1 Features

• Wide input voltage range of 3 V to 65 V

• 10.5-μA no-load quiescent current

• –40°C to 150°C junction temperature range

• Fixed (3.3 V and 5 V) or adjustable output voltages

• Meets EN55022 / CISPR 22 EMI standards

• Integrated 2-Ω PMOS buck switch

– Supports 100% duty cycle for low dropout

• Integrated 1-Ω NMOS synchronous rectifier

– Eliminates external rectifier diode

• Programmable current limit setpoint (four levels)

• Selectable PFM or COT mode operation

• 1.223-V ±1% internal voltage reference

• 900-μs internal or programmable soft start

• Active slew rate control for low EMI

• Diode emulation mode and pulse skipping for ultrahigh

light-load efficiency performance

• Monotonic start-up into prebiased output

• No loop compensation or bootstrap components

• Precision enable and input UVLO with hysteresis

• Pin-to-pin compatible with the LM5166

• Thermal shutdown protection with hysteresis

• 10-pin, 3-mm × 3-mm VSON package

• Use TPSM265R1 module for faster time to market

• Create a custom regulator design using

WEBENCH® Power Designer

2 Applications

• 4–20 mA loop-powered sensors

• Automotive and battery-powered equipment

• High-voltage LDO replacement

• Industrial control systems

• General-purpose bias supplies

3 Description

The LM5165 device is a compact, easy-to-use, 3-

V to 65-V, ultra-low IQ synchronous buck converter

with high efficiency over wide input voltage and load

current ranges. With integrated high-side and low-side

power MOSFETs, up to 150-mA of output current

can be delivered at fixed output voltages of 3.3 V

or 5 V or at an adjustable output. The converter is

designed to simplify implementation while providing

options to optimize the performance for the target

application. Pulse Frequency Modulation (PFM) mode

is selected for optimal light-load efficiency or Constant

On-Time (COT) control for nearly constant operating

frequency. Both control schemes do not require loop

compensation while providing excellent line and load

transient response and short PWM on-time for large

step-down conversion ratios.

The high-side P-channel MOSFET can operate at

100% duty cycle for lowest dropout voltage and does

not require a bootstrap capacitor for gate drive. Also,

the current limit setpoint is adjustable to optimize

inductor selection for a particular output current

requirement. Selectable and adjustable start-up timing

options include minimum delay (no soft start),

internally fixed (900 μs), and externally programmable

soft start using a capacitor. An open-drain PGOOD

indicator can be used for sequencing, fault reporting,

and output voltage monitoring. The LM5165 buck

converter is available in a 10-pin, 3-mm × 3-mm,

thermally- enhanced VSON-10 package with 0.5-mm

pin pitch. The LM5165 and LM5165X is also available

in the VSSOP-10 package.