Texas Instruments | Power Consumption Summary for KeyStone C66x Devices (Rev. B) | Application notes | Texas Instruments Power Consumption Summary for KeyStone C66x Devices (Rev. B) Application notes

Texas Instruments Power Consumption Summary for KeyStone C66x Devices (Rev. B) Application notes
Application Report
SPRABI5B – September 2011 – Revised February 2017
Power Consumption Summary for KeyStone C66x Devices
.......................................................................................... High-Performance and Multicore Processors
ABSTRACT
This application report discusses estimating the power consumption of Texas Instruments KeyStone
Digital Signal Processors (DSP) using a provided device-specific power spreadsheet.
The power consumption of the device is highly application-dependent, therefore, the provided power
spreadsheet allows a number of variables to be set according to the intended application to calculate
accurate estimates of device power consumption. This spreadsheet can be used to model power
consumption to assist in power supply design, thermal design, and so forth. To obtain good results from
the spreadsheet, realistic usage parameters must be entered.
The data found in this document and in the device-specific power spreadsheet were measured from
devices at the maximum end of the power consumption range for production devices. No production
devices will have average power consumption that exceeds the spreadsheet values; therefore, the
spreadsheet values may be used for board thermal analysis and power supply design as a maximum
long-term average.
The device-specific power spreadsheet can be found on your device’s product page.
1
2
3
4
5
Contents
Activity-Based Models .......................................................................................................
Spreadsheet Parameters ...................................................................................................
Using the Power Estimation Spreadsheet ................................................................................
Using the Results ............................................................................................................
References ...................................................................................................................
SPRABI5B – September 2011 – Revised February 2017
Submit Documentation Feedback
Power Consumption Summary for KeyStone C66x Devices
Copyright © 2011–2017, Texas Instruments Incorporated
2
2
3
5
5
1
Activity-Based Models
1
www.ti.com
Activity-Based Models
Power consumption for the device can vary widely depending on the use of on-chip resources. Therefore,
power consumption cannot be estimated accurately without an understanding of the components of the
device in use and the usage patterns for those components. By providing the usage parameters that
describe what is being used on the device and how it is being used, accurate power consumption values
can be obtained for power supply and thermal analysis. Expected power consumption for worse-case
utilization can be determined by choosing usage parameters closest to the real-use case.
The power spreadsheet divides the power consumption into two major components: baseline power and
activity power.
1.1
Baseline Power
Baseline power consumption is the power consumed that is independent of chip activity, such as:
• Static leakage power
• Core power
– Clock tree
– Internal memory
– On-chip module power
Baseline power is highly dependent on voltage, temperature, and DSP/ARM® frequency.
1.2
Activity Power
Activity power consumption is power that is consumed by all active parts of the device:
• CorePac
• ARM (when applicable)
• Enhanced direct memory access (EDMA3)
• Peripherals
• And so on
The activity power is independent of temperature, but highly dependent on the activity levels of the DSP,
ARM, EDMA3, peripherals, and so forth. In the power spreadsheet, activity power is separated by the
major modules and peripherals within the device. Therefore, the individual module and peripheral power
consumption can be estimated independently. This helps with tailoring power consumption to specific
applications.
Module and peripheral activity power consumption includes some necessary EDMA3 and DSP activity
used to transfer data on-chip and off-chip when required. The power consumption associated with EDMA3
and DSP activity has been minimized to show only power consumption with respect to the
module/peripheral tested.
2
Spreadsheet Parameters
The spreadsheet provides configurable parameters that allow the estimation of power consumption based
on configured usage parameters. To ensure realistic results, verify that the spreadsheet is configured
accurately. For more details, see Section 3.1.
The parameters are as follows:
• Device Speed Grade: The speed grade of the devices ordered from TI.
• Operating Frequency: (or also referred as just Frequency) Specifies the customer applications
intended frequency of operation for a module and peripheral or the frequency of the external interface
to that module.
• Modes: Selects the peripheral-specific configuration mode.
• Status: Specifies whether a peripheral is Enabled and configured for use, or Disabled and
unconfigured.
ARM is a registered trademark of ARM Limited.
All other trademarks are the property of their respective owners.
2
Power Consumption Summary for KeyStone C66x Devices
SPRABI5B – September 2011 – Revised February 2017
Submit Documentation Feedback
Copyright © 2011–2017, Texas Instruments Incorporated
Spreadsheet Parameters
www.ti.com
•
•
•
•
•
2.1
% Utilization: Specifies the relative amount of time the module is active or in use versus off or idle.
