ZHCSNY0B May 2020 – January 2023 BQ25798
PRODUCTION DATA
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 说明（续）
- 6 Device Comparison
- 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 Device Power-On-Reset
- 9.3.2 PROG Pin Configuration
- 9.3.3 Device Power Up from Battery without Input Source
- 9.3.4 Device Power Up from Input Source
- 9.3.5 Dual-Input Power Mux
- 9.3.6 Buck-Boost Converter Operation
- 9.3.7 USB On-The-Go (OTG)
- 9.3.8 Power Path Management
- 9.3.9 Battery Charging Management
- 9.3.10 Integrated 16-Bit ADC for Monitoring
- 9.3.11 Status Outputs ( STAT, and INT)
- 9.3.12 Ship FET Control
- 9.3.13
Protections
- 9.3.13.1
Voltage and Current Monitoring
- 9.3.13.1.1 VAC Over-voltage Protection (VAC_OVP)
- 9.3.13.1.2 VBUS Over-voltage Protection (VBUS_OVP)
- 9.3.13.1.3 VBUS Under-voltage Protection (POORSRC)
- 9.3.13.1.4 System Over-voltage Protection (VSYS_OVP)
- 9.3.13.1.5 System Short Protection (VSYS_SHORT)
- 9.3.13.1.6 Battery Over-voltage Protection (VBAT_OVP)
- 9.3.13.1.7 Battery Over-current Protection (IBAT_OCP)
- 9.3.13.1.8 Input Over-current Protection (IBUS_OCP)
- 9.3.13.1.9 OTG Over-voltage Protection (OTG_OVP)
- 9.3.13.1.10 OTG Under-voltage Protection (OTG_UVP)
- 9.3.13.2 Thermal Regulation and Thermal Shutdown
- 9.3.13.1
Voltage and Current Monitoring
- 9.3.14 Serial Interface
- 9.4 Device Functional Modes
- 9.5 Register Map
- 10Application and Implementation
- 11Power Supply Recommendations
- 12Layout
- 13Device and Documentation Support
- 14Mechanical, Packaging, and Orderable Information
10.2.2.4 Output (VSYS) Capacitor
In the boost mode operation, the output current is discontinuous, which dominates the output RMS ripple current and output voltage ripple. The output capacitors should have enough ripple current rating to absorb the output AC current and have large enough capacitance to maintain the small output voltage ripple. For the boost mode operation, the output RMS ripple current is calculated by the equation (8) and the output voltage ripple is calculated by the equation (9), where D = (1 - VBUS / VSYS).
The worst case output RMS ripple current and output voltage ripple both occur at the lowest VBUS input voltage. The SYS voltage is approximately 8V for the 2s battery configuration, so the worst case is 5V VBUS condition. Low ESR ceramic capacitor such as X7R or X5R is preferred for the output decoupling capacitor and should be placed close to the SYS and GND pins of the IC. The voltage rating of the capacitor must be higher than the normal input voltage level. The capacitor with 16V or higher voltage rating is preferred for the 2s battery configuration. 1*0.1 μF + 5*10 μF capacitors are suggested for up to 5A charging current.