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

7.3.2.1 NiMH Battery Charging Profile

The device charges NiMH batteries in constant current mode only. The charge current programmed by ISET is the only current applied over the charging cycle, as shown in Figure 7-1. The charge termination method for the device is timer-based. The charge safety timer, tSAFETY, sets the charging duration. Programming the charge safety timer is done with a pulldown resistor on the TMR pin.

Intermittent charging is designed to replenish the natural self-discharge of NiMH cells by restarting a short charge cycle (20% of tSAFETY) when the output voltage falls below the VRECHG threshold. If the intermittent charging function is disabled and a full charge cycle has been completed (safety timer expired with VOUT above VRECHG), the device does not start a new charge cycle automatically and requires input supply or TS pin toggle to initiate a new charge cycle.

If battery voltage is above VRECHG at power up, the battery is considered full and the device does not charge. Once the battery voltage falls below VRECHG, the device automatically begins charging. If the intermittent charging function is disabled, a single charge cycle is initiated with the safety timer duration programmed by the TMR pin. If intermittent charging is enabled, an intermittent charge cycle is initiated for 20% of the TMR programmed value.

When the charge timer (full-length or intermittent) expires, the battery voltage is checked again. If the battery voltage is below VRECHG, a fault is reported through the STAT pin and further charging is prevented. If the charge timer expires with VOUT above VRECHG, the STAT pin indicates charge completed. In the case where the TS fault is within the cool threshold, VOUT_OVP is automatically reduced to VOUT_OVP_TSCOOL voltage.

If the charger is in thermal regulation during charging, the actual charging current will be less than the programmed value. Termination by timer is still enabled, but the charging safety timer is counted at half the clock rate. For more information, refer to Section 7.3.2.2.

Figure 7-1 NiMH Battery Charging Profile with Intermittent Charging Disabled
Figure 7-2 NiMH Battery Charging Profile with Intermittent Charging Enabled