Linear公司的LTC3225是可編程的超大電容充電器,能對兩個串聯(lián)的超大電容器充電到固定的4.8V/5.3V(可選擇),輸入電壓從2.8V/3V到5.5V.自動的電池平衡能防止過壓對電容的損害,但是不要平衡電阻.本文介紹了LTC3225的主要性能,方框圖以及典型的應(yīng)用電路和5V超大電容備份電源電路圖.

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)

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

　　

　　　　　　　　　　　　　　　　　　圖1. LTC3225簡化方框圖

　　　　　　　　　　　　　

　　　　　　　　　　　　　　　　　　　　　　圖2. LTC3225典型應(yīng)用

　　


　　　　　　　　　　　　　　　　　　圖3. 5V超大電容備份電源電路圖