REF19x series [REF192, REF191]: allowable sink current at REF192 Output pin

Question

Hi, i'm Jeong Ho Lee from vpixmedical 
 Firstly, i appreciate to your help about last question of potentiometer. 
 It really helps! 
 Anyway, I have a question about REF19x series. 
 We try to use REF19x as a kind of reference(?) voltage at -IN pin of AD8138. (See schematic below)

When input signal(PMT signal) of +IN pin of AD8138 above 2.5 V, because of feedback loop of AD8138, i think current will flow from '-IN' pin of AD8138 to 'Out' pin of REF192. 
 That means sink current occur to REF192. 
 We do experiment of the output of REF 192 but there's no change of REF192 output while input signal change 0 V to 5 V. 
 
 It works but, we really concern about that is either abnormal or not.(I can't find data of how much sink current REF19x series can take) 
 
 Question 1. How much sink current REF192 can take? 
 2. Is it okay to change REF192 to REF191 on above schematic? 
 
 Thank you

ADIApproved · Accepted Answer

Hi Jeong Ho Lee, 
 
 The REF192 is not tested to sink current. Sinking current using this might/might not cause problem for the device. It is not guaranteed by the datasheet. To be sure for the product to work, I recommend using a sinking resistor. 
 For the second question, I think there is no problem in Voltage Reference side. It's just a question of does changing your voltage from 2.5V to 2.048V applicable in your application. 
 
 Regards, 
 Mon)

Partner Forums

Partner Libraries

Products Mentioned

REF19x series [REF192, REF191]: allowable sink current at REF192 Output pin