## Overview of the XR79110EVB The **XR79110EVB** is the evaluation board for the **XR79110**, a 10A synchronous step-down Power Module. This board is designed to demonstrate the performance of MaxLinear’s (formerly Exar) power management technology, which integrates the controller, drivers, bootstrap diode/capacitor, and MOSFETs into a single package. --- ### Core Electronic Components The evaluation board consists of several critical categories of components that facilitate high-efficiency power conversion: | Component Type | Description | Function | | :--- | :--- | :--- | | **Integrated Module** | XR79110 Power Module | Contains the PWM controller, MOSFETs, and inductor. | | **Input Capacitors** | Bulk Electrolytic & Ceramic | Filters input noise and provides energy storage for switching. | | **Output Capacitors** | Low ESR Ceramic | Reduces output voltage ripple and handles load transients. | | **Programming Resistors** | SMD Resistors (e.g., $R_{FB}$, $R_{TON}$) | Sets output voltage, switching frequency, and current limit. | | **Soft-Start Cap** | $C_{SS}$ Ceramic Capacitor | Controls the ramp-up time of the output voltage to prevent inrush. | --- ### Key Functional Circuits #### 1. The Power Stage The heart of the board is the XR79110 module. Unlike traditional buck converters, the **inductor** is internal to the module, which simplifies PCB layout and reduces Electromagnetic Interference (EMI). #### 2. Feedback Loop ($V_{OUT}$ Setting) The output voltage is determined by a resistor divider network. - **Formula:** $V_{OUT} = 0.6V \times (1 + \frac{R_1}{R_2})$ - By swapping these resistors on the EVB, users can adjust the output from **0.6V to 5.5V**. #### 3. Constant On-Time (COT) Control The EVB utilizes a **Patented COT control engine**. It provides: * Fast transient response. * No loop compensation required (simplifies design). * Pseudo-fixed frequency operation. --- ### Technical Specifications (Board Level) | Feature | Value / Range | | :--- | :--- | | **Input Voltage ($V_{IN}$)** | 4.5V to 22V | | **Output Current ($I_{OUT}$)** | Up to 10A | | **Switching Frequency** | 400kHz to 800kHz | | **Efficiency** | Up to 93% | | **Protection** | OCP, OTP, UVLO, and Short-circuit | --- ### Typical Application Schematic Layout ```mermaid graph LR Vin[Vin: 4.5V-22V] --> Cin[Input Caps] Cin --> Module[XR79110 Module] Module --> Cout[Output Caps] Cout --> Vout[Vout: 0.6V-5.5V] Module -.-> FB[Feedback Resistors] FB -.-> Module ``` ---