Cirrus Logic CRD5490 User Manual

CRD5490-Z Power Monitor

CRD5490-Z

Features

• Easy-to-use Power Monitoring Reference Design

– Plug one side into a wall outlet and an electric load

into the other side.

– Read real time measurements on the PC GUI via

USB in seconds.

• Real Time Measurements:

– Line Voltage – Load Current – Active Power – Reactive Power – Apparent Power – Power Factor – Fundamental Line Frequency – Temperature

• Operational Voltage 90VAC to 260 VAC

• Maximum RMS Load Current 15A

• Factory Calibrated and Recalibration Capable

• Compact AC/DC Buck Converter

• Onboard PIC18 Microcontroller

• Windows

GUI Software

Overview

The CRD5490-Z is designed to evaluate the functionality and performance of the CS5490 power/energy measurement device. The CRD5490-Z integrates an efficient and compact AC/ DC drop capacitor/buck power supply, voltage and current sensors, and low-cost USB MCU. This compact, complete power monitor system integrates easily in any design evaluation.

The CRD5490-Z was designed with a graphical user interface (GUI) for power measurements and calibration execution. A full-featured GUI is provided to access real time line voltage, load current, active power, reactive power, apparent power, power factor, and temperature. The software provides full access and control of the CS5490 calibration and configuration without having to learn specialized commands.

ORDERING INFORMATION

CRD5490-Z Reference Design

Cirrus Logic, Inc.

http://www.cirrus.com

APR‘12

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CRD5490-Z

Contacting Cirrus Logic Support

For all product questions and inquiries contact a Cirrus Logic Sales Representative. To find the one nearest to you go to www.cirrus.com

IMPORTANT NOTICE

Cirrus Logic, Inc. and its subsidiaries ("Cirrus") believe that the information contained in this document is accurate and reliable. However, the information is subject to change without notice and is provided "AS IS" without warranty of any kind (express or implied). Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, indemnification, and limitation of liability. No responsibility is assumed by Cirrus for the use of this information, including use of this information as the basis for manufacture or sale of any items, or for infringement of patents or other rights of third parties. This document is the property of Cirrus and by furnishing this information, Cirrus grants no license, express or implied under any patents, mask work rights, copyrights, trademarks, trade secrets or other intellectual property rights. Cirrus owns the copyrights associated with the information contained herein and gives consent for copies to be made of the information only for use within your organization with respect to Cirrus integrated circuits or other products of Cirrus. This consent does not extend to other copying such as copying for general distribution, advertising or promotional purposes, or for creating any work for resale.

CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE ("CRITICAL APPLICATIONS"). CIRRUS PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED FOR USE IN PRODUCTS SURGICALLY IMPLANTED INTO THE BODY, AUTOMOTIVE SAFETY OR SECURITY DEVICES, LIFE SUPPORT PRODUCTS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF CIRRUS PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER'S RISK AND CIRRUS DISCLAIMS AND MAKES NO WARRANTY, EXPRESS, STATUTORY OR IMPLIED, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR PARTICULAR PURPOSE, WITH REGARD TO ANY CIRRUS PRODUCT THAT IS USED IN SUCH A MANNER. IF THE CUSTOMER OR CUSTOMER'S CUSTOMER USES OR PERMITS THE USE OF CIRRUS PRODUCTS IN CRITICAL APPLICATIONS, CUSTOMER AGREES, BY SUCH USE, TO FULLY INDEMNIFY CIRRUS, ITS OFFICERS, DIRECTORS, EMPLOYEES, DISTRIBUTORS AND OTHER AGENTS FROM ANY AND ALL LIABILITY, INCLUDING ATTORNEYS' FEES AND COSTS, THAT MAY RESULT FROM OR ARISE IN CONNECTION WITH THESE USES.

Microsoft Visual Studio, Windows 7, and Windows XP are either trademarks or registered trademarks of Microsoft Corporation.

IMPORTANT SAFETY INSTRUCTIONS

Read and follow all safety instructions prior to using this demonstration board.

This Engineering Evaluation Unit or Demonstration Board must only be used for assessing IC performance in a laboratory setting. This product is not intended for any other use or incorporation into products for sale.

This product must only be used by qualified technicians or professionals who are trained in the safety procedures associated with the use of demonstration boards.

Risk of Electric Shock

• The direct connection to the AC power line and the open and unprotected boards present a serious risk of electric shock and can cause serious injury or death. Extreme caution needs to be exercised while handling this board.

