The LTC2924 is a power supply sequencer designed for use with power supplies, including shutdown pins or modules using external N-channel MOSFETS in series. Capable of input monitoring and enabling four supplies in sequence during both power up and power down, the IC provides a simple, flexible, and compact solution in a 16-pin SSOP.

Multiple LTC2924s can be easily cascaded to sequence eight, 12, or a virtually unlimited number of voltages. However, with minimal external circuitry, a single LTC2924 can sequence six power supplies. With its precise 1% input monitoring and versatile sequencing abilities, the device is ideally suited for multi-supply systems, such as telecommunications equipment, optical systems, servers, and base stations.

For designs using modules or DC/DC converters without enabling inputs, an internally regulated charge pump provides gate drive voltage for the MOSFETs in series following the DC/DC converter. The Timer pin can provide an optional delay between the completion of a supply’s powering on and the enabling of the next supply. The PowerGood timer sets the time allowed for a power supply to turn on after it has been enabled and asserts a fault should a supply fail to enter regulation within the allotted time interval. The Done pin reports the successful completion of the power supply sequencing to a system controller. The LTC2924 is offered at $2.65 for 1,000-piece quantities.

Linear Technology Corp.
www.linear.com