充电芯片4054学习手册
- 芯片封装
- 管脚介绍
- 芯片应用电路
芯片封装
管脚介绍
| NAME | FUNCTION |
|---|---|
| CHRG | Open-Drain Charger Status indication pin. When the battery is charging, the CHRG pin is pulled low by an internal N-channel MOSFET. When the charge cycle is completed, a weak pull-down of approximately 20μA is connected to the CHRG pin, indicating an “AC present” condition. When the SGM4054 detects an undervoltage lockout condition, CHRG is forced high impedance. |
| BAT | Charge Current Output pin, connecting with Li-ion battery. Provides charge to 4.2V. An internal precision resistor divider from this pin sets the float voltage which is disconnected in shutdown mode. |
| V+ | Positive Input Supply Voltage. Provides power to the charger. V+ can range from 4.25V to 6.5V and should be bypassed with at least a 1μF capacitor. When V+ drops to within 54mV of the BAT pin voltage, the SGM4054 enters shutdown mode, dropping IBAT to less than 3μA. |
| PROG | Charge Current Program, Charge Current Monitor and Shutdown control Pin. The charge current is programmed by connecting a 1% resistor from RPROG pin to ground. When charging in constant-current mode, this pin servos to 1V. In all modes, the voltage on this pin can be used to measure the charge current using the following formula: IBAT = (VPROG/RPROG) • 1000 The PROG pin can also be used to shut down the charger. Disconnecting the program resistor from ground allows a 3uAcurrent to pull this pin to High When it reaches the 1.23V shutdown threshold voltage, the charger enters shutdown mode, charging stops and the input supply current drops to 25μA, this pin is also clamped to approximately 2.4V. Driving this pin to voltages beyond the clamp voltage will draw currents as high as 1.5mA. Reconnecting RPROG to ground will return the charger to normal operation. |
芯片应用电路
典型应用
扩展应用
The charge status output has three different states: strong pull-down (~10mA), weak pull-down (~20µA) and high impedance. The strong pull-down state indicates that the SGM4054 is in a charge cycle. Once the charge cycle has terminated, the pin state is determined by undervoltage lockout conditions. A weak pull-down indicates that V+ meets the UVLO conditions and the SGM4054 is ready to charge. High impedance indicates that the SGM4054 is in undervoltage lockout mode: either V+ is less than 100mV above the BAT pin voltage or insufficient voltage is applied to the V+ pin. A microprocessor can be used to distinguish between these three states—this method is discussed in the Applications Information section.
To detect when the SGM4054 is in charge mode, force the digital output pin (OUT) high and measure the voltage at the CHGR pin. The N-channel MOSFET will pull the pin voltage low even with the 2k pull-up resistor. Once the charge cycle terminates, the N-channel MOSFET is turned off and a 20µA current source is connected to the CHGR pin. The IN pin will then be pulled high by the 2k pull-up resistor. To determine if there is a weak pull-down current, the OUT pin should be forced to a high impedance state. The weak current source will pull the IN pin low through the 800k resistor; if CHGR is high impedance, the IN pin will be pulled high, indicating that the part is in a UVLO state.
1. 当充电时，强下拉电流使得IN管教监测到低电平；当充满时弱下拉电流为20uA，此时上拉2K电阻只能分压40mV，IN监测到的是高电平则认为充饱了。
2. 当充饱时开启监测是否移除充电桩的操作，OUT配置为高阻，若没有移除充电桩，弱下拉电流20uA乘以800K上拉电阻，分压接近VDD电压，IN输入电压为低电平；若移除了充电桩，CHGR为高阻态，IN输入电压为高电平。
3. OUT输出为高，若检测到输入为高，则认为在充电状态；若输入为低，则进入判断是充饱了还是已经移除了充电器；把OUT置为高阻态，若IN检测为低，则认为充饱了，若检测为高则认为充电桩移除了。