% Write: Specifies the relative amount of time (considering active time only) the module is transmitting
versus receiving.
Bits: Specifies the number of data bits to be used in a selectable-width interface.
Lane: Specifies the number of lanes used by that interface.
% Switching: Specifies the probability that any one data bit on the relative data bus will change state
from one cycle to the next.
Power Domains Details
Power domains and associated clock domains within the device (except the Always On domain) can be
disabled or enabled by software. When a power domain is disabled, the peripherals and memories in that
domain are put to sleep to reduce leakage dissipation, and the peripherals are held in reset and clockgated, reducing the baseline and activity power consumption of the device.
The device-specific power spreadsheet allows you to disable or enable a power domain in the model by
selecting Disabled or Enabled status for the peripheral in the drop down menu of the status column.
For more information on power domains that can be disabled and the Power Sleep Controller, see the
device-specific Data Manual and the KeyStone Architecture Power Sleep Controller (PSC) User's Guide
(SPRUGV4).
2.2
Device Modules/Peripherals
For information on modules and peripherals available on a device, see the device-specific data manual.
3
Using the Power Estimation Spreadsheet
The use of the power estimation spreadsheet involves entering the appropriate usage parameters as input
data in the spreadsheet. The following steps show the general flow:
1. Choose the appropriate Speed Grade of the part ordered from TI.
2. Choose the appropriate DSP operating frequency: 1200 MHz to 800 MHz.
3. Choose the case temperature for which you want to estimate power: 0°C to 100°C.
4. Enable the appropriate peripherals used for your application including the mode, frequency, and bus
width for that peripheral, if applicable.
5. Enter the appropriate peripherals' or modules' % utilization, % writes, and % switching values.
For best results, enter the information from left to right, starting at the top and moving downward. As the
spreadsheet is being configured, the settings are checked for conflicts. For example, it checks to see if the
specified clock frequency is within the allowed range.
The spreadsheet takes the input information and displays the details of power consumption for the chosen
configuration.
3.1
Choosing Appropriate Values
Acceptable values are determined by design and the correct values to enter will be clear.
You can disable unused modules and peripherals in the spreadsheet by selecting the Disabled tab in the
column labeled Status. To choose the appropriate values, you need a good understanding of the read and
write balance, bit switching required estimation, and utilization of the user application.
3.1.1
% Utilization
For modules other than the CorePac, utilization is simply the percentage of the time the module spends
doing something useful, versus being unused or idle. For these peripherals, the value is just the average
over time. For example, if the DDR3 performs reads and writes one-quarter of the time and has no data to
move for the other three-quarters of the time (though it continues to perform background tasks like
refreshes), this would be considered 25% utilization.
SPRABI5B – September 2011 – Revised February 2017
Submit Documentation Feedback
Power Consumption Summary for KeyStone C66x Devices
Copyright © 2011–2017, Texas Instruments Incorporated
3
Using the Power Estimation Spreadsheet
www.ti.com
The CorePac utilization is not as straightforward, because there are varying degrees of use for the
CorePac. The spreadsheet estimates the CorePac activity with respect to three levels of execution:
% Signal Processing (SP) Utilization, % Control Code (CC) Utilization, and % Idle Utilization. The sum of
these three execution levels cannot exceed 100%, and only % Signal Processing Utilization and % Control
Code Utilization are able to be explicitly entered into the spreadsheet. Some devices allow power gating a
specific CorePac by completely disabling that specific CorePac. For more information, see the devicespecific spreadsheets and data manuals.
If the sum of % Signal Processing Utilization and % Control Code Utilization is less than 100%, then the
spreadsheet assumes that the remaining percentage is Idle Utilization. The three levels of execution are
described in more detail below:
• % Signal Processing (SP) Utilization is used to represent scenarios with high levels of CorePac
activity. This corresponds to the case in which all eight instructions fetched by the CorePac are
executed in parallel each for CorePac clock cycle, resulting in all eight functional units being active
every cycle. Few CorePac algorithms will achieve 100% CorePac utilization because this requires
execution of all eight function units every cycle with no stalls. Even intense applications do not spend
all of the time executing such highly parallel code.
• % Control Code (CC) Utilization is used to represent scenarios with low levels of activity. This could
embody some type of task-polling loop or background task. The activity for this case represents the
execution of approximately two functional units every clock cycle. This type of code typically accounts
for 30% of program execution.
• % Idle Utilization is used to represent the case in which the CorePac is active, but is not doing useful
work (NOP execution). This parameter cannot be explicitly entered into the spreadsheet, and is
assumed to be the remaining utilization percentage when % Signal Processing Utilization and
% Control Code do not sum to 100% (% Idle Utilization = 100% - % Signal Processing Utilization % Control Code Utilization).
