FEATURES
• Ultra High Efficiencies (95% possible)
• High Efficiency Over a 3A to Milliamperes
Load Range
• Synchronous Switching of Internal NMOS
Power FETs
• Wide Input Voltage Range (4.5V to 18V)
• Output Voltage Adjustable from 1.5V to 16V
• Automatic Low-Power Sleep Mode
• Logic-Controlled Micropower Shutdown (IQSD ≤
25 μA)
• Frequency Adjustable up to 300 kHz
• Frequency Synchronization with External
Signal
• Programmable Soft-Start
• Short-Circuit Current Limiting
• Thermal Shutdown
• Available in 24-lead Small-Outline Package

APPLICATIONS
• Notebook and Palmtop Personal Computers
• Portable Data Terminals
• Modems
• Portable Instruments
• Global Positioning Devices (GPSs)
• Battery-Powered Digital Devices

DESCRIPTION
The LM2650 is a step-down DC/DC converter
featuring high efficiency over a 3A to milliamperes
load range. This feature makes the LM2650 an ideal
fit in battery-powered applications that demand long
battery life in both run and standby modes.
The LM2650 also features a logic-controlled
shutdown mode in which it draws at most 25μA from
the input power supply.
The LM2650 employs a fixed-frequency pulse-width
modulation (PWM) and synchronous rectification to
achieve very high efficiencies. In many applications,
efficiencies reach 95%+ for loads around 1A and
exceed 90% for moderate to heavy loads from 0.2A
to 2A.
A low-power hysteretic or "sleep" mode keeps
efficiencies high at light loads. The LM2650 enters
and exits sleep mode automatically as the load
crosses "sleep in" and "sleep out" thresholds. The
LM2650 provides nodes for programming both
thresholds via external resistors. A logic input allows
the user to override the automatic sleep feature and
keep the LM2650 in PWM mode regardless of the
load level.
An optional soft-start feature limits current surges
from the input power supply at start up and provides
a simple means of sequencing multiple power
supplies.