DAC AD7836 and ADC AD7865

Dear Madam / Sir,

Kindly clarify the following points:

1. AD7836 requires 5-V for logic circuit and +/- 15-V and Vref+ and Vref- for the analog section.

Is there any powering sequence for these voltages or can we power up simultaneously.

Of course each power source will have its own time to reach rated value.

2. In the case of ADC AD7865, it requires single 5-V supply.

But analog inputs are applied through op-amp which are powered by +/- 15-V

Can op-amp power come earlier to +5-V supply.

Or op-amp power applied after +5-V

Thankful for your explanation.

With Regards

Nandakumar