SLOS823D December   2012  – March 2020 THS4531A

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     1-kHz FFT Plot on Audio Analyzer
  4. 4 Revision History
  5. 5 Related Products
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics: VS = 2.7 V
    6. 7.6 Electrical Characteristics: VS = 5 V
    7. 7.7 Typical Characteristics
      1. 7.7.1 Typical Characteristics: VS = 2.7 V
      2. 7.7.2 Typical Characteristics: VS = 5 V
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Input Common-Mode Voltage Range
        1. 8.3.1.1 Setting the Output Common-Mode Voltage
      2. 8.3.2 Power Down
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1  Frequency Response, and Output Impedance
      2. 9.1.2  Distortion
      3. 9.1.3  Slew Rate, Transient Response, Settling Time, Overdrive, Output Voltage, and Turnon and Turnoff Time
      4. 9.1.4  Common-Mode and Power Supply Rejection
      5. 9.1.5  VOCM Input
      6. 9.1.6  Balance Error
      7. 9.1.7  Single-Supply Operation
      8. 9.1.8  Low-Power Applications and the Effects of Resistor Values on Bandwidth
      9. 9.1.9  Driving Capacitive Loads
      10. 9.1.10 Audio Performance
      11. 9.1.11 Audio On and Off Pop Performance
    2. 9.2 Typical Applications
      1. 9.2.1 SAR ADC Performance: THS4531A and ADS8321 Combined Performance
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curve
      2. 9.2.2 Audio ADC Driver Performance: THS4531A and PCM4204 Combined Performance
        1. 9.2.2.1 Detailed Design Procedure
        2. 9.2.2.2 Application Curves
      3. 9.2.3 SAR ADC Performance: THS4531A and ADS7945 Combined Performance
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
        3. 9.2.3.3 Application Curve
      4. 9.2.4 Differential-Input to Differential-Output Amplifier
        1. 9.2.4.1 AC-Coupled, Differential-Input to Differential-Output Design Issues
      5. 9.2.5 Single-Ended to Differential FDA Configuration
        1. 9.2.5.1 Input Impedance
      6. 9.2.6 Single-Ended Input to Differential Output Amplifier
        1. 9.2.6.1 AC-Coupled Signal Path Considerations for Single-Ended Input to Differential Output Conversion
        2. 9.2.6.2 DC-Coupled Input Signal Path Considerations for Single-Ended to Differential Conversion
        3. 9.2.6.3 Resistor Design Equations for the Single-Ended to Differential Configuration of the FDA
      7. 9.2.7 Differential Input to Single-Ended Output Amplifier
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

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8.3.2 Power Down

The power down pin is internally connected to a CMOS stage which must be driven to a minimum of 2.1 V to ensure proper high logic.

THS4531A Newfigure89.gifFigure 68. Simplified Power-Down Internal Circuit

If 1.8-V logic is used to drive the pin, a shoot through current of up to 100 µA may develop in the digital logic causing the overall quiescent current to exceed the 2 µA of maximum disabled quiescent current specified in the Electrical Characteristics: VS = 2.7 V.

To properly interface to 1.8-V logic with minimal increase in additional current draw, a logic-level translator like the SN74AVC1T45 device can be used.

Alternatively, the same function can be achieved using a diode and pullup resistor as shown in Figure 69.

THS4531A pd_iface_los823.gifFigure 69. THS4531A Power Down Interface to 1.8-V Logic Microcontroller

The voltage at the power down pin will be a function of the supply voltage, input logic level, and diode drop. As long as the diode is forward biased, the power down voltage is calculated using Equation 3.

Equation 3. THS4531A eq_Vpd_los823.gif

where

  • VL is the logic level voltage.
  • Vf is the forward voltage drop across the diode.

This means for 1.8-V logic, the forward voltage of the diode should be greater than 0.3 V but less than 0.7 V to keep the power down logic level above 2.1 V and less than 0.7 V respectively.

For example, if 1N914 is selected as the diode with a forward voltage of approximately 0.4 V, the translated logic voltages will be 0.4 V for disabled operation and 2.2 V for enabled operation.

Use Equation 4 to calculate the additional current draw.

Equation 4. THS4531A eq_ipd_los823.gif

Equation 2 shows that larger values of RPU result in a smaller additional current. A reasonable value of RPU is 500 kΩ where an additional current draw of 5.2 µA is expected while the device is in operation and 1.6 µA when disabled.