Please help me with issues about instrumentation amplifier AD8553

Hi CoKa 

Thank you for reaching out. We are validating your inquiries; we will need additional information from your circuit design before anything else. May I know what applications you intend to use for the two (2) AD8533 (U10 and U13)? If this circuit was designed to drive an ADC?

Can you expound further on the table that you provided and your design requirements? i.e. target Gain, expected output,  Input range, etc… I see you are using two (2) types of input: one is pure DC and another is AC( is this a sinusoidal wave w/ frequency of 1kHz?, is there any DC offsets for the AC input?). Then, please provide a scope shot on Pin2(VINP), Pin9(VINN), Pin7(VREF), and Pin4(VO) for the two (2)  input conditions.

I suggest we run several diagnostics on your design; Hence, will use the existing U13 circuit and please do the following:

1. Isolate this circuit by disconnecting other circuitries connecting to C39 or Ch4 node.
2. Remove R74 and R75.
3. Change CH4_P input from +25Vdc to 3.6Vdc.
4. Check if the Vout is the same = 4.23V.
5. Lower Down your CH4_P input from 0.8 to 3.5Vdc
6. Check if the Vout will be similar to CH4_P input.

Please let me know if this helps.

Regads,

Arsol

Hi CoKa 

Thank you for reaching out. We are validating your inquiries; we will need additional information from your circuit design before anything else. May I know what applications you intend to use for the two (2) AD8533 (U10 and U13)? If this circuit was designed to drive an ADC?

Can you expound further on the table that you provided and your design requirements? i.e. target Gain, expected output,  Input range, etc… I see you are using two (2) types of input: one is pure DC and another is AC( is this a sinusoidal wave w/ frequency of 1kHz?, is there any DC offsets for the AC input?). Then, please provide a scope shot on Pin2(VINP), Pin9(VINN), Pin7(VREF), and Pin4(VO) for the two (2)  input conditions.

I suggest we run several diagnostics on your design; Hence, will use the existing U13 circuit and please do the following:

1. Isolate this circuit by disconnecting other circuitries connecting to C39 or Ch4 node.
2. Remove R74 and R75.
3. Change CH4_P input from +25Vdc to 3.6Vdc.
4. Check if the Vout is the same = 4.23V.
5. Lower Down your CH4_P input from 0.8 to 3.5Vdc
6. Check if the Vout will be similar to CH4_P input.

Please let me know if this helps.

Regads,

Arsol