SLUSDY5 June   2022 BQ25172

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  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 Timing Requirements
    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 Power Up from Input Source
        1. 7.3.1.1 ISET Pin Detection
        2. 7.3.1.2 TMR Pin Detection
        3. 7.3.1.3 VSET Pin Detection
        4. 7.3.1.4 Charger Power Up
      2. 7.3.2 Battery Charging Features
        1. 7.3.2.1 NiMH Battery Charging Profile
        2. 7.3.2.2 Charging Safety Timers
        3. 7.3.2.3 Battery Cold, Hot Temperature Qualification (TS Pin)
      3. 7.3.3 Status Outputs (STAT)
        1. 7.3.3.1 Charging Status Indicator (STAT)
      4. 7.3.4 Protection Features
        1. 7.3.4.1 Input Overvoltage Protection (VIN OVP)
        2. 7.3.4.2 Output Overvoltage Protection (BAT OVP)
        3. 7.3.4.3 Output Overcurrent Protection (BAT OCP)
        4. 7.3.4.4 Thermal Regulation and Thermal Shutdown (TREG and TSHUT)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown or Undervoltage Lockout (UVLO)
      2. 7.4.2 Sleep Mode
      3. 7.4.3 Active Mode
        1. 7.4.3.1 Standby Mode
      4. 7.4.4 Fault Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 NiMH Charger Design Example
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.1.1 ISET Pin Detection

After a valid VIN is plugged in and VTS > VTS_EN, the device checks the resistor on the ISET pin for a short circuit (RISET < RISET_SHORT). If a short condition is detected, the charger remains in the FAULT state until the input or TS pin is toggled. If the ISET pin is open-circuit, the charger proceeds through pin detection and starts the charger with no charge current. The ISET pin is monitored while charging and changes in RISET while the charger is operating immediately translates to changes in charge current.

An external pulldown resistor (±1% or better is recommended to minimize charge current error) from the ISET pin to GND sets the charge current as:

Equation 1. GUID-40D0B89F-0D4F-4D54-ACBF-9D822205B48B-low.gif

where:

  • ICHG is the desired charge current
  • KISET is a gain factor found in the electrical characteristics
  • RISET is the pulldown resistor from the ISET pin to GND

For charge currents below 50 mA, an extra RC circuit is recommended on ISET to achieve a more stable current signal. For greater accuracy at lower currents, part of the current-sensing FET is disabled to give better resolution.