Figure 1. ADS-112 Functional Block Diagram
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
ADS-112
12-Bit, 1MHz, Low-Power
Sampling A/D Converters
FEATURES
12-bit resolution
No missing codes
1MHz minimum sampling rate
Functionally complete
Small 24-pin DDIP
Low-power, 1.3 Watts
Three-state output buffers
Samples to Nyquist frequencies
GENERAL DESCRIPTION
DATEL's ADS-112 is a 12-bit, functionally complete, sampling
A/D converter that is packaged in a space-saving 24-pin DDIP.
Requiring 15V and +5V supplies, a minimum sampling rate of
1MHz is achieved while only dissipating 1.3 Watts. The
ADS-112 digitizes signals up to Nyquist frequencies. Models
are available for use in either commercial (0 to + 70C) or
military (55 to +125C) operating temperature ranges.
Typical applications include spectrum, transient, vibration and
waveform analysis. This device is also ideally suited for radar,
sonar, video digitization, medical instrumentation and high-
speed data acquisition systems.
INPUT/OUTPUT CONNECTIONS
PIN
FUNCTION
PIN
FUNCTION
1
BIT 12 (LSB)
24
15V SUPPLY
2
BIT 11
23
ANALOG GROUND
3
BIT 10
22
+15V SUPPLY
4
BIT 9
21
+10V REFERENCE
5
BIT 8
20
BIPOLAR
6
BIT 7
19
ANALOG INPUT
7
BIT 6
18
COMP BIN
8
BIT 5
17
ENABLE (1-12)
9
BIT 4
16
START CONVERT
10
BIT 3
15
EOC
11
BIT 2
14
DIGITAL GROUND
12
BIT 1 (MSB)
13
+5V SUPPLY
REF
R
E
G
I
S
T
E
R
R
E
G
I
S
T
E
R
3
-
S
T
A
T
E
O
U
T
P
U
T
R
E
G
I
S
T
E
R
12 BIT 1 (MSB)
11 BIT 2
10 BIT 3
9 BIT 4
8 BIT 5
7 BIT 6
6 BIT 7
5 BIT 8
4 BIT 9
3 BIT 10
2 BIT 11
1 BIT 12 (LSB)
TIMING AND
CONTROL LOGIC
BIPOLAR 20
+10V REF. 21
START CONVERT 16
EOC 15
D
I
G
I
T
A
L
C
O
R
R
E
C
T
I
O
N
L
O
G
I
C
DAC
FLASH
ADC
COMP BIN 18
BUFFER
+
S/H
ANALOG INPUT 19
17 ENABLE (1-12)
S
2
S
1
13
+5V SUPPLY
22
+15V SUPPLY
23
ANALOG GROUND
14
DIGITAL GROUND
24
15V SUPPLY
ADS-112
2
FUNCTIONAL SPECIFICATIONS
(T
A
= +25C, V
CC
= 15V, +V
DD
=+5V, 1MHz sampling rate, and a minimum 1 minute
warmup unless otherwise specified.)
ANALOG INPUTS
MIN.
TYP.
MAX.
UNITS
Input Voltage Range
Bipolar
--
5
--
Volts
Unipolar
--
0 to +10
--
Volts
Input Impedence
4.5
5
--
k
Input Capacitance
--
6
15
pF
DIGITAL INPUTS
Logic Levels
Logic "1"
+2.0
--
--
Volts
Logic "0"
--
--
+0.8
Volts
Logic Loading "1"
--
--
+10
A
Logic Loading "0"
--
--
600
A
PERFORMANCE
Resolution
12 Bits
No Missing Codes
(12 Bits; f
in
= 1MHz)
Over the operating temperature range
Integral Non-Linearity
+25C
--
1/4
3/4
LSB
0C to +70C
--
1/4
3/4
LSB
55C to +125C
--
1/2
1.5
LSB
Differential Non-Linearity
+25C
--
1/4
3/4
LSB
0C to +70C
--
1/4
3/4
LSB
55C to +125C
--
1/2
1
LSB
Full Scale Absolute Accuracy
+25C
--
0.13
0.25
%FSR
0C to +70C
--
0.15
0.44
%FSR
55C to +125C
--
0.25
0.78
%FSR
Unipolar Zero Error
0C to +70C
--
0.074
0.265
%FSR
55C to +125C
--
0.224
0.43
%FSR
Bipolar Zero Error
0C to +70C
--
0.074
0.166
%FSR
55C to +125C
--
0.124
0.210
%FSR
Bipolar Offset Error
0C to +70C
--
0.1
0.38
%FSR
55C to +125C
--
0.3
0.60
%FSR
Gain Error
0C to +70C
--
0.1
0.38
%
55C to +125C
--
0.3
0.60
%
Internal Reference Voltage, +25C
+9.98
+10.0
+10.02
Volts
Drift
--
5
30
ppm/C
External Current
--
--
1.5
mA
DYNAMIC PERFORMANCE
In-Band Harmonics (0.5dB)
dc to 100kHz
--
81
75
dB
100kHz to 500kHz
--
75
70
dB
Total Harm. Distort. (0.5dB)
dc to 100kHz
--
78
75
dB
100kHz to 500kHz
--
73
68
dB
DYNAMIC PERF. (cont)
MIN.
