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The Intersil ISL8723 and ISL8724 are 4 channel sequencers controlling the on and off sequence of voltages with undervoltage supply fault protection and a "sequence completed" signal (RESET). For larger systems, more than 4 voltages can be sequenced by a simple connection of multiple IC's. These sequencers use an integrated charge pump to drive 4 external low-cost N-channel MOSFET switch gates above the IC bias voltage by 5.3V. These IC's can be biased from and control any supply from 2.5V to 5V and additionally monitor any voltage above 0.7V. Individual product descriptions follow.

The four channel ISL8723 (ENABLE input), ISL8724 (ENABLE input) offer the designer 4 voltage control when it is required that all four rails are in minimal compliance prior to turn on and that compliance must be maintained during operation. The ISL8723 has a low power standby mode when it is disabled suitable for battery powered applications.

External resistors provide flexible voltage threshold programming of monitored voltages. Delay and sequencing timing are programmable by external capacitors for both ramp up and ramp down.

Key Features

• Enables arbitrary turn-on and turn-off sequencing of up to four power supplies (0.7V to 5V)
• Operates from 2.5V to 5V supply voltage
• Supplies VDD +5.3V of charge pumped gate drive
• Adjustable voltage slew rate for each rail
• Multiple sequencers can be easily daisy-chained to sequence an infinite number of independent voltages
• Glitch immunity
• Undervoltage lockout for each monitored supply voltage
• 30µA Sleep State (ISL8723)
• Active high (ISL8723) or low (ISL8724) ENABLE input
• Pb-free (RoHS compliant)

Applications

• Graphics cards
• FPGA/ASIC/microprocessor/PowerPC supply sequencing
• Network Routers
• Telecommunications Systems