• Avoid contact with the exposed conductor or terminals of components on the board. High voltage is present on exposed conductor and it may be present on terminals of any components directly or indirectly connected to the AC line.

• Dangerous voltages and/or currents may be internally generated and accessible at various points across the board.

• Charged capacitors store high voltage, even after the circuit has been disconnected from the AC line.

• Make sure that the power source is off before wiring any connection. Make sure that all connectors are well

connected before the power source is on.

• Follow all laboratory safety procedures established by your employer and relevant safety regulations and guidelines, such as the ones listed under, OSHA General Industry Regulations - Subpart S and NFPA 70E.

Suitable eye protection must be worn when working with or around demonstration boards. Always

comply with your employer’s policies regarding the use of personal protective equipment.

All components and metallic parts may be extremely hot to touch when electrically active.

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1. CHARACTERISTICS AND SPECIFICATIONS

1.1 Recommended Operating Conditions

Parameter Symbol Min Typ Max Unit

Reference

Line Voltage V

Load Current

Peak Current I

Fundamental Frequency Freq 5 - 2000 Hz

Ambient Operating Temperature T

RMS

PEAK

1.2 Electrical Characteristics

Parameter Symbol Min Typ Max Unit

Reference

Power Consumption (V

Accuracy (PF=1, Sample Count 8000 - 2 second, Temp Compensation Enabled)

RMS Voltage (90-260V

RMS Current (15mA-15A)

Active Power (1.5W-3900W)

= 240V, 50Hz) P

)

V

I

P

RMS

AVG

90 - 260 V

--15A

--22A

-40 85

-0.6-W

0.1

C

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WARNING

High Voltage Hazard

When the CRD5490-Z is connected to AC lines, high voltage is present inside the box.

Do not remove the protective cover from the CRD5490-Z when power is connected.

The evaluation board connects directly to the AC power line and presents a serious risk of

electric shock and can cause serious injury or death. Extreme caution needs to be

exercised while handling this box. Make sure that the power source is off before wiring any

connection. Make sure that all connectors are well connected before the power source is

turned on. Make sure all AC power line wiring is secured to the box and away from contact

before the power source is on.

Refer to additional warnings at the beginning of this document.

Load

Current

Sensor

Voltage

Divide Sensor

+3.3V

Voltage

Input

Current Input

MCU

USB

Cap. Drop

+ Buc k Supply

Isolation

CS5490

CRD5490-Z

RESET

Figure 1. System Block Diagram

2. HARDWARE OVERVIEW

The CRD5490-Z includes sensors (line voltage and current shunt), a power supply, a CS5490 power monitor calculation engine, isolation, and an MCU. Figure 1 shows connections of each block.

Make sure that the power source is off before wiring any connection. The AC source is connected to plug IEC 60320 C14, and the AC load is connected to connector IEC 60320 C13. Make sure that all connectors are well connected before the power source is turned on. Make sure all AC power line wiring is secured to the box and away from contact before the power source is on.

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VOUT

VIN

Figure 2. Voltage Sensor Attenuator

OUTVIN

R1 R2+

--------------------- -

 176m V

RMS

=

Eq. 1

R1 R2

OUT

--------------

1– 1000

260V

176m V

-------------------

1– 1.47M ===

Eq. 2

SHUNT

OUT

SHUNT

------------------ -

35.36mV 15A

------------------------

2.35m == =

Eq. 3

2.1 Line Voltage Sensor

The high-voltage AC line is attenuated using a voltage divider sensor comprised of five 1206 resistors before being supplied to the CS5490 voltage channel input. Figure 2 shows the resistor diagram for line voltage sensing. R1 is actually four large-value resistors, which increases the voltage rating. R2 is one 1K sense resistor. Refer to the vendor’s specifications for voltage compliance.

The divider ratio is determined by the maximum input range of the CS5490 voltage channel (176mV

RMS

) and the

maximum line voltage. The division ratio is determined by Equation 1.

For a line voltage, V

= 260V

, and R2 = 1K, R1 can be solved. See Equation 2:

RMS

To give a 115% margin and to select common resistor values, R1 = 115% 1.47M is selected and composed of four resistors: 4 422k.

The voltage sense resistor (R2) must be referenced to the same potential as the current sensor and CS5490 power supply (located either on the Line or Neutral). By design, the CRD5490-Z is referenced to the Line side after the fuse. To switch the sensor reference, Line and Neutral of both the load and the source could be switched, and the fuse should be placed on the line externally.

