The MAX1830/MAX1831 constant-off-time, pulse-widthmodulated
(PWM) step-down DC-DC converters are
ideal for use in 5V and 3.3V to low-voltage conversion
necessary in notebook and subnotebook computers.
These devices feature internal synchronous rectification
for high efficiency and reduced component count. They
require no external Schottky diode. The internal 45mΩ
PMOS power switch and 55mΩ NMOS synchronous-rectifier
switch easily deliver continuous load currents up to
3A. The MAX1830 produces preset +2.5V, +1.8V, or
+1.5V output voltage or an adjustable output from +1.1V
to VIN. The MAX1831 produces preset +3.3V, +2.5V, and
+1.5V output voltages and an adjustable output from
+1.1V to VIN. They achieve efficiencies as high as 94%.
The MAX1830/MAX1831 use a unique current-mode,
constant-off-time, PWM control scheme, which includes
Idle Mode? to maintain high efficiency during lightload
operation. The programmable constant-off-time
architecture sets switching frequencies up to 1MHz,
allowing the user to optimize performance tradeoffs
between efficiency, output switching noise, component
size, and cost. Both devices are designed for continuous
output currents up to 3A, an internal digital
soft-start to limit surge currents during startup, a 100%
duty cycle mode for low-dropout operation, and a
low-power shutdown mode that disconnects the input
from the output and reduces supply current below
1μA.The MAX1830/MAX1831 are available in 16-pin
QSOP packages.
For similar devices that provide continuous output
currents of 1A to 3A, refer to the MAX1644, MAX1623,
and MAX1742/MAX1842/MAX1843 data sheets.
Applications
5V or 3.3V to Low-Voltage Conversion
CPU I/O Supplies
Chipset Supplies
Notebook and Subnotebook Computers