a
FEATURES
AC and DC Characterized and Specified (K, B, T
Grades)
128k Conversions per Second
1 MHz Full Power Bandwidth
500 kHz Full Linear Bandwidth
80 dB S/N+D (K, B, T Grades)
Twos Complement Data Format (Bipolar Mode)
Straight Binary Data Format (Unipolar Mode)
10 M Input Impedance
16-Bit Bus Interface (See AD679 for 8-Bit Interface)
Onboard Reference and Clock
10 V Unipolar or Bipolar Input Range
MIL-STD-883 Compliant Versions Available
14-Bit 128 kSPS
Complete Sampling ADC
AD779*
FUNCTIONAL BLOCK DIAGRAM
PRODUCT DESCRIPTION
PRODUCT HIGHLIGHTS
The AD779 is a complete, multipurpose 14-bit monolithic
analog-to-digital converter, consisting of a sample-hold amplifier
(SHA), a microprocessor compatible bus interface, a voltage
reference and clock generation circuitry.
The AD779 is specified for ac (or “dynamic”) parameters such
as S/N+D ratio, THD and IMD which are important in signal
processing applications. In addition, the AD779K, B and T
grades are fully specified for dc parameters which are important
in measurement applications.
The 14 data bits are accessed by a 16-bit bus in a single read
operation. Data format is straight binary for unipolar mode and
twos complement binary for bipolar mode. The input has a full-
scale range of 10 V with a full power bandwidth of 1 MHz and a
full linear bandwidth of 500 kHz. High input impedance (10 MΩ)
allows direct connection to unbuffered sources without signal
degradation.
This product is fabricated on Analog Devices’ BiMOS process,
combining low power CMOS logic with high precision, low
noise bipolar circuits; laser-trimmed thin-film resistors provide
high accuracy. The converter utilizes a recursive subranging
algorithm which includes error correction and flash converter
circuitry to achieve high speed and resolution.
The AD779 operates from +5 V and
±
12 V supplies and
dissipates 560 mW (typ). Twenty-eight-pin plastic DIP and
ceramic DIP packages are available.
*Protected
by U.S. Patent Numbers 4,804,960; 4,814,767; 4,833,345;
4,250,445; 4,808,908; RE30,586.
l. COMPLETE INTEGRATION: The AD779 minimizes
external component requirements by combining a high speed
sample-hold amplifier (SHA), ADC, 5 V reference, clock
and digital interface on a single chip. This provides a fully
specified sampling A/D function unattainable with discrete
designs.
2. SPECIFICATIONS: The AD779K, B and T grades provide
fully specified and tested ac and dc parameters. The AD779J,
A and S grades are specified and tested for ac parameters; dc
accuracy specifications are shown as typicals. DC specifica-
tions (such as INL, gain and offset) are important in control
and measurement applications. AC specifications (such as
S/N+D ratio, THD and IMD) are of value in signal process-
ing applications.
3. EASE OF USE: The pinout is designed for easy board lay-
out, and the single cycle read output provides compatibility
with 16-bit buses. Factory trimming eliminates the need for
calibration modes or external trimming to achieve rated
performance.
4. RELIABILITY: The AD779 utilizes Analog Devices’
monolithic BiMOS technology. This ensures long term
reliability compared to multichip and hybrid designs.
5. The AD779 is available in versions compliant with MIL-
STD-883. Refer to the Analog Devices Military Products
Databook or current AD779/883B data sheet for detailed
specifications.
