1 Features

1• Versatile Synchronous Buck DC-DC Controller

– Wide Input Voltage Range of 6 V to 42 V

– Adjustable Output Voltage From 0.8 V to 40 V

• Meets EN55022 / CISPR 22 EMI Standards

• Lossless RDS(on) or Shunt Current Sensing

• Switching Frequency From 100 kHz to 1 MHz

– SYNC In and SYNC Out Capability

• 40-ns Minimum On-Time for High VIN / VOUT Ratio

• 140-ns Minimum Off-Time for Low Dropout

• 0.8-V Reference With ±1% Feedback Accuracy

• 7.5-V Gate Drivers for Standard VTH MOSFETs

– 14-ns Adaptive Dead-Time Control

– 2.3-A Source and 3.5-A Sink Capability

– Low-Side Soft-Start for Prebiased Start-Up

• Adjustable Soft-Start or Optional Voltage Tracking

• Fast Line and Load Transient Response

– Voltage-Mode Control With Line Feedforward

– High Gain-Bandwidth Error Amplifier

• Precision Enable Input and Open-Drain Power

Good Indicator for Sequencing and Control

• Inherent Protection Features for Robust Design

– Hiccup Mode Overcurrent Protection

– Input UVLO With Hysteresis

– VCC and Gate Drive UVLO Protection

– Thermal Shutdown Protection With Hysteresis

• VQFN-20 Package With Wettable Flanks

• Create a Custom Design Using the LM25145 With

WEBENCH® Power Designer

2 Applications

• Telecom Infrastructure

• Factory Automation

• Test and Measurement

• Industrial Motor Drives

3 Description

The LM25145 42-V synchronous buck controller is

designed to regulate from a high input voltage source

or from an input rail subject to high voltage transients,

minimizing the need for external surge suppression

components. A high-side switch minimum on-time of

40 ns facilitates large step-down ratios, enabling the

direct step-down conversion from a 24 V nominal

input to low-voltage rails for reduced system

complexity and solution cost. The LM25145 continues

to operate during input voltage dips as low as 6 V, at

nearly 100% duty cycle if needed, making it well

suited for high-performance industrial control, robotic,

datacom, and RF power amplifier applications.

Forced-PWM (FPWM) operation eliminates frequency

variation to minimize EMI, while a user-selectable

diode emulation feature lowers current consumption

at light-load conditions. Cycle-by-cycle overcurrent

protection is accomplished by measuring the voltage

drop across the low-side MOSFET or by using an

optional current sense resistor. The adjustable

switching frequency as high as 1 MHz can be

synchronized to an external clock source to eliminate

beat frequencies in noise-sensitive applications.