Datasheet

UCD90124A
SLVSAN8 –JANUARY 2012 www.ti.com
Table 1. PIN FUNCTIONS (continued)
PIN NAME PIN NO. I/O TYPE DESCRIPTION
INPUT POWER AND GROUNDS
RESET 9 Active-low device reset input. Hold low for at least 2 μs to reset the device.
V33FB 58 3.3-V linear regulator feedback connection. Leave unconnected.
V33A 46 Analog 3.3-V supply. Refer to the layout guidelines section.
V33D 45 Digital core 3.3-V supply. Refer to the layout guidelines section.
V33DIO1 7 Digital I/O 3.3-V supply. Refer to the layout guidelines section.
V33DIO2 44 Digital I/O 3.3-V supply. Refer to the layout guidelines section.
BPCap 47 1.8-V bypass capacitor – tie 0.1-μF capacitor to analog ground.
AVSS1 49 Analog ground
AVSS2 48 Analog ground
AVSS3 64 Analog ground
DVSS1 8 Digital ground
DVSS2 26 Digital ground
DVSS3 43 Digital ground
QFP ground pad NA Thermal pad – tie to ground plane.
FUNCTIONAL DESCRIPTION
TI FUSION GUI
The Texas Instruments Fusion Digital Power Designer is provided for device configuration. This PC-based
graphical user interface (GUI) offers an intuitive I
2
C/PMBus interface to the device. It allows the design engineer
to configure the system operating parameters for the application without directly using PMBus commands, store
the configuration to on-chip nonvolatile memory, and observe system status (voltage, etc). Fusion Digital Power
Designer is referenced throughout the data sheet as Fusion GUI and many sections include screenshots. The
Fusion GUI can be downloaded from www.ti.com.
PMBUS INTERFACE
The PMBus is a serial interface specifically designed to support power management. It is based on the SMBus
interface that is built on the I
2
C physical specification. The UCD90124A supports revision 1.1 of the PMBus
standard. Wherever possible, standard PMBus commands are used to support the function of the device. For
unique features of the UCD90124A, MFR_SPECIFIC commands are defined to configure or activate those
features. These commands are defined in the UCD90xxx Sequencer and System Health Controller PMBUS
Command Reference (SLVU352). The most current UCD90xxx PMBus Command Reference can be found within
the TI Fusion Digital Power Designer software:
http://focus.ti.com/docs/toolsw/folders/print/fusion_digital_power_designer.html via the Help Menu (Help,
Documentation & Help Center, Sequencers tab, Documentation section).
This document makes frequent mention of the PMBus specification. Specifically, this document is PMBus Power
System Management Protocol Specification Part II – Command Language, Revision 1.1, dated 5 February 2007.
The specification is published by the Power Management Bus Implementers Forum and is available from
www.pmbus.org.
The UCD90124A is PMBus compliant, in accordance with the Compliance section of the PMBus specification.
The firmware is also compliant with the SMBus 1.1 specification, including support for the SMBus ALERT
function. The hardware can support either 100-kHz or 400-kHz PMBus operation.
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