Linear公司的LTC3225是可编程的超大电容充电器,能对两个串联的超大电容器充电到固定的4.8V/5.3V(可选择),输入电压从2.8V/3V到5.5V.自动的电池平衡能防止过压对电容的损害,但是不要平衡电阻.本文介绍了LTC3225的主要性能,方框图以及典型的应用电路和5V超大电容备份电源电路图.

LTC3225 150mA Supercapacitor Charger
The LTC 3225 is a programmable supercapacitor charger designed to charge two supercapacitors in series to a fixed output voltage (4.8V/5.3V selectable) from a 2.8V/3V
to 5.5V input supply. Automatic cell balancing prevents overvoltage damage to either supercapacitor. No balancing resistors are required.
Low input noise, low quiescent current and low external parts count (one flying capacitor, one bypass capacitor at VIN and one programming resistor) make the LTC3225 ideally suited for small battery-powered applications. Charging current level is programmed with an external resistor. When the input supply is removed, the LTC3225 automatically enters a low current state, drawing less than 1μA from the supercapacitors.

The LTC3225 is available in a 10-lead 3mmX2mm DFN package.

主要特性:
Low Noise Constant Frequency Charging of Two Series Supercapacitors
Automatic Cell Balancing Prevents Capacitor Overvoltage During Charging
Programmable Charging Current (Up to 150mA)
Selectable 2.4V or 2.65V Regulation per Cell
Automatic Recharge
IVIN = 20μA in Standby Mode
ICOUT < 1μA When Input Supply is Removed
No Inductors
Tiny Application Circuit (3mm &#61655;&#61472;2mm DFN Package,
All Components <1mm High)

应用:
Current Limited Applications with High Peak Power Loads (LED Flash, PCMCIA Tx Bursts, HDD Bursts,GPRS/GSM Transmitter)
Backup Supplies

　　

　　　　　　　　　　　　　　　　　　图1. LTC3225简化方框图

　　　　　　　　　　　　　

　　　　　　　　　　　　　　　　　　　　　　图2. LTC3225典型应用

　　


　　　　　　　　　　　　　　　　　　图3. 5V超大电容备份电源电路图