19-1737; Rev 0; 7/00
External Four-Input Feedback Integrator for
The MAX1804 feedback integrator is designed to
improve voltage regulation in power-supply systems.
The device corrects line- and load-regulation problems,
and can be used to compensate for voltage drops in
power-management distribution lines.
The regulation set point is determined by an external
reference voltage applied at the ADJ pin. The differ-
ence between that reference and MAX1804 feedback is
integrated, and a correction current is applied to the
voltage regulator’s feedback.
The MAX1804’s four inputs allow voltage monitoring in
several local and remote locations to correct for distribu-
tion losses caused by long traces, connectors, and
switches. This eliminates the wasteful practice of perma-
nently adjusting the regulator’s output voltage high
enough to correct for worst-case voltage drops. This is
especially helpful in systems where the load current
varies widely and portions of the load are often shut down
or disconnected (for example, in notebook computers).
If a load switch is opened and the output voltage
sensed at one input falls, the MAX1804 automatically
disables that input and adjusts the regulator’s output
voltage to the lowest of remaining active inputs. If all
inputs are disabled, the OUT pin is in a high-imped-
ance state and makes no output voltage correction.
When SHDN is low, the MAX1804 draws less than 1µA
and its inputs and output are high impedance. The
MAX1804 is available in a 10-pin µMAX package, about
half the size of an 8-pin SOIC.
o High Precision (±1% max Error)
o Low Power (25µA Supply Current)
o Automatic Input Disable
o Shutdown (1µA max Supply Current)
o Inputs and Outputs High Impedance in Shutdown
or When V+ = 0
o +2.7V to +5.5V Supply Range
o 2.8V to 5.5V Regulation Adjust Range
o Parallelable for More than Four Inputs
o 10-Pin µMAX Package
-40°C to +85°C
Pin Configuration appears at end of data sheet.
Remote Feedback Regulators
Servers and Workstations
Subnotebooks and PDAs
Typical Operating Circuit
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