Overview
The LM3478QMMX/NOPB is a high-efficiency, low-side N-Channel MOSFET controller designed for switching regulators. Produced by Texas Instruments, this device is part of the LM3478Q-Q1 series, which is AEC-Q100 qualified and manufactured on an automotive grade flow. It is suitable for use in various topologies such as boost, flyback, and SEPIC converters. The LM3478QMMX/NOPB features a fixed frequency, Pulse Width Modulated (PWM) current mode control architecture, allowing for adjustable switching frequencies between 100 kHz and 1 MHz using a single external resistor. This controller is designed to provide superior bandwidth and transient response, along with cycle-by-cycle current limiting and internal soft-start to limit inrush current at startup.
Key Specifications
| Parameter | Min | Max | Unit |
|---|---|---|---|
| Input Voltage | 2.97 | 40 | V |
| FB Pin Voltage | -0.4 | 7 | V |
| FA/SD Pin Voltage | -0.4 | 7 | V |
| Peak Driver Output Current (<10µs) | 1 | A | |
| Junction Temperature | 150 | °C | |
| Lead Temperature (Vapor Phase, 60 s) | 215 | °C | |
| Thermal Shutdown | 165 | °C | |
| Thermal Shutdown Hysteresis | 10 | °C | |
| Shutdown Current (Over Temperature) | 10 µA | ||
| Internal Reference Accuracy (Over Temperature) | ±2.5% |
Key Features
- 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
- Wide Supply Voltage Range of 2.97 V to 40 V
- 100-kHz to 1-MHz Adjustable Clock Frequency
- Power Saving Shutdown Mode Reduces Total Supply Current to 5 µA
- Create a Custom Design Using the LM3478 with the WEBENCH Power Designer
Applications
- Distributed Power Systems
- Battery Chargers
- Offline Power Supplies
- Telecom Power Supplies
- Automotive Power Systems
Q & A
- What is the LM3478QMMX/NOPB used for?
The LM3478QMMX/NOPB is used as a low-side N-Channel MOSFET controller for switching regulators in various power supply topologies such as boost, flyback, and SEPIC converters.
- What is the adjustable frequency range of the LM3478QMMX/NOPB?
The switching frequency can be adjusted between 100 kHz and 1 MHz using a single external resistor.
- What are the key features of the LM3478QMMX/NOPB?
Key features include internal push-pull driver, current limit and thermal shutdown, frequency compensation, internal soft start, current mode operation, and undervoltage lockout with hysteresis.
- What is the thermal shutdown temperature of the LM3478QMMX/NOPB?
The thermal shutdown temperature is 165°C with a hysteresis of 10°C.
- What is the shutdown current of the LM3478QMMX/NOPB over temperature?
The shutdown current is 10 µA over temperature.
- What is the internal reference accuracy of the LM3478QMMX/NOPB?
The internal reference accuracy is ±2.5% over temperature.
- What are the typical applications of the LM3478QMMX/NOPB?
Typical applications include distributed power systems, battery chargers, offline power supplies, telecom power supplies, and automotive power systems.
- What package types are available for the LM3478QMMX/NOPB?
The device is available in 8-lead VSSOP-8 and SOIC-8 packages.
- How does the LM3478QMMX/NOPB handle over-voltage protection?
The device includes an over-voltage comparator that senses the feedback voltage and resets the RS latch to prevent the output voltage from rising under over-voltage conditions.
- Can the LM3478QMMX/NOPB be used in automotive applications?
Yes, the LM3478Q-Q1 series is AEC-Q100 qualified and manufactured on an automotive grade flow, making it suitable for automotive power systems.
