The **LMS-D4W-R/Q** is a high-performance **Step-Down (Buck) Voltage Regulator** manufactured by **Lumissil Microsystems** (a division of ISSI). It is specifically designed for high-voltage automotive and industrial applications where efficiency and space are critical. --- ### ## Technical Specifications Below are the key electronic parameters for the LMS-D4W-R/Q: | Parameter | Specification | | :--- | :--- | | **Input Voltage Range** | 4.5V to 40V | | **Output Voltage Range** | Adjustable (0.8V to 0.9 × Vin) | | **Maximum Output Current** | 4A | | **Switching Frequency** | 200kHz to 2.2MHz (Programmable) | | **Efficiency** | Up to 95% | | **Package Type** | QFN-20 (4mm x 4mm) | | **Operating Temp** | -40°C to +125°C (Automotive Grade) | --- ### ### Key Internal Components & Features 1. **Synchronous Rectification**: It integrates high-side and low-side power MOSFETs. This eliminates the need for an external Schottky diode, reducing heat and improving efficiency. 2. **Current Mode Control**: The part uses peak current mode control for fast transient response and simple loop compensation. 3. **Frequency Synchronization**: The "Q" in the part number often denotes AEC-Q100 qualification (automotive standard). It features a `SYNC` pin to synchronize the switching frequency with an external clock to minimize EMI (Electromagnetic Interference). 4. **Protection Circuitry**: * **UVLO**: Under-Voltage Lockout. * **OTP**: Over-Temperature Protection (Thermal Shutdown). * **OCP**: Over-Current Protection with "hiccup mode" to prevent damage during short circuits. --- ### ### Typical Application Circuit When designing with this part, the following external components are required: ```yaml Components: - Inductor (L): Typically 2.2µH to 10µH (depends on switching frequency). - Input Capacitor (Cin): Low ESR Ceramic (e.g., 10µF - 47µF). - Output Capacitor (Cout): Ceramic or Polymer for low ripple. - Feedback Resistors (R1, R2): To set the target output voltage. ``` --- ### ### Pin Functionality (Selected) * **VIN**: Power supply input. * **SW**: Switching node connected to the inductor. * **BST**: Bootstrap pin for the high-side gate driver. * **EN**: Enable pin (High = On, Low = Off). * **FB**: Feedback input for voltage regulation. * **VCC**: Internal LDO output for powering internal logic.