Linear LTM2987 Manuale utente
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DEMO MANUAL DC2023A
DESCRIPTION
16-Channel Power Supply
System Featuring the LTM2987
Power System Manager
TheDC2023Aisademonstration system fortheLT M
®
2987
16-channel I2C/SMBus/PMBus power system manager
with EEPROM. The LTM2987 monitors and controls 16
power supply rails. The DC2023A demonstrates the abil-
ity of the LTM2987 to sequence, trim, margin, supervise,
monitor, and log faults for 16 power supply rails. Each
power supply channel’s output voltage is monitored and
the LTM2987 monitors its own internal die temperature.
The DC2023A is a single circuit board that contains sixteen
independentpowersupplyrails.Theboard employs sixteen
LT C
®
3405A 300mA switch-mode regulators, which are
configured tobecontrolled bytheLTM2987. The LTM2987
is available in a µModule
®
(micromodule) package and
contains two LTC2977 devices. This board provides a
sophisticated 16-channel digitally programmable power
supply system. The rail voltages are programmable within
the trim range shown in the Performance Summary.
This demonstration system is supported by the
LTpowerPlay™graphical user interface(GUI) that enables
complete control of all the features of the LTM2987. To-
gether,the LTpowerPlay software and DC2023Ahardware
system create a powerful development environment for
designing and testing LTM2987 configuration settings.
These settings can be stored in the device’s internal
EEPROM or in a file. This file can later be used to order
pre-programmed devices or to program devices in a
production environment. The software displays all of
the configuration settings and real time measurements
from the LTM2987. Telemetry allows easy access and
decoding of the fault log created by the LTM2987. The
board comes pre-programmed with the EEPROM values
appropriate for the sixteen power supplies used on the
DC2023A. Just plug and play!
Multiple DC2023A board sets can be cascaded together
to form a high channel count power supply (see Multi-
Board Arrays). This cascaded configuration demonstrates
features of the LTM2987 which enable timing and fault
information to be shared across multiple ICs. The user can
L, LT, LTC, LTM, Linear Technology, the Linear logo and µModule are registered trademarks
and PowerPlay is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
configure up to eight DC2023A boards, thereby control-
ling up to 128 separate power supply rails. Larger arrays
of LTM2987s are supported through programmable I2C
base address or bus segmentation.
The DC2023A 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-
I2C/SMBus/PMBus Controller. The following is a checklist
of items which can be obtained from the LT C website or
LT C Field Sales.
• USB-to-I2C/SMBus/PMBus Controller (DC1613)
• LTpowerPlay Software
DC2023A Features
• Sequence, Trim, Margin, and Supervise Sixteen 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 Multi-Channel Fault Management
• Automatic Fault Logging to Internal EEPROM
• Operates Autonomously without Additional Software
• Sixteen OV/UV VOUT and Tw o VIN Supervisors
• Telemetry Reads Back VIN, VOUT, and Temperature
• 16-Channel Time-Based Output Sequencer
• I2C/SMBus Serial Interface
• IntegratedDecoupling Capacitors andPull-Up Resistors
• Powered from 6V to 14VDC
• Available in 144-Lead 15mm ×15mm BGA
Design files for this circuit board are available at
http://www.linear.com/demo
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DEMO MANUAL DC2023A
PERFORMANCE SUMMARY
GLOSSARY OF TERMS
Specifications are at TA= 25°C
POWER SUPPLY CHANNEL CH(0:7) CH(8:15)
Manager 1/2 LTM2987 1/2 LTM2987
Nominal Untrimmed Output Voltages 1.0V, 1.1V, 1.2V, 1.3V, 1.4V, 1.5V, 1.7V, 1.8V 2.0V, 2.2V, 2.5V, 2.7V, 3.0V, 3.1V, 3.2V, 3.3V
Rated Output Current 0.3A
Default Margin Range ±5%
Output Trim Range (VFS_VDAC = 1.38V) +13/–19 % +11/–15%
Temperature 2 Internal
Common Characteristics—Specifications Valid Over Full Operating Temperature Range
PARAMETER CONDITIONS
VALUE
MIN TYP MAX UNITS
Supply Input Voltage Range 6 14 V
ADC Total Unadjusted Error VIN_ADC ≥ 1V ±0.25 %
ADC Voltage Sensing Input Range Differential Voltage: VIN_ADC = (VSENSEP[n] – VSENSEM[n]) 0 6 V
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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DEMO MANUAL DC2023A
LTpowerPlay GUI SOFTWARE
LTpowerPlay is a powerful Windows-based development
environment that supports Linear Technology Power
System Management ICs with EEPROM, including the
LTM2987 16-channel PMBus Power System Manager.
