UCD9081 8-Channel Power Supply Sequencer and Monitor With Error Logging

1 Features

• Single Supply Voltage: 3.3 V
• Low Power Consumption: 3-mA Nominal Supply Current
• Sequences and Monitors Eight Voltage Rails
• Rail Voltages Sampled With 3.2-mV Resolution
• Internal or External Voltage Reference
• Four Configurable Digital Outputs for Power-On-Reset and Other Functions
• Configurable Digital Output Polarity
• Flexible Rail Sequencing Based on Timeline (ms), Parent Rail Regulation Window, or Parent Rail Achieving Defined Threshold
• Independent Under- and Overvoltage Thresholds Per Rail
• Configurable Regulation Expiration Times Per Rail
• Flexible Alarm Processing: Ignore, Log Only, Retry n Times, Retry Continuously, Sequence, Parent Rail Can Shutdown Child Rails
• Alarm Conditions Logged With Timestamp: Under- and Overvoltage Glitch, Sustained Under- and Overvoltage, Rail Did Not Start
• On-Chip Flash for Storing User Data
• Error Logging to Flash for System Failure Analysis
• I2C™ Interface for Configuration and Monitoring
• Microsoft Windows™ GUI for Configuration and Monitoring

Functional Block Diagram

2 Applications

• Telecommunications Switches
• Servers
• Networking Equipment
• Test Equipment
• Industrial
• Any System Requiring Sequencing of Multiple Voltage Rails

3 Description

The UCD9081 power-supply sequencer controls the enable sequence of up to eight independent voltage rails and provides four general-purpose digital outputs (GPO). The device operates from a 3.3-V supply, provides 3.2-mV resolution of voltage rails, and requires no external memory or clock. The UCD9081 monitors the voltage rails independently and has a high degree of rail sequence and alarm response options. The sequencing of rails can be based on timed events or on timed events in conjunction with other rails achieving regulation or a voltage threshold. In addition, each rail is monitored for undervoltage and overvoltage glitches and thresholds. Each rail the UCD9081 monitors can be configured to shut down a user-defined set of other rails and GPOs, and alarm conditions are monitored on a per-rail basis.

Figure 20 shows the UCD9081 power-supply sequencer in a typical application.

1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application Diagram

4 Revision History

Changes from B Revision (December 2010) to C Revision

• Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information sectionGo
• Deleted Ordering Information table; see POA at the end of the data sheetGo
• Added Thermal Information tableGo
• Moved Timing Parameters for I²C Interface table and I²C Timing diagram to SpecificationsGo
• Moved content in Monitoring the UCD9081 to Register MapsGo

Changes from A Revision (September 2008) to B Revision

• Added Note 1 to the PIN FUNCTIONS tableGo
• Added Note regarding state of enable and digital I/O pins when the device contains factory configurationGo
• Added a reference to the UCD9081 Programming GuideGo

Changes from * Revision (June 2008) to A Revision

• Changed the data sheet from Product Preview to Production; multiple changes throughoutGo
• Changed first RAIL voltage equation From: × V_REF To: × V_R+ Go
• Changed second RAIL voltage equation From: × V_REF To: × V_R+ Go

5 Pin Configuration and Functions