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.