Motherboard Power Supply Solution with a 5-Bit Programmable Switching Controller and Two Linear Regulator Controllers The LM2638MX is a switching regulator controller manufactured by National Semiconductor (NSC).  

### **Specifications:**  
- **Input Voltage Range:** 4.5V to 30V  
- **Output Voltage Range:** Adjustable from 1.25V to 5V  
- **Switching Frequency:** 300kHz  
- **Output Current:** Up to 5A (with external components)  
- **Efficiency:** Up to 90%  
- **Operating Temperature Range:** -40°C to +85°C  
- **Package:** SOIC-16  

### **Descriptions:**  
The LM2638MX is a high-efficiency, step-down (buck) switching regulator controller designed for DC-DC conversion applications. It provides a regulated output voltage with high efficiency by driving an external N-channel MOSFET.  

### **Features:**  
- **Adjustable Output Voltage** via external resistors  
- **Synchronous Rectification** for improved efficiency  
- **Soft-Start** to limit inrush current  
- **Undervoltage Lockout (UVLO)** for protection  
- **Current Limit Protection**  
- **Thermal Shutdown**  
- **Wide Input Voltage Range**  

This information is based on the manufacturer's datasheet. For detailed application notes, refer to the official NSC documentation.

Motherboard Power Supply Solution with a 5-Bit Programmable Switching Controller and Two Linear Regulator Controllers