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.