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ADS1258: current consumption of reference pin

assaf matia
Prodigy 230 points
Part Number: ADS1258
Other Parts Discussed in Thread: REF6041,

Hi,

 

In the datasheet it is mentioned that when exiting SLEEP mode there is a small current consumption from the VREFP/N inputs. since I am using LM4040-4.1V for the reference with required capacitors, I need to know:

 

  1. what is the maximum amount of possible current through this pin to see I can supply it (and for how long does this current exists..)

 

  1. In normal operation can I assume load of about 40K so the current is max 4.096V/40K which is less than 1mA...
  • 0
    TI__Mastermind 40191 points

    Hi assaf matia,

    I was unable to find characterization data for this comment in the data sheet. My guess is that this was simply an observation made by the validation team when the device was being developed ~20 years ago, which is why there is no actual data provided in the Electrical Characteristics section of the data sheet

    You can measure this transient current by placing a small resistance in series with the VREFP pin, and then measure the voltage across this resistance using an oscilloscope as the device comes out of SLEEP mode. Then you can calculate the transient current draw. However, considering that the ADS1258 VREF pins are unbuffered, I would not recommend using a shunt voltage reference for the ADS1258. I would instead suggest using the REF6041, which is a high performance reference with an integrated output buffer. This VREF should allow you to get the best performance out of the ADC.

    -Bryan