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.

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)

? I2C 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