CS5461A
Single Phase, Bi-directional Power/Energy IC
Features Description
Energy Data Linearity: 0.1% of Reading over The CS5461A is an integrated power measure-
1000:1 Dynamic Range
ment device which combines two
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 and V , Apparent and Active (Real) Power
RMS RMS
accurately measure instantaneous current and
- Energy-to-pulse Conversion for Mechanical
voltage, and calculate V , I , instanta-
RMS RMS
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
The CS5461A is optimized to interface to shunt
Meets Accuracy Spec for IEC, ANSI, & JIS.
resistors or current transformers for current mea-
Low Power Consumption surement, and to resistive dividers or potential
transformers for voltage measurement.
Current Input Optimized for Sense Resistor.
The CS5461A features a bi-directional serial in-
GND-referenced Signals with Single Supply
terface for communication with a processor, and
On-chip 2.5 V Reference (25 ppm/C typ)
a programmable energy-to-pulse output func-
tion. Additional features include on-chip
Power Supply Monitor
functionality to facilitate system-level calibration,
Simple Three-wire Digital Serial Interface
temperature sensor, voltage sag detection, and
2
Auto-boot Mode from Serial E PROM.
phase compensation.
Power Supply Configurations:
ORDERING INFORMATION:
VA+ = +5 V; AGND = 0 V; VD+ = +3.3 V to +5 V
See Page 43.
VA+ RESET VD+
IIN+ 4th Order Digital
HPF
PGA
Modulator Filter
Option MODE
IIN-
CS
SDI
Power
SDO
Temperature
Calculation
Serial
VREFIN x1
Sensor
Engine SCLK
Interface
INT
E1
VIN+
2nd Order Digital HPF
E-to-F E2
x10
VIN- Modulator Filter Option
E3
System Clock
Voltage Power
/K Calibration
VREFOUT
Clock Generator
Reference
Monitor
AGND PFMON XIN XOUT CPUCLK DGND
APR 11
Copyright Cirrus Logic, Inc. 2011
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 ,V ) . . . . . . . . . . . . . . . . . . . .27
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