SNAS468D September   2008  – December 2014 ADC161S626

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Converter Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Reference Input (VREF)
      2. 7.3.2 Sample and Hold
        1. 7.3.2.1 Input Settling
      3. 7.3.3 Serial Digital Interface
        1. 7.3.3.1 CS Input
        2. 7.3.3.2 SCLK Input
        3. 7.3.3.3 Data Output
    4. 7.4 Device Functional Modes
      1. 7.4.1 Differential Input Operation
      2. 7.4.2 Single-Ended Input Operation
      3. 7.4.3 Short Cycling
      4. 7.4.4 Burst Mode Operation
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
  9. 9 Power Supply Recommendations
    1. 9.1 Analog and Digital Power Supplies
    2. 9.2 Voltage Reference
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Specification Definitions
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9 Power Supply Recommendations

9.1 Analog and Digital Power Supplies

Any ADC architecture is sensitive to spikes on the power supply, reference, and ground pins. These spikes may originate from switching power supplies, digital logic, high power devices, and other sources. Power to the ADC161S626 should be clean and well bypassed. A 0.1 µF ceramic bypass capacitor and a 1 µF to 10 µF capacitor should be used to bypass the ADC161S626 supply, with the 0.1 µF capacitor placed as close to the ADC161S626 package as possible.

Since the ADC161S626 has both the VA and VIO pins, the user has three options on how to connect these pins. The first option is to tie VA and VIO together and power them with the same power supply. This is the most cost effective way of powering the ADC161S626 but is also the least ideal. As stated previously, noise from VIO can couple into VA and adversely affect performance. The other two options involve the user powering VA and VIO with separate supply voltages. These supply voltages can have the same amplitude or they can be different. VA can be set to any value between +4.5V and +5.5V; while VIO can be set to any value between +2.7V and +5.5V.

Best performance will typically be achieved with VA operating at 5V and VIO at 3V. Operating VA at 5V offers the best linearity and dynamic performance when VREF is also set to 5V; while operating VIO at 3V reduces the power consumption of the digital logic. Operating the digital interface at 3V also has the added benefit of decreasing the noise created by charging and discharging the capacitance of the digital interface pins.

9.2 Voltage Reference

The reference source must have a low output impedance and needs to be bypassed with a minimum capacitor value of 0.1 µF. A larger capacitor value of 1 µF to 10 µF placed in parallel with the 0.1 µF is preferred. While the ADC161S626 draws very little current from the reference on average, there are higher instantaneous current spikes at the reference.

VREF of the ADC161S626, like all A/D converters, does not reject noise or voltage variations. Keep this in mind if VREF is derived from the power supply. Any noise and/or ripple from the supply that is not rejected by the external reference circuitry will appear in the digital results. The use of an active reference source is recommended. The LM4040 and LM4050 shunt reference families and the LM4120 and LM4140 series reference families are excellent choices for a reference source.