CS5490
Two Channel Energy Measurement IC
Features Description
The CS5490 is a high-accuracy, two-channel, energy measure-
Superior Analog Performance with Ultra-low Noise Level &
High SNR
ment analog front end.
Energy Measurement Accuracy of 0.1% over a 4000:1
th
The CS5490 incorporates independent 4 order Delta-Sigma an-
Dynamic Range
th alog-to-digital converters for both channels, reference circuitry,
Two Independent 24-bit, 4 -order, Delta-Sigma
and the proven EXL signal processing core to provide active, re-
Modulators for Voltage and Current Measurements
active, and apparent energy measurement. In addition, RMS and
Configurable Digital Output for Energy Pulses, Interrupt,
power factor calculations are available. Calculations are output
zero-crossing, and Energy Direction
via a configurable energy pulse, or direct UART serial access to
Supports Shunt Resistor, CT, and Rogowski Coil Current
on-chip registers. Instantaneous current, voltage, and power
Sensors
measurements are also available over the serial port. The
On-chip Measurements/Calculations:
two-wire UART minimizes the cost of isolation where required.
- Active, Reactive, and Apparent Power
- RMS Voltage and Current
A configurable digital output provides energy pulses, zero-cross-
- Power Factor and Line Frequency
ing, energy direction, or interrupt functions. Interrupts can be
- Instantaneous Voltage, Current, and Power
generated for a variety of conditions including voltage sag or
Overcurrent, Voltage Sag, and Voltage Swell Detection
swell, overcurrent, and more. On-chip register integrity is assured
Ultra-fast On-chip Digital Calibration via checksum and write protection. The CS5490 is designed to in-
terface to a variety of voltage and current sensors, including shunt
Configurable No-load Threshold for Anti-creep
resistors, current transformers, and Rogowski coils.
Internal Register Protection via Checksum and Write
Protection
On-chip functionality makes digital calibration simple and ultra
UART Serial Interface
fast to minimize the time required at the end of the customer pro-
On-chip Temperature Sensor
duction line. Performance across temperature is ensured with an
On-chip Voltage Reference (25ppm/C Typ.)
on-chip voltage reference with low drift. A single 3.3V power sup-
Single 3.3 V Power Supply
ply is required, and power consumption is low at <13mW. To
Ultra-fine Phase Compensation
minimize space requirements, the CS5490 is offered in a low-cost
Low Power Consumption: <13 mW
16-pin SOIC package.
Power Supply Configurations:
ORDERING INFORMATION
- GNDA = 0 V, VDDA: +3.3 V
See Page 57.
Low-cost 16-pin SOIC Package
VDDA VDDD
RESET
CS5490
IIN+
4th Order Digital
HPF
PGA
Modulator Filter
IIN- Option
UART
RX
Serial
TX
Interface
VIN+
4th Order Digital HPF
10x
Calculation
Modulator Filter Option
VIN-
Configurable
VREF+ Digital DO
Voltage Temperature
Output
Reference Sensor
VREF-
System Clock
Clock Generator
GNDA XIN XOUT MODE
Cirrus Logic, Inc.
Copyright Cirrus Logic, Inc. 2013 MAR13
CS5490
TABLE OF CONTENTS
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
2. Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
2.1 Analog Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
2.1.1 Voltage Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
2.1.2 Current Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
2.1.3 Voltage Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
2.1.4 Crystal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
2.2 Digital Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
2.2.1 Reset Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
2.2.2 Digital Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
2.2.3 UART Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
2.2.3.1 UART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
2.2.4 MODE Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3. Characteristics & Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
4. Signal Flow Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
4.1 Analog-to-Digital Converters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
4.2 Decimation Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
4.3 IIR Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
4.4 Phase Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
4.5 DC Offset & Gain Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
4.6 High-pass & Phase Matching Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
4.7 Digital Integrators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
4.8 Low-rate Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
4.8.1 Fixed Number of Samples Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
4.8.2 Line-cycle Synchronized Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
4.8.3 RMS Current & Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.8.4 Active Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.8.5 Reactive Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.8.6 Apparent Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.8.7 Peak Voltage & Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.8.8 Power Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.9 Average Active Power Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.10 Average Reactive Power Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
5. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
5.1 Power-on Reset (POR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
5.2 Power Saving Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
5.3 Zero-crossing Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
5.4 Line Frequency Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
5.5 Energy Pulse Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
5.5.1 Pulse Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
5.5.2 Pulse Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5.6 Voltage Sag, Voltage Swell, and Overcurrent Detection . . . . . . . . . . . . . . . . . . . . .21
5.7 Phase Sequence Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
5.8 Temperature Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
2 DS982F3