1 Features
• Sequence and monitor up to 24 analog or digital
(power good) rails + 8 digital only rails
• PWM margining on up to 16 rails
• Cascade up to 4 devices to sequence up to 128
rails
• Active trim function allows user to trim output
voltage
• Monitor and respond to OV, UV, time-out, and GPItriggered
faults
• Flexible sequencing dependencies, delay times,
Boolean logic, and GPIO configurations
• Rail status dependent sequencing, delay times,
and LGPO pins for complex sequencing
applications
• Four rail profiles for adaptive voltage identification
(AVID) voltage regulator
• Nonvolatile fault event logging with RTC and
timestamping
– Single-event fault log (100 entries)
– Black box fault log saves fault information and
status of all rails - for the first fault and the last
fault before a power down event
• Continue monitoring rails during configuration
activities to maximize up-time
• Programmable watchdog timer and system reset
• GPI Controlled Rail Groups
• SEU mitigation & ECC (single-error correct +
double-error detect)
• PMBus™ 1.2 compliant
• PMBus security profile Level 0 with custom
commands to enable features in security profile
Level 2

2 Applications
• Wired networking
• Wireless infrastructure
• Datacom module
• Data center and enterprise computing
• Factory automation and control
• Test and measurement
• Medical

3 Description
The UCD91320 device is a 32-rail PMBus controlled
power sequencer.
Dedicated pins (MONx) monitor up to 32 voltage rails
in either analog or digital modes. 32 rail enable (ENx)
pins allow regulators to be sequenced. 16 margining
(MARx) pins can be used to push regulators to high or
low limits (margins) for testing, or actively trim outputs
for enhanced accuracy. The output state of 16 logical
GPO (LGPOx) pins can be controlled by the state of
GPIs, rail status, and other LGPOs.
Nonvolatile event logging preserves fault events after
power dropout. The Black Box Fault Log preserves
the fault information and the status of all rails. This
occurs for the first fault as well as the last fault before
a power down event. The cascading feature offers
convenient ways to manage up to 128 voltage rails.
A user defined fault pin coordinates the cascaded
devices to take synchronized fault responses.
The user can select up to 8 groups of rail
configurations using 3 GPIs. These configurations can
implement system low-power modes as outlined in the
Advanced Configuration and Power Interface (ACPI)
specification.
The Sequencer Studio™ software is an intuitive PCbased
graphic user interface (GUI) that can configure,
store, and monitor all system operating parameters.