The **MIC79110** is a high-efficiency, simple-to-use linear Li-Ion battery charger designed for portable applications. It is often utilized in systems where space is limited and heat dissipation needs to be managed effectively. --- ## 1. Core Technical Specifications The MIC79110 series is known for its "Simple Non-Linear" approach to charging. Below is a breakdown of the typical electronic characteristics: | Feature | Specification (Typical) | | :--- | :--- | | **Input Voltage Range** | 4.5V to 16V | | **Charge Current** | Up to 1.2A (Programmable) | | **Output Voltage Accuracy** | ±0.75% to ±1.5% | | **Package Types** | MLF® (3x3mm) or SOIC-8 | | **Regulation Type** | Linear with Thermal Shutdown | --- ## 2. Key Electronic Components & Functions To understand the "parts" of the MIC79110, we must look at its internal functional blocks: ### A. The Pass Transistor * **Type:** Internal P-Channel MOSFET. * **Role:** Acts as the variable resistor that controls the flow of current from the Input (Vcc) to the Battery (BAT). Because it is a linear charger, the power dissipated is $(V_{in} - V_{bat}) \times I_{charge}$. ### B. Current Sense Circuitry * **Role:** Monitors the charging current. Usually, an external resistor is used to set the maximum fast-charge current. * **Mechanism:** When the voltage across the internal/external sense nodes reaches a threshold, the IC throttles the gate of the pass transistor to maintain a constant current (CC Mode). ### C. Precision Voltage Reference * **Role:** Ensures the battery is not overcharged. * **Importance:** Li-Ion batteries are sensitive to voltage; the MIC79110 uses a high-precision bandgap reference to stop charging exactly at 4.2V (or the specified termination voltage). ### D. Thermal Regulation Loop * **Mechanism:** Unlike standard thermal shutdown, the MIC79110 has a "Thermal Control Loop." If the internal die temperature rises too high, it automatically reduces the charge current rather than turning off completely. This ensures the device continues to charge safely at the maximum possible rate. --- ## 3. Typical Pin Configuration When integrating this component, these are the primary pins used: 1. **VCC:** Power input. 2. **BAT:** Connects to the positive terminal of the Li-Ion cell. 3. **GND:** System ground and heat sink (especially the exposed pad). 4. **PROG:** A resistor connected here sets the charge current. 5. **STAT (or LED):** Open-drain output that indicates charging status. --- ## 4. Why the "_07" Suffix? In Microchip/Micrel nomenclature, suffixes like **_07** or **-4.2** usually designate: * **Voltage Variant:** Specifying a fixed 4.1V or 4.2V termination. * **Packing/Format:** Such as Tape and Reel vs. Tube. * **Lead-free Status:** Indicators for RoHS compliance. --- ## 5. Application Circuit Example ```mermaid graph LR Input[DC Input 5V] --> VCC[MIC79110 VCC] VCC --> PassTransistor[Internal MOSFET] PassTransistor --> BAT[Battery +] PROG[Prog Pin] --- Rset[Resistor to GND] STAT[Stat Pin] --- LED[Charging Indicator] ```