FEATURES
35 MSPS Encode Rate
16 pF Input Capacitance
550 mW Power Dissipation
Industry-Standard Pinouts
MIL-STD-883 Compliant Versions Available
APPLICATIONS
Professional Video Systems
Special Effects Generators
Electro-Optics
Digital Radio
Electronic Warfare (ECM, ECCM, ESM)
GENERAL DESCRIPTION
The AD9048 is an 8-bit, 35 MSPS flash converter, made on a
high speed bipolar process, which is an alternate source for the
TDC1048 unit, offers enhancements over its predecessor.
Lower power dissipation makes the AD9048 attractive for a
variety of system designs.
Because of its wide bandwidth, it is an ideal choice for real-time
conversion of video signals. Input bandwidth is flat with no
missing codes.
Clocked latching comparators, encoding logic and output buffer
registers operating at minimum rates of 35 MSPS preclude a
need for a sample-and-hold (S/H) or track-and-hold (T/H) in
most system designs using the AD9048. All digital control
inputs and outputs are TTL compatible.
Devices operating over two ambient temperature ranges and
with two grades of linearity are available. Linearities of either
0.5 LSB or 0.75 LSB can be ordered for a commercial range of
0°C to 70°C or extended case temperatures of –55°C to +125°C.
Video A/D Converter
AD9048
FUNCTIONAL BLOCK DIAGRAM
12
NLINV
28
NMINV
23
V
R
R
R
CONVERT
IN
18
T
R
R
R/2
27
M
R/2
R
R
26
B
17
6 10
V
CC
1
2
127
128
254
255
8 9
7
V
EE
Commercial versions are packaged in 28-lead DIPs; extended
temperature versions are available in ceramic DIP and ceramic
LCC packages. Both commercial units and MIL-STD-883 units
are standard products.
The AD9048 A/D converter is available in versions compliant
with MIL-STD-883. Refer to the Analog Devices Military Prod-ucts Databook or current AD9048/883B data sheet for detailed
specifications.
AD9048
E
N
C
O
D
L
I
A
N
T
G
C
H
L
O
G
I
C
11
5
19
DGND AGND
25
1
2
3
4
13
14
15
16
D1 (MSB)
D2
D3
D3
D5
D6
D7
D8 (LSB)
REV. E
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 that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
(typical with nominal supplies unless otherwise noted)
ABSOLUTE MAXIMUM RATINGS
VCC to DGND . . . . . . . . . . . . . . . . . . . –0.5 V dc to +7.0 V dc
AGND to DGND . . . . . . . . . . . . . . . . –0.5 V dc to +0.5 V dc
to AGND . . . . . . . . . . . . . . . . . . . +0.5 V dc to –7.0 V dc
V
EE
V
, VRT or VRB to AGND . . . . . . . . . . . . . . . . . . 0.5 V to V
IN
VRT to VRB . . . . . . . . . . . . . . . . . . . . . . –2.2 V dc to +2.2 V dc
CONV, NMINV or NLINV to DGND –0.5 V dc to +5.5 V dc
Applied Output Voltage to DGND . . –0.5 V dc to +5.5 V dc
Applied Output Current, Externally Forced
FullVI120120120120mA
Nominal Power Dissipation25°CV550550550550mW
Reference Ladder Dissipation25°CV45454545mW
NOTES
1
Maximum ratings are limiting values to be applied individually, and beyond which
the serviceability of the device may be impaired. Functional operation under any of
these conditions is not necessarily implied. Exposure to absolute maximum rating
conditions for extended periods of time may affect device reliability.
2
Applied voltage must be current-limited to specified range.
3
Forcing voltage must be limited to specified range.
4
Current is specified as negative when flowing into the device.
5
Output High; one pin to ground; one second duration.
6
Typical thermal impedances (no air flow) are as follows:
Ceramic DIP: θJA = 49°C/W;
JLCC: θJA = 59°C/W; θJC = 19°C/W.
θJC = 15°C/W, LCC: θJA = 69°C/W;
θ
= 21°C/W,
JC
To calculate junction temperature (TJ), use power dissipation (PD) and thermal
impedance: TJ = PD (θJA) + T
7
Measured with VIN = 0 V and CONVERT low (sampling mode).
8
Determined by beat frequency testing for no missing codes.
9
VRT ≥ VRB under all circumstances.
= PD (θJC) = + T
AMBIENT
CASE
.
