1 Features

1• Input Voltage Operating Range From 3 V to 42 V

• Emulated Peak Current Mode Control

• Smooth Transition Between Step-Down and Step-

Up Modes

• Switching Frequency Programmable to 500 KHz

• Oscillator Synchronization Capability

• Internal High Voltage Bias Regulator

• Integrated High and Low-Side Gate Drivers

• Programmable Soft-Start Time

• Ultra-Low Shutdown Current

• Enable Input

• Wide Bandwidth Error Amplifier

• 1.5% Feedback Reference Accuracy

• Thermal Shutdown

• Package: 20-Pin HTSSOP (Exposed Pad)

• Create a Custom Design Using the LM25118 With

the WEBENCH® Power Designer

2 Applications

Industrial Buck-Boost Supplies

3 Description

The LM25118 wide voltage range Buck-Boost

switching regulator controller features all of the

functions necessary to implement a highperformance,

cost-efficient Buck-Boost regulator

using a minimum of external components. The Buck-

Boost topology maintains output voltage regulation

when the input voltage is either less than or greater

than the output voltage making it especially suitable

for automotive applications. The LM25118 operates

as a buck regulator while the input voltage is

sufficiently greater than the regulated output voltage

and gradually transitions to the buck-boost mode as

the input voltage approaches the output. This dualmode

approach maintains regulation over a wide

range of input voltages with optimal conversion

efficiency in the buck mode and a glitch-free output

during mode transitions. This easy-to-use controller

includes drivers for the high-side buck MOSFET and

the low-side boost MOSFET. The control method of

the regulator is based upon current mode control

using an emulated current ramp. Emulated current

mode control reduces noise sensitivity of the pulsewidth

modulation circuit, allowing reliable control of

the very small duty cycles necessary in high input

voltage applications. Additional protection features

include current limit, thermal shutdown, and an

enable input. The device is available in a powerenhanced,

20-pin HTSSOP package featuring an

exposed die attach pad to aid thermal dissipation.