Cirrus Logic CS5471-BS Datasheet
CS5471
Dual-Channel Delta-Sigma Analog-to-Digital Converter
Features
l Synchronous Sampling
l On-chip 1.2 V Reference (25 ppm/°C typ.)
l Power Supply Configurations:
– VA+ = +3 V; VA- = -2 V; VD+ = +3 V
– Supply tolerances ±10%
l Power Consumption
– 10 mW Typical at VD+ = +3 V
l Simple Four-wire Serial Interface
l Charge Pump Driver output generates
negative power supply.
l Ground-Referenced Bipolar Inputs
VA+
Description
The CS5471 is a highly integrated Delta-Sigma (∆Σ) Analog-to-Digital Converter (ADC) developed for the Power
Measurement Industry. The CS5471 combines two ∆Σ
ADCs, decimation filters, and a serial interface on a single chip. The CS5471 interfaces directly to a current
transformer or shunt to measure current, and resistive
divider or transformer to measure voltage. The product
features a serial interface for communication with a micro-controller or DSP. The product is initialized and fully
functional upon reset, and includes a Voltage Reference.
ORDERING INFORMATION:
CS5471-BS -40°C to +85°C 20-pin SSOP
RESET
VD+
GAIN
IIN
IIN
VIN
VIN
VREFIN
VREFOUT
+
-
+
-
x1, 20
x1
x1
Voltage
Reference
AGND
4th Order∆ΣModulator
2nd Order∆ΣModulator
Preliminary Product Information
P.O. Box 17847, Austin, Texas 78760
(512) 445 7222 FAX: (512) 445 7581
http://www.cirrus.com
SE
Decimation Filter
Decimation Filter
CLOCK
VA-
This document contains information for a new product.
Cirrus Logic reserves the right to modify this product without notice.
Copyright Cirrus Logic, Inc. 2001
(All Rights Reserved)
XIN
Pulse Output
Serial
Interface
Regulator
DGND
OWRS
SDO
FSO
SCLK
CPD
DS480PP5
JUL ‘01
1
TABLE OF CONTENTS
3. CHARACTERISTICS AND SPECIFICATIONS ........................................................................ 3
ANALOG CHARACTERISTICS ................................................................................................ 3
DIGITAL CHARACTERISTICS ................................................................................................. 4
RECOMMENDED OPERATING CONDITIONS ....................................................................... 5
ABSOLUTE MAXIMUM RATINGS ........................................................................................... 5
SWITCHING CHARACTERISTICS .......................................................................................... 6
4. GENERAL DESCRIPTION ....................................................................................................... 7
4.1 Theory of Operation ........................................................................................................... 7
4.2 Performing Measurements ................................................................................................. 7
4.3 High Rate Digital Filters ..................................................................................................... 8
4.4 Serial Interface ................................................................................................................... 8
4.5 System Initialization ........................................................................................................... 9
4.6 Analog Inputs ..................................................................................................................... 9
4.7 Voltage Reference ............................................................................................................. 9
4.8 Using the Charge Pump Drive Pin ..................................................................................... 9
4.9 PCB Layout ...................................................................................................................... 10
5. PIN DESCRIPTION.................................................................................................................. 11
6. PACKAGE DIMENSIONS........................................................................................................ 13
CS5471
LIST OF FIGURES
Figure 1. Serial Port Timing............................................................................................................. 6
Figure 2. Typical Connection Diagram ............................................................................................7
Figure 3. Serial Port Data Transfer ................................................................................................. 8
Figure 4. Close-up of One Frame.................................................................................................... 9
Figure 5. Generating VA- with a Charge Pump ............................................................................. 10
Contacting Cirrus Logic Support
For a complete listing of Direct Sales, Distributor, and Sales Representative contacts, visit the Cirrus Logic web site at:
http://www.cirrus.com/corporate/contacts/sales/cfm
Preliminary product information describes products which are in production, but for which full characterization data is not yet available. Advance product information describes products which are in development and subject to development changes. Cirrus Logic, Inc. has made best efforts to ensure 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). No responsibility is assumed by Cirrus Logic, Inc. for the use of this information, nor for infringements of patents or other rights
of third parties. This document is the property of Cirrus Logic, Inc. and implies no license under patents, copyrights, trademarks, or trade secrets. No part of
this publication may be copied, reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photographic, or
otherwise) without the prior written consent of Cirrus Logic, Inc. Items from any Cirrus Logic website or disk may be printed for use by the user. However, no
part of the printout or electronic files may be copied, reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical,
photographic, or otherwise) without the prior written consent of Cirrus Logic, Inc.Furthermore, no part of this publication may be used as a basis for manufacture
or sale of any items without the prior written consent of Cirrus Logic, Inc. The names of products of Cirrus Logic, Inc. or other vendors and suppliers appearing
in this document may be trademarks or service marks of their respective owners which may be registered in some jurisdictions. A list of Cirrus Logic, Inc. trademarks and service marks can be found at http://www.cirrus.com.
