Features and Benefits
- Wide Input Voltage Range: Up to 32V (40V Absolute Maximum)
- Programmable Charge Current Up to 4A
- Selectable C/10 or On-board Timer Termination
- Dynamic Charge Rate Programming/Soft-Start
- Programmable Input Current Limit
- 0.5% Float Voltage Accuracy
- 7.5% Charge Current Accuracy
- 4% C/10 Detection Accuracy
- NTC Resistor Temperature Monitor
- Auto-Recharge at 97.5% Float Voltage
- Auto-Precondition <70% Float Voltage
- Bad Battery Detection with Auto-Reset
- Average Current Mode, Synchronous Switcher
- User Programmable Frequency
- Low Profile (0.75mm) 5mm × 6mm 36-Pin QFN Package
The LT3651 is a 1 cell 4A Li-Ion/Polymer battery charger that operates with input voltages up to 32V. An efficient monolithic average current mode synchronous switching regulator provides constant current, constant voltage charging with programmable maximum charge current. A charging cycle starts with battery insertion or when the battery voltage drops 2.5% below the float voltage. Charger termination is selectable as either charge current or internal safety timer timeout. Charge current termination occurs when the charge current falls to one-tenth the programmed maximum current (C/10). Timer based termination is typically set to three hours and is user programmable (charging continues below C/10 until timeout). Once charging is terminated, the LT3651 supply current drops to 85μA into a standby mode.
The LT3651 offers several safety features. A discharged battery is preconditioned with a small trickle charge and generates a signal if unresponsive. A thermistor monitors battery temperature, halting charging if out of range. Excessive die temperature reduces charge current. Charge current is also reduced to maintain constant input current to prevent excessive input loading.
The LT3651 is available in a 5mm × 6mm 36-pin QFN package.
- Industrial Handheld Instruments
- 12V to 24V Automotive and Heavy Equipment
- Desktop Cradle Chargers
- Notebook Computers
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.
Evaluation Kits (2)
Demonstration circuit 1362A-A (4.2V fixed output) is a 4A high voltage Li-Ion battery charger featuring the LT3651EUHE-4.2. The LT3651 is a complete, high power Li-Ion battery charger that can operate over a wide input voltage range. The charger is a constant-current, constant-voltage type with a maximum charge current of 4A that can be externally set. A precondition feature trickle charges a low voltage battery and bad battery detection provides a signal if the battery doesn’t respond to preconditioning. The LT3651EUHE is available in a 36-lead (5mm × 6mm) QFN surface mount package with two exposed thermal pads.
Demonstration circuit 1362A-B (fixed 4.1V output) is a 4A high voltage Li-Ion battery charger featuring the LT3651EUHE-4.1. The LT3651 is a complete, high power Li-Ion battery charger that can operate over a wide input voltage range. The charger is a constant-current, constant-voltage type with a maximum charge current of 4A that can be externally set. A precondition feature trickle charges a low voltage battery and bad battery detection provides a signal if the battery doesn’t respond to preconditioning. The LT3651EUHE is available in a 36-lead (5mm × 6mm) QFN surface mount package with two exposed thermal pads.
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
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Sample & Buy
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.