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Application NotesAN-171: Reverse Voltage Protection for Battery Chargers
Features and Benefits
- 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
- LT1571-1: 200kHz, Adjustable Voltage
- LT1571-2: 200kHz, Fixed 8.2V or 8.4V
- LT1571-5: 500kHz, Fixed 4.1V or 4.2V
The LT1571 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 (LT1571-1, LT1571-2) or 500kHz (LT1571-5) 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.
- Cellular Phones, PDAs, Notebook Computers, Portable Instruments
- Cradle Chargers for Li-Ion, NiCd, NiMH and Lead-Acid Rechargeable Batteries
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
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