The software supports a variety of different tasks. You
can use LTpowerPlay to evaluate Linear Technology ICs
by connecting to a demo board system. LTpowerPlay can
also be used in an offline mode (with no hardware pres-
ent) in order to build a multi-chip configuration file that
can be saved and reloaded at a later time. LTpowerPlay
provides unprecedented 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 I2C/SMBus/PMBus
Controller to communicate with one of many potential tar-
gets, including the DC2023A 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 LT C power
system management products visit Help, View Online
Help on the LTpowerPlay menu.
Figure 1. Screen Shot of the LTpowerPlay GUI
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DEMO MANUAL DC2023A
QUICK START PROCEDURE
Thefollowing proceduredescribes howto setup aDC2023A
demo system.
1. Download and install the LTpowerPlay GUI:
http://www.linear.com/ltpowerplay
2. Remove the board from the ESD protective bag
and place it on a level surface. Connect the DC1613
I2C/SMBus/PMBus Controller to the DC2023A board
using the 12-pin ribbon cable.
3. Confirm that the CONTROL switch is set to the RUN
position.
4. Plug the USB to I2C/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-I2C/SMBus/PMBus Controller supplies
~100mA of current which should be sufficient for a
single demo board.
5. Ifmultiple boards arebeing powered, connect a+12VDC
power supply with > 0.5A capacity to the VIN input jack
of the DC2023A.
6. Launch the LTpowerPlay GUI.
a. The GUI automatically identifies the DC2023A and
builds a system tree. The system tree on the left hand
side should look like this:
Figure 2. Connecting DC2023A board and the DC1613 I2C/SMBus/PMBus Controller
Note:For multiple board arrays, the GUI automatically
ensures each device has a unique address. In this
scenario, it isrecommended 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 DC2023A
QUICK START PROCEDURE
b. A green message box will be displayed for a few
seconds in the lower left hand corner confirming
that the DC2023A 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 16
channels. Slide the switch to RUN to enable, OFF to
disable 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 DC2023A 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” icon, then click on the
“PC->RAM” arrow. This loads the configuration into
the working RAM of the LTM2987.
3. To store the configuration to NVM (EEPROM), click on
the “RAM->NVM” icon.
Figure 3. DC2023A Top Side Details
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DEMO MANUAL DC2023A
Margin All Rails
The LTM2987 power manager on the DC2023A not only
monitors each of the sixteen outputs but can margin the
outputs either high or low. Margining is the operation
that moves a rail either up or down for testing purposes.
It allows a system to be fully characterized over supply
limits without the use of external hardware or resources.
The GUI provides an easy way to margin all rails high
or all low by clicking one of four buttons. To invoke the
margining dialog, click the GroupOp icon in the toolbar.
The buttons labeled “ignore faults” will margin
without creating a fault even if the fault limits
are exceeded.
COMMON DEMO BOARD OPERATIONS
A look at the telemetry window shows the effect of the
margin high or margin low operation. The following screen
shot shows all rails going from nominal set points to
margin high, margin low, and back to nominal voltages.
Each LTC2977 inside the module has a multiplexed ADC
that is used to provide voltage, current, and temperature
readback values. The telemetry plot in the GUI is similar to
amulti-channel oscilloscope whichis capable of displaying
any parameter that is displayed in the telemetry window.
Due to the nature of a multiplexed ADC converter, it has
an associated ADC loop time. The total ADC loop time
(~100ms to 160ms) for a given channel is dependent on
the device’s configuration. Refer to the LTM2987 data
sheet for complete ADC timing specifications.
Creating a Fault
There is a pushbutton on the DC2023A board that is used
to force a fault and demonstrate the demo board’s ability to
detect it and respond according to the configuration. When
depressed, the pushbutton creates a fault on channel 10,
the 2.5V output (GUI channel U1:2). The user should see
all outputs power off, the fault LED momentarily illuminate,
thealert LED illuminate continuously, and all rails sequence
back on after a retry period. The user may also short any
power supply output indefinitely. This
is a good way to induce UV faults and
shows that a shorted channel will not be
damaged. Use a jumper wire or a coin
to short any output.
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DEMO MANUAL DC2023A
COMMON DEMO BOARD OPERATIONS
The LTM2987 has a feature which allows it to sequence its
channels off in a controlled manner, as opposed to turning
all rails off immediately. The SequenceOffOnFault bit in the
MFR_CONFIG_LTC2977registersets this behavior on each
channel. The DC2023A demo board has been configured
to sequence off all channels when a fault occurs. Pressing
the “CREATE FAULT” pushbutton causes the FAULT pin
to be asserted low which triggers all rails to power down
based on the TOFF_DELAY times.
