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ADM1073ARU

Full-Feature −48 V Hot Swap Controller

Analog Devices 

Full-Feature −48 V Hot Swap Controller

ADM1073

FEATURES

Precision inrush linear current limit

Soft start inrush current limit profiling

Precision maximum on-time in current limit

Maximum on-time modulated by FET drain voltage for

additional SOA protection

Adjustable PWM retry scheme and multiple device cascading

capability for charging large capacitive loads

Limited number of PWM cycles for FET SOA protection under

short circuit condition

Ability to configure device as continuous autoretry with a

5-second cooling period

Shunt regulator topology to allow very large transient input

supplies

Separate UV and OV pins for programming allowable input

supply window

Programmable OV hysteresis using current source into pin

when supply is high

Programmable UV hysteresis using current sink from pin

when supply is low

PWRGD output indicates when capacitor charging complete

SPLYGD output indicates when supply is within

valid window

LATCHED output indicates the end of the retry cycle before

load capacitance is charged

SHDN input for user-commanded shutdown

RESTART input for user-triggered 5-second shutdown and

autorestart— virtual card reseat

FUNCTIONAL BLOCK DIAGRAM

OV

UV

SS

TIMER

VIN

VCC AND

REFERENCE

GENERATOR

OVERVOLTAGE

DETECTOR

UNDERVOLTAGE

DETECTOR

SOFT START

CONTROL

tON CONTROL

5 SECOND

SHUTDOWN

SPLYGD

FOLDBACK

AND PWRGD

PWRGD

DRAIN

VIN

100mV(MAX)

50µA

GATE

FAULT TIMER

AND CONTROL

OSCILLATOR PWM

TIMEOUT

SENSE

VEE

SHDN

RESTART

LATCHED

Figure 1.

APPLICATIONS

Central office switching

Telecommunication and data communication equipment

−48 V distributed power systems

Negative power supply control

High availability servers

−48 V power supply modules

Disk arrays

GENERAL DESCRIPTION

The ADM1073 is a full-feature, negative voltage, hot swap

controller that allows boards to be safely inserted and removed

from a live −48 V backplane. The part provides precise and

robust current limiting, and protection against both transient

and nontransient short circuits in overvoltage and undervoltage

conditions. The ADM1073 can operate from a negative voltage

of −18 V to −80 V and can tolerate transient voltages of up to

−200 V.

Inrush current is limited to a programmable value by control-

ling the gate drive of an external N-channel FET. The maximum

current limit is set by the choice of the sense resistor, RSENSE.

A built-in soft start function allows control of the inrush

current profile by an external capacitor on the soft start (SS)

pin.

An external capacitor on the TIMER pin determines the time

for which the FET gate is controlled to be high when maximum

inrush current flows. The ADM1073 employs a limited consec-

utive retry scheme, whereby, if the load capacitance is not fully

charged within one attempt, the FET gate is pulled low and

retries after a cooling period.

(continued on Page 3)

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable.

However, no responsibility is assumed by Analog Devices for its use, nor for any

infringements of patents or other rights of third parties that may result from its use.

Specifications subject to change without notice. No license is granted by implication

or otherwise under any patent or patent rights of Analog Devices. Trademarks and

registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

www.analog.com

Fax: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved.

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