ADS7822
DESCRIPTION
The ADS7822 is a 12-bit sampling analog-to-digital
converter (A/D) with guaranteed specifications over a
2.7V to 3.6V supply range. It requires very little power
even when operating at the full 75kHz rate. At lower
conversion rates, the high speed of the device enables
it to spend most of its time in the power down mode--
the power dissipation is less than 60
W at 7.5kHz.
The ADS7822 also features operation from 2.0V to
5V, a synchronous serial interface, and a differential
input. The reference voltage can be set to any level
within the range of 50mV to V
CC
.
Ultra low power and small size make the ADS7822
ideal for battery operated systems. It is also a perfect
fit for remote data acquisition modules, simultaneous
multi-channel systems, and isolated data acquisition.
The ADS7822 is available in a plastic mini-DIP-8, an
SOIC-8, or an MSOP-8 package.
12-Bit High Speed 2.7V
microPower Sampling
ANALOG-TO-DIGITAL CONVERTER
1996 Burr-Brown Corporation
PDS-1358C
Printed in U.S.A., May, 2000
International Airport Industrial Park Mailing Address: PO Box 11400, Tucson, AZ 85734 Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 Tel: (520) 746-1111
Twx: 910-952-1111 Internet: http://www.burr-brown.com/ Cable: BBRCORP Telex: 066-6491 FAX: (520) 889-1510 Immediate Product Info: (800) 548-6132
FEATURES
q
75kHz SAMPLING RATE
q
MICRO POWER:
0.54mW at 75kHz
0.06mW at 7.5kHz
q
POWER DOWN: 3
A max
q
MINI-DIP-8, SOIC-8, AND MSOP-8
q
DIFFERENTIAL INPUT
q
SERIAL INTERFACE
SAR
Control
Serial
Interface
D
OUT
Comparator
S/H Amp
CS/SHDN
DCLOCK
+In
V
REF
In
CDAC
APPLICATIONS
q
BATTERY OPERATED SYSTEMS
q
REMOTE DATA ACQUISITION
q
ISOLATED DATA ACQUISITION
q
SIMULTANEOUS SAMPLING,
MULTI-CHANNEL SYSTEMS
OPA658
ADS7822
ADS7822
For most current data sheet and other product
information, visit www.burr-brown.com
SBAS062
2
ADS7822
SPECIFICATIONS
At 40
C to +85
C, +V
CC
= +2.7V, V
REF
= +2.5V, f
SAMPLE
= 75kHz, f
CLK
= 16 f
SAMPLE
, unless otherwise specified.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN
assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user's own risk. Prices and specifications are subject
to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not
authorize or warrant any BURR-BROWN product for use in life support devices and/or systems.
ADS7822
ADS7822B
ADS7822C
PARAMETER
CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
ANALOG INPUT
Full-Scale Input Span
+In (In)
0
V
REF
T
T
T
T
V
Absolute Input Range
+In
0.2
V
CC
+0.2
T
T
T
T
V
In
0.2
+1.0
T
T
T
T
V
Capacitance
25
T
T
pF
Leakage Current
1
T
T
A
SYSTEM PERFORMANCE
Resolution
12
T
T
Bits
No Missing Codes
11
12
T
Bits
Integral Linearity Error
0.5
2
0.5
1
0.25
0.75
LSB
(1)
Differential Linearity Error
0.5
2
0.5
1
0.25
0.75
LSB
Offset Error
3
T
1
LSB
Gain Error
3
T
1
LSB
Noise
33
T
T
Vrms
Power Supply Rejection
82
T
T
dB
SAMPLING DYNAMICS
Conversion Time
12
T
T
Clk Cycles
Acquisition Time
1.5
T
T
Clk Cycles
Throughput Rate
75
T
T
kHz
DYNAMIC CHARACTERISTICS
Total Harmonic Distortion
V
IN
= 2.5Vp-p at 1kHz
82
T
T
dB
SINAD
V
IN
= 2.5Vp-p at 1kHz
71
T
T
dB
Spurious Free Dynamic Range
V
IN
= 2.5Vp-p at 1kHz
86
T
T
dB
REFERENCE INPUT
Voltage Range
0.05
V
CC
T
T
T
T
V
Resistance
CS = GND, f
SAMPLE
= 0Hz
5
T
T
G
CS = V
CC
5
T
T
G
Current Drain
At Code 710h
8
40
T
T
T
T
A
f
SAMPLE
= 7.5kHz
0.8
T
T
A
CS = V
CC
0.001
3
T
T
T
T
A
DIGITAL INPUT/OUTPUT
Logic Family
CMOS
T
T
Logic Levels:
V
IH
I
IH
= +5
A
2.0
5.5
T
T
T
T
V
V
IL
I
IL
= +5
A
0.3
0.8
T
T
T
T
V
V
OH
I
OH
= 250
A
2.1
T
T
V
V
OL
I
OL
= 250
A
0.4
T
T
V
Data Format
Straight Binary
T
T
POWER SUPPLY REQUIREMENTS
V
CC
Specified Performance
2.7
3.6
T
T
T
T
V
See Notes 2 and 3
2.0
2.7
T
T
T
T
V
See Note 3
3.6
5.25
T
T
T
T
V
Quiescent Current
200
325
T
T
T
T
A
f
SAMPLE
= 7.5kHz
(4,5)
20
T
T
A
f
SAMPLE
= 7.5kHz
(5)
180
T
T
A
Power Down
CS = V
CC
3
T
T
A
TEMPERATURE RANGE
Specified Performance
40
+85
T
T
T
T
C
T
Specifications same as ADS7822.
