1 Features

1• 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

2 Applications

• Distributed Power Systems

• Battery Chargers

• Offline Power Supplies

• Telecom Power Supplies

• Automotive Power Systems

• Wide Supply Voltage Range of 2.97 V to 40 V

• 100-kHz to 1-MHz Adjustable Clock Frequency

• ±2.5% (Over Temperature) Internal Reference

• 10-μA Shutdown Current (Over Temperature)

3 Description

The LM3478 is a versatile Low-Side N-Channel

MOSFET controller for switching regulators. It is

suitable for use in topologies requiring a low side

MOSFET, such as boost, flyback, SEPIC, etc.

Moreover, the LM3478 can be operated at extremely

high switching frequency in order to reduce the

overall solution size. The switching frequency of the

LM3478 can be adjusted to any value between 100

kHz and 1 MHz by using a single external resistor.

Current mode control provides superior bandwidth

and transient response, besides cycle-by-cycle

current limiting. Output current can be programmed

with a single external resistor.

The LM3478 has built-in features such as thermal

shutdown, short-circuit protection, over voltage

protection, etc. Power saving shutdown mode

reduces the total supply current to 5 μA and allows

power supply sequencing. Internal soft-start limits the

inrush current at start-up.