REV. B
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
AD779–SPECIFICATIONS
AC SPECIFICATIONS
Parameter
SIGNAL-TO-NOISE AND DISTORTION (S/N+D) RATIO
–0.5 dB Input (Referred to 0 dB Input)
–20 dB Input (Referred to –20 dB Input)
–60 dB Input (Referred to –60 dB Input)
TOTAL HARMONIC DISTORTION (THD)
@ +25°C
T
MIN
to T
MAX
PEAK SPURIOUS OR PEAK HARMONIC COMPONENT
FULL POWER BANDWIDTH
FULL LINEAR BANDWIDTH
INTERMODULATION DISTORTION (IMD)
2
2nd Order Products
3rd Order Products
500
–90
–90
MIN
(T
MIN
to T
MAX
, V
CC
= +12 V 5%, V
EE
= –12 V
f
lN
= 10.009 kHz unless otherwise noted)
1
5%, V
DD
= +5 V
10%, f
SAMPLE
= 128 kSPS,
AD779K/B/T
Min
Typ
Max
80
60
20
81
61
21
–90
0.003
–88
0.004
–90
1
500
–84
0.006
–82
0.008
–84
AD779J/A/S
Min
Typ
Max
78
58
18
79
59
19
–90
0.003
–88
0.004
–90
1
–84
0.006
–82
0.008
–84
Units
dB
dB
dB
dB
%
dB
%
dB
MHz
kHz
–84
–84
–90
–90
–84
–84
dB
dB
DIGITAL SPECIFICATIONS
(All device types T
Parameter
LOGIC INPUTS
V
IH
High Level Input Voltage
V
IL
Low Level Input Voltage
I
IH
High Level Input Current
I
IL
Low Level Input Current
C
IN
Input Capacitance
LOGIC OUTPUTS
V
OH
High Level Output Voltage
V
OL
I
OZ
C
OZ
Low Level Output Voltage
High Z Leakage Current
High Z Output Capacitance
to T
MAX
, V
CC
= +12 V
5%, V
EE
= –12 V
Min
2.0
0
–10
–10
5%, V
DD
= +5 V
Max
V
DD
0.8
+10
+10
10
10%)
Units
V
V
µA
µA
pF
V
V
V
µA
pF
Test Conditions
V
IN
= V
DD
V
IN
= 0 V
I
OH
= 0.1 mA
I
OH
= 0.5 mA
I
OL
= 1.6 mA
V
IN
= V
DD
4.0
2.4
–10
0.4
+10
10
NOTES
1
f
IN
amplitude = –0.5 dB (9.44 V p-p) bipolar mode full scale unless otherwise indicated. All measurements referred to a –0 dB (9.997 V p-p) input signal
unless otherwise noted.
2
f
A
= 9.08 kHz, f
B
= 9.58 kHz, with f
SAMPLE
= 128 kSPS.
Specifications subject to change without notice.
–2–
REV. B
AD779
DC SPECIFICATIONS
(T
Parameter
TEMPERATURE RANGE
J, K Grades
A, B Grades
S, T Grades
ACCURACY
Resolution
Integral Nonlinearity (INL)
Differential Nonlinearity (DNL)
Unipolar Zero Error
1
(@ +25°C)
Bipolar Zero Error
1
(@ +25°C)
Gain Error
1, 2
(@ +25°C)
Temperature Drift
Unipolar Zero
3
J, K Grades
A, B Grades
S, T Grades
Bipolar Zero
3
J, K Grades
A, B Grades
S, T Grades
Gain
3
J, K Grades
A, B Grades
S, T Grades
Gain
4
J, K Grades
A, B Grades
S, T Grades
ANALOG INPUT
Input Ranges
Unipolar Mode
Bipolar Mode
Input Resistance
Input Capacitance
Input Settling Time
Aperture Delay
Aperture Jitter
INTERNAL VOLTAGE REFERENCE
Output Voltage
5
External Load
Unipolar Mode
Bipolar Mode
POWER SUPPLIES
Power Supply Rejection
V
CC
= +12 V
±
5%
V
EE
= –12 V
±
5%
V
DD
= +5 V
±
10%
Operating Current
I
CC
I
EE
I
DD
Power Consumption
NOTES
1
Adjustable to zero. See Figures 5 and 6.
2
Includes internal voltage reference error.
3
Includes internal voltage reference drift.
4
Excludes internal voltage reference drift.
5
With maximum external load applied.
*% FSR = percent of full-scale range.
Specifications subject to change without notice.
MIN
to T
MAX
, V
CC
= +12 V
5%, V
EE
= –12 V
5%, V
DD
= +5 V
10% unless otherwise noted)
AD779K/B/T
Min
Typ
Max
0
–40
–55
14
14
±
1
0.05
0.05
0.09
0.04
0.05
0.09
0.02
0.04
0.08
0.09
0.10
0.20
0.04
0.05
0.09
+70
+85
+125
±
2
0.07
0.07
0.11
0.05
0.07
0.10
0 04
0.06
0.09
0.11
0.16
0.25
0.05
0.07
0.10
Units
°C
°C
°C
Bits
LSB
Bits
% FSR*
% FSR
% FSR
% FSR
% FSR
% FSR
% FSR
% FSR
% FSR
% FSR
% FSR
% FSR
% FSR
% FSR
% FSR
AD779J/A/S
Min
Typ
Max
0
–40
–55
14
14
0.08
0.08
0.12
0.04
0.05
0.09
0.02
0.04
0.08
0.09
0.10
0.20
0.04
0.05
0.09
±
2
+70
+85
+125
0
–5
10
10
+10
+5
1.5
10
150
0
–5
10
10
+10
+5
1.5
10
150
V
V
MΩ
pF
µs
ns
ps
V
mA
mA
4.98
5.02
+1.5
+0.5
±
6
±
6
±
6
18
25
8
560
20
34
12
745
4.98
5.02
+1.5
+0.5
±
6
±
6
±
6
18
25
8
560
20
34
12
745
LSB
LSB
LSB
mA
mA
mA
mW
REV. B
–3–
AD779
TIMING SPECIFICATIONS
(All device types T
MIN
to T
MAX
, V
CC
= +12 V
5%, V
DD
= +5 V 10%)
Parameter
Conversion Rate
1
Convert Pulse Width
Aperture Delay
Conversion Time
Status Delay
Access Time
2, 3
Float Delay
5
Output Delay
OE
Delay
Read Pulse Width
Conversion Delay
Symbol
t
CR
t
CP
t
AD
t
C
t
SD
t
BA
t
FD
t
OD
t
OE
t
RP
t
CD
Min
0.097
5
0
10
10
10
20
100
400
5%, V
EE
= –12 V
Max
7.8
3.0
20
6.3
400
100
57
4
80
0
Units
µs
µs
ns
µs
ns
ns
ns
ns
ns
ns
ns
ns
NOTES
1
Includes Acquisition Time.
