voltage controlled block in my chip. the control voltage will be generated by a outside device, and tuned manually during chip test. Does anyone know the precision that the outside voltage control signal can achieve normally? thx in advance

thats interesting. You want manual control, but to very high precision ? Its hard to say what precision if its manual... like maybe a multiturn potentiometer ?

You can get multiturns of 12. One quarter turn is quite achievable manually. Maybe with +/- 10% accuracy.

So that gives you 12 x 4 = 1/48 th of the voltage across the pot per quarter turn
Lets say your total range is 5v. So 1/48th turn ~ 0.1042 volts per quarter turn.
And a +/- 10% on this would make it ~ +/- 10mV accuracy.

Good enough for your app ?

If not, you can get multiturns of upto 25, maybe more. Then your precision would be ~ 5mV

Of course by this time the actual linearity accuracy of the preset will start having an effect, so the calculation gets harder.

thanks for your reply kripacharya, i found a description of a device in the website of Agilent. Can we say that if we use the Low-range volts, amps 25W mode of this power suply, we can generate any voltage between 0 to 7V with an accuracy of 0.016% + 1.5 mV?

6625A Precision System Power Supply, 25W or 50W, 2 outputs
Output Ratings (1 output each)

Low-range volts, amps 25W: 0 to 7 V, 0 to 15 mA
Low-range volts, amps 50W: 0 to 16 V, 0 to 200 mA
High range volts, amps 25W: 0 to 50 V, 0 to 500 mA
High range volts, amps 50W: 0 to 50 V, 0 to 1 A or, 0 to 16 V, 0 to 2 A

Programming Accuracy at 25°C ±5°C (1 output each)

Voltage 25W: 0.016% + 1.5 mV (low), 10 mV (high)
Voltage 50W: 0.016% + 53 mV (low), 10 mV (high)
Current 25W: 0.04% + 15 µA (low), 100 µA (high)
Current 50W: 0.04% + 185 µA (low), 500 µA (high)

Ripple & Noise (20 Hz to 20 MHz) 1 output each

Voltage rms: 500 µV
Peak-to-peak: 3 mV
Current rms: 0.1 mA

Can we say that if we use the Low-range volts, amps 25W mode of this power suply, we can generate any voltage between 0 to 7V with an accuracy of 0.016% + 1.5 mV?

6625A Precision System Power Supply, 25W or 50W, 2 outputs
Low-range volts, amps 25W: 0 to 7 V, 0 to 15 mA

Programming Accuracy at 25°C ±5°C (1 output each)

Voltage 25W: 0.016% + 1.5 mV (low), 10 mV (high)

Ripple & Noise (20 Hz to 20 MHz) 1 output each

Voltage rms: 500 µV
Peak-to-peak: 3 mV

LoL !! yes i suppose you could. Though a bit more expensive than a multiturn i think.

your accuracy of 0.016% implies ~ +/- 1mV at 7V output, and i suppose lesser at lesser voltages.

However I didn't quite understand the Ripple & Noise spec. which seems to be worse than the Accuracy spec.

EDIT:
just had a quick look at the actual Agilent document... where it says accuracy is 0.16% and not 0.016% !!
That means an accuracy of ~ 11mV at max voltage ?

But I still don't get the meaning of the " +1.5mV(low), 10mV (high)" part

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To continue with the potentiometer concept , you can use (one possibility) a combination of these two items to a very high degree of accuracy & reliablity at a comparatively miniscule cost --

GP02-geared-potentiometer
multi-turn pot

Last edited:

LoL !! yes i suppose you could. Though a bit more expensive than a multiturn i think.

your accuracy of 0.016% implies ~ +/- 1mV at 7V output, and i suppose lesser at lesser voltages.

However I didn't quite understand the Ripple & Noise spec. which seems to be worse than the Accuracy spec.

EDIT:
just had a quick look at the actual Agilent document... where it says accuracy is 0.16% and not 0.016% !!
That means an accuracy of ~ 11mV at max voltage ?

But I still don't get the meaning of the " +1.5mV(low), 10mV (high)" part

- - - Updated - - -

To continue with the potentiometer concept , you can use (one possibility) a combination of these two items to a very high degree of accuracy & reliablity at a comparatively miniscule cost --

GP02-geared-potentiometer
multi-turn pot

I think " +1.5mV(low), 10mV (high)" means for the low-range voltage mode 0 to 7 V, the minimum voltage step is 1.5mV, and for high-range voltage mode 0-50V, it is 10mV

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