Connecting Vref on AD5338R

Question

If I want to use an external reference with the AD5338R, how should I connect this to Vref? If I tie Vref to the desired reference voltage (5V for example), will I kill the chip? 
 
 My fear is that by connecting, a 5V rail straight to the Vref pin, this could cause problems since at startup the internal voltage reference generator is on, and driving Vref at 2.5V. 
 
 I could put some resistance between the rail (5V) and Vref (2.5V) but from experience, when the internal reference is off, the voltage at Vref is slightly less than 5V (presumably due to some leakage current? or even just current through the resistor string?). 
 
 What is the best way here? 
 
 (by the way, i understand that for 5V, I could just leave Vref disconnected and set the GAIN to x2, but I want to know another option) 
 
 Thanks!

ADIApproved · Accepted Answer

Hi Ollie, 
 Just to clarify what I meant on my last reply. The AD5338 (without the reference) is the same as the AD5338R in the following aspects: 
 
 They both use I2C protocol 
 Both are dual channel 
 Both are 10-bit DAC 
 
 They are different in some aspects namely: 
 
 They use different packages 
 They are not the same die 
 They have different pin-outs 
 They use different software 
 They have different specification parameters 
 
 Apologies if this has caused any confusion. 
 To answer your question, there will be a temporary short circuit, the internal die will be heat a little bit, as they try to drive the max current but nothing else, as it will be temporary. This is under the assumption that the reference will be switched from internal to external. 
 Regards, 
 Mark