10
Outputs terminated with 40 pF and eight 10 Ω pull-up resistors.
11
Interval from 50% point of leading edge CONVERT pulse to change in
output data.
12
For full-scale step input, 8-bit accuracy attained in specified time.
13
Recovers to 8-bit accuracy in specified time after –3 V input overvoltage.
14
Output time skew includes high-to-low and low-to-high transitions as well as
bit-to-bit time skew differences.
15
Measured at 20 MHz encode rate with analog input 1 dB below full scale.
16
Measured at 35 MHz encode rate with analog input 1 dB below full scale.
17
RMS signal to rms noise.
18
Peak signal to rms noise.
19
DC to 8 MHz noise bandwidth with 1.248 MHz slot; four sigma loading;
20 MHz encode.
20
Clock frequency = 4 × NTSC = 14.32 MHz. Measured with 40-IRE
modulated ramp.
Specifications subject to change without notice.
EXPLANATION OF TEST LEVELS
Test Level I– 100% production tested.
Test Level II– 100% production tested at 25°C and
sample tested at specific temperatures.
Test Level III – Sample tested only.
Test Level IV – Parameter is guaranteed by design and
characterization testing.
Test Level V– Parameter is a typical value only.
Test Level VI – All devices are 100% production tested at
25°C. 100% production tested at temperature
extremes for military temperature devices;
sample tested at temperature extremes for
commercial/industrial devices.
REV. E
–3–
AD9048
14
13
12
11
10
9
8
1
2
3
4
7
6
5
17
16
15
20
19
18
28
27
26
25
24
23
22
21
TOP VIEW
(Not to Scale)
AD9048
NC = NO CONNECT
NMINV
R
M
R
B
AGND
NC
V
IN
NC
NC
NC
AGND
R
T
CONVERT
D8 (LSB)
D7
(MSB) D1
D2
D3
D4
DGND
V
CC
V
EE
V
EE
V
EE
V
CC
DGND
NLINV
D5
D6
WARNING!
ESD SENSITIVE DEVICE
ORDERING GUIDE
Package
ModelLinearityTemperatureOption
1
PIN CONFIGURATIONS
DIP (D Package)
AD9048JJ0.75 LSB0°C to 70°CJ-28A
AD9048KJ0.5 LSB0°C to 70°CJ-28A
AD9048JQ0.75 LSB0°C to 70°CD-28
AD9048KQ0.5 LSB0°C to 70°CD-28
AD9048SE
AD9048TE
AD9048SQ
2
0.75 LSB–55°C to +125°CE-28A
2
0.5 LSB–55°C to +125°CE-28A
2
0.75 LSB–55°C to +125°CD-28
AD9048TQ20.5 LSB–55°C to +125°CD-28
NOTES
1
E = Leadless Ceramic Chip Carrier; J = J-Leaded Ceramic; D = Cerdip.
2
For temperature designation only. MIL-STD-883 and Standard Military
Drawing available.
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the AD9048 features proprietary ESD protection circuitry, permanent damage may
occur on devices subjected to high-energy electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.
EE
–4–
DGND
V
CC
V
EE
V
EE
V
EE
V
CC
DGND
J-Leaded Ceramic (J Package)
R
R
NMINV
(MSB) D1
D2
D3
D4
D4
5
6
7
8
9
10
11
12
NLINV
NC = NO CONNECT
AGND
26
B
27
M
28
1
2
3
4
DGND
NC = NO CONNECT
13 14 15 16 17 18
B
M
R
D3
D2
3426
2
AD9048
TOP VIEW
(Not to Scale)
D5
D6
IN
V
NC
AD9048
TOP VIEW
TOP VIEW
(Not to Scale)
(Not to Scale)
CC
VEEVEEV
V
NMINV
D1 (MSB)
28 271
D7
(LSB) D8
NC
NC
EE
R
T
R
CONVERT
NC
AGND
1921 2025 242223
115106789
CC
V
DGND
25
AGND
24
NC
23
V
22
NC
21
NC
20
NC
19
AGND
18
R
T
17
CONVERT
16
D8 (LSB)
15
D7
14
D6
13
D5
12
NLINV
IN
REV. E
PIN FUNCTION DESCRIPTIONS
AD9048
PinDescription
D1–D8Eight digital outputs. D1 (MSB) is the most
significant bit of the digital output word;
D8 (LSB) is the least significant bit.