2
1. CHARACTERISTICS AND SPECIFICATIONS
CS5471
ANALOG CHARACTERISTICS (T
= -40 °C to +85 °C; +2.7V < VA+ < +3.5V; +2.7V < VD+ < +3.5V;
A
VA- = -2 V ±10%; External VREF+ = 1.2 V; XIN = 4.000 MHz; AGND, DGND = 0.0V.) (See Notes 1 and 2)
Parameter Symbol Min Typ Max Unit
Accuracy (All Channels)
Total Harmonic Distortion THD 74 - - dB
Common Mode Rejection (DC, 50, 60 Hz) CMRR 80 - - dB
Common Mode + Signal on Input VA- - VA+ V
Input Sampling Rate - XIN/4 - Hz
Analog Inputs (Current Channel)
Differential Input Voltage Range Gain=20
[ (v
IIN+) - (vIIN-) ] Gain=1
Bipolar Offset Gain=20
Gain=1
IIN -
VOS
VOS
±40
-
-
-
±800
0.500
10
1
20
-
-
mV
mV
mV
mV
Crosstalk (Channel-to-Channel) (50, 60 Hz) - - -120 dB
Input Capacitance Gain=20
Gain=1
IC
IC
-
-
-
-
20
1
pF
pF
Effective Input Impedance (Note 3)
Gain=20
Gain=1
Noise (Referred to Input)
0-60 Hz Gain=20
Gain=1
0-1 kHz Gain=20
Gain=1
0-2 kHz Gain=20
Gain=1
EII
EII
50
-
-
500
--
-
600
1
20
2.5
50
3.75
75
kΩ
kΩ
µV
µV
µV
µV
µV
µVrms
Analog Inputs (Voltage Channel)
Differential Input Voltage Range
[ (v
VIN+) - (vVIN-) ]
VIN - ±800 - mV
Bipolar Offset Gain=1 VOS - 20 25 mV
Crosstalk with Current Channel (50, 60 Hz) - - -120 dB
Input Capacitance IC - - 0.2 pF
Effective Input Impedance (Note 3) EII - 3 4 MΩ
Noise (Referred to Input)
0-60 Hz
0-1 kHz
0-2 kHz
-
-
-
-
-
-
20
50
75
µV
µV
µV
Dynamic Characteristics
High Rate Filter Output Word Rate OWRS = “0”
OWRS = “1”
OWR
OWR
-
-
XIN/2048
XIN/1024
-
-
Hz
Hz
rms
rms
rms
rms
rms
0-pk
rms
rms
rms
Notes: 1. Specifications guaranteed by design, characterization, and/or test.
2. Analog signals are relative to AGND and digital signals to DGND unless otherwise noted.
3. Effective Input Impedance (EII) varies with clock frequency (XIN) and Input Capacitance (IC)
EII = 1/(IC*XIN/4)
3
CS5471
ANALOG CHARACTERISTICS (Continued)
Parameter Symbol Min Typ Max Unit
Reference Output
Output Voltage REFOUT 1.15 - 1.25 V
Temperature Coefficient - 20 50 ppm/°C
Load Regulation (Output Current 1µA Source or Sink) ∆V
R
Power Supply Rejection PSRR 60 - - dB
Reference Input
Input Voltage Range VREF+ 1.15 1.2 1.25 V
Input Capacitance - - 10 pF
Input CVF Current - - 1 µA
Power Supplies
Power Supply Currents I
A+
I
D+
PSCA
PSCD
Power Consumption (Note 4) PC - - 15 mW
Power Supply Rejection (DC, 50, 60 Hz)
PSRR 60 - - dB
(see Note 5)
-610mV
-
-
-
-
1.5
2.5
mA
mA
Notes: 4. All outputs unloaded. All inputs CMOS level.
