Linear 公司的LT3652是完整的降压电池充电器,输入电压从4.95V到32V,具有恒流/恒压充电特性,最大充电电流可达2A,当LT3652连接到太阳能电池板时,它的输入调整回路能使电池板保持在峰值输出功率.充电电流精度达5%,可编程的安全定时器能在充电时间到了时终止充电. LT3652可用在太阳能应用,遥控监视站, LiFePO4电池应用和手提仪表.本文介绍了LT3652的主要特性,方框图以及多种应用电路和演示板的指标,详细电路与所用材料清单.
LT3652 Power Tracking 2A Battery Charger for Solar Power
The LT 3652 is a complete monolithic step-down battery charger that operates over a 4.95V to 32V input voltage range. The LT3652 provides a constant-current/ constant-voltage charge characteristic, with maximum charge current externally programmable up to 2A. The charger employs a 3.3V fl oat voltage feedback reference,so any desired battery float voltage up to 14.4V can be programmed with a resistor divider.
The LT3652 employs an input voltage regulation loop, which reduces charge current if the input voltage falls below a programmed level, set with a resistor divider. When the LT3652 is powered by a solar panel, the input regulation loop is used to maintain the panel at peak output power.
The LT3652 can be configured to terminate charging when charge current falls below 1/10 of the programmed maximum (C/10). Once charging is terminated, the LT3652 enters a low-current (85μA) standby mode. An auto-recharge feature starts a new charging cycle if the battery voltage falls 2.5% below the programmed fl oat voltage.
The LT3652 also contains a programmable safety timer, used to terminate charging after a desired time is reached. This allows top-off charging at currents less than C/10.
Input Supply Voltage Regulation Loop for Peak Power Tracking in (MPPT) Solar Applications
Wide Input Voltage Range: 4.95V to 32V (40V Abs Max)
Programmable Charge Rate Up to 2A
User Selectable Termination: C/10 or On-Board Termination Timer
Resistor Programmable Float Voltage Up to 14.4V Accommodates Li-Ion/Polymer, LiFePO4, SLA, NiMH/NiCd Chemistries
No VIN Blocking Diode Required for Battery Voltages ≤ 4.2V
1MHz Fixed Frequency
0.5% Float Voltage Reference Accuracy
5% Charge Current Accuracy
2.5% C/10 Detection Accuracy
Binary-Coded Open-Collector Status Pins
3mm.3mm DFN12 Package
Solar Powered Applications
Remote Monitoring Stations
LiFePO4 (Lithium Phosphate) Applications
Portable Handheld Instruments
12V to 24V Automotive Systems
Demonstration Circuit 1568A is a 2A Monolithic Multi-Chemistry battery charger for solar power applications featuring the LT3652EDD. The LT3652 is a complete mid-power Li-Ion battery charger that can operate over a wide input voltage range. The charger employs a 3.3V float voltage feedback reference that allows the battery float voltage to be adjusted up to 14.4V. R10 and R11, in the demonstration circuit, set the float voltage and are 0603 resistors to accommodate the use of 0.1% resistors if desired. The circuit is constructed with 1% resistors which could introduce as much as a 1.56% error in the float voltage. Replacing these resistors with 0.1% resistors would introduce less than a 0.154% error. The LT3652 has an input voltage regulation loop which reduces charge current if the input falls below a programmed level, set with a resistor divider. The charger is a CC/CV charger with a maximum charge current of 2A. A precondition feature trickle charges a lowvoltage battery, and bad battery detection provides a signal if the battery doesn’t respond to
The LT3652EDD is available in a 12-lead (3mm × 3mm) DFN surface mount package with an exposed pad.
Typical Specifications (25℃)