SMH4804
-48V Programmable Hot Swap Sequencing Power Controller
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FEATURES AND APPLICATIONS
INTRODUCTION
The SMH4804 is a user-programmable -48V power supply
controller designed to control the hot-swapping of plug-in
cards and to sequence supplies in a distributed power
environment. The SMH4804 drives an external power
MOSFET switch that connects the bus side supply to the
card side load and controls in-rush current while providing
both current regulation and over-current protection. When
the source and drain voltages of the external MOSFET are
within specification, the SMH4804 asserts four PG[4:1]#
power-good logic outputs either simultaneously or
sequenced at programmable intervals to enable DC-DC
converters to distribute card side power.
Additional features of the device include: UV and OV
monitor, master enable or temperature sense input (EN/
TS), 2.5V and 5V reference outputs for expanding monitor
functions, two Pin-Detect enable inputs (PD1# and PD2#)
for card insertion verification, and duty-cycle or latched
over-current protection modes. All features are
programmed in nonvolatile registers through the I
2
C
interface which is simplified with the SMX3200 interface
adapter and Windows GUI software available from Summit
Microelectronics. Engineers can program the device
directly in-circuit with units of voltage, current and time,
allowing fast design cycles.
Features:
• Soft Starts Main Power Supply on Card Insertion or
System Power Up
• In-Rush Current Limiting
• Master Enable to Allow System Control of Power Up or
Down
• Programmable Independent Control of up to 4 DC/DC
Converters via 4 Power Good Signals, PG[4:1]#
• Highly Programmable Circuit Breaker Level and Mode
– Programmable Quick-Trip™ Value, Current
Limiting, Duty Cycle Times, and Over-Current Filter
• Programmable Host Voltage Fault Monitoring
– Programmable UV/OV Filter and UV Hysteresis
• Programmable Fault Mode: Latched or Duty Cycle
• Internal Shunt Regulator Allows for a Wide Supply
Range (typically -32 to -72 Volts)
• I
2
C 2-Wire Serial Bus Interface for Programming,
Power On/Off and Operational Status
Applications:
• Telecom Hot-Swap Card
• Distributed Power Architectures
• Power-on LAN, IEEE 802.3
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SIMPLIFIED APPLICATION DRAWING
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Figure 1. SMH4804 Simplified Application Diagram
© SUMMIT
Microelectronics, Inc. 2002 • 300 Orchard City Drive #131 • Campbell CA 95006 • Phone 408 378-6461 • Fax 408 378-6596 • www.summitmicro.com
2050 3.7 10/30/02
1
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
