ADS8866: running two ADC from same external reference supply

Iouri Markin

Part Number: ADS8866
Other Parts Discussed in Thread: REF6030, , REF5030

Hello,

We are building data acquisition system based on ADS8866 (Vd = 3v3 V analog 3V3 sampling rate 30KHZ), and external reference voltage supply REF6030 we have two questions we want to ask.

1. Would be possible to run two ADS8866 from single reference voltage source ie REF6030, or we need to have two dedicated reference sources for each ADC?

2. Before the ADC we have non-inverting OPAMP amplifier circuit to boost the gain of the incoming signal, we would like to bias amplifier to Vref/2. Question:

can we use simple resistor divider and connect it to Vout of REF6030,

or should we put an OPAMP buffer between Vref output of the REF6030and our OPAMP circuit,

or opamp bias circuit has to be independent from REF6030 which is also supply ADC reference?

Please advise,

Stalker

over 5 years ago

0 Keith Nicholas over 5 years ago

TI__Mastermind 42060 points

Hello Stalker,

1. Since you are sampling at 30ksps, you may be able to share a single REF6030 between two ADS8866's. However, we have not verified this approach.

2. You can use a resister divider directly connected to the REF6030. You should add a filter capacitor to reduce noise at the output of the divider (Vref/2)

I would suggest using a single reference, such as REF6030 or REF5030, and an individual buffer for each ADS8866. The buffer will then drive the transient currents of each ADC, and you can add additional filtering to the output of the reference. The below circuit should work well. You can also connect a resistor divider on the Vref node to generate Vref/2.

Regards,
Keith Nicholas
Precision ADC Applications

0 Iouri Markin over 5 years ago in reply to Keith Nicholas

Intellectual 630 points

Thank you Keith. This is really help

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ADS8866: running two ADC from same external reference supply