AD8302 Start-up time

Question

Hi Analog, 
 I am using AD8302 in a low-power project, and in order to minimize power consumption, I am planning to toggle the chip's supply voltage off in the timeframes when the chip's outputs (VMAG, VPHS) are not sampled by the external ADC and turn it back on before the next sampling event. 
 I checked the datasheet and found out that there is no info available about the start-up time of the device. The response time of the device to signal phase/power change is provided though as typically less than 500 ns for 1% settings, which is great for my timings, but I am not sure how much delay will be added on top of that for the initial warmup. 
 So, is there any measured or estimated value available for the start-up time of AD8302? 
 
 Thanks, 
 Mehran

Bruce_H · Accepted Answer

Hi Mehran, 
 Sorry we don't have the requested startup time information. 
 Looking at the basic design, it seems likely that external capacitors will contribute significantly to the startup time. In particular, notice the large valued input coupling capacitors, typically 1nF, which charge up through 4k series resistors (ref. datasheet page 5, Circuit A). The charge time will be reduced by using smaller input coupling capacitors, just big enough to adequately cover the lowest expected input frequency.

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AD8302 Start-up time

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