SNOSD29E December   2016  – April 2018 TLV8541 , TLV8542 , TLV8544

UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Low Power PIR Motion Detector
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
    1.     Pin Functions: TLV8541 DBV
    2.     Pin Functions: TLV8542 D & RUG
    3.     Pin Functions: TLV8544 PW & D
  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
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
    4. 8.4 Device Functional Modes
      1. 8.4.1 Rail-To-Rail Input
      2. 8.4.2 Supply Current Changes Over Common Mode
      3. 8.4.3 Design Optimization With Rail-To-Rail Input
      4. 8.4.4 Design Optimization for Nanopower Operation
      5. 8.4.5 Common-Mode Rejection
      6. 8.4.6 Output Stage
      7. 8.4.7 Driving Capacitive Load
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application: Battery-Powered Wireless PIR Motion Detectors
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Calculation of the Cutoff Frequencies and Gain of Stage A:
        2. 9.2.2.2 Calculation of the Cutoff Frequencies and Gain of Stage B
        3. 9.2.2.3 Calculation of the Total Gain of Stages A and B
        4. 9.2.2.4 Window Comparator Stage
        5. 9.2.2.5 Reference Voltages
      3. 9.2.3 Application Curve
    3. 9.3 Typical Application: 60-Hz Twin T Notch Filter
      1. 9.3.1 Design Requirements
      2. 9.3.2 Detailed Design Procedure
      3. 9.3.3 Application Curve
    4. 9.4 Dos and Don'ts
  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 Development Support
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Related Links
    4. 12.4 Receiving Notification of Documentation Updates
    5. 12.5 Community Resources
    6. 12.6 Trademarks
    7. 12.7 Electrostatic Discharge Caution
    8. 12.8 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2.2 Calculation of the Cutoff Frequencies and Gain of Stage B

As shown in Figure 32, amplifier B is an inverting bandpass filter and gain stage. Capacitor C4 creates an AC coupled path between the A and the B stages. Thus the signal level must be shifted at the input of the amplifier B. This is done by connecting a midpoint voltage of the reference voltage dividers comprising R10, R9, R8 and R7 to the non-inverting input of amplifier B, biasing the input signal to the mid-rail (1.65 V). A very large feedback resistor R3 is chosen to minimize the dynamic current due to presence of peak-to-peak noise voltage at the output of this stage.

The low cutoff frequency of the filter of the stage B is:

Equation 5. TLV8544 TLV8542 TLV8541 eq4-SNAA301.gif

Choosing R4 = 68.1 kΩ and C4 = 3.3 μF, the low cutoff frequency is fClow = 0.71 Hz. The high cutoff frequency of the filter is:

Equation 6. TLV8544 TLV8542 TLV8541 eq5-SNAA301.gif

For R3 = 15 MΩ and C3 = 1000 pF, the high cutoff frequency is fChigh= 10.6 Hz. The gain of the stage is:

Equation 7. TLV8544 TLV8542 TLV8541 eq6-SNAA301.gif

For R3 = 15 MΩ and R4 = 68.1 kΩ, the gain is calculated |G| = 220.26 V/V (46.9 dB).