ZHCSLN5D december 2010 – september 2020 BQ24133
PRODUCTION DATA
- 1
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 Description (continued)
- 6 Device Comparison Table
- 7 Pin Configuration and Functions
- 8 Specifications
-
9 Detailed Description
- 9.1 Overview
- 9.2 Functional Block Diagram
- 9.3
Feature Description
- 9.3.1 Battery Voltage Regulation
- 9.3.2 Battery Current Regulation
- 9.3.3 Battery Precharge Current Regulation
- 9.3.4 Input Current Regulation
- 9.3.5 Charge Termination, Recharge, And Safety Timers
- 9.3.6 Power Up
- 9.3.7 Input Undervoltage Lockout (UVLO)
- 9.3.8 Input Overvoltage/Undervoltage Protection
- 9.3.9 Enable and Disable Charging
- 9.3.10 System Power Selector
- 9.3.11 Converter Operation
- 9.3.12 Automatic Internal Soft-Start Charger Current
- 9.3.13 Charge Overcurrent Protection
- 9.3.14 Charge Undercurrent Protection
- 9.3.15 Battery Detection
- 9.3.16 Battery Short Protection
- 9.3.17 Battery Overvoltage Protection
- 9.3.18 Temperature Qualification
- 9.3.19 MOSFET Short Circuit and Inductor Short Circuit Protection
- 9.3.20 Thermal Regulation and Shutdown Protection
- 9.3.21 Timer Fault Recovery
- 9.3.22 Charge Status Outputs
- 9.4 Device Functional Modes
- 10Application and Implementation
- 11Power Supply Recommendations
- 12Layout
- 13Device and Documentation Support
- 14Mechanical, Packaging, and Orderable Information
9.3.5 Charge Termination, Recharge, And Safety Timers
The charger monitors the charging current during the voltage regulation phase. Termination is detected when the SRN voltage is higher than recharge threshold and the charge current is less than the termination current threshold, as calculated below:
where
- VISET is the voltage on the ISET pin.
- RSR is the sense resistor.
There is a 25-ms deglitch time during transition between fast charge and precharge.
As a safety backup, the charger also provides an internal fixed 30 minutes precharge safety timer and a programmable fast charge timer. The fast charge time is programmed by the capacitor connected between the TTC pin and AGND, and is given by the formula:
where
- CTTC is the capacitor connected to TTC.
- KTTC is the constant multiplier.
A new charge cycle is initiated when one of the following conditions occurs:
- The battery voltage falls below the recharge threshold
- A power-on-reset (POR) event occurs
- ISET pin toggled below 40 mV (disable charge) and above 120 mV (enable charge)
Pull the TTC pin to AGND to disable both termination and fast charge safety timer (reset timer). Pull the TTC pin to VREF to disable the safety timer, but allow charge termination.