For more information about the CorePac architecture, operation, or instruction set, see the TMS320C66x
DSP CPU and Instruction Set Reference Guide (SPRUGH7).
System level issues may also reduce utilization. Although the spreadsheet will accept 100% utilization for
all peripherals, this is not possible in reality. As memory and EDMA3 bandwidth is consumed, peripheral
activity is throttled back due to these bottlenecks, and, therefore, 100% utilization is not achievable. In
applications with a lot of memory and/or EDMA3 usage, individual module utilization numbers should be
entered, while keeping this overall limitation in mind.
3.1.2
% Writes
Peripherals that transmit as much as they receive have 50% writes (the spreadsheet will assume the
remaining 50% of the time is spent on reads). In some applications, peripherals transmit in only one
direction, or have a known balance of data movement. In these cases, the % writes option is not available
for configuration. For the peripherals that have the % write configuration, 50% is a typical number that
should be used.
3.1.3
% Switching
Random data has a 50% chance that any bit will change from one cycle to the next. Some applications
may be able to predict this chance using some a priori information about the data set. If there is a property
of the algorithm that allows prediction of the bit changes, the application-specific probability can be used.
All other applications should use the default number of 50%.
3.2
Peripheral Enabling and Disabling
As mentioned previously, the device includes the capability to disable peripherals to reduce power
consumption. This can be done by configuring the Power Sleep Controller. The spreadsheet also allows
you to disable peripherals controlled by the PSC to ensure the peripherals' dynamic power is not included
in the power calculation if the peripheral is not being used. For more information, see the device-specific
data manual and the Power Sleep Controller (PSC) for KeyStone Devices User Guide (SPRUGV4).
4
Power Consumption Summary for KeyStone C66x Devices
SPRABI5B – September 2011 – Revised February 2017
Submit Documentation Feedback
Copyright © 2011–2017, Texas Instruments Incorporated
Using the Results
www.ti.com
A peripheral can be enabled or disabled in the spreadsheet from the column labeled Status. If a peripheral
is disabled, the CVDD and I/O power for the peripheral will be 0. If the peripheral is enabled with 0%
utilization, the activity power for CVDD and I/O will be 0. However, the peripheral will have baseline power
consumption due to enabling/clocking the peripheral. For more information, see the KeyStone Architecture
Power Sleep Controller (PSC) User's Guide (SPRUGV4).
4
Using the Results
The power data presented in this document and the device-specific power spreadsheet were collected
from devices considered to be at the maximum end of power consumption for production devices. No
production units will have average power consumption that exceeds the spreadsheet values. The power
consumption estimated by the spreadsheet is the maximum average power consumption. While transient
currents may cause power to spike above the spreadsheet values for a small amount of time, over a long
period of time, the observed average power consumption will be below the spreadsheet value. Therefore,
the spreadsheet values may be used for board thermal analysis and power supply design as a maximum
long-term average.
4.1
Adjusting I/O Power Results
I/O power is dependent not only on the DSP and activity, but also on the load being driven. For loads with
CMOS inputs, the power required to drive the trace dominates; therefore, the power will scale based on
the capacitance loading.
4.2
Spreadsheet Layout and Details
The following sections discuss the spreadsheet layout and details.
4.2.1
Baseline Section of Spreadsheet
The baseline power portion of the results section consolidates the average power associated with leakage,
clock tree, and phase-locked loop (PLL) power. The clock tree power includes the power consumed by
active clocks within the system.
4.2.2
Activity Section of Spreadsheet
The activity section contains the average power consumption associated with enabling a peripheral along
with power consumed due to peripheral activity. The activity levels of a peripheral are defined by the
peripheral frequency, % utilization, % writes, % switching, bus width, and peripheral mode.
4.2.3
Totals Section of Spreadsheet
The totals section provides the total in each column for each power supply for Baseline plus Activity
power. The total (mW) is equal to the total power for CVDD and I/O, for example, total device power.
4.3
Current vs. Power Variable Option
There is an option on the spreadsheet that can be used to get the estimates across each of the power
rails and the total in terms of Power (in mW) and Current (in mA).
