ZHCSG47C February   2017  – December 2022

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  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 Electrical Characteristics
    6. 6.6 Switching Characteristics
    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 Device Enable (EN)
      2. 7.3.2 Adjustable Power-Good Threshold (PG, PGADJ)
      3. 7.3.3 Adjustable Power-Good Delay Timer (DELAY)
      4. 7.3.4 Undervoltage Shutdown
      5. 7.3.5 Current Limit
      6. 7.3.6 Thermal Shutdown
      7. 7.3.7 Integrated Watchdog
        1. 7.3.7.1 Window Watchdog (WTS, ROSC, FSEL and WRS)
        2. 7.3.7.2 Standard Watchdog (WTS, ROSC and FSEL)
        3. 7.3.7.3 Watchdog Service Signal and Watchdog Fault Outputs (WD and WDO)
        4. 7.3.7.4 ROSC Status Detection (ROSC)
        5. 7.3.7.5 Watchdog Enable (PG and WD_EN)
        6. 7.3.7.6 Watchdog Initialization
        7. 7.3.7.7 Window Watchdog Operation (WTS = Low)
        8. 7.3.7.8 Standard Watchdog Operation (WTS = High)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation With Input Voltage Lower Than 4 V
      2. 7.4.2 Operation With Input Voltage Higher Than 4 V
  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
        1. 8.2.2.1 Input Capacitor
        2. 8.2.2.2 Output Capacitor
        3. 8.2.2.3 Power-Good Threshold
        4. 8.2.2.4 Power-Good Delay Period
        5. 8.2.2.5 Watchdog Setup
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 接收文档更新通知
    3. 9.3 支持资源
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 术语表
  10. 10Mechanical, Packaging, and Orderable Information

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

7.3.7.2 Standard Watchdog (WTS, ROSC and FSEL)

These devices work in the standard watchdog mode when the watchdog type selection (WTS) pin is connected to a high voltage level. The same as in window watchdog mode, the user can set the duration of the watchdog window by adjusting the external resistor (RROSC) value at the ROSC pin and setting the voltage level at the FSEL pin. The current through the RROSC resistor sets the clock frequency of the internal oscillator. The user can adjust the duration of the watchdog window (the watchdog timer period) by changing the resistor value. A high voltage level at the FSEL pin sets the watchdog window duration to 5 times as long as that of a low voltage level with same external component configuration.

The duration of the watchdog window and the duration of the fault output are multiples of the internal oscillator frequency, as shown by the following equations:

FSEL low
Equation 9. t(WD) = RROSC × 0.5 × 10-6
FSEL high
Equation 10. t(WD) = RROSC × 2.5 × 10-6
Watchdog initialization
Equation 11. t(WD_INI) = 8 × t(WD)

where:

  • t(WD) is the duration of the watchdog window
  • RROSC is the resistor connected at the ROSC pin
  • t(WD_INI) is the duration of the watchdog initialization

For all the foregoing items, the unit of resistance is Ω and the unit of time is s

Compared with window watchdog, there is no closed window in standard watchdog mode. The standard watchdog receives a service signal at any time within the watchdog window. The watchdog fault occurs when not servicing watchdog during the watchdog window.