AGNDOne of two analog ground returns. Both
grounds should be connected together and to
low impedance ground plane near the AD9048.
DGNDOne of two digital ground returns. Both
grounds should be connected together and to
low impedance ground plane near the AD9048.
V
CC
V
EE
Positive supply terminals; nominally +5.0 V.
Negative supply terminals; nominally –5.2 V.
CONVERTInput for conversion signal; sample of analog
input signal taken on rising edge of this pulse.
–5.2V
0.1F
V
EE
V
IN
CONVERT
AD9048
R
B
R
T
DIGITAL
GROUND
AD1
AD2
–2.0V
100
510
PinDescription
R
B
Most negative reference voltage for internal
reference ladder.
R
M
R
T
Midpoint tap on internal reference ladder.
Most positive reference voltage for internal
reference ladder.
V
IN
Analog input signal pin.
NMINV“Not Most Significant Bit Invert.” In normal
operation, this pin floats high; logic LOW at
NMINV inverts most significant bit of digital
output word [D1 (MSB)].
NLINV“Not Least Significant Bit Invert.” In normal
operation, this pin floats high; logic LOW at
NLINV inverts the seven least significant bits
of the digital output word.
+5.0V
V
CC
(MSB) D1
(LSB) D8
ANALOG
GROUND
D2
D3
D4
D5
D6
D7
1k
LOAD
RESISTORS
0.1F
ALL RESISTORS 5%
ALL CAPACITORS 20%
ALL SUPPLY VOLTAGES 5%
Refer to the Functional Block Diagram of the AD9048. The
AD9048 comprises three functional sections: a comparator
array, encoding logic and output latches.
Within the array, the analog input signal to be digitized is
compared with 255 reference voltages. The outputs of all comparators whose references are below the input signal level will be
high; outputs whose references are above that level will be low.
The n-of-255 code that results from this comparison is applied
to the encoding logic where it is converted into binary coding.
When it is inverted with dc signals applied to the NLINV and/or
NMINV pins, it becomes two’s complement.
After encoding, the signal is applied to the output latch circuits
where it is held constant between updates controlled by the
application of CONVERT pulses.
The AD9048 uses strobed latching comparators in which comparator outputs are either high or low, as dictated by the analog
input level. Data appearing at the output pins have a pipeline
delay of one encode cycle.
Input signal levels between the references applied to R
(Pin 26) will appear at the output as binary numbers
and R
B
(Pin 18)
T
between 0 and 255, inclusive. Signals outside that range will
show up as either full-scale positive or full-scale negative outputs. No damage will occur to the AD9048 as long as the input
is within the voltage range of V
to +0.5 V.
EE
The significantly reduced input capacitance of the AD9048
lowers the drive requirements of the input buffer/amplifier and
also induces much smaller phase shift in the analog input signal.
Applications that depend on controlled phase shift at the converter input can benefit from using the AD9048 because of its
inherently lower phase shift.
The CONVERT, analog input and digital output circuits are
shown in Figure 3.
System timing, which provides details on delays through the
AD9048 as well as the relationships of various timing events, is
shown in Figure 4.
N+1
ANALOG
INPUT
CONVERT
OUTPUT
DATA
N
t
PD
APERTURE
DELAY
t
OH
N– 1
DATA
CHANGING
N
N+2
DATA
CHANGING
N+1
Figure 4. Timing Diagram
Dynamic performance of the AD9048, i.e., typical signal-tonoise ratio, is illustrated in Figures 3 and 4.
Designs that use the AD9048 or any other high speed device
must follow some basic layout rules to ensure optimum
performance.
The first requirement is to have a large, low impedance ground
plane under and around the converter. If the system uses separate
analog and digital grounds, both should be solidly connected
together, and to the ground plane, as closely to the AD9048 as
practical to avoid ground loop currents.
Ceramic 0.1 µF decoupling capacitors should be placed as closely
as possible to the supply pins of the AD9048. For decoupling
low frequency signals, use 10 µF tantalum capacitors, also con-
nected as closely as practical to voltage supply pins.
Within the AD9048, reference currents may vary because of
coupling between the clock and input signals. As a result, it is
important that the ends of the reference ladder, R
(Pin 28), be connected to low impedances (as measured
R
B
(Pin 18) and
T
from ground).
If the AD9048 is being used in a circuit in which the reference
is not varied, a bypass capacitor to ground is strongly recommended. In applications that use varying references, they must
be driven from a low impedance source.