• With the variable set to Power - it uses CVDD = SmartReflex Voltage to provide total power estimates
in mW
• With the variable set to Current - it uses CVDD = 0.9 V to provide total current estimates in mA
5
References
•
•
•
KeyStone Architecture Power Sleep Controller (PSC) User's Guide (SPRUGV4)
TMS320C66x DSP CPU and Instruction Set Reference Guide (SPRUGH7)
KeyStone Architecture Power Sleep Controller (PSC) User's Guide (SPRUGV4)
SPRABI5B – September 2011 – Revised February 2017
Submit Documentation Feedback
Power Consumption Summary for KeyStone C66x Devices
Copyright © 2011–2017, Texas Instruments Incorporated
5
IMPORTANT NOTICE FOR TI DESIGN INFORMATION AND RESOURCES
Texas Instruments Incorporated (‘TI”) technical, application or other design advice, services or information, including, but not limited to,
reference designs and materials relating to evaluation modules, (collectively, “TI Resources”) are intended to assist designers who are
developing applications that incorporate TI products; by downloading, accessing or using any particular TI Resource in any way, you
(individually or, if you are acting on behalf of a company, your company) agree to use it solely for this purpose and subject to the terms of
this Notice.
TI’s provision of TI Resources does not expand or otherwise alter TI’s applicable published warranties or warranty disclaimers for TI
products, and no additional obligations or liabilities arise from TI providing such TI Resources. TI reserves the right to make corrections,
enhancements, improvements and other changes to its TI Resources.
You understand and agree that you remain responsible for using your independent analysis, evaluation and judgment in designing your
applications and that you have full and exclusive responsibility to assure the safety of your applications and compliance of your applications
(and of all TI products used in or for your applications) with all applicable regulations, laws and other applicable requirements. You
represent that, with respect to your applications, you have all the necessary expertise to create and implement safeguards that (1)
anticipate dangerous consequences of failures, (2) monitor failures and their consequences, and (3) lessen the likelihood of failures that
might cause harm and take appropriate actions. You agree that prior to using or distributing any applications that include TI products, you
will thoroughly test such applications and the functionality of such TI products as used in such applications. TI has not conducted any
testing other than that specifically described in the published documentation for a particular TI Resource.
You are authorized to use, copy and modify any individual TI Resource only in connection with the development of applications that include
the TI product(s) identified in such TI Resource. NO OTHER LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE TO
ANY OTHER TI INTELLECTUAL PROPERTY RIGHT, AND NO LICENSE TO ANY TECHNOLOGY OR INTELLECTUAL PROPERTY
RIGHT OF TI OR ANY THIRD PARTY IS GRANTED HEREIN, including but not limited to any patent right, copyright, mask work right, or
other intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
regarding or referencing third-party products or services does not constitute a license to use such products or services, or a warranty or
endorsement thereof. Use of TI Resources may require a license from a third party under the patents or other intellectual property of the
third party, or a license from TI under the patents or other intellectual property of TI.
TI RESOURCES ARE PROVIDED “AS IS” AND WITH ALL FAULTS. TI DISCLAIMS ALL OTHER WARRANTIES OR
REPRESENTATIONS, EXPRESS OR IMPLIED, REGARDING TI RESOURCES OR USE THEREOF, INCLUDING BUT NOT LIMITED TO
ACCURACY OR COMPLETENESS, TITLE, ANY EPIDEMIC FAILURE WARRANTY AND ANY IMPLIED WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF ANY THIRD PARTY INTELLECTUAL
PROPERTY RIGHTS.
TI SHALL NOT BE LIABLE FOR AND SHALL NOT DEFEND OR INDEMNIFY YOU AGAINST ANY CLAIM, INCLUDING BUT NOT
LIMITED TO ANY INFRINGEMENT CLAIM THAT RELATES TO OR IS BASED ON ANY COMBINATION OF PRODUCTS EVEN IF
DESCRIBED IN TI RESOURCES OR OTHERWISE. IN NO EVENT SHALL TI BE LIABLE FOR ANY ACTUAL, DIRECT, SPECIAL,
COLLATERAL, INDIRECT, PUNITIVE, INCIDENTAL, CONSEQUENTIAL OR EXEMPLARY DAMAGES IN CONNECTION WITH OR
ARISING OUT OF TI RESOURCES OR USE THEREOF, AND REGARDLESS OF WHETHER TI HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
You agree to fully indemnify TI and its representatives against any damages, costs, losses, and/or liabilities arising out of your noncompliance with the terms and provisions of this Notice.
This Notice applies to TI Resources. Additional terms apply to the use and purchase of certain types of materials, TI products and services.
These include; without limitation, TI’s standard terms for semiconductor products http://www.ti.com/sc/docs/stdterms.htm), evaluation
modules, and samples (http://www.ti.com/sc/docs/sampterms.htm).
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2017, Texas Instruments Incorporated
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Related manuals

Download PDF

advertising