SBVS303B March   2017  – February 2018 TPS3890-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Circuit
      2.      VITN Accuracy vs Temperature
  4. 4 Revision History
  5. 5 Device Comparison Table
  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
    6. 7.6 Timing Requirements
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 User-Configurable RESET Delay Time
      2. 8.3.2 Manual Reset (MR) Input
      3. 8.3.3 RESET Output
      4. 8.3.4 SENSE Input
        1. 8.3.4.1 Immunity to SENSE Pin Voltage Transients
    4. 8.4 Device Functional Modes
      1. 8.4.1 Normal Operation (VDD > VDD(min))
      2. 8.4.2 Above Power-On-Reset But Less Than VDD(min) (VPOR < VDD < VDD(min))
      3. 8.4.3 Below Power-On-Reset (VDD < VPOR)
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
  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 Device Nomenclature
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2 Detailed Design Procedure

The primary constraint for this application is choosing the correct device to monitor the supply voltage of the microprocessor. The TPS389018-Q1 has a negative threshold of 1.73 V and a positive threshold of 1.74 V, making the device suitable for monitoring a 1.8-V rail. The secondary constraint for this application is the reset delay time that must be at least 1 ms to allow the Delfino microprocessor enough time to startup up correctly. Because a minimum time is required, the worst-case scenario is a supervisor with a high CT charging current (ICT) and a low CT comparator threshold (VCT). For applications with ambient temperatures ranging from –40°C to +125°C, CCT can be calculated using ICT(Max), VCT(MIN), and solving for CCT in Equation 1 such that the minimum capacitance required at the CT pin is 1.149 nF. If standard capacitors with ±20% tolerances are used, then the CT capacitor must be 1.5 nF or larger to ensure that the 1-ms delay time is met.

A 0.1-µF decoupling capacitor is connected to the VDD pin as a good analog design practice and a 1-MΩ resistor is used as the RESET pullup resistor to minimize the current consumption when RESET is asserted. The MR pin can be connected to an external signal if desired or connected to VDD if not used.