ZHCSRF8 December   2022 TPS3435

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 器件比较
  6. 6 Pin Configuration and 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
    6. 7.6 Timing Requirements
    7. 7.7 Switching Characteristics
    8. 7.8 Timing Diagrams
    9. 7.9 Typical Characteristics
  8. 8 详细说明
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 Timeout Watchdog Timer
        1. 8.3.1.1 tWD Timer
        2. 8.3.1.2 Watchdog Enable Disable Operation
        3. 8.3.1.3 tSD Watchdog Start Up Delay
        4. 8.3.1.4 SET Pin Behavior
      2. 8.3.2 Manual RESET
      3. 8.3.3 WDO Output
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Output Assert Delay
        1. 9.1.1.1 Factory-Programmed Output Assert Delay Timing
        2. 9.1.1.2 Adjustable Capacitor Timing
      2. 9.1.2 Watchdog Timer Functionality
        1. 9.1.2.1 Factory-Programmed Timing Options
        2. 9.1.2.2 Adjustable Capacitor Timing
    2. 9.2 Typical Applications
      1. 9.2.1 Design 1: Monitoring a Standard Microcontroller for Timeouts
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Setting the Watchdog Timeout Period
          2. 9.2.1.2.2 Setting Output Assert Delay
          3. 9.2.1.2.3 Setting the Startup Delay
          4. 9.2.1.2.4 Calculating the WDO Pullup Resistor
        3. 9.2.1.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 接收文档更新通知
    2. 12.2 支持资源
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 术语表
  13. 13Mechanical, Packaging, and Orderable Information

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9.1.1.2 Adjustable Capacitor Timing

The TPS3435 also utilizes a programmable output assert delay, using a precision current source to charge an external capacitor upon device startup. By monitoring the voltage on the CRST pin, the TPS3435 can be programmed to have a desired output assert delay. The typical delay time resulting from a given external capacitance on the CRST pin can be calculated by Equation 3, where tWDO is the output assert delay time in seconds and CCRST is the capacitance in microfarads.

Equation 3. tWDO (sec) = 4.95 × 106 × CCRST (F)

Note that in order to minimize the difference between the calculated output assert delay time and the actual output assert delay time, use a high-quality ceramic dielectric COG, X5R, or X7R capacitor and minimize parasitic board capacitance around this pin. Table 9-1 lists the output assert delay time ideal capacitor values for CCRST.

Table 9-1 Output Assert Delay Time for Common Ideal Capacitor Values
CCRST

OUTPUT ASSERT

DELAY TIME (tWDO)		UNIT
MIN(1)TYPMAX(1)
10 nF

39.6

49.5

59.4

ms
100 nF

396

495

594

ms
1 μF

3960

4950

5940

ms
(1) Minimum and maximum values are calculated using ideal capacitors.