# Overview of the MCP1663 The **MCP1663** is a high-voltage, fixed-frequency, Peak Current Mode step-up (Boost) DC-DC converter produced by Microchip Technology. It is designed to derive high output voltages from low-voltage sources, commonly used for powering strings of LEDs, sensors, or bias circuits. --- ## 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Input Voltage Range** | 2.4V to 5.5V | | **Output Voltage Range** | Up to 32V | | **Switching Frequency** | 500 kHz | | **Integrated Switch Resistance** | 360 mΩ (Typical) | | **Peak Current Limit** | 1.8A (Typical) | | **Package Options** | SOT-23-5 or 2x3 TDFN | | **Quiescent Current** | 80 µA (Typical) | --- ## 2. Pin Configuration and Functions The MCP1663 typically comes in a **5-pin SOT-23** package. Understanding the pins is essential for PCB design: 1. **SW (Switch Node):** The drain of the internal N-channel MOSFET. Connect the inductor and Schottky diode here. 2. **GND (Ground):** The reference ground for the device. 3. **FB (Feedback):** Connects to a resistor divider to set the output voltage. The internal reference is usually **1.227V**. 4. **EN (Enable):** Logic high enables the device; logic low puts it in shutdown mode (< 1 µA). 5. **VIN (Input Voltage):** Power supply input for the internal control circuitry. --- ## 3. Critical External Components To build a functional circuit with the MCP1663, the following passive components are required: ### A. The Inductor ($L$) Since the MCP1663 operates at 500 kHz, inductor values typically range from **4.7 µH to 10 µH**. The inductor must have a saturation current higher than the peak switch current (1.8A). ### B. The Schottky Diode ($D$) A fast-switching Schottky diode is required to maintain efficiency. It must have a reverse voltage rating higher than the desired output voltage ($V_{OUT}$). ### C. Feedback Resistor Divider ($R_1, R_2$) The output voltage is determined by the formula: $$V_{OUT} = V_{FB} \times \left(1 + \frac{R_1}{R_2}\right)$$ *Where $V_{FB} = 1.227V$.* --- ## 4. Application Circuit Example Below is a conceptual representation of a basic boost circuit: ```text L (4.7uH) D (Schottky) Vin ----UUUUU---------|>|----------- Vout | | [ SW ] [ R1 ] | | [MCP1663]-------[ FB ] | | [GND] [ R2 ] | [GND] ``` --- ## 5. Key Advantages * **Integrated Power Transistor:** No need for an external MOSFET, saving PCB space. * **Start-up into High Load:** Capable of starting up with a significant load attached. * **Protection:** Includes Undervoltage Lockout (UVLO), Overvoltage Protection (OVP), and Thermal Shutdown.