FEATURES
8-Bit flash A/D converter
20MHz sampling rate
Complete support circuitry
Low power, 1.5W
7MHz full power bandwidth
Sample-hold not required
Three-state outputs
MIL-STD-883 versions
GENERAL DESCRIPTION
The ADC-228 combines analog front-end circuitry and a flash
A/D converter to digitize high-speed analog signals at a rate of
20 million samples per second. The ADC-228 contains an
8-bit, 20MHz, flash A/D, a wideband analog input buffer, a
precision voltage reference, temperature compensation
circuitry, reference trims, and a three-state output buffer in a
24-pin package.
The ADC-228 offers significant savings by combining all of the
circuitry in a single package. Valuable board real estate is
saved, and design time and manufacturing costs are reduced.
The ADC-228 is housed in a 24-pin ceramic DDIP package
and is available in the commercial, 0 to +70C, or military,
55 to +125C, temperature ranges. A MIL-STD-883 version
is also available. Operation is from 15V and +5V power
supplies.
IN N O VA T IO N a n d E X C E L L E N C E
ADC-228
8-Bit, 20MHz, Complete
Flash A/D Converter
Figure 1. Functional Block Diagram
PIN
FUNCTION
PIN
FUNCTION
1
+5V SUPPLY
24
BIT 8 (LSB)
2
GROUND
23
BIT 7
3
+5V REFERENCE OUT
22
BIT 6
4
GROUND
21
BIT 5
5
ANALOG INPUT
20
NO CONNECTION
6
GROUND
19
+15V SUPPLY
7
GROUND
18
CLOCK INPUT
8
NLINV
17
BIT 4
9
NMINV
16
BIT 3
10
15V SUPPLY
15
BIT 2
11
CS1
14
BIT 1 (MSB)
12
CS1
13
NO CONNECTION
INPUT/OUTPUT CONNECTIONS
13 NO CONNECTION
20 NO CONNECTION
14 BIT 1 (MSB)
15 BIT 2
16 BIT 3
17 BIT 4
21 BIT 5
22 BIT 6
23 BIT 7
24 BIT 8 (LSB)
3 +5V REF. OUT
TRI-STATE
BUFFER
8-BIT
20MHz
FLASH
CONVERTER
LINEARIZATION
& TEMPERATURE
COMPENSATION
NETWORK
INPUT
BUFFER
CS1 11
CS1 12
NLINV 8
NMINV 9
CLOCK 18
ANALOG INPUT 5
+15V SUPPLY 19
GROUND 4
GROUND 7
GROUND 6
15V SUPPLY 10
+5V SUPPLY 1
VOLTAGE
REFERENCE
NETWORK
GROUND 2
DATEL, Inc., 11 Cabot Boulevard, Mansfield, MA 02048-1151 (U.S.A.)
Tel: (508) 339-3000 Fax: (508) 339-6356
For immediate assistance (800) 233-2765
ADC-228
FUNCTIONAL SPECIFICATIONS
(Apply over the operating temperature range with 20MHz clock and 15V and +5V
power supply voltages, unless otherwise specified.)
ANALOG INPUTS
MIN.
TYP.
MAX.
UNITS
Single-Ended, Non-Isolated
Input Range, dc-20MHz
0
--
+5.0
Volts
Input Resistance
2.45
2.5
2.55
k
Input Capacitance
--
5
10
pF
DIGITAL INPUTS
Logic Levels
Logic 1
+2.0
--
--
Volts
Logic 0
--
--
+0.8
Volts
Logic Loading
Logic 1
--
--
+160
A
Logic 0
--
--
0.5
mA
Clock Pulse Widths
"High"
25
--
--
ns
"Low"
19
--
--
ns
DIGITAL OUTPUTS
Coding
Resolution
Logic Levels
Logic 1
+2.4
--
--
Volts
Logic 0
--
--
+0.4
Volts
Logic Loading
Logic 1
--
--
1
mA
Logic 0
--
--
+1
mA
Output Data Valid Delay
From Rising Edge
--
30
40
ns
Output Hold Time
5
--
--
ns
PERFORMANCE
Sampling Rate
20
--
--
MHz
Differential Linearity
Code Transitions
--
0.5
0.75
LSB
Code Centers
--
0.25
0.5
LSB
Integral Linearity, +25C
End-point
--
0.5
0.75
LSB
Best-fit Line
--
0.35
0.5
LSB
Over Temperature End-point
--
--
1
LSB
Best-fit Line
--
--
1
LSB
Zero-Scale Offset
Code "0" to "1" Transition
+25C
--
--
0.5
LSB
55 to +125C
--
0.5
1.5
LSB
Gain error
--
0.5
1.5
LSB
Full Scale Absolute Accuracy
--
0.5
1.5
LSB
Differential Gain
--
2
--
%
Differential Phase
--
1
--
deg.
