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OPA2277-EP: Voltage seems can't be forced with positive input

Part Number: OPA2277-EP
Other Parts Discussed in Thread: DAC9881, OPA2277, DAC9881EVM, REF5050


I am using OPA2277-EP as kelvin connection for DAC's reference voltage such as Fig.1 .

                                                                      ( Fig.1: OPA2277-EP test circuit ---- referenced from SLAU279A  p20   )

Firstly, OPA227-EP is operated with +/- 14.5V  and  "positive input A" is about 5V. 

My cognition is that

1.Due to kelvin connection's purpose, VREFH-F1 should be forced to 5V

2.If this circuit work normally, the current consumption should be about 800 μA per amplifier  ( fortunately when I measure the current from OP_SENS_V+ , It was about 1580 μA   )

However when I power up this circuit, I found that 

1. VREFH-F1 can't be forced to 5V but 5.6V and finally went up slowly to 13.56 ~ 13.58 V

2. VREFL-F1 can be about 0V ( this result is ok, seems the "positive input B" is connected to AVSS  )

Whether there is something wrong about Fig.1 or my cognition ?

Thank you for any suggestion and help.