EVAL AD7841 page 4 Circuit Schematic

Question

1. The +ve and -ve references are generated and applied to the DAC. 
 2. In the -ve reference part, ADR02 produces 5-V reference. Its output is connected to inverting input of op-amp (U7, OP1177) 
 This scheme of using an op-amp is not clear. 
 Can anyone elaborate on this scheme. 
 I presume that the purpose is to generate - 5V reference. 
 But the scheme is not clear. 
 Thanks in advance to those who can clarify this point. 
 Nanda

ADIApproved · Accepted Answer

The ADR02 normally gives a +5V output. Using it with the OP1177 as on the evaluation board generates a -5V reference voltage. 
 Because the non-inverting pin of the OP1177 is at ground, the inverting pin will also be 0V. The ADR02 will generate +5V between VOUT and GND meaning that the GND pin goes to -5V giving the negative reference voltage.)