Aperture Delay
--
8
--
ns
Aperture Jitter
--
50
--
ps
No Missing Codes
Power Supply Rejection
DYNAMIC PERFORMANCE
MIN.
TYP.
MAX.
UNITS
Total Harm. Distortion, 0.5dB
DC to 2.5 MHz
--
55
53
dB
2.5 MHz to 5 MHz
--
50
48
dB
5 MHz to 10 MHz
--
39
36
dB
Signal-to-Noise Ratio
and Distortion, 0.5dB
DC to 2.5 MHz
44
49
--
dB
2.5 MHz to 5 MHz
43
46
--
dB
5 MHz to 10 MHz
35
38
--
dB
Signal-to-Noise Ratio
w/o Distortion, 0.5 dB
DC to 2.5 MHz
45
48
--
dB
2.5 MHz to 5 MHz
45
48
--
dB
5 MHz to 10 MHz
42
45
--
dB
Effective Bits, 0.5dB
DC to 2.5 MHz
7.1
7.75
--
Bits
2.5 MHz to 5 MHz
6.9
7.4
--
Bits
5 MHz to 10 MHz
5.6
6.1
--
Bits
Input Bandwidth
Full Power
7
--
--
MHz
Small Signal (20dB)
40
--
--
MHz
POWER SUPPLY
Power Supply Range
+15V Supply
+11
+15
+15.75
Volts
15V Supply
11
15
15.75
Volts
+5V Supply
+4.75
+5
+5.25
Volts
Power Supply Current
+15V Supply
--
--
+30
mA
15V Supply
--
--
10
mA
+5V Supply
--
--
+230
mA
Power Dissipation
12V, +5V Nominal
--
1.4
1.65
Watts
Over full supply range
--
1.6
1.85
Watts
15V, +5V Nominal
--
1.5
1.75
Watts
PHYSICAL/ENVIRONMENTAL
Operating Temp. Range, Case
ADC-228MC
0 to +70C
ADC-228MM, ADC-228/883
55 to +125C
Storage Temp. Range
65 to +150C
Package Type
24-pin, ceramic DDIP
Weight
0.3 ounces (8.5 grams)
Footnotes:
At full power input and chip selects enabled.
See Technical Note 3.
For 10-step, 40 IRE NTSC ramp test.
ABSOLUTE MAXIMUM RATINGS
PARAMETER
LIMITS
Power Supply Voltage,
Pin 1
0.5 to +7V
Pin 19
0.3 to +18V
Pin 10
+0.3 to 18V
Digital Inputs, Pins 8,9,11,12,18
0.5 to +5.5V
Analog Input, Pin 5
6 to +7.5V
Digital Outputs
0.5 to +5.5V (short circuit protected to ground)
Lead Temp. (10 seconds)
+300C
Over the operating temperature range
0.02% FSR/ %V
S
maximum
Straight bin., comp. bin., two's
comp.,
comp. two's comp.
8 bits
2
ADC-228
Table 2. ADC-228 Bipolar Output Coding
(Assumes analog input is externally offset)
TECHNICAL NOTES
1. Rated performance requires using good high-frequency
techniques. The analog and digital ground pins are
connected to each other internally. Avoid ground related
problems by connecting the grounds to one point, the
ground plane beneath the converter. Due to the inductance
and resistance of the power supply return paths, return the
analog and digital ground separately to the power supplies.
2. Bypass all the analog and digital supplies and the +5V
REFERENCE (pin 3) to ground with a 4.7F, 25V tantalum
electrolytic capacitor in parallel with a 0.1F ceramic
capacitor.
3. DATEL uses conservative definitions when specifying
integral linearity (end-point) and differential linearity (code
transition). The specifications using the less conservative
definitions have also been provided as a comparative
specification for products specified this way.
4. Single conversions (one-shot mode) would require another
clock edge to read out data. Users desiring to provide just
a single clock pulse could use the circuit shown in Figure 2
to obtain the data.
STRAIGHT BIN.
COMP. BIN.
