The **MIC79110BML** is a high-accuracy, fixed-voltage, linear Li-Ion battery charger controller manufactured by Microchip (formerly Micrel). It is designed to be a simple and efficient solution for charging single-cell lithium-ion batteries. --- ### 1. Key Technical Specifications | Parameter | Value / Range | | :--- | :--- | | **Input Voltage Range** | 4.5V to 16V | | **Output Voltage (Fixed)** | 4.2V (Single-cell Li-Ion) | | **Charging Current** | Adjustable via external resistor (typically up to 1.2A) | | **Package Type** | MLF-10 (Micro Lead Frame) | | **Operating Temperature** | -40°C to +125°C | --- ### 2. Major Electronic Components & Features The MIC79110BML integrates several critical functions into a small 3x3mm footprint: #### A. Internal Pass Transistor Unlike some controllers that require an external MOSFET, the MIC79110 often features an integrated pass element, reducing the total Bill of Materials (BOM). #### B. Precision Voltage Regulation It maintains a **±0.75% accuracy** over the entire temperature range. This is vital for Li-Ion batteries, as overcharging by even 50mV can significantly reduce cycle life or cause safety issues. #### C. Built-in Safety Mechanisms * **Thermal Shutdown:** Protects the IC from overheating during high-current charging. * **Current Limiting:** Prevents the battery from being charged at a rate higher than its specification. * **Reverse Polarity Protection:** Prevents damage if the input source or battery is connected incorrectly. #### D. Charge Status Indicators The chip includes pins for status LEDs (usually labeled `STAT1` and `STAT2`) to indicate whether the battery is: 1. Charging 2. Fully Charged 3. In a Fault condition --- ### 3. Pinout Functional Description | Pin Name | Function | | :--- | :--- | | **VIN** | Supply Input Voltage. | | **BATT** | Output to the battery positive terminal. | | **GND** | System Ground. | | **PROG** | Current programming pin; a resistor from this pin to GND sets the charge current. | | **EN** | Enable pin (High = ON, Low = OFF). | | **STAT** | Status output for monitoring the charging cycle. | --- ### 4. Typical Application Circuit The MIC79110 is used in a "Linear" configuration. While less efficient than switching chargers (buck-converters), it generates zero EMI/RFI noise, making it ideal for sensitive audio or radio equipment. ```text Input (5V-12V) ----> [ VIN ] [ BATT ] ----> (+) Battery (4.2V) | | [ PROG ] [ GND ] ----> (-) Battery / Ground | | (R_program) | | | Ground Ground ``` ---