The ADS7818 is a 12-bit sampling analog-to-digital
converter (A/D) complete with sample/hold, internal
2.5V reference, and synchronous serial interface. Typi-
cal power dissipation is 11mW at a 500kHz through-
put rate. The device can be placed into a power down
mode which reduces dissipation to just 2.5mW. The
input range is zero to two times the reference voltage,
and the internal reference can be overdriven by an
external voltage.
Low power, small size, and high-speed make the
ADS7818 ideal for battery operated systems such as
wireless communication devices, portable multi-chan-
nel data loggers, and spectrum analyzers. The serial
interface also provides low-cost isolation for remote
data acquisition. The ADS7818 is available in a plas-
tic mini-DIP-8 or an MSOP-8 package and is guaran-
teed over the –40°C to +85°C temperature range.
APPLICATIONS
q
BATTERY OPERATED SYSTEMS
q
DIGITAL SIGNAL PROCESSING
q
HIGH SPEED DATA ACQUISITION
q
WIRELESS COMMUNICATION SYSTEMS
CLK
SAR
CONV
+In
CDAC
–In
S/H Amp
Comparator
Serial
Interface
DATA
Buffer
Internal
+2.5V Ref
V
REF
10kΩ ±30%
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
NOTES: (1) Ideal input span, does not include gain or offset error. (2) LSB means Least Significant Bit, with V
REF
equal to +2.5V, one LSB is 1.22mV. (3) Measured
relative to an ideal, full-scale input (+In – (–In)) of 4.999V. Thus, gain error includes the error of the internal voltage reference. (4) Calculated on the first nine
harmonics of the input frequency. (5) If the internal reference is required to source current to an external load, the reference voltage will change due to the internal
10kΩ resistor. (6) Can vary
±30%.
V
IN
V
IN
V
IN
V
IN
= 5Vp-p at 100kHz
= 5Vp-p at 100kHz
= 5Vp-p at 100kHz
= 5Vp-p at 100kHz
SINAD > 68dB
CONDITIONS
MIN
TYP
MAX
MIN
T
T
T
T
T
T
T
±1
±0.8
±2
±12
70
50
150
1.2
1.625
0.350
500
5
30
350
72
–78
70
78
350
2.50
20
0.6
2.0
to Internal Reference Voltage
10
CMOS
|I
IH
|
≤
+5µA
|I
IL
|
≤
+5µA
I
OH
= –500µA
I
OL
= 500µA
3.0
–0.3
3.5
Straight Binary
Specified Performance
f
SAMPLE
= 500kHz
Power Down
f
SAMPLE
= 500kHz
Power Down
4.75
2.2
0.5
11
2.5
–40
5.25
T
T
T
T
T
T
V
CC
+0.3
0.8
0.4
T
T
T
T
T
T
V
mA
mA
mW
mW
°C
2.55
T
T
T
T
T
T
–82
72
82
T
T
T
T
T
T
T
T
T
±2
±5
±30
±50
±0.5
±0.5
±1
±7
T
T
T
T
±1
±1
T
±15
±35
ADS7818PB, EB
TYP
MAX
T
T
T
UNITS
+In – (–In)
+In
–In
0
–0.2
–0.2
15
1
12
12
5
V
CC
+0.2
+0.2
V
V
V
pF
µA
Bits
Bits
LSB
(2)
LSB
LSB
LSB
LSB
dB
dB
µVrms
LSB
µs
µs
kHz
ns
ps
ns
dB
dB
dB
dB
kHz
V
µA
ppm /°C
mV
V
kΩ
25°C
–40°C to +85°C
DC, 0.2Vp-p
1MHz, 0.2Vp-p
Worst Case
∆,
+V
CC
= 5V
±5%
–72
70
75
–75
68
72
I
OUT
= 0
Static Load
I
OUT
= 0
4.75V
≤
V
CC
≤
5.25V
2.475
2.525
50
2.48
2.52
T
T
T
T
T
T
T
V
V
V
V
20
T
+85
T
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.
®
ADS7818
2
ABSOLUTE MAXIMUM RATINGS
(1)
+V
CC
to GND ............................................................................ –0.3V to 6V
Analog Inputs to GND .............................................. –0.3V to (V
CC
+ 0.3V)
Digital Inputs to GND ............................................... –0.3V to (V
CC
+ 0.3V)
Power Dissipation .......................................................................... 325mW
Maximum Junction Temperature ................................................... +150°C
Operating Temperature Range ......................................... –40°C to +85°C
Storage Temperature Range .......................................... –65°C to +150°C
Lead Temperature (soldering, 10s) ............................................... +300°C
NOTE: (1) Stresses above those listed under “Absolute Maximum Ratings” may
cause permanent damage to the device. Exposure to absolute maximum condi-
tions for extended periods may affect device reliability.
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.
