Critical loads often employ parallel-connected power
supplies with redundancy in order to enhance system
reliability. The MAX8535/MAX8536/MAX8585 are highly
integrated but inexpensive MOSFET controllers that provide
isolation and redundant power capability in high-reliability
systems. The MAX8535/MAX8585 are used in 12V
systems, and have an internal charge pump to drive the
gates of the n-channel pass elements to VCC + 10V. The
MAX8536 is used in 3.3V and 5V systems, with a chargepump
output of VCC + 5V.
During startup, the MAX8535/MAX8536/MAX8585 monitor
the voltage drop across external MOSFETs. Once
VCC approaches or exceeds the bus voltage, the
MOSFETs are turned on. The MAX8535/MAX8536/MAX8585 feature a dual-purpose TIMER input. A single
external resistor from TIMER to ground sets the turn-on
speed of the external MOSFETs. Optionally, the TIMER
input can be used as a logic-enable pin. Once the
device is turned on, the MAX8535/MAX8536/MAX8585
monitor the load, protecting against overvoltage, undervoltage,
and reverse-current conditions.
Overvoltage and undervoltage fault thresholds are
adjustable and can be disabled. The current-limit trip
points are set by the external MOSFETs' RDS(ON),
reducing component count. An open-drain logic-low
fault output indicates if an overvoltage, undervoltage, or
reverse-current fault occurs.
All devices come in a space-saving 8-pin µMAX®
package and are specified over the extended -40°C to
+85°C temperature range.
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