Summary of LIR1220 BATTERY CHARGER PLUGS IN USB
The LIR1220 is a 12.5 mm by 2 mm, 1.1 g lithium-ion rechargeable coin cell with 3.6 V nominal voltage, ~12 mAh capacity, 43 Wh/kg energy density, and about 500 half cycles. It requires CC/CV charging to 4.2 V at 0.5C (6 mA). The MCP73831 linear charge management controller is recommended for compact CC/CV charging, offering selectable charge voltages (4.20, 4.35, 4.40, 4.50 V), preconditioning, and charge termination suitable for small devices and wearables.
Parts used in the LIR1220 Battery Charger Project:
- LIR1220 lithium-ion rechargeable coin cell (12.5 mm x 2 mm, 3.6V, ~12 mAh)
- MCP73831 linear charge management controller IC
- USB power source (implied for USB charger application)
- Resistor to set charging current for MCP73831 (to achieve 6 mA)
- Capacitors as recommended for MCP73831 stability (implied)
The LIR1220 is a 12.5 mm. lithium-ion rechargeable coin cell. It is a relatively new technology. Traditionally, li-ion coin cells are non-rechargeable but for some situations, rechargeable compact cells are desired.
Coin cells like CR2032 are ultra-compact and are used in a variety of compact systems like wearables and if something with this form factor is made rechargeable, then it can be used for a wide range of small form factor applications. The new LIR1220 offers a high energy density 43Wh/kg and has a half cycle of approximately 500 cycles.
To get an idea about the compactness of the battery, it is 12.5mm in diameter and 2mm thick. In addition, the nominal weight is 1.1g. Due to these advantages, LIR1220 finds its place in applications like wearables, Bluetooth headsets, body sensors, medical devices, wireless sensors, remote controls, toys, networking devices, and many others.
The battery has a nominal voltage of 3.6V and a typical nominal capacity of 12mAh. It must be charged with a Constant-Current-Constant-Voltage (CC/CV) charger. These chargers can supply a fixed current and fixed voltage regardless of the load resistance. The voltage that the battery must be charged is 4.2V (advised by the manufacturer) and the current to supplied while charging should be 0.5C. 0.5C means 0.5 times the battery capacity which in this case is 12mAh. Therefore, the charging current should be 6mA. All this data is crucial in setting the output voltage and current of the battery charger circuit.
Battery Charger IC
For charging the battery, we are turning our attention to a linear charge management controller IC, MCP73831. MCP73831 is a very advanced charge management controller for applications where space is a constraint. This small-sized IC is very economical and finds its applications in Lithium-Ion/Lithium-Polymer Battery Chargers, Personal Data Assistants, Cellular Telephones, Digital Cameras, MP3 Players, Bluetooth Headsets, USB Chargers, and many others.
The charge controller IC uses Constant-Current-Constant-Voltage (CC/CV) charging algorithm which is compatible with our LIR1220 battery. The charging voltage can be fixed from four available options: 4.20V, 4.35V, 4.40V, or 4.50V. In addition, the IC also comes with selectable preconditioning and charge termination. Preconditioning means when the battery voltage is less than the preconditioning threshold set, then the IC goes into trickle charging or preconditioning mode.
Read more: LIR1220 BATTERY CHARGER PLUGS IN USB
- What is the nominal voltage of the LIR1220?
The nominal voltage is 3.6V. - What is the typical nominal capacity of the LIR1220?
The typical nominal capacity is 12 mAh. - To what voltage must the LIR1220 be charged?
The manufacturer advises charging the battery to 4.2V. - What charging current should be used for the LIR1220?
Charge at 0.5C, which for a 12 mAh cell is 6 mA. - What charging algorithm is required for the LIR1220?
The battery must be charged with a Constant-Current-Constant-Voltage (CC/CV) charger. - Which charger IC is recommended in the article?
The MCP73831 linear charge management controller IC is recommended. - What selectable charge voltages does the MCP73831 offer?
The MCP73831 can be configured for 4.20V, 4.35V, 4.40V, or 4.50V charging voltages. - Does the MCP73831 support preconditioning and charge termination?
Yes, the IC offers selectable preconditioning and charge termination. - What applications are suitable for the LIR1220?
Applications include wearables, Bluetooth headsets, body sensors, medical devices, wireless sensors, remote controls, toys, and networking devices.
