The MAX8737 dual high-power linear regulator controllers
use external n-channel MOSFETs to generate
two independent low-voltage supplies for notebook
computers. The MAX8737 delivers low output voltages
from 0.5V to 2.5V (±5mV no-load accuracy). The external
components allow scalable current design with
loads up to 5A with excellent load regulation (1%). The
regulator operates from a low input voltage, which also
reduces the power dissipation in the external n-channel
MOSFET. The controller powers the external MOSFET
gate driver from the standard 5V system supply.
The MAX8737 includes current and thermal limits to
prevent damage to the linear regulator. The MAX8737
uses an external resistive divider to fold back the current
limit, reducing the overall power dissipation. The
MAX8737 uses an external resistive-divider in series
with the current-sense input (CS_), providing foldback
current-limit protection, and effectively reducing the
short-circuit power dissipation.
An output undervoltage timeout is available for low-cost
applications that omit the current-sense resistor. The
output undervoltage (UVP) timing depends on the magnitude
of the voltage at VOUT. The UVP detects and
shuts down the LDO if the output voltage drops out of
regulation. The controller uses an adjustable reference
input (REFIN_) to set the nominal output voltage
(VOUT_), which minimizes the cost and makes the stability
independent of the output voltage.
Each linear regulator features an adjustable soft-start
function, and generates a delayed power-good
(PGOOD) signal that signals when the linear regulator
is in regulation. The MAX8737 is a low-cost solution
requiring few external components and is available in a
small, 4mm x 4mm, 16-pin thin QFN package.
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