Figure 5. Sequencing Off (SeqOffOnFault=0)
Figure 4 shows FAULTB asserting low, and each of the
channels sequencing off per the TOFF_DELAY settings.
Figure 5 shows the same except that the 3.0V rail (CH12)
does not have its SequenceOffOnFault bit set. The 3.0V
rail powers down immediately as defined by the fault
response setting.
Clearing a Fault
To clear a fault, the user may click the CF icon in the GUI
or simply push the RESET pushbutton on the demo board.
In both cases, the red (+) on the CF icon and alert LED
on the board will be cleared. You will notice that all rails
are automatically re-enabled after a programmable retry
period. The alert LED may be cleared by pushing the Clear
Faults (CF) icon in the GUI. After clearing faults, the system
tree may remain “yellow” if any non-volatile fault
logs are present. For further information, see the
Working with the Fault Log section.
Resetting The DC2023A
A reset pushbutton is provided on the board. To reset all
devices on the DC2023A board and reload the EEPROM
contents into operating memory (RAM), press RESET
(SW1) on the DC2023A.
DC2023A LEDs
Each individual channel on DC2023A also has its own
green “power good” LED (CH0 through CH15). When USB
power (DC1613 Controller) or external power (6-14V jack)
is applied, the +5V green LED will illuminate, indicating
that the LTM2987 is powered. The red LEDs will illuminate
when an alert or a fault has occurred.
Figure 4. Sequencing Off (SeqOffOnFault=1)
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DEMO MANUAL DC2023A
Sequencing Output Channels
The LTM2987 has been pre-programmed to different
TON_DELAY values for each channel. The TON_DELAY
parameter isapplied toeach device relative toits respective
CONTROL pin. When multiple demo boards are connected
together, all CONTROL pins are wire OR’d. Therefore the
TON delays are enforced relative to one edge. The same
applies to TOFF_DELAY values. When the CONTROL
switch is set to the OFF position, all rails will power down
sequentially based on each of the device’s TOFF_DELAY
values. Figure 6 shows an oscilloscope screen capture of
COMMON DEMO BOARD OPERATIONS
Figure 6. Sequencing Output Channels with DC2023A Using TON_DELAY and TOFF_DELAY
Figure 8. TOFF_DELAY Configuration
Figure 7. TON_DELAY Configuration
three output rails sequencing up and down in response
to the CONTROL pin.
Each channel has an LED which visually indicates if the
channel has power. When the CONTROL pin is switched
on and off, you will observe the relative on/off timing of
the 16 channels.
For the LTM2987, the TON_DELAY and TOFF_DELAY
values extend to 13.1 seconds, providing very long on
and off sequencing of power supply rails.
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DEMO MANUAL DC2023A
COMMON DEMO BOARD OPERATIONS
Figure 9. Why Am I Off Tool in the LTpowerPlay GUI
Why Am I Off? Tool
Use the Why am I Off tool in the LTpowerPlay GUI to di-
agnose the reason a power supply channel is turned off.
The tool can be located in the top right corner of the GUI,
next to the Register Information tab. Hover your cursor
over this tab to show the tool.
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DEMO MANUAL DC2023A
ADVANCED DEMO BOARD OPERATIONS
What Is a Fault Log?
A fault log is a non-volatile record of the power system
leading up to the time of fault. It holds the most recent
monitored values (up-time, voltage, current, temperature)
that can be analyzed to help determine the cause of the
fault. It is a powerful diagnostic feature of the LTM2987
on the DC2023A demo board.
Create a Fault and Fault Log
To create a fault log, you must create a fault, as described
in the Creating a Fault section. If multiple boards are
configured, select the appropriate device in the system
tree by clicking on the appropriate LTM2987 chip. We will
proceed to work with the fault log.
Working with the Fault Log
Once a fault has occurred, the Fault Log (FL) icon will show
a red (+) sign on it, indicating that the GUI has detected a
fault log in the device. Clicking the icon will bring
up a dialog box. Note that it is context sensitive.
Be sure that the desired device is selected in the
system tree.
Notice that the checkbox “Log to EEPROM on Fault” is
checked. Once a fault occurs, the device will automatically
write the fault log data to EEPROM (NVM). At this point,
the log is locked and will not change until it is cleared by
the user. To read the EEPROM log data, first click the “NVM
to RAM” button. At this point the RAM Log is locked and
not updated even though the telemetry readings continue.
Click the “Read RAM Log” button. The log data will appear
in the text box below.
Indice
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