Notes: (1) LSB means Least Significant Bit. With V
REF
equal to +2.5V, one LSB is 0.61mV. (2) The maximum clock rate of the ADS7822 is less than 1.2MHz in this
power supply range. (3) See the Typical Performance Curves for more information. (4) f
CLK
= 1.2MHz, CS = V
CC
for 145 clock cycles out of every 160. (5) See the
Power Dissipation section for more information regarding lower sample rates.
3
ADS7822
ELECTROSTATIC
DISCHARGE SENSITIVITY
Electrostatic discharge can cause damage ranging from per-
formance degradation to complete device failure. Burr-
Brown Corporation recommends that all integrated circuits
be handled and stored using appropriate ESD protection
methods.
ESD damage can range from subtle performance degrada-
tion to complete device failure. Precision integrated circuits
may be more susceptible to damage because very small
parametric changes could cause the device not to meet
published specifications.
ABSOLUTE MAXIMUM RATINGS
(1)
V
CC
....................................................................................................... +6V
Analog Input .............................................................. 0.3V to (V
CC
+ 0.3V)
Logic Input ............................................................................... 0.3V to 6V
Case Temperature ......................................................................... +100
C
Junction Temperature .................................................................... +150
C
Storage Temperature ..................................................................... +125
C
External Reference Voltage .............................................................. +5.5V
NOTE: (1) Stresses above these ratings may permanently damage the device.
PIN
NAME
DESCRIPTION
1
V
REF
Reference Input.
2
+In
Non Inverting Input.
3
In
Inverting Input. Connect to ground or to remote ground sense point.
4
GND
Ground.
5
CS/SHDN
Chip Select when LOW, Shutdown Mode when HIGH.
6
D
OUT
The serial output data word is comprised of 12 bits of data. In operation the data is valid on the falling edge of DCLOCK. The
second clock pulse after the falling edge of CS enables the serial output. After one null bit the data is valid for the next 12 edges.
7
DCLOCK
Data Clock synchronizes the serial data transfer and determines conversion speed.
8
+V
CC
Power Supply.
PIN CONFIGURATION
PIN ASSIGNMENTS
1
2
3
4
8
7
6
5
+V
CC
DCLOCK
D
OUT
CS/SHDN
V
REF
+In
In
GND
ADS7822
PDIP-8,
SOIC-8,
MSOP-8
PACKAGE/ORDERING INFORMATION
MAXIMUM
MAXIMUM
INTEGRAL
DIFFERENTIAL
LINEARITY
LINEARITY
PACKAGE
SPECIFICATION
ERROR
ERROR
DRAWING
TEMPERATURE
PACKAGE
ORDERING
TRANSPORT
PRODUCT
(LSB)
(LSB)
PACKAGE
NUMBER
(1)
RANGE
MARKING
(2)
NUMBER
(3)
MEDIA
ADS7822E
2
2
MSOP-8
337
40
C to +85
C
A22
ADS7822E/250
Tape and Reel
ADS7822E
"
"
"
"
"
"
ADS7822E/2K5
"
ADS7822EB
1
1
MSOP-8
337
40
C to +85
C
A22
ADS7822EB/250
Tape and Reel
ADS7822EB
"
"
"
"
"
"
ADS7822EB/2K5
"
ADS7822EC
0.75
0.75
MSOP-8
337
40
C to +85
C
A22
ADS7822EC/250
Tape and Reel
