Figure 1. Functional Block Diagram
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
CS2 12
NO CONNECTION 8
NO CONNECTION 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
FEATURES
■ 8-Bit fl ash A/D converter
■ 20MHz sampling rate
■ Complete support circuitry
■ Low power, 900mW
■ Sample-hold not required
■ Three-state outputs
■ MIL-STD-883 versions
PRODUCT OVERVIEW
The ADC-228A combines analog front-end
circuitry and a fl ash A/D converter to digitize
high-speed analog signals at a rate of 20 million
samples per second. The ADC-228A contains an
8-bit, 20MHz, fl ash 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-228A offers signifi cant 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-228A is housed in a 24-pin ceramic
DDIP package and is available in the commercial,
0 to +70°C, or military, –55 to +125°C, tem-
perature ranges. A MIL-STD-883 version is also
available. Operation is from ±15V and +5V power
supplies.
INPUT/OUTPUT CONNECTIONS
Pin FUNCTION Pin FUNCTION
1+5V SUPPLY 24 BIT 8 (LSB)
2GROUND 23 BIT 7
3+5V REFERENCE OUT 22 BIT 6
4GROUND 21 BIT 5
5ANALOG INPUT 20 NO CONNECTION
6GROUND 19 +15V SUPPLY
7GROUND 18 CLOCK INPUT
8NO CONNECTION 17 BIT 4
9NO CONNECTION 16 BIT 3
10 –15V SUPPLY 15 BIT 2
11 CS1 14 BIT 1 (MSB)
12 CS2 13 NO CONNECTION
ADC-228A
8-Bit, 20MHz, Complete Flash A/D Converter
®®
DATEL • 11 Cabot Boulevard, Mansfi eld, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: help@datel.com
31 Mar 2011 ADC-228A.B02 Page 1 of 4
ABSOLUTE MAXIMUM RATINGS
PARAMETER LIMITS
Power Supply Voltage, Pin 1 –0.3 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 –3.8 to +6.6V
Digital Outputs –0.5 to +5.5V
(short circuit protected to ground)
Lead Temp. (10 seconds) +300°C
FUNCTIONAL SPECIFICATIONS
(Apply over the operating temperature range with 20MHz clock and ±15V and +5V
power supply voltages, unless otherwise specifi ed.)
ANALOG INPUTS MIN. TYP. MAX. UNITS
Single-Ended, Non-Isolated
Input Range, dc-20MHz 0 — +5.0 Volts
Input Resistance 1.95 2 — kΩ
Input Capacitance — 5 10 pF
DIGITAL INPUTS
Logic Levels
Logic 1 +2.0 — — Volts
Logic 0 — — +0.8 Volts
Logic Loading
Logic 1 — — +160 μA
Logic 0 — — –0.5 mA
Clock Pulse Widths
"High" 20 — — ns
"Low" 20 — — 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 — — 40 ns
Output Hold Time 6 — — ns
PERFORMANCE
Sampling Rate ➀ 20 — — MHz
Differential Linearity
Code Transitions,
+25°C — ±0.5 ±0.75 LSB
0 to +70°C — ±0.5 ±0.75 LSB
–55 to +125°C — ±0.5 ±0.85 LSB
Integral Linearity, +25°C
End-point — ±0.5 ±1 LSB
Best-fi t Line — ±0.35 ±0.75 LSB
Over Temperature End-point — — ±1.75 LSB
Best-fi t Line — — ±1 LSB
Zero-Scale Offset
Code "0" to "1" Transition
+25°C — ±0.5 ±1 LSB
–55 to +125°C — ±0.5 ±1.5 LSB
PERFORMANCE MIN. TYP. MAX. UNITS
Gain error — ±0.5 ±1.5 LSB
Full Scale Absolute Accuracy — ±0.5 ±1.5 LSB
Differential Gain ➁ — 2 — %
Differential Phase ➁ — 1 — deg.