2.2 Shunt Current Resistor

The CRD5490-Z implements current sensing using a low-resistance shunt. When a shunt is used, the current channel’s signal amplitude will be set by the shunt resistor using Ohm's Law, V = IR. To keep power dissipation low, it is necessary to use a low-resistance shunt. The current channel of the CS5490 provides a high gain setting (50x) to enable the use of a low-valued shunt. The maximum input amplitude for the current channel is 35mV 50x gain range.

Applying Ohm's law, V

OUT

= I

SHUNT

R

, use Equation 3 to solve for R

SHUNT

RMS

in the

To give an 85% margin, the shunt should be reduced by R

= 85%2.35m = 2 m. The power rating of the

SHUNT

shunt should be at least twice the power dissipation on the shunt with the maximum continuous load current. With a maximum 15A load current, the CRD5490-Z uses a 2W shunt resistor.

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Drop Capacitor

and Rectifier

Buck

Converter

+35 V +3 .3V

CS5490

Figure 3. Power Supply Option 1

Drop Capacitor

and Rectifier

+3.3V

Regulator

+6V +3 .3V

CS5490

Figure 4. Power Supply Option 2

2.3 Power Supply

The CRD5490-Z contains two separate power supply domains: isolated +5V USB supply and +3.3V non-isolated CS5490 power supply derived from the power line. The +3.3V non-isolated power supply circuit is designed to reduce the overall supply volume by creating a two-stage drop capacitor and buck supply.

By selecting an efficient buck design instead of a simple voltage regulator, the rectified supply voltage is raised, the transferred power is increased, and the drop capacitor value is reduced. Reducing the value substantially reduces the capacitor's size. If size is not a factor, the more expensive buck design could be replaced with a simple voltage regulator. Figure 3 and Figure 4 show the two options evaluated for the CRD5490-Z design. Contact Cirrus Logic sales for assistance with a cost-reduced, regulator-only design.

2.4 MCU Purpose

The CRD5490-Z is designed to minimize the requirements of the MCU. Virtually any low-cost MCU with non-volatile memory (NVM) can be used with the CS5490 device and software. The microchip MCU has the following purposes in the CRD5490-Z:

– Store and reload calibration coefficients – Perform USB to UART transactions that mimic a serial COM port

USB transactions are sent from the PC to the MCU. The MCU reads the first byte (character) and determines whether it should transmit the remaining bytes to the CS5490 as a Write/Read/DSP command or store or recall as calibration coefficients into NVM. All responses from the CS5490 are directly translated back to the PC via the MCU.

MCU UART communication transactions can be viewed at the bottom of the GUI. Characters sent or received are displayed in hexadecimal format. Refer to Figure 26.

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Figure 5. Location of the Unzipped Files

3. SOFTWARE OVERVIEW

The evaluation board comes with software and a USB cable to link the evaluation board to the PC. The evaluation software was developed with Microsoft

™

. The following procedure is based on Windows XP.

3.1 Installation Procedure

Follow the steps below to install the GUI and the CDC driver software:

1. Access the following web site: http://www.cirrus.com/en/support

2. Click the Energy Measurement link.

3. Click the CRD5490 link. The Software License web page is displayed.

4. To agree with the terms and conditions, click the Agree button. The File Download window is displayed.

5. Click the Save button. The Save As window is displayed.

6. Select a location to store the compressed folder.

7. Click the Save button. The Download complete window is displayed.

8. Click the Open Folder button. The location where the compressed folder is stored is displayed.

9. Right-click on the compressed folder, and click Extract All.

10. Select a location to extract the files.

11. Navigate to the location where the extracted files are stored and double-click on the setup.exe file.

Visual Studio® and was designed to run with Windows XP™ and Windows

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Figure 6. Application Install - Security Warning Window

The application will verify system requirements. The Application Install - Security Warning window is displayed.

12. Click the Install button.

13. Follow the instructions of the Microsoft.Net Framework installation.

The Microsoft.Net Framework may need to be installed on the system. Internet access may be required to install the Framework or language packs. The download will start automatically. If installation stops after Framework is installed, select setup.exe from step 11.

The installation program will automatically load the application after installation. If the CDC driver is already installed and the CRD5490-Z is connected (AC power and USB cable), then the CRD5490-Z will be recognized and ready.

If the CDC driver is not installed, connect the USB and AC power source, then install the serial CDC Driver when Windows recognizes the device. Refer to Appendix 2: CDC Driver Installation on page 26 for more details.

14. If necessary, execute the GUI using the next section, 3.1.1 Executing the GUI.

3.1.1 Executing the GUI

1. From the Start menu, click All Programs.

2. Click Cirrus Logic.

3. Click Cirrus Power Monitor (CS5490). The GUI is launched.

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WARNING

High Voltage Hazard

When the CRD5490-Z is connected to AC lines, high voltage is present inside

the box. Do not remove the protective cover from the CRD5490-Z when power is

connected.

The evaluation board connects directly to the AC power line and presents a serious risk of

electric shock and can cause serious injury or death. Extreme caution needs to be

exercised while handling this box. Make sure that the power source is off before wiring any

connection. Make sure that all connectors are well connected before the power source is

turned on. Make sure all AC power line wiring is secured to the box and away from contact

before the power source is on.

Refer to additional warnings at the beginning of this document.

Figure 7. Cirrus Logic - Power monitor Window

3.2 Using the Software

Before launching the software, ensure that all of the cables connected to the CRD5490-Z are installed (as described in the Hardware Overview section on page 4) and connect the board to an open USB port on the PC using the provided cable. Once the board is powered through the AC line and USB, the software program can be launched.

3.3 Start-up Window

When the software is launched, the Cirrus Logic - Power Monitor window is displayed. This window contains information about the software's title, version, and device revision number. See Figure 7.

The tabs in this window provide access to GUI functions. The following subsections describe the tabs in this window.

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Figure 8. Connection Tab with Communication Error Displayed

3.3.1 Connection Tab

The Connection tab displays the USB communication with CRD5490-Z board. At startup, the GUI attempts to establish a connection to the CRD5490-Z to the PC through the last USB device connected.

Once the USB communication has been established, the CS5490 serial port will report the Device Revision on the Connection tab. If the software is unable to establish a communication link with the CRD5490-Z board, a message is displayed indicating that the initial communication has failed. This message is displayed in Figure 8.

3.3.1.1 Common Causes of Communication Error

• No AC power

• USB cable is not connected

• USB cable to the CRD was not the last device connected before loading the GUI

• Windows is not given time to recognize the device and assign a serial port

• The wrong serial port is assigned because the GUI was loaded before the above items were met

3.3.1.2 Fixing Communication Problems

1. Close the GUI.

2. Remove the power to the CRD5490-Z by turning off the AC source.

3. Remove the power to the MCU by removing the USB cable from the PC.

4. Check that the AC power connections are secure.

5. Connect the USB cable to the PC.

6. Wait for Windows to detect the CDC Device. Verify the port by opening the Device Manager and reviewing the port assignments (run “devmgmt.msc” at a command prompt or Windows 7 search).

7. Apply AC power and wait a second.

8. Reload the GUI.

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Figure 9. Quick Measurements Tab - Idle

Figure 10. Quick Measurements Tab - Continuous Convert

3.3.2 Quick Measurements Tab

The Quick Measurements tab displays reported power data from the CS5490 device in real time as continuous conversions are performed. Refer to the CS5490 data sheet, entitled Two Channel Energy Measurement IC, for more information about continuous conversion.

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Figure 11. Graphics Tab

The Connection, Graphics, and Quick Measurements tabs may be viewed with the conversions running, but the continuous conversions should be stopped before moving to the Data Table, Calibration, or Register Write/ Read tabs.

3.3.2.1 START Button

The START button starts continuous conversions execution until the STOP button is clicked. The power measurements are updated with present values in the CS5490 data registers after each conversion. The refresh rate is configured by the SampleCount or CycleCount register.

3.3.2.2 Change Sample Count Button

Whether this option is available depends on the CS5490 device revision and configuration. The default low-rate refresh rate for data is 1 second, or 4000 samples. Click the Change Sample Count button to change the SampleCount register. Enter a larger number of samples to slow the low-rate refresh rate. It is not recommended to reduce the SampleCount below 2000 samples.

3.3.2.3 Change Cycle Count Button

Whether this option is available depends on the CS5490 device revision and configuration. The default low-rate refresh rate for data is 1 second, or 100 line cycles at 50Hz. The CS5490 counts the samples in a half-line cycle and updates the SampleCount register automatically based on the CycleCount entered. Click the Change Cycle Count button to change the CycleCount register. Enter a larger number of cycles to slow the low-rate refresh rate. It is not recommended to reduce the CycleCount 50 cycles.

3.3.3 Graphics Tab

The Graphics tab displays the power data of the CS5490 versus low-rate samples in individual charts. To view data in real time, click the START button on the Quick Measurements tab, which initiates conversions, and then click the Graphics tab to bring it forward.

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