1 Features
1• Monitor and sequence 12 voltage rails
– All rails sampled every 400 μs
– 12-bit ADC with 2.5-V, 0.5% internal VREF
– Sequence based on time, rail and pin
dependencies
– Four programmable undervoltage and
overvoltage thresholds per monitor
• Nonvolatile error and peak-value logging per
monitor (up to 12 fault detail entries)
• Closed-loop margining for 10 Rails
– Margin output adjusts rail voltage to match
user-defined margin thresholds
• Programmable watchdog timer and system reset
• Flexible digital I/O configuration
• Pin-selected rail states
• Multiphase PWM clock generator
– Clock frequencies from 15.259 kHz to
125 MHz
– Capability to configure independent clock
outputs for synchronizing switch-mode power
supplies
• JTAG and I2C/SMBus/PMBus™ interfaces
• Fan control and monitoring system functions.
– Supports four fans with five user-defined
speed-vs-temperature setpoints
– Supports two-, three-, and four-wire fans

2 Applications
• Industrial ATE
• Telecommunications and networking equipment
• Servers and storage systems
• Any system requiring sequencing and monitoring
of multiple power rails

3 Description
The UCD90124A is a 12-rail PMBus/I2C addressable
power-supply sequencer and monitor. The device
integrates a 12-bit ADC for monitoring up to 12
power-supply voltage inputs. Twenty-six GPIO pins
can be used for power supply enables, power-on
reset signals, external interrupts, cascading, or other
system functions. Twelve of these pins offer PWM
functionality. Using these pins, the UCD90124A offers
support for fan control, margining, and generalpurpose
PWM functions.
Specific power states can be achieved using the Pin-
Selected Rail States feature. This feature allows with
the use of up to 3 GPIs to enable and disable any
rail. This is useful for implementing system low-power
modes and the Advanced Configuration and Power
Interface (ACPI) specification that is used for
hardware devices.
The TI Fusion Digital Power™ designer software is
provided for device configuration. This PC-based
graphical user interface (GUI) offers an intuitive
interface for configuring, storing, and monitoring all
system operating parameters.