ADS7822EC
"
"
"
"
"
"
ADS7822EC/2K5
"
ADS7822P
2
2
Plastic DIP-8
006
40
C to +85
C
ADS7822P
ADS7822P
Rails
ADS7822PB
1
1
Plastic DIP-8
006
40
C to +85
C
ADS7822PB
ADS7822PB
Rails
ADS7822PC
0.75
0.75
Plastic DIP-8
006
40
C to +85
C
ADS7822PC
ADS7822PC
Rails
ADS7822U
2
2
SOIC-8
182
40
C to +85
C
ADS7822U
ADS7822U
Rails
ADS7822U
"
"
"
"
"
"
ADS7822U/2K5
Tape and Reel
ADS7822UB
1
1
SOIC-8
182
40
C to +85
C
ADS7822UB
ADS7822UB
Rails
ADS7822UB
"
"
"
"
"
"
ADS7822UB/2K5 Tape and Reel
ADS7822UC
0.75
0.75
SOIC-8
182
40
C to +85
C
ADS7822UC
ADS7822UC
Rails
ADS7822UC
"
"
"
"
"
"
ADS7822UC/2K5 Tape and Reel
NOTE: (1) For detail drawing and dimension table, please see end of data sheet or Package Drawing File on Web. (2) Performance Grade information is marked
on the reel. (3) Models with a slash(/) are available only in Tape and reel in quantities indicated (e.g. /250 indicates 250 units per reel, /2K5 indicates 2500 devices
per reel). Ordering 2500 pieces of "ADS7822E/2K5" will get a single 2500-piece Tape and Reel. For detailed Tape and Reel mechanical information, refer to the
www.burr-brown.com web site under Applications and Tape and Reel Orientation and Dimensions.
4
ADS7822
TYPICAL PERFORMANCE CURVES
At T
A
= +25
C, V
CC
= +2.7V, V
REF
= +2.5V, f
SAMPLE
= 75kHz, f
CLK
= 16 f
SAMPLE
, unless otherwise specified.
DIFFERENTIAL LINEARITY ERROR vs CODE
1.00
0.75
0.50
0.25
0.00
0.25
0.50
0.75
1.00
Differential Linearity Error (LSB)
0
2048
4095
Code
INTEGRAL LINEARITY ERROR vs CODE
1.00
0.75
0.50
0.25
0.00
0.25
0.50
0.75
1.00
Integral Linearity Error (LSB)
0
2048
4095
Code
QUIESCENT CURRENT vs V
CC
400
350
300
250
200
150
100
Quiescent Current (
A)
1
2
3
4
5
V
CC
(V)
MAXIMUM SAMPLE RATE vs V
CC
1000
100
10
1
Sample Rate (kHz)
1
2
3
4
5
V
CC
(V)
SUPPLY CURRENT vs TEMPERATURE
350
300
250
200
150
100
50
Supply Current (
A)
50
25
0
25
50
75
100
Temperature (
C)
POWER DOWN SUPPLY CURRENT
vs TEMPERATURE
120
100
80
60
40
20
0
Supply Current (nA)
50
25
0
25
50
75
100
Temperature (
C)
5
ADS7822
TYPICAL PERFORMANCE CURVES
(Cont.)
At T
A
= +25
C, V
CC
= +2.7V, V
REF
= +2.5V, f
SAMPLE
= 75kHz, f
CLK
= 16 f
SAMPLE
, unless otherwise specified.
CHANGE IN GAIN vs TEMPERATURE
0.15
0.1
0.05
0
0.05
0.1
0.15
Delta from 25
C (LSB)
50
25
0
25
50
75
100
Temperature (
C)
CHANGE IN OFFSET vs REFERENCE VOLTAGE
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0.2
0.4
0.6
0.8
Change in Offset (LSB)
1
2
3
4
5
Reference Voltage (V)
V
CC
= 5V
CHANGE IN OFFSET vs TEMPERATURE
0.6
0.4
0.2
0
0.2
0.4
0.6
Delta from 25
C (LSB)
50
25
0
25
50
75
100
Temperature (
C)
CHANGE IN GAIN vs REFERENCE VOLTAGE
2.5
2.0
1.5
1.0
0.5
0.0
0.5
1.0
1.5
Change in Gain (LSB)
1
2
3
4
5
Reference Voltage (V)
V
CC
= 5V
EFFECTIVE NUMBER OF BITS
vs REFERENCE VOLTAGE
12
11.75
11.5
11.25
11
10.75
10.5
10.25
10
Effective Number of Bits (rms)
0.1
1
10
Reference Voltage (V)
V
CC
= 5V
PEAK-TO-PEAK NOISE vs REFERENCE VOLTAGE
10
9
8
7
6
5
4
3
2
1
0
Peak-to-Peak Noise (LSB)
0.1
1
10
Reference Voltage (V)
V
CC
= 5V
PDF 
ZIP