afnan.bashir
Member
I know AD620 is an old part but it is available at my place. I intend to develop a Load Cell amplifier. Load cell is 2mV/V. I am planing to use AD620 for it. Following are my calculations:
Excitation Voltage for Load Cell = 5V
Full Scale for load of 140 kg = 2mV X 5V = 10mV
Gain = Vout/Vin = 5000mV/10mv = 500
From formula of Rg we calculate it to be 98.99 Ohm
I have worked on Following schematic:
What is the problem?
1.If I leave the pin 5 open then Min Voltage is 1.9 and max is 4.2 volts. If pin5 is grounded then min voltage is 0.6 and max is 1.9 (strange)
2.the max voltage (4V) is reached at 6 mv Input. even gain calculation is done. But we have added 100 Ohm resistance instead of 98.99 Ohm.
3.Is there any difference between AD620AN, AD620AR and AD620ANZ ?
4.In some circuits i see that at sense + and sense - sometimes before feeding these to operational amplifiers some resistance is added. what is the purpose of adding these keeping in mind the voltage is already in mV
5.Can you suggest load cell amplifier other than INA125 because that is not available
Excitation Voltage for Load Cell = 5V
Full Scale for load of 140 kg = 2mV X 5V = 10mV
Gain = Vout/Vin = 5000mV/10mv = 500
From formula of Rg we calculate it to be 98.99 Ohm
I have worked on Following schematic:
What is the problem?
1.If I leave the pin 5 open then Min Voltage is 1.9 and max is 4.2 volts. If pin5 is grounded then min voltage is 0.6 and max is 1.9 (strange)
2.the max voltage (4V) is reached at 6 mv Input. even gain calculation is done. But we have added 100 Ohm resistance instead of 98.99 Ohm.
3.Is there any difference between AD620AN, AD620AR and AD620ANZ ?
4.In some circuits i see that at sense + and sense - sometimes before feeding these to operational amplifiers some resistance is added. what is the purpose of adding these keeping in mind the voltage is already in mV
5.Can you suggest load cell amplifier other than INA125 because that is not available
Attachments
Last edited: