DEMO MANUAL DC2028A
8-Channel Power Supply
System Featuring the LTC2977
PMBus Power System Manager
Description
The DC2028A is a demonstration system that showcases
the
LTC
®
2977,
an 8-channel I
2
C/SMBus/PMBus Power
System Manager with EEPROM. The LTC2977 monitors
and controls eight power supply rails. The DC2028A
demonstrates the ability of the LTC2977 to sequence, trim,
margin, supervise, monitor, and log faults for eight power
supplies. Each power supply channel’s output voltage is
monitored and the LTC2977 monitors its own internal die
temperature.
The DC2028A is a single circuit board that contains eight
independent power supply rails. The board employs eight
LTC3405A 300mA switch mode regulators, which are
configured to be controlled by the LTC2977. The DC2028A
demo board provides a sophisticated 8-channel digitally
programmable power supply system. The rail voltages
are programmable within the trim range shown in Table 1.
This demonstration system is supported by the
LTpowerPlay™ graphical user interface (GUI) which enables
complete control of all the features of the device. Together,
the LTpowerPlay software and DC2028A hardware system
create a powerful development environment for designing
and testing configuration settings of the LTC2977. These
settings can be stored in the device’s internal EEPROM or
in a file. This file can later be used to order preprogrammed
devices or to program devices in a production environment.
The software displays all of the configuration settings and
real time measurements from the Power System Manage-
ment IC. Telemetry allows easy access and decoding of
the fault log created by the LTC2977. The board comes
preprogrammed with the EEPROM values appropriate for
the eight power supply rails on the DC2028A. Just plug
and play!
Multiple DC2028A boards can be cascaded together to
form a high channel count power supply (see Multi-Board
Arrays). This cascaded configuration demonstrates fea-
tures of the LTC Power System Management ICs which
enable timing and fault information to be shared across
multiple Power System Management ICs. The user can
configure up to eight DC2028A boards, thereby controlling
up to 64 separate power supply rails. Larger board arrays
can be built using programmable I
2
C base addresses or
bus segmentation.
The DC2028A demo board can be powered by an external
power supply, such as a 12VDC supply. Communication
with the software is provided through the DC1613 USB-to-
I
2
C/SMBus/PMBus controller. The following is a checklist
of items which can be obtained from the LTC website or
LTC Field Sales.
•
USB-to-I
2
C/SMBus/PMBus Controller (DC1613)
•
LTpowerPlay Software
Design files for this circuit board are available at
http://www.linear.com/demo
Dc2028A FeAtures
n
Sequence, Trim, Margin, and Supervise Eight Power
Supplies
Manage Faults, Monitor Telemetry, and Create Fault
Logs
PMBus Compliant Command Set
Supported by LTpowerPlay GUI
Margin or Trim Supplies to 0.25% Accuracy
Fast OV/UV Supervisors per Channel
Supports Multichannel Fault Management
Automatic Fault Logging to Internal EEPROM
Operates Autonomously without Additional SW
Eight OV/UV V
OUT
and One V
IN
Supervisor
Telemetry Reads Back V
IN
, V
OUT
, and Temperature
8-Channel Time-Based Output Sequencer
I
2
C/SMBus Serial Interface
Powered from 6V to 14V
LTC2977 Available in 64-Lead QFN Package
n
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L,
LT, LTC, LTM, Linear Technology, and the Linear logo are registered trademarks and
LTpowerPlay is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents including 7382303, 7420359 and
7940091.
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DEMO MANUAL DC2028A
perFormAnce summAry
POWER SUPPLY CHANNEL
Manager/Controller
Nominal Untrimmed Output Voltages
Rated Output Current
Default Margin Range
Output Trim Range (V
FS_VDAC
= 1.38V)
Temperature
Specifications are at T
A
= 25°C
CH(0:7)
LTC2977
1.2V, 1.5V, 1.8V, 2.0V,
2.5V, 2.7V, 3.0V, 3.3V
0.3A
±5%
+15%/–11%
1 Internal
Common Characteristics
PARAMETER
Supply Input Voltage Range
ADC Total Unadjusted Error
ADC Voltage Sensing Input Range
V
IN_ADC
≥ 1V
CONDITIONS
Specifications Valid Over Full Operating Temperature Range
MIN
6
Differential Voltage: V
IN_ADC
= (V
SENSEP[n]
– V
SENSEM[n]
)
0
TYP
MAX
14
±0.25
6
UNITS
V
%
V
GLossAry oF terms
The following list contain terms used throughout the
document.
Channel
– The collection of functions that monitor, su-
pervise, and trim a given power supply rail.
EEPROM
– Non-volatile memory (NVM) storage used to
retain data after power is removed.
Margin
– Term used typically in board level testing that
increases/decreases the output voltage to look for sensi-
tivity/marginality problems.
Monitor
– The act of measuring voltage, current, and
temperature readings.
NVM
– Non-volatile memory, see EEPROM.
PMBus
– An industry standard power management proto-
col with a fully defined command language that facilitates
communication with power converters and other devices
in a power system.
Rail
– The final output voltage that the power supply
controller manages.
Supervise
– The act of quickly responding to a voltage,
current, temperature condition that is compared to pre-
programmed values (fault settings).
Trim
– The act of adjusting the final output voltage. A servo
loop is typically used to trim the voltage.
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2
DEMO MANUAL DC2028A
Ltpowerplay Gui soFtWAre
LTpowerPlay is a powerful Windows based development
environment that supports Linear Technology power
system management ICs with EEPROM, including the
LTC2977 8-channel PMBus Power System Manager. The
software supports a variety of different tasks. You can use
LTpowerPlay to evaluate Linear Technology ICs by con-
necting to a demo board system. LTpowerPlay can also
be used in an offline mode (with no hardware present) in
order to build a multi-chip configuration file that can be
saved and reloaded at a later time. LTpowerPlay provides
unprecedented system level diagnostic and debug features.
It becomes a valuable diagnostic tool during board bring
up to program or tweak the power management scheme
in a system or to diagnose power issues when bringing
up rails. LTpowerPlay utilizes the DC1613 I
2
C/SMBus/
PMBus controller to communicate with one of many po-
tential targets, including the DC2028A demo system or a
customer board. The software also provides an automatic
update feature to keep the software current with the latest
set of device drivers and documentation. The LTpowerPlay
software can be downloaded from:
http://www.linear.com/ltpowerplay
To access technical support documents for LTC Power
System Management Products visit Help, View Online
Help on the LTpowerPlay menu.
Figure 1. Screenshot of the LTpowerPlay GUI
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DEMO MANUAL DC2028A
Quick stArt proceDure
The following procedure describes how to set up a DC2028A demo system.
1. Download and install the LTpowerPlay GUI:
www.linear.com/ltpowerplay
2. Remove the board from the ESD protective bag and place it on a level surface. Connect the DC1613 I
2
C/SMBus/
PMBus controller to the DC2028A board using the 12-pin ribbon cable.
Figure 2. Connecting DC2028A Board and the DC1613 I
2
C/SMBus/PMBus Controller
3. Confirm that the CONTROL switch is set to the RUN position.
4. Plug the USB-to-I
2
C/SMBus/PMBus controller into a USB port on your PC. The board should power-up with all power
good LEDs and 5V LED illuminated green. The USB-to-I
2
C/SMBus/PMBus controller supplies ~100mA of current
which should be sufficient for a single demo board.
5. If multiple boards are being powered, connect a 12VDC power supply with > 0.5A capacity to the V
IN
input jack of
the DC2028A.
6. Launch the LTpowerPlay GUI.
a. The GUI automatically identifies the DC2028A and builds a system tree for each
power manager. The system tree on the left hand side will look like this:
Note: For multiple board arrays, the GUI automatically ensures each device has
a unique address. In this scenario, it is recommended at this point to store these
addresses to NVM (EEPROM) by clicking the RAM to NVM icon in
the toolbar.
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DEMO MANUAL DC2028A
Quick stArt proceDure
b. A green message box will be displayed momentarily in the lower left hand corner confirming that the DC2028A
is communicating.
c. Save the demo board configuration to a (*.proj) file by clicking the Save icon. This creates a backup file. Name
it whatever you want.
7. The CONTROL switch is configured to control all eight channels. Slide the switch to RUN to enable, OFF to dis-
able all channels. For multiple board arrays, the CONTROL switch is wired to a signal that is common across all
boards. All CONTROL switches must be set to the RUN position to enable all boards.
LOADING A DC2028A CONFIGURATION (*.proj) FILE WITH THE GUI
1. In the upper left hand corner of the GUI, File > Open > browse to your *.proj file. This will load the file into the GUI.
2. Click on the Go Online
working RAM of the LTC2977.
3. To store the configuration to NVM (EEPROM), click on the RAM->NVM icon.
icon, then click on the PC->RAM icon.
This loads the configuration into the
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