problem @ connecting h-bridge inverter to INA118 (instrumentation amplifier)

[zizi110]

Hi all,
i must measure ac voltage output of H-bridge inverter by INA118.
the VDC of H-bridge is about 24v. so the output voltage vary between approximately +24v and -24v.
the output of INA118 is connected to ADC of micro that its supply is 3.3 volt.
the gain of INA118 can be changed between 1 to 10,000.
so how can i connect the output of inverte to this instrumentation amplifier?
if i use IA in single supply mode that v+=36v and v-=0v, and its differential input varies between +24v and -24v, and GAIN=1,
then what should be the vref of IA?
how can i controll the output of IA to be in range of 0 t0 3.3, to be ok for ADC input range?

i am confused, please help...:???:

 

[FvM]

INA118 isn't particularly suited for this application because it has a minimal gain of 1. Use a different instrumentation amplifier or a differential voltage divider in front of INA118.

 

[zizi110]

thanks Fvm,
do you know any instrumentation amplifier with gain lower than unity?

 

[FvM]

A difference amplifier like INA157, or a similar amplifier topology setup on your own.