The LT1769CFE current mode PWM battery charger is a simple, efficient solution to fast charge modern rechargeable batteries including lithium-ion (Li-Ion), nickel-metal-hydride (NiMH) and nickel-cadmium (NiCd) that require constant-current and/or constant-voltage charging. The internal switch is capable of delivering 2A** DC current (3A peak current). Charge current can be programmed by resistors or a DAC to within 5%. With 0.5% reference voltage accuracy, the LT1769CFE meets the critical constant-voltage charging requirement for Li-Ion cells.
A third control loop is provided to regulate the current drawn from the input AC adapter. This allows simultaneous operation of the equipment and battery charging without overloading the adapter. Charge current is reduced to keep the adapter current below specified levels.
The LT1769CFE can charge batteries ranging from 1V to 20V. Ground sensing of current is not required and the battery’s negative terminal can be tied directly to ground. A saturating switch running at 200kHz gives high charging efficiency and small inductor size. A blocking diode is not required between the chip and the battery because the chip goes into sleep mode and drains only 3µA when the wall adapter is unplugged.
Feature
- Simple Solution to Charge NiCd, NiMH and Lithium Rechargeable Batteries—Charging Current Programmed by Resistors or DAC
- Adapter Current Limit Allows Maximum Possible Charging Current During System Use*
- Precision 0.5% Accuracy for Voltage Mode Charging
- High Efficiency Current Mode PWM with 3A Internal Switch
- 5% Charge Current Accuracy
- Adjustable Undervoltage Lockout
- Automatic Shutdown When AC Adapter is Removed
- Low Reverse Battery Drain Current: 3µA
- Current Sensing Can Be at Either Terminal of the Battery
- Charging Current Soft Start
- Shutdown Control
- Available in 20-Lead Exposed Pad TSSOP and 28-Lead Narrow SSOP Packages
Applications
- Chargers for NiCd, NiMH, Lead-Acid, Lithium Rechargeable Batteries
- Switching Regulators with Precision Current Limit
(Picture: Pinout)
