LT1571

Features:

 Fast Charging of Li-Ion, NiMH and NiCd Batteries
 Simple Charge Current Programming Requires Only
    One Low Cost, 1/32W Resistor
 High Efficiency Charger with Up to
    1.5A Charge Current
 Precision 0.6% Internal Voltage Reference
 Preset Battery Voltages: 4.1V, 4.2V, 8.2V, 8.4V
 500kHz or 200kHz Switching Frequency
    Minimizes Charger Size
 Low Reverse Battery Drain Current: 5µA
 Flag Indicates Li-Ion Charge Completion
 5% Typical Charge Current Accuracy
 Low Shutdown Current
 LT1571-5: 500kHz, Fixed 4.1V or 4.2V
    LT1571-1: 200kHz, Adjustable Voltage
    LT1571-2: 200kHz, Fixed 8.2V or 8.4V


Application

Cellular Phones, PDAs, Notebook Computers,
    Portable Instruments
 Cradle Chargers for Li-Ion, NiCd, NiMH and
    Lead-Acid Rechargeable Batteries


Pinout




Specifications

Supply Voltage (V_CC) ..............................................  28V
BOOST Pin Voltage with Respect to V_CC .................  20V
FLAG Pin Voltage ..................................................... V_CC
IBAT (Average) ........................................................1.5A
Switch Current (Peak) ..............................................  2A
Storage Temperature Range ............. 65°C to 150°C
Operating Ambient
Temperature Range (Note 2) ..............  40°C to 85°C
Operating Junction
Temperature Range ........................... 40°C to 125°C
Lead Temperature (Soldering, 10 sec) ................ 300°C


Description

The LT^® 1571 PWM battery charger is a simple, efficient solution to fast-charge rechargeable batteries including lithium-ion (Li-Ion), nickel-metal-hydride (NiMH) and nickel-cadmium (NiCd) using constant-current and/or constant-voltage control. The internal switch is capable of delivering 1.5A DC current (2A peak current). The onboard current sense resistor (0.1Ω) allows simple charge current programming to within 5% accuracy using a low cost external resistor. The constant-voltage output can be selected for 4.1V or 4.2V per cell with 0.6% accuracy.

LT1571 can charge batteries ranging from 1V to 20V. A saturating switch operating at 200kHz or 500kHz  gives high efficiency and small charger size. A logic output (flag) indicates Li-Ion near full charge when the charge current drops to 20% of the programmed value. The LT1571-1 and LT1571-2 are in a 28-pin fused lead narrow SSOP power package. The LT1571-5 is in a 16-pin fused lead narrow SSOP power package.