TYP.
MAX.
UNITS
Signal-to-Noise Ratio
(wo/distort., 0.5dB)
dc to 100kHz
68
72
--
dB
100kHz to 500kHz
67
71
--
dB
Signal-to-Noise Ratio
(& distort., 0.5dB)
dc to 100kHz
66
70
--
dB
100kHz to 500kHz
66
70
--
dB
Two-tone Intermodulation
Distortion (f
in
= 75kHz,
105kHz, f
s
= 1MHz, 0.7dB)
--
88
80
dB
Two-tone Intermodulation
Distortion (f
in
= 480kHz,
490kHz, f
s
= 1MHz, 0.7dB)
--
68
65
dB
Input Bandwith (3dB)
Small Signal (20dB input)
8
10
--
MHz
Large Signal (0.5dB input)
6
8
--
MHz
Slew Rate
--
150
--
V/s
Apperture Delay TIme
--
--
20
ns
Effect. Aperture Delay Time
--
--
16
ns
Apperture Uncertainity (Jitter)
RMS
--
--
15
ps
Peak
--
--
50
ps
Overvoltage Recovery Time
--
--
1000
ns
S/H Acquisition Time
160
250
280
ns
Conversion Rate
(Changing Inputs)
+25C
1
--
--
MHz
0C to +70C
1
--
--
MHz
55C to +125C
1
--
--
MHz
DIGITAL OUTPUTS
Output Coding
Pin 18 High
Pin 18 Low
Logic Level
Logic "1"
+2.4
--
--
Volts
Logic "0"
--
--
+0.4
Volts
Logic Loading "1"
--
--
160
A
Logic Loading "0"
--
--
+6.4
mA
POWER REQUIREMENTS
Power Supply Ranges
+15V Supply
+14.25
+15.0
+15.75
Volts
15V Supply
14.25
15.0
15.75
Volts
+5V Supply
+4.75
+5.0
+5.25
Volts
Power Supply Current
+15V Supply
--
+24
+35
mA
15V Supply
--
40
48
mA
+5V Supply
--
+80
+95
mA
Power Dissipation
--
1.3
1.7
Watts
Power Supply Rejection
--
--
0.07
%FSR%V
PHYSICAL/ENVIRONMENTAL
Operating Temp. Range, Case
ADS-112MC
0
--
+70
C
ADS-112MM, 883
55
--
+125
C
Storage Temperature Range
65
--
+150
C
Package Type
24-pin, metal-sealed, ceramic DDIP
Weight
0.42 ounces (12 grams)
ABSOLUTE MAXIMUM RATINGS
PARAMETERS
LIMITS
UNITS
+15V Supply (Pin 22)
0 to +18
Volts
15V Supply (Pin 24)
0 to 18
Volts
+5V Supply (Pin 13)
0 to +6
Volts
Digital Inputs (Pin 16, 17, 18)
0.3 to +V
DD
+0.3
Volts
Analog Input (Pin 19)
9 to +15
Volts
Lead Temp. (10 seconds)
+300
C
See Tech Note 1
6.02
(SNR + Distortion) 1.76 + 20 log
Full Scale Amplitude
Actual Input Amplitude
Effective bits is equal to:
See Table 3 also
For 12V, +5V operation, contact DATEL
Staight binary/Offset binary
Complementary binary
Complementary offset binary
ADS-112
3
has an internal pull-up resistor on this pin. To obtain
complementary binary or complementary offset binary
output coding, tie pin 18 to ground. The pin 18 signal is
compatible with CMOS/TTL logic levels for those users
desiring dynamic control of this function.
5. To enable the three-state outputs, connect ENABLE (pin 17)
to a logic "0" (low). To disable, connect pin 17 to a logic "1"
(high).
6. Do not change the status of pin 18 when EOC is high.
7. Re-initiating the START CONVERT (pin 16) while EOC is a
logic "1" (high) will result in a new conversion sequence.
TIMING
Figure 2 shows the relationship between the various input
signals. The timing shown applies over the operating
temperature range and over the operating power supply
range. These times are guaranteed by design.
TECHNICAL NOTES
1. Applications which are unaffected by endpoint errors or
remove them through software will use the typical connec-
tions shown in Figure 3. Remove system errors or adjust
the small initial errors of the ADS-112 to zero using the
optional external circuitry shown in Figure 4. The external
adjustment circuit has no effect on the throughput rate.
2. For best performance, always connect the analog and
digital ground pins to a ground plane beneath the converter.
The analog and digital grounds are not connected to each
other internally.
3. Bypass the analog and digital supplies and the +10V
reