AD7626 Ref input current value

Hi to all,

my acquisition and processing board has 12 AD7626 channels interfaced with a FPGA.

I have to provide a voltage reference source for all ADCs in simultaneous acquisition mode at 10MSPS.

So, following the application note "Voltage Reference Design for Precision Successive-Approximation ADCs" by Alan Walsh,

I choose the topology using a unit gain op-amp amplifier for each ADC (each op-amp fed from a unique ADR4540 voltage reference): see the topology below suggested in the AD7626 datasheet.

Supposing a AD7626 Vref input current value of 3.3mA average (10 times the AD7980; 1MSPS Pulsar ADC), I should

select a op-amp with internal output impedance low as 0.01 Ohm at 10MHz: this value is too low even for hi-speed op-amp like ADA4841.

So my question is regarding the AD7626 Ref input current value: is my hypothesis correct (Iref = 10 * Irref_AD7980)?

May be the AD7626 has a different internal topology and, for this reason, the Iref value is negligible and is not provided?

Thank you for any help.

Parents Reply Children
No Data