Power Sequencing Controllers

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.