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SY8821 Sample Application
General Description

SY8821 is an IC specially designed for charge cradle of Bluetooth headset. The device is integrated with a charger and a boost inside. The charging current can be adjusted externally. The discharge module integrates two switches for output current limiting protection. Load in detection, load existing detection, and load current detection are also available. The IC integrates NTC protection function to charge and discharge the battery more safely.
SY8821 supports discharge control through an enable signal EN, so the MCU can control the discharge function of the IC directly through EN. SY8821 integrates a single-wire state code output, which is convenient for the IC to report the IC state to the MCU. SY8821 suits the Bluetooth headset charging compartment perfectly. It greatly simplifies the peripheral circuits and components, providing a simple and easy-to-use solution for charge cradle of Bluetooth earphone.
SY8821 use QFN16 3mm*3mm package.

Features

Standby current in auto recognition state: 5uA

Standby current in constant output state: 2.5uA

Charge current is set by external resistor

Charge current up to 1A

Charging current temperature adjustment function, the charging current automatically decreases with the increase of temperature

charge termination current: C/10, automatically recharge

4.20V/4.35V charging float voltage with ±1% accuracy

Over voltage protection is integrated

Synchronous boost output is 5.05V with high efficiency up to 93%@0.1A 

Load in detection  Support load current detection. Light load turn off current: 4.5mA 

Load current two-level overcurrent protection

Supports 5.05V constant output

Thermal regulation for boost output

Overcurrent protection, short circuit protection, overvoltage protection, and over temperature protection are integrated for discharge module

Enable control and state control

State code output  IEC 62368 certified

1-4 LED display mode, external automatically detection

KEY version:Integrated button function, click to start the discharge and battery display, long press the button for 3 seconds to close the discharge

HALL version:Support HALL chip direct drive, automatically start discharging when the box is closed, and the headset will automatically turn on and reconnect when the box is opened

Typical Application Circuit Diagram
Applications

Charge cradle of Bluetooth headset 

 Portable lithium battery application 

Other low-power power application