PIN CONFIGURATION
Top View
V
REF
+In
–In
GND
1
2
ADS7818
3
4
Plastic Mini-DIP-8
8
7
6
5
+V
CC
CLK
DATA
CONV
V
REF
+In
–In
GND
1
2
ADS7818
3
4
MSOP-8
8
7
6
5
+V
CC
CLK
DATA
CONV
PIN ASSIGNMENTS
PIN
1
2
3
4
5
6
NAME
V
REF
+In
–In
GND
CONV
DATA
DESCRIPTION
Reference Output. Decouple to ground with a 0.1µF ceramic capacitor and a 2.2µF tantalum capacitor.
Non-Inverting Input.
Inverting Input. Connect to ground or to remote ground sense point.
Ground.
Convert Input. Controls the sample/hold mode, start of conversion, start of serial data transfer, type of serial transfer, and power
down mode. See the Digital Interface section for more information.
Serial Data Output. The 12-bit conversion result is serially transmitted most significant bit first with each bit valid on the rising edge
of CLK. By properly controlling the CONV input, it is possibly to have the data transmitted least significant bit first. See the Digital
Interface section for more information.
Clock Input. Synchronizes the serial data transfer and determines conversion speed.
Power Supply. Decouple to ground with a 0.1µF ceramic capacitor and a 10µF tantalum capacitor.
7
8
CLK
+V
CC
PACKAGE/ORDERING INFORMATION
MAXIMUM
INTEGRAL
LINEARITY
ERROR
(LSB)
±2
MAXIMUM
DIFFERENTIAL
LINEARITY
ERROR
(LSB)
N/S
(4)
PRODUCT
ADS7818E
PACKAGE
MSOP-8
PACKAGE
DRAWING
NUMBER
(1)
337
SPECIFICATION
TEMPERATURE
RANGE
–40°C to +85°C
PACKAGE
MARKING
(2)
A18
ORDERING
NUMBER
(3)
ADS7818E/250
ADS7818E/2K5
ADS7818EB/250
ADS7818EB/2K5
ADS7818P
ADS7818PB
TRANSPORT
MEDIA
Tape and Reel
Tape and Reel
Tape and Reel
Tape and Reel
Rails
Rails
"
ADS7818EB
"
±1
"
±1
"
MSOP-8
"
337
"
–40°C to +85°C
"
A18
"
ADS7818P
ADS7818PB
"
±2
±1
"
N/S
(4)
±1
"
Plastic DIP-8
"
006
"
–40°C to +85°C
"
ADS7818P
ADS7818PB
"
"
"
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 ”ADS7818E/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) N/S = Not Specified, typical only. However, 12-Bits no missing
codes is guaranteed over temperature.
®
3
ADS7818
TYPICAL PERFORMANCE CURVES
At T
A
= +25°C, V
CC
= +5V, f
SAMPLE
= 500kHz, f
CLK
= 16 • f
SAMPLE
, and internal +2.5V reference, unless otherwise specified.
CHANGE IN FULL-SCALE ERROR
vs TEMPERATURE
2
0
Delta from 25°C (LSB)
2.0
1.6
CHANGE IN OFFSET vs TEMPERATURE
–2
–4
–6
–8
–10
–40
Delta from 25°C (LSB)
1.2
0.8
0.4
0.0
–0.4
–40
–20
0
20
40
60
80
100
–20
0
20
40
60
80
100
Temperature (°C)
Temperature (°C)
POWER-DOWN SUPPLY CURRENT
vs TEMPERATURE
470
SUPPLY CURRENT vs TEMPERATURE
2.3
2.2
Power-down Supply Current (µA)
460
Supply Current (mA)
450
440
430
420
410
400
390
–40
2.1
2.0
1.9
1.8
1.7
1.6
–40
f
SAMPLE
= 500kHz
f
SAMPLE
= 125kHz
–20
0
20
40
60
80
100
–20
0
20
40
60
80
100
Temperature (°C)
Temperature (°C)
SUPPLY CURRENT vs SAMPLE RATE
2.4
2.3
0.4
CHANGE IN INTEGRAL LINEARITY and
DIFFERENTIAL LINEARITY vs SAMPLE RATE
Delta from f
SAMPLE
= 500kHz (LSB)
0.3
0.2
0.1
0.0
–0.1
–0.2
–0.3
100
Change in Differential
Linearity (LSB)
200
300
400
500
600
Change in Integral
Linearity (LSB)
Supply Current (mA)
2.2
2.1
2.0
1.9
1.8
1.7
100
200
300
400
500
600
Sample Rate (kHz)
Sample Rate (kHz)
®
ADS7818
4
TYPICAL PERFORMANCE CURVES
(Cont.)
At T
A
= +25°C, V
CC
= +5V, f
SAMPLE
= 500kHz, f
CLK
= 16 • f
SAMPLE
, and internal +2.5V reference, unless otherwise specified.
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