Overview
The LM3478MAX/NOPB, produced by Texas Instruments, is a versatile Low-Side N-Channel MOSFET controller designed for use in switching regulators. This component is particularly suited for topologies that require a low-side MOSFET, such as boost, flyback, and SEPIC converters. The LM3478 offers high efficiency and the ability to operate at extremely high switching frequencies, which helps in reducing the overall solution size. It features a fixed frequency, Pulse Width Modulated (PWM) current mode control architecture, providing superior bandwidth and transient response along with cycle-by-cycle current limiting.
Key Specifications
| Parameter | Minimum | Typical | Maximum | Unit |
|---|---|---|---|---|
| Supply Voltage (VIN) | 2.97 | - | 40 | V |
| Junction Temperature Range (TJ) | -40 | - | 125 | °C |
| Switching Frequency (FSW) | 100 kHz | - | 1 MHz | - |
| Internal Reference Voltage (VFB) | 1.2416 | 1.26 | 1.2843 | V |
| Feedback Voltage Line Regulation (ΔVLINE) | - | 0.001 | - | %/V |
| Undervoltage Lockout (VUVLO) | 2.85 | - | 2.97 | V |
| Thermal Shutdown (TSD) | - | - | 165 | °C |
| Shutdown Current (ISD) | - | 10 | - | µA |
Key Features
- 8-lead VSSOP-8 and SOIC-8 packages
- Internal Push-Pull Driver With 1-A Peak Current Capability
- Current Limit and Thermal Shutdown
- Frequency Compensation Optimized With a Capacitor and a Resistor
- Internal Soft Start
- Current Mode Operation
- Undervoltage Lockout With Hysteresis
- Create a Custom Design Using the LM3478 with the WEBENCH Power Designer
- Overvoltage Protection (OVP) for the output voltage
- Short-circuit protection and slope compensation
Applications
- Distributed Power Systems
- Battery Chargers
- Offline Power Supplies
- Telecom Power Supplies
- Automotive Power Systems
- Boost, flyback, and SEPIC converters
Q & A
- What is the operating supply voltage range of the LM3478?
The LM3478 operates within a supply voltage range of 2.97 V to 40 V.
- What are the available package types for the LM3478?
The LM3478 is available in 8-lead VSSOP-8 and SOIC-8 packages.
- What is the maximum switching frequency of the LM3478?
The LM3478 can operate at switching frequencies up to 1 MHz.
- Does the LM3478 have built-in thermal protection?
Yes, the LM3478 includes thermal shutdown and short-circuit protection features.
- How is the switching frequency of the LM3478 adjusted?
The switching frequency can be adjusted using a single external resistor connected to the FA/SD pin.
- What is the purpose of the internal soft-start feature in the LM3478?
The internal soft-start feature limits the inrush current at startup, helping to prevent voltage spikes and ensuring a smooth startup process.
- Can the LM3478 be used in automotive power systems?
Yes, the LM3478 is suitable for use in automotive power systems due to its robust features and wide operating temperature range.
- Does the LM3478 support overvoltage protection?
Yes, the LM3478 includes overvoltage protection (OVP) to prevent the output voltage from rising beyond a safe level.
- How does the LM3478 handle undervoltage conditions?
The LM3478 features undervoltage lockout with hysteresis to ensure stable operation and prevent malfunction during low input voltage conditions.
- Can the LM3478 be used in high-efficiency step-up (boost) converters?
Yes, the LM3478 is commonly used in high-efficiency step-up (boost) converters due to its current mode operation and high switching frequency capability.
