AD627 question about the REFERENCE INPUT , what is this means?
Rin 125K

KCC Quizzes AQQ303 about the radius of a circle
1. Quote of the month: "When I die, I want to die like my grandfather who died peacefully in his sleep. Not screaming like all the passengers in his car" - Will Rogers
2. Quiz AQQ304 about finding the radius of a circle
Good luck, and try to be
View All
August Monthly Blog Quiz! Read the blog, take the quiz, and you could win a gift card
Important: Read the blog first . The quiz questions are all based on the content of the blog:
Stay in the loop and win! Read the blog Current Output Driving Industrial Loops , then take our quick five-question quiz for a chance to win a gift card
View All
AD627
Production
The AD627 is an integrated, micropower instrumentation amplifier that delivers rail-to-rail output swing on single and dual (+2.2 V to ±18 V) supplies...
Datasheet
AD627 on Analog.com
AD627 question about the REFERENCE INPUT , what is this means?
Rin 125K

Hi roy.wang,
This is the input impedance seen at the AD627's reference input given that there's no gain-setting resistor connected on the RG pins. You want to avoid adding resistance to this reference terminal as it will introduce voltage error. It's also mentioned on the datasheet that this REF pin should be tied to a low impedance input.
Looking at the AD627's datasheet, the theory of operation explained in detail the transfer function given that there's no gain-setting resistor present. It explains how the matching and precision of these resistors ensures low error of the part.
Hope this helps roy.wang.
Best Regards,
Dann
Rin has 125K input impedance when RG resistor is not connected?