Lithium-Ion Battery Charger Circuit using MCP73831

Lithium-Ion Battery Charger Circuit

This post is about a tested sample circuit of a Lithium-Ion Battery charger that can be used to charge any 3.7V, 500mA Li-Ion battery using a 5V DC (USB, Solar Panel, DC Adapter) power supply. The circuit is designed using a microchip MCP73831/2 IC. MCP73831 is a highly advanced linear charge management controller for use in space-limited, cost-sensitive applications. This IC employs a constant current/constant voltage charge algorithm with selectable preconditioning and charges termination.

So let’s learn about the MCP73831 IC as well as its feature and way of implementation. It is also called a Miniature Single-Cell, full integrated Li-Ion Li-Polymer Charge Management Controllers. You may check the 5V 3A USB Charger Circuit.

Features of MCP73831

Let’s discuss the features of MCP73831 Li-Ion/Li-Po Charger 4.2V, 500mA. Its features are as follows:

1. Linear Charge Management Controller:

• Integrated Pass Transistor
• Integrated Current Sense
• Reverse Discharge Protection

1. High Accuracy Preset Voltage Regulation: + 0.75%
2. Four Voltage Regulation Options: 4.20V, 4.35V, 4.40V, 4.50V
3. Programmable Charge Current: 15 mA to 500 mA
4. Constant Current & Constant Voltage Charge Algorithm with Selectable Pre-Conditioning Charge Termination.
5. Selectable End-of-Charge Control: 5%, 7.5%, 10%, or 20%
6. Constant Current value can be set with 1 external resistor.
7. Automatic Power-Down: Limits Charge Current based on die temperature during high power & high ambient condition.
8. Thermal Regulation: Optimizes the charge cycle time maintaining device reliability
9. Temperature Range: -40°C to +85°C
10. Packaging:

– 8-Lead, 2 mm x 3 mm DFN
– 5-Lead, SOT-23

Applications of MCP73831

MCP73831 has a wide range of applications in small portable devices due to its miniature size and best battery management capability. Some of the devices where it’s widely used are:

1. Lithium-Ion/Lithium-Polymer Battery Chargers
2. Personal Data Assistants
3. Cellular Telephones
4. Digital Cameras
5. MP3 Players
6. Bluetooth Headsets
7. USB Chargers

Pins Description of MCP73831

1. Charge Status Output (STAT)
STAT is output for connection to an LED for charge status indication. Alternatively, a pull-up resistor can be applied for interfacing to a host microcontroller. STAT is a tri-state logic output on the MCP73831 and an open-drain output on the MCP73832.

2. Battery Management 0V Reference (VSS)
Connect to negative terminal of battery and input supply.

3. Battery Charge Control Output (VBAT)
Connect to the positive terminal of the battery. The drain terminal of the internal P-channel MOSFET pass transistor. Bypass to VSS with a minimum of 4.7 µF to ensure loop stability when the battery is disconnected.

4. Battery Management Input Supply (VDD)
A supply voltage of [VREG (typical) + 0.3V] to 6V is recommended. Bypass to VSS with a minimum of 4.7 µF.

5. Current Regulation Set (PROG)
Preconditioning, fast charge, and termination currents are scaled by placing a resistor from PROG to VSS. The charge management controller can be disabled by allowing the PROG input to float.

Designing 3.7 V, 500 mA Lithium-Ion Battery Charger Circuit

This is the tiniest little Li-ion/Li-po charger, so handy you can keep it any project box. It’s also easy to use. Simply plug in the input contact into any USB port or any 5V DC Supply and a 3.7V/4.2V lithium polymer or lithium-ion rechargeable battery into the output plug on the other end.

Li-ion batteries need to be charged following a carefully controlled constant current/constant voltage (CV-CC) pattern that is unique to this cell chemistry. Overcharging and careless handling of a Li-ion cell can cause permanent damage, or instability and potential danger!

Charging is performed in three stages: first a preconditioning charge, then a constant-current fast charge and finally a constant-voltage trickle charge to keep the battery topped-up. The charge current is 100mA by default, so it will work with any size battery and USB port. If you want you can easily change it over to 500mA mode by soldering closed the jumper on the back, for when you’ll only be charging batteries with 500mAh size or larger.

PCB Designing & Ordering Online

If you don’t want to assemble the circuit on a breadboard and you want PCB for the project, then here is the PCB for you.

First I designed the Schematic using EasyEDA. Then I converted the schematic to PCB. The PCB Board for Lithium-Ion Battery Charger looks something like below.

The Gerber File for the PCB is given below. You can simply download the Gerber File and order the PCB from ALLPCB at 1$ only.

You can use this Gerber file to order high quality PCB for this project. To do that visit the ALLPCB official website by clicking here: https://www.allpcb.com/.

You can now upload the Gerber File by choosing the Quote Now option. From these options, you can choose the Material Type, Dimensions, Quantity, Thickness, Solder Mask Color and other required parameters.

After filling all details, select your country and shipping method. Finally you can place the order.

You can assemble the components on the PCB Board.