Aperture Delay — 8 — ns
Aperture Jitter — 50 — ps
No Missing Codes
Power Supply Rejection
DYNAMIC PERFORMANCE
Total Harm. Distortion, –0.5dB
DC to 2.5 MHz — –55 –53 dB
2.5 MHz to 5 MHz — –49 –44 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 41 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 44 49 — 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 6.8 7.4 — Bits
5 MHz to 10 MHz 5.6 6.1 — Bits
Input Bandwidth
Large Signal (–3dB) 15 — — 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 — +12 +20 mA
–15V Supply — –13 –20 mA
+5V Supply — +70 +80 mA
Power Dissipation
±15V, +5V Nominal — 0.7 0.9 Watts
PHYSICAL/ENVIRONMENTAL
Operating Temp. Range, Case
ADC-228AMC 0 to +70°C
ADC-228AMM, ADC-228A/883 –55 to +125°C
Storage Temp. Range –65 to +150°C
Package Type 24-pin, ceramic DDIP
Weight 0.3 ounces (8.5 grams)
Footnotes:
➀ At full power input and chip selects enabled.
➁ For 10-step, 40 IRE NTSC ramp test.
Over the operating temperature range
±0.02% FSR/ %VS maximum
Straight Binary
8 Bits
ADC-228A
8-Bit, 20MHz, Complete Flash A/D Converter
®®
DATEL • 11 Cabot Boulevard, Mansfi eld, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: help@datel.com
31 Mar 2011 ADC-228A.B02 Page 2 of 4
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
4.7μF, 25V tantalum electrolytic capacitor in parallel with a 0.1μF ceramic capacitor.
ANALOG INPUT CODE STRAIGHT BIN.
+4.96V +FS – 1 LSB 1111 1110
+3.75V + 3/4 FS 1100 0000
+2.50V + 1/2 FS 1000 0000
+1.25V + 1/4 FS 0100 0000
+0.02V + 1 LSB 0000 0001
0.00V ZERO 0000 0000
Table 1. ADC-228A Unipolar Output Coding Table 2. Chip Select Truth Table
CS2
Pin 12
CS1
Pin 11 Bits 1-8
0 0 Three State Mode
0 1 Three State Mode
1 0 Data Outputted
1 1 Three State Mode
Figure 2. ADC-228A Timing Diagram
SAMPLE
N + 2
SAMPLE
N + 1
SAMPLE
N
OUTPUT
HOLD TIME
DATA
N
DATA
N + 1
DATA
N + 2
CLOCK
DIGITAL
OUTPUT
OUTPUT
DELAY
Figure 3. ADC-228A Typical Connections
24
23
B8 (LSB)
B7
9kΩ
51Ω19
VIN 5
+15V
*Optional +
2, 4, 6, 7
+5V REFERENCE OUT
NO CONNECTION
3
8, 9, 13, 20
22 B6
21 B5
17 B4
16 B3
CS1 12
CLOCK 18
ANALOG
INPUT
15 B2
14
+
+
B1 (MSB)
4.7F
0.1F
101
–15V
+5V
CS1 11
* Use optional resistor only if
amp is not used to drive input.
ADC-228A
+
0.1F
0.1F
0.1F
4.7F
4.7F
4.7F
EE
R = V /1.667mA
ADC-228A
8-Bit, 20MHz, Complete Flash A/D Converter
®®
DATEL • 11 Cabot Boulevard, Mansfi eld, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: help@datel.com
31 Mar 2011 ADC-228A.B02 Page 3 of 4
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)
112
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 SAMPLING RATE
ADC-228AMC 0 to +70°C 20MSPS
ADC-228AMM –55 to +125°C 20MSPS
ADC-228A/883 * –55 to +105°C 15MSPS
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 specifi cations
DATEL's initial qualifi cation was done at 15MSPS and as a Mil-STD-883 Class G product per
customer request. Mil-STD-883 Class G allows for a reduced temperature range (–55°C to
+105°C) that applies to this device. Contact DATEL if a 20MSPS rate or a Mil-STD-883 Class
H (–55°C to +125°C) temperature range is desired.
*
ADC-228A
8-Bit, 20MHz, Complete Flash A/D Converter
. 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. Specifi cations are subject to change
without notice.
www.datel.com • e-mail: help@datel.com
®®
DATEL
11 Cabot Boulevard, Mansfi eld, MA 02048-1151 USA
ITAR and ISO 9001/14001 REGISTERED
31 Mar 2011 ADC-228A.B02 Page 4 of 4