1 Features

1• 27-μA Quiescent Current in Regulation

• High Efficiency at Light Load (DCM and PFM)

• Meets EN55022/CISPR 22 EMI standards

• Integrated Synchronous Rectification

• Adjustable Frequency Range: 200 kHz to 2.2 MHz

(500 kHz default)

• Frequency Synchronization to External Clock

• Internal Compensation

• Stable with Almost Any Combination of Ceramic,

Polymer, Tantalum, and Aluminum Capacitors

• Power-Good Flag

• Soft Start into a Pre-Biased Load

• Internal Soft-Start: 4.1 ms

• Extendable Soft-Start Time by External Capacitor

• Output Voltage Tracking Capability

• Precision Enable to a Program System UVLO

• Output Short Circuit Protection with Hiccup Mode

• Overtemperature Thermal Shutdown Protection

• Create a Custom Design Using the LM43603 with

the WEBENCH® Power Designer

2 Applications

• Industrial Power Supplies

• Telecommunications Systems

• Sub-AM Band Automotive

• General Purpose Wide VIN Regulation

• High Efficiency Point-Of-Load Regulation

3 Description

The LM43603 regulator is an easy-to-use

synchronous step-down DC-DC converter capable of

driving up to 3 A of load current from an input voltage

ranging from 3.5 V to 36 V (42 V abs max). The

LM43603 provides exceptional efficiency, output

accuracy and dropout voltage in a very small solution

size. An extended family is available in 0.5-A, 1-A,

and 2-A load current options in pin to pin compatible

packages. Peak current mode control is employed to

achieve simple control loop compensation and cycleby-

cycle current limiting. Optional features such as

programmable switching frequency, synchronization,

power-good flag, precision enable, internal soft-start,

extendable soft-start, and tracking provide a flexible

and easy to use platform for a wide range of

applications. Discontinuous conduction and automatic

frequency modulation at light loads improve light load

efficiency. The family requires few external

components and pin arrangement allows simple,

optimum PCB layout. Protection features include

thermal shutdown, VCC undervoltage lockout, cycleby-

cycle current limit, and output short circuit

protection. The LM43603 device is available in the

HTSSOP / PWP 16 leaded package (5.1 mm × 6.6

mm × 1.2 mm) and VSON-16 package with wettable

flanks. HTSSOP package is pin-to-pin compatible

with LM43600, LM43601, LM43602, LM46000,

LM46001, LM46002. VSON-16 package is only pinto-

pin compatible with LM43602.