ZHCSG36D December   2016  – November 2017 TLV8541 , TLV8542 , TLV8544

UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.  

  1. 特性
  2. 应用
  3. 说明
    1.     Device Images
      1.      低功耗 PIR 运动检测器
  4. 修订历史记录
  5. 说明 (续)
  6. Pin Configuration and Functions
    1.     Pin Functions: TLV8541 DBV
    2.     Pin Functions: TLV8542 D (X2QFN RUG Package Preview)
    3.     Pin Functions: TLV8544 PW (D SOIC Package Preview)
  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. 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. 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. 12器件和文档支持
    1. 12.1 器件支持
      1. 12.1.1 开发支持
    2. 12.2 文档支持
      1. 12.2.1 相关文档
    3. 12.3 相关链接
    4. 12.4 接收文档更新通知
    5. 12.5 社区资源
    6. 12.6 商标
    7. 12.7 静电放电警告
    8. 12.8 Glossary
  13. 13机械、封装和可订购信息

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

Detailed Design Procedure

Referring to Figure 32, the TLV8544 4-channel op amp is powered directly by a 3.3-V CR2032 coin battery. The first two amplifier stages of the TLV8544 implement active filter functionality. The remaining two amplifiers of the TLV8544 are used for building a window comparator. The comparator flags the detection of a motion event to an ultra-low-power wireless microcontroller on the same board. Due to the higher gain in the filter stages and higher output noise from the sensor, it is necessary to optimize the placement of the high-frequency filter pole and the window comparator thresholds to avoid false detection.

The first two amplifiers (A and B) in the circuit are used in identical active bandpass filters with corner frequencies of 0.7 and 10.6 Hz. Each filter stage has a gain of about 220 V/V to account for the reduced sensitivity of the sensor due to the low current biasing of the PIR sensor. Considering the 8-kHz unity gain bandwidth (UGBW) product of the TLV8544, the bandwidth of each stage is limited to approximately 36 Hz. The above choice of cutoff frequencies give a relatively wide bandwidth to detect a person running in the field of view, yet narrow enough to limit the peak-to-peak noise at the output of the filters.

Amplifier A is a noninverting gain/filter stage providing the high input impedance needed to prevent loading of the sensor. The DC gain of the stage due to the presence of C6 is unity. Therefore, the sensor output provides the bias voltage needed at the A stage to avoid clipping of the lower cycle of the input signal. Diodes D1 and D2 limit the output signal, avoiding overdriving of the second stage and consequently placing a large charge on coupling capacitor C4, which helps with the recovery time.