Error rate of capacitor between EXT_CAP and Vss

Question

I'm using two AD5271 in pallarell, one for control brightness of LED and one for control sensitivity photo diode. Datasheet discribes 1uF capacitor should be connected between EXT_CAP and Vss and the voltage rating of capacitor should be ≧7V. 
 My question is error rate of capacitance. In my board, both AD5271 has 1uF capacitor between EXT_CAP and Vss, and most of boards works fine, but some boards fell into uncontrolable state of RDAC value, and the capacitor of these boards are corrupted in short-mode. 
 So I want to know the error rate of capacitance. If you have any suggestions or information, let me know.

EZAutoReply · Accepted Answer

Hi Azki, 
 
 We do not have data regarding the error rate of the capacitance. I have few questions regarding your setup. what is your Vdd and Vss? What is your capacitor voltage rating? You can increase the voltage rating of your capacitor as having a lower voltage rating can affect the capacitance of the capacitor. How does the board fail? What do you do before it fails? 
 
 Best Regards, 
 Yokki)