Antor
Member level 2
Hello there,
I want to measure line-neutral voltage with single supply AD623.
Grid Line-Neutral voltage 220Vrms
Input signal for inamp swings between -1V and 1V (Zero crossing at 0V).
I want my output signal Vpp=2V, signal swings between 1.5V and 3.5V (zero crossing at 2.5V.)
The circuit on attachment works perfectly.
Now my first question is about choosing best Vcm.
Should I choose Vcm as 1V ? (to shift the negative alternance peak to 0)
or should I choose Vcm more like 2V ? (more than needed)
Second question
Which one is best to get references for Vcm and Vref ?
Voltage divider with resistors > opamp buffer > follower > to where needed
Using a voltage regulator (TLV431 like advised here before) > opamp buffer > follower > to where needed
Option 1 disadvantage = because I'm using 7805 as 5Vdc supply. And I really don't trust it.
Option 2 disadvantage = choosing and finding correct resistors in market are truely painfull. I can't always get exact reference as I wanted.
Which option should I go for ?
Rg = inf (gain=1)
Figure 1 Vcm=0 V (Connected to DC neutral)
Figure 2 Vcm=1.1 V
I want to measure line-neutral voltage with single supply AD623.
Grid Line-Neutral voltage 220Vrms
Input signal for inamp swings between -1V and 1V (Zero crossing at 0V).
I want my output signal Vpp=2V, signal swings between 1.5V and 3.5V (zero crossing at 2.5V.)
The circuit on attachment works perfectly.
Now my first question is about choosing best Vcm.
Should I choose Vcm as 1V ? (to shift the negative alternance peak to 0)
or should I choose Vcm more like 2V ? (more than needed)
Second question
Which one is best to get references for Vcm and Vref ?
Voltage divider with resistors > opamp buffer > follower > to where needed
Using a voltage regulator (TLV431 like advised here before) > opamp buffer > follower > to where needed
Option 1 disadvantage = because I'm using 7805 as 5Vdc supply. And I really don't trust it.
Option 2 disadvantage = choosing and finding correct resistors in market are truely painfull. I can't always get exact reference as I wanted.
Which option should I go for ?
Rg = inf (gain=1)
Figure 1 Vcm=0 V (Connected to DC neutral)
Figure 2 Vcm=1.1 V