ANALOG
NMINV = 0
NMINV = 1
INPUT
CODE
NLINV = 0
NLINV = 1
+4.96V
+FS 1 LSB
1111 1110
0000 0001
+3.75V
+ 3/4 FS
1100 0000
0011 1111
+2.50V
+ 1/2 FS
1000 0000
0111 1111
+1.25V
+ 1/4 FS
0100 0000
1011 1111
+0.02V
+ 1 LSB
0000 0001
1111 1110
0.00V
ZERO
0000 0000
1111 1111
Table 1. ADC-228 Unipolar Output Coding
TWO'S
COMP.
COMP.
TWO'S COMP.
ANALOG
NMINV = 1
NMINV = 0
INPUT
CODE
NLINV = 0
NLINV = 1
+2.480V
+FS 1 LSB
0111 1111
1000 0000
+1.250V
+1/2 FS
0100 0000
1011 1111
+0.020V
+1 LSB
0000 0001
1111 1110
+0.000V
ZERO
0000 0000
1111 1111
1.250V
1/2 FS
1100 0000
0011 1111
2.480V
FS + 1 LSB
1000 0001
0111 1110
2.500V
FS
1000 0000
0111 1111
CLOCK
OUT
74HC86
CLOCK
IN
100pF
50ns
40ns
25ns
PULSES
DATA N
SAMPLED
DATA N
VALID
250
Figure 3. ADC-228 Typical Connections
Figure 2. ADC-228 Single Clock Pulse
Circuit and Operation
24
23
B8 (LSB)
B7
9k
51
19
V
IN
5
+15V
*Optional
+
2, 4, 6, 7
+5V REFERENCE OUT
NO CONNECTION
3
13, 20
22
B6
21
B5
17
B4
16
B3
CS1 12
CLOCK 18
ANALOG
INPUT
15
B2
14
+
+
B1 (MSB)
4.7F
NLINV 8
NMINV 9
0.1F
10
1
15V
+5V
CS1 11
* Use optional resistor only if
amp is not used to drive input.
ADC-228
+
0.1F
0.1F
0.1F
4.7F
4.7F
4.7F
EE
R = V /1.667mA
3
Table 3. Chip Select Truth Table
Figure 4. ADC-228 Timing Diagram
SAMPLE
N + 2
SAMPLE
N + 1
SAMPLE
N
OUTPUT
HOLD TIME
DATA
N 1
DATA
N
DATA
N + 1
CLOCK
DIGITAL
OUTPUT
OUTPUT
DELAY
CS1
CS1
Pin 12
Pin 11
Bits 1-8
0
0
Three State Mode
0
1
Three State Mode
1
0
Data Outputted
1
1
Three State Mode
ADC-228
MECHANICAL DIMENSIONS INCHES (mm)
0.200 MAX.
(5.080)
0.235 MAX.
(5.969)
0.600 0.010
(15.240)
0.80 MAX.
(20.32)
0.100 TYP.
(2.540)
0.100
(2.540)
0.018 0.002
(0.457)
0.100
(2.540)
0.040
(1.016)
1.31 MAX.
(33.27)
1
12
13
24
1.100
(27.940)
0.190 MAX.
(4.826)
0.010
(0.254)
+0.002
0.001
SEATING
PLANE
0.025
(0.635)
Dimension Tolerances (unless otherwise indicated):
2 place decimal (.XX) 0.010 (0.254)
3 place decimal (.XXX) 0.005 (0.127)
Lead Material: Kovar alloy
Lead Finish: 50 microinches (minimum) gold plating
over 100 microinches (nominal) nickel plating
ORDERING INFORMATION
MODEL
TEMPERATURE RANGE
ADC-228MC
0 to +70C
ADC-228MM
55 to +125C
ADC-228/883
55 to +125C
Receptacle for PC board mounting can be ordered through AMP Inc., part # 3-331272-8
(component lead socket), 24 required. Contact DATEL for 883 product specifications
IN N O VA T IO N a n d E X C E L L E N C E
DATEL makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein
do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without notice. The DATEL logo is a registered DATEL, Inc. trademark.
DS-0211B
10/96
ISO 9001
ISO 9001
R
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DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151
Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356
Internet: www.datel.com E-mail:sales@datel.com
Data Sheet Fax Back: (508) 261-2857
DATEL (UK) LTD. Tadley, England Tel: (01256)-880444
DATEL S.A.R.L. Montigny Le Bretonneux, France Tel: 1-34-60-01-01
DATEL GmbH Mnchen, Germany Tel: 89-544334-0
DATEL KK Tokyo, Japan Tel: 3-3779-1031, Osaka Tel: 6-354-2025
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