2
Measured from the falling edge of
OE/EOCEN
(0.8 V) to the time at which the
data lines/EOC cross 2.0 V or 0.8 V. See Figure 4.
3
C
OUT
= 100 pF.
4
C
OUT
= 50 pF.
5
Measured from the rising edge of
OE/EOCEN
(2.0 V) to the time at which the
output voltage changes by 0.5 V. See Figure 4; C
OUT
= 10 pF.
Specifications subject to change without notice.
Figure 3. EOC Timing
Figure 1. Conversion Timing
Figure 2. Output Timing
Figure 4. Load Circuit for Bus Timing Specifications
–4–
REV. B
AD779
ABSOLUTE MAXIMUM RATINGS
1
Specification
V
CC
V
BE
V
CC2
V
DD
AGND
AIN, REF
IN
Digital Inputs
Digital Outputs
Max Junction
Temperature
Operating Temperature
J and K Grades
A and B Grades
S and T Grades
Storage Temperature
Lead Temperature
(10 sec max)
With
Respect
To
AGND
AGND
V
EE
DGND
DGND
AGND
DGND
DGND
Min
–0.3
–18
–0.3
0
–1
V
EE
–0.5
–0.5
Max
+18
+0.3
+26.4
+7
+1
V
CC
+7
V
DD
+0.3
175
Units
V
V
V
V
V
V
V
V
°C
°C
°C
°C
°C
°C
0
–40
–55
–65
+70
+85
+125
+150
+300
NOTES
1
Stresses above those listed under “Absolute Maximum Ratings” may cause
permanent damage to the device. This is a stress rating only and functional
operation of the device at these or any other conditions above those indicated in the
operational sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
2
The AD779 is not designed to operate from
±
15 V supplies.
ESD SENSITIVITY
The AD779 features input protection circuitry consisting of large “distributed” diodes and
polysilicon series resistors to dissipate both high energy discharges (Human Body Model) and fast,
low energy pulses (Charged Device Model). Per Method 3015.2 of MIL-STD-883C, the AD779
has been classified as a Category 1 device.
Proper ESD precautions are strongly recommended to avoid functional damage or performance
degradation. Charges as high as 4000 volts readily accumulate on the human body and test
equipment and discharge without detection. Unused devices must be stored in conductive foam or
shunts, and the foam should be discharged to the destination socket before devices are removed. For
further information on ESD precautions, refer to Analog Devices’
ESD Prevention Manual.
ORDERING GUIDE
1
WARNING!
ESD SENSITIVE DEVICE
Model
2
AD779JN
AD779KN
AD779JD
AD779KD
AD779AD
AD779BD
AD779SD
AD779TD
Temperature Range
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
–40°C to +85°C
–40°C to +85°C
–55°C to +125°C
–55°C to +125°C
Tested and Specified
AC
AC + DC
AC
AC + DC
AC
AC + DC
AC
AC + DC
Package Description
28-Pin Plastic DIP
28-Pin Plastic DIP
28-Pin Ceramic DIP
28-Pin Ceramic DIP
28-Pin Ceramic DIP
28-Pin Ceramic DIP
28-Pin Ceramic DIP
28-Pin Ceramic DIP
Package Option
3
N-28
N-28
D-28
D-28
D-28
D-28
D-28
D-28
NOTES
1
For two cycle read (8+16 bits) interface to 8-bit buses, see AD679.
2
For details on grade and package offerings screened in accordance with MIL-STD-883, refer to the Analog Devices Military Products Databook or current
AD779/883B data sheet.
3
D = Ceramic DIP; N = Plastic DIP.
REV. B
–5–
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