CS5461A
Single Phase, Bi-directional Power/Energy IC
Features
• Energy Data Linearity: ±0.1% of Reading over
1000:1 Dynamic Range
Description
The CS5461A is an integrated power measure-
ment device which combines two
∆Σ
analog-to-digital converters, power calculation
• On-chip Functions:
engine, energy-to-frequency converter, and a
-
Instantaneous Voltage, Current, and Power
serial interface on a single chip. It is designed to
-
I
RMS
and V
RMS
, Apparent and Active (Real) Power
accurately measure instantaneous current and
-
Energy-to-pulse Conversion for Mechanical
voltage, and calculate V
RMS
, I
RMS
, instanta-
Counter/Stepper Motor Drive
neous power, apparent power, and active power
-
System Calibrations and Phase Compensation
for single-phase, 2- or 3-wire power metering
-
Temperature Sensor
applications.
-
Voltage Sag Detect
• Meets Accuracy Spec for IEC, ANSI, & JIS.
• Low Power Consumption
• Current Input Optimized for Sense Resistor.
• GND-referenced Signals with Single Supply
• On-chip 2.5 V Reference (25 ppm/°C typ)
• Power Supply Monitor
• Simple Three-wire Digital Serial Interface
• “Auto-boot” Mode from Serial E
2
PROM.
• Power Supply Configurations:
VA+ = +5 V; AGND = 0 V; VD+ = +3.3 V to +5 V
VA+
RESET
The CS5461A is optimized to interface to shunt
resistors or current transformers for current mea-
surement, and to resistive dividers or potential
transformers for voltage measurement.
The CS5461A features a bi-directional serial in-
terface for communication with a processor, and
a programmable energy-to-pulse output func-
tion. Additional features include on-chip
functionality to facilitate system-level calibration,
temperature sensor, voltage sag detection, and
phase compensation.
ORDERING INFORMATION:
See
Page 43.
VD+
IIN+
IIN-
PGA
4th Order
∆Σ
Modulator
Digital
Filter
HPF
Option
MODE
CS
Power
Calculation
Engine
SDI
Serial
Interface
SDO
SCLK
INT
VREFIN
x1
Temperature
Sensor
VIN+
VIN-
x10
2nd Order
∆Σ
Modulator
Digital
Filter
HPF
Option
E-to-F
E1
E2
E3
VREFOUT
Voltage
Reference
Power
Monitor
System
Clock
/K
Clock
Generator
Calibration
AGND
PFMON
XIN
XOUT CPUCLK
DGND
http://www.cirrus.com
Copyright
©
Cirrus Logic, Inc. 2008
(All Rights Reserved)
APR ‘08
DS661F2
CS5461A
TABLE OF CONTENTS
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
2. Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
3. Characteristics & Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Analog Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Voltage Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Digital Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Switching Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4. Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.1 Digital Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.2 Voltage and Current Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3 Power Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.4 Linearity Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.1 Analog Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.1.1 Voltage Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.1.2 Current Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.2 High-pass Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.3 Performing Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.4 Energy Pulse Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.4.1 Normal Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.4.2 Alternate Pulse Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.4.3 Mechanical Counter Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.4.4 Stepper Motor Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
5.4.5 Pulse Output E3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.4.6 Anti-creep for the Pulse Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.4.7 Design Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
5.5 Voltage Sag-detect Feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.6 No Load Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.7 On-chip Temperature Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.8 Voltage Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.9 System Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
5.10 Power-down States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.11 Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.12 Event Handler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5.12.1 Typical Interrupt Handler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.13 Serial Port Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.13.1 Serial Port Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.14 Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
6. Register Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.1 Configuration Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.2 Current and Voltage DC Offset Register ( I
DCoff
,V
DCoff
) . . . . . . . . . . . . . . . . . . . . 27
2
DS661F2
CS5461A
6.3 Current and Voltage Gain Register ( I
gn
,V
gn
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.4 Cycle Count Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.5 PulseRateE
1,2
Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.6 Instantaneous Current, Voltage and Power Registers ( I , V , P ) . . . . . . . . . . . . . . 28
6.7 Active (Real) Power Registers ( P
Active
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.8 I
RMS
and V
RMS
Registers ( I
RMS
, V
RMS
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.9 Power Offset Register ( P
off
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.10 Status Register and Mask Register ( Status , Mask ) . . . . . . . . . . . . . . . . . . . . . . 29
6.11 Current and Voltage AC Offset Register ( V
ACoff
, I
ACoff
) . . . . . . . . . . . . . . . . . . . 30
6.12 PulseRateE
3
Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.13 Temperature Register ( T ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.14 System Gain Register ( SYSGain ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.15 Pulsewidth Register ( PW ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.16 E3 Pulse Width Register ( PulseWidth ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.17 Voltage Sag Duration Register ( VSAG
Duration
) . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.18 Voltage Sag Level Register ( VSAG