5. Definition for PSRR: VREFIN tied to VREFOUT, VA+ = VD+ = 3V, AGND = DGND = 0V, VA- = -2V
(using charge-pump circuit with CPD). In addition, a 106.07 mV rms (60 Hz) sinewave is imposed onto
the VA+ and VD+ pins. The “+” and “-” input pins of both input channels are shorted to VA-.
Instantaneous digital output data words are then collected for the channel under test. From these data
samples, the rms value (standard deviation) of the digital sinusoidal output signal is calculated, and this
rms value is converted into the rms value of the sinusoidal voltage (measured in mV) that would need
to be applied at the channel’s inputs, in order to cause the same digital sinusoidal output. This voltage
is then defined as Veq. PSRR is then (in dB)
106.07
------------- ---
log⋅=
V
eq
DIGITAL CHARACTERISTICS (T
PSRR 20
= -40 °C to +85 °C; +2.7V < VA+ < +3.5V; +2.7V < VD+ < +3.5V;
A
VA- = -2 V ±10%; AGND, DGND = 0.0 V) (See Note 6)
Parameter Symbol Min Typ Max Unit
High-Level Input Voltage V
Low-Level Input Voltage V
High-Level Output Voltage I
Low-Level Output Voltage I
= -5.0 mA V
out
= 5.0 mA V
out
Input Leakage Current (Note 7) I
3-State Leakage Current I
Digital Output Pin Capacitance C
OH
OL
in
OZ
out
IH
0.6 VD+ - VD+ V
IL
0.0 - 0.8 V
(VD+) - 1.0 - - V
--0.4V
-±1±10µA
--±10µA
-9-pF
Notes: 6. All measurements performed under static conditions.
7. For OWRS and GAIN
pins, input leakage current is 30 µA (Max).
4
CS5471
RECOMMENDED OPERATING CONDITIONS (AGND, DGND = 0.0 V)
Parameter Symbol Min Typ Max Unit
DC Power Supplies Positive Digital
Positive Analog
Negative Analog
Voltage Reference Input VREF+ - 1.2 - V
ABSOLUTE MAXIMUM RATINGS (AGND, DGND = 0.0 V; See Note 8.)
Parameter Symbol Min Typ Max Unit
DC Power Supplies Positive Digital
Positive Analog
Negative Analog
Input Current, Any Pin Except Supplies (Note 9 and 10) I
Output Current I
Power Dissipation (Note 11) PDN - - 500 mW
Analog Input Voltage All Analog Pins V
Digital Input Voltage All Digital Pins V
Ambient Operating Temperature T
Storage Temperature T
VD+
VA+
VA-
VD+
VA+
VA-
IN
OUT
INA
IND
A
stg
2.7
2.7
-2.2
-0.3
-0.3
-2.5
--±10mA
--±25mA
VA- - 0.3 - (VA+) + 0.3 V
-0.3 - (VD+) + 0.3 V
-40 - 85 °C
-65 - 150 °C
3.0
3.0
-2.0
-
-
3.5
3.5
-1.8
+3.5
+3.5
-0.3
V
V
V
V
V
V
Notes: 8. All voltages with respect to AGND.
9. Applies to all pins including continuous over-voltage conditions at the analog input (AIN) pins.
10. Transient current of up to 100 mA will not cause SCR latch-up. Maximum input current for a power
supply pin is ±50 mA.
11. Total power dissipation, including all input currents and output currents.
WARNING: Operation at or beyond these limits may result in permanent damage to the device.
Normal operation is not guaranteed at these extremes.
5
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