MAX8585

Features:

` Simple, Integrated, and Inexpensive ORing MOSFET Controller
` ORing MOSFET Drive for 12V (MAX8535/MAX8585) and 3.3V or 5V  (MAX8536) Bus
` Eliminates ORing Diode Power Dissipation and Reverse Leakage Current
` Provides N + 1 Redundant Supply Capability for Highly Reliable Systems
` Isolates Failed Supply from Output Bus in <1s
` Reverse-Current Flow Detection
` Programmable Soft-Start
` Logic-Enable Input
` Adjustable Overvoltage and Undervoltage Trip Points
` Fault-Indicator Output
` Space-Saving 8-Pin MAX Package


Application

Silver Box Supplies for Servers
On-Board Redundant Power Supplies in Blade Servers
Network/Telecom Power Supplies Rectifiers
Redundant Power Supplies in High-Availability Systems

Specifications

GATE to GND (MAX8535/MAX8535A/MAX8585)...-0.3V to +28V
V_CC to GND (MAX8535/MAX8535A/MAX8585) .....-0.3V to +18V
CS, FAULT to GND
(MAX8535/MAX8535A/MAX8585)...........................-0.3V to +15V
GATE to GND (MAX8536) ............................... -0.3V to (V_CC + 6V)
V_CC, CS, FAULT to GND (MAX8536) ..........................-0.3V to +6V
OVP, UVP, TIMER to GND..........................................-0.3V to +6V
Continuous Power Dissipation (T_A = +70°C)
8-Pin MAX (derate 4.5mW/°C above +70°C) ...............362mW
Operating Temperature Range .........................-40°C to +85°C
Storage Temperature Range ..........................-65°C to +150°C
Junction Temperature ....................................................+150°C
Lead Temperature (soldering, 10s) ................................+300°C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.


Description

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 V_CC + 10V. The MAX8536 is used in 3.3V and 5V systems, with a chargepump output of V_CC + 5V.

During startup, the MAX8535/MAX8536/MAX8585 monitor the voltage drop across external MOSFETs. Once V_CC 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 of MAX8585 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.

MAX8585 come in a space-saving 8-pin MAX® package and are specified over the extended -40°C to +85°C temperature range.