ADM1087 Datasheet

• Provide time delays between enabling of regulators
• Can be cascaded with regulators for multiple supply sequencing
• Output stages
  High voltage (up to 22 V) open-drain output (ADM1087)
• Power supply monitoring from 0.6 V
• Capacitor adjustable time delays
• High voltage (up to 22 V) enable input
• Low power consumption (15 µA)
• Specified over –40°C to +125°C temperature range
• 6-lead SC70 package

• Desktop/notebook computers, servers
• Low power portable equipment
• Routers
• Base stations
• Line cards
• Graphics cards 

The ADM1087 are Simple Sequencing^™ circuits which provide a time delay between the enabling of voltage regulators at power-up in multiple supply systems. When the output voltage of the first regulator reaches a preset threshold, a time delay is initiated before an enable signal allows subsequent regulators to power-up. Any number of these devices can be cascaded with regulators to allow sequencing of multiple power supplies.

Threshold levels can be set with a pair of external resistors in a voltage divider configuration. By choosing appropriate resistor values, the threshold can be adjusted to monitor voltages as low as 0.6V.

The ADM1087 has an active-low (ENOUT) output. Both the ADM1087 have open-drain output stages which can be pulled up to voltage levels as high as 22V through an external resistor. This level shifting property of the ADM1087 ensures compatibility with enable input logic levels of different regulators and converters.

All four models have a dedicated enable input pin which allows the output signal to the regulator to be controlled externally. This is an active-low input (ENIN) for the ADM1087.

The Simple Sequencers^™ are specified over the extended –40°C to +125°C temperature range, and with low current consumption of 15µA (typ) and 6-lead SC70 packaging, they are suitable for low power portable applications.