Level
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.19 No Load Threshold Interval Register ( LoadIntv) . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.20 No Load Threshold ( LoadMin ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.21 Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.22 Temperature Gain Register ( T
Gain
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.23 Temperature Offset Register ( T
off
) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
6.24 Apparent Power Register ( S ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
7. System Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.1 Channel Offset and Gain Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.1.1 Calibration Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.1.1.1 Duration of Calibration Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.1.2 Offset Calibration Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.1.2.1 DC Offset Calibration Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.1.2.2 AC Offset Calibration Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.1.3 Gain Calibration Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.1.3.1 AC Gain Calibration Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.1.3.2 DC Gain Calibration Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.1.4 Order of Calibration Sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.2 Phase Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
7.3 Active Power Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
8. Auto-boot Mode Using E
2
PROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
8.1 Auto-Boot Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
8.2 Auto-Boot Data for E
2
PROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
8.3 Suggested E
2
PROM Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
9. Basic Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
10. Package Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
11. Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
12. Environmental, Manufacturing, & Handling Information . . . . . . . . . . . . . . . . . . . . . . . 43
13. Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
DS661F2
3
CS5461A
LIST OF FIGURES
Figure 1. CS5461A Read and Write Timing Diagrams ........................................................................... 11
Figure 2. Data Flow. ................................................................................................................................ 13
Figure 3. Normal Format on pulse outputs E1 and E2............................................................................ 16
Figure 4. Alternate Pulse Format on E1 and E2 ..................................................................................... 17
Figure 5. Mechanical Counter Format on E1 and E2.............................................................................. 17
Figure 6. Stepper Motor Format on E1 and E2 ....................................................................................... 18
Figure 7. Voltage Sag Detect .................................................................................................................. 19
Figure 8. Oscillator Connection............................................................................................................... 20
Figure 9. Calibration Data Flow............................................................................................................... 35
Figure 10. System Calibration of Offset. ................................................................................................. 35
Figure 11. System Calibration of Gain .................................................................................................... 36
Figure 12. Example of AC Gain Calibration ............................................................................................ 36
Figure 13. Another Example of AC Gain Calibration .............................................................................. 36
Figure 14. Typical Interface of E
2
PROM to CS5461A ............................................................................ 38
Figure 15. Typical Connection Diagram
(Single-phase, 2-wire – Direct Connect to Power Line)
........... 39
Figure 17. Typical Connection Diagram
(Single-phase, 3-wire)..............................................................
40
Figure 16. Typical Connection Diagram
(Single-phase, 2-wire – Isolated from Power Line)
.................. 40
Figure 18. Typical Connection Diagram
(Single-phase, 3-wire – No Neutral Available)
......................... 41
LIST OF TABLES
Table 1. Current Channel PGA Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 2. E1 and E2 Pulse Output Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Table 3. Interrupt Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4
DS661F2
CS5461A
1. OVERVIEW
The CS5461A is a CMOS monolithic power measurement device with a computation engine and an en-
ergy-to-frequency pulse output. The CS5461A combines a programmable-gain amplifier, two
∆Σ
ana-
log-to-digital converters (ADCs), system calibration and a computation engine on a single chip.
The CS5461A is designed for power measurement applications and is optimized to interface to a cur-
rent-sense resistor or transformer for current measurement, and to a resistive divider or potential trans-
former for voltage measurement. The voltage and current channels provide programmable gains to
accommodate various input levels from a wide variety of sensing elements. With single +5 V supply on
VA+/AGND, both of the CS5461A’s input channels can accommodate common mode as well as signal
levels between (AGND - 0.25 V) and VA+.
Additionally, the CS5461A is equipped with a computation engine that calculates I
RMS
, V
RMS
, apparent
power and active (real) power. To facilitate communication to a microprocessor, the CS5461A includes a
simple three-wire serial interface which is SPI™ and Microwire™ compatible. The CS5461A provides
three outputs for energy registration. E1 and E2 are designed to directly drive a mechanical counter or
stepper motor, or interface to a microprocessor. The pulse output E3 is designed to assist with meter cal-
ibration.
DS661F2
5
MCU
京公网安备 11010802033920号
EEWORLD
