LM2831 Datasheet, PDF (1/27 Pages) National Semiconductor (TI) – High Frequency 1.5A Load - Step-Down DC-DC Regulator

August 2006
LM2831
High Frequency 1.5A Load - Step-Down DC-DC
Regulator
General Description
The LM2831 regulator is a monolithic, high frequency, PWM
step-down DC/DC converter in a 5 pin SOT23 and a 6 Pin
LLP package. It provides all the active functions to provide
local DC/DC conversion with fast transient response and
accurate regulation in the smallest possible PCB area. With
a minimum of external components, the LM2831 is easy to
use. The ability to drive 1.5A loads with an internal 130 mΩ
PMOS switch using state-of-the-art 0.5 µm BiCMOS technol-
ogy results in the best power density available. The world-
class control circuitry allows on-times as low as 30ns, thus
supporting exceptionally high frequency conversion over the
entire 3V to 5.5V input operating range down to the minimum
output voltage of 0.6V. Switching frequency is internally set
to 550 kHz, 1.6 MHz, or 3.0 MHz, allowing the use of
extremely small surface mount inductors and chip capaci-
tors. Even though the operating frequency is high, efficien-
cies up to 93% are easy to achieve. External shutdown is
included, featuring an ultra-low stand-by current of 30 nA.
The LM2831 utilizes current-mode control and internal com-
pensation to provide high-performance regulation over a
wide range of operating conditions. Additional features in-
clude internal soft-start circuitry to reduce inrush current,
pulse-by-pulse current limit, thermal shutdown, and output
over-voltage protection.
Features
n Space Saving SOT23-5 Package
n Input voltage range of 3.0V to 5.5V
n Output voltage range of 0.6V to 4.5V
n 1.5A output current
n High Switching Frequencies
1.6MHz (LM2831X)
0.55MHz (LM2831Y)
3.0MHz (LM2831Z)
n 130mΩ PMOS switch
n 0.6V, 2% Internal Voltage Reference
n Internal soft-start
n Current mode, PWM operation
n Thermal Shutdown
n Over voltage protection
Applications
n Local 5V to Vcore Step-Down Converters
n Core Power in HDDs
n Set-Top Boxes
n USB Powered Devices
n DSL Modems
Typical Application Circuit
20174864
20174881
© 2006 National Semiconductor Corporation DS201748
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