ZHCSBK4G March 2013 – March 2019
PRODUCTION DATA.
- 1 特性
- 2 应用
- 3 说明
- 4 修订历史记录
- 5 Pin Configuration and Functions
- 6 Specifications
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3
Feature Description
- 7.3.1 Maximum Power Point Tracking
- 7.3.2 Battery Undervoltage Protection
- 7.3.3 Battery Overvoltage Protection
- 7.3.4 Battery Voltage within Operating Range (VBAT_OK Output)
- 7.3.5 Storage Element / Battery Management
- 7.3.6 Programming OUT Regulation Voltage
- 7.3.7 Step Down (Buck) Converter
- 7.3.8 Nano-Power Management and Efficiency
- 7.4 Device Functional Modes
- 8 Application and Implementation
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文档支持
- 12机械、封装和可订购信息
7.3.3 Battery Overvoltage Protection
To prevent rechargeable batteries from being exposed to excessive charging voltages and to prevent over charging a capacitive storage element, the over-voltage (VBAT_OV) threshold level must be set using external resistors. This is also the voltage value to which the charger will regulate the VSTOR/VBAT pin when the input has sufficient power. The VBAT_OV threshold when the battery voltage is rising is given by Equation 2:
The sum of the resistors is recommended to be no higher than 13 MΩ that is, ROV1 + ROV2 = 13 MΩ. Spreadsheet SLUC484 provides help on sizing and selecting the resistors. The overvoltage threshold when battery voltage is decreasing is given by VBAT_OV minus VBAT_OV_HYST. Once the voltage at the battery exceeds VBAT_OV threshold, the boost charger is disabled. The charger will start again once the battery voltage drops by VBAT_OV_HYST. When there is excessive input energy, the VBAT pin voltage will ripple between the VBAT_OV and the VBAT_OV_HYST levels.
CAUTION
If VIN_DC is higher than VSTOR and VSTOR is equal to VBAT_OV, the input VIN_DC is pulled to ground through a small resistance to stop further charging of the attached battery or capacitor. It is critical that if this case is expected, the impedance of the source attached to VIN_DC be higher than 20 Ω and not a low impedance source.