Hello everyone,
I'm designing a three channel ADC conversion using the ADS8860 at a 1MSPS. I would like to use only one reference voltage for all three channels with the REF5045 and the proposed circuitry of the datasheet with the OPA333 and THS4281. I'm designing the output buffer capacitor (C_BUF_FLT), so that the reference voltage stays within 1 LSB error at the start of each conversion. For that I'm considering the reference input current of all three channels, that is, Iref=3 x 300 uA, and a maximal conversion time of Tcon_max=710 us. For a 16 bits conversion with 4.5V, results in a 10uF output capacitor (ESR=220 mOhm). My question here is, should this output capacitor be enough to stay within the 1LSB voltage error? or is there something else I should consider in the design when using multiple ADC converters with the same voltage reference? perhaps a 100nF capacitors at the REF-PIN to decouple the high frequency currents produced by the ADC reference input?
I would appreciate yours thoughts on this.
Thank you
