SNVSBA1B April   2019  – April 2020 TPS3840-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Circuit
  4. 4 Revision History
  5. 5 Device Comparison
  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 Input Voltage (VDD)
        1. 8.3.1.1 VDD Hysteresis
        2. 8.3.1.2 VDD Transient Immunity
      2. 8.3.2 User-Programmable Reset Time Delay
      3. 8.3.3 Manual Reset (MR) Input
      4. 8.3.4 Output Logic
        1. 8.3.4.1 RESET Output, Active-Low
        2. 8.3.4.2 RESET Output, Active-High
    4. 8.4 Device Functional Modes
      1. 8.4.1 Normal Operation (VDD > VDD(min))
      2. 8.4.2 VDD Between VPOR and 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 1: Dual Rail Monitoring with Power-Up Sequencing
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Design 2: Automotive Off-Battery Monitoring
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves: TPS3840EVM
  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 Nomenclature
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2.1 Design Requirements

This design requires voltage supervision on a 12-V power supply voltage rail with possibility of the 12-V rail rising up as high as 42 V. The undervoltage fault occurs when the power supply voltage drops below 7.7 V.

PARAMETER DESIGN REQUIREMENT DESIGN RESULT
Power Rail Voltage Supervision Monitor 12-V power supply for undervoltage condition, trigger a undervoltage fault at 7.7 V. TPS3840-Q1 provides voltage monitoring with 1% accuracy with device options available in 0.1 V variations. Resistor dividers are calculated based on device variant and desired threshold voltage.
Maximum Input Power Operate with power supply input up to 42 V. The TPS3840-Q1 limits VDD to 10 V but can monitor voltages higher than the maximum VDD voltage with the use of an external resistor divider.
Output logic voltage Open-Drain Output Topology Due to large variance in battery voltage, an open-drain output is recommended to provide the correct reset signal.
Maximum system current consumption 35 uA when power supply is at 12 V typical TPS3840-Q1 requires 350 nA (typical) and the external resistor divider will also consume current. There is a tradeoff between current consumption and voltage monitor accuracy but generally set the resistor divider to consume 100 times current into VDD.
Voltage Monitor Accuracy Typical voltage monitor accuracy of 2.5%. The TPS3840-Q1 has 1% typical voltage monitor accuracy. By decreasing the ratio of resistor values, the resistor divider will consume more current but the accuracy will increase. The resistor tolerance also needs to be accounted for.
Delay when returning from fault condition RESET delay of at least 200 ms when returning from a undervoltage fault. CCT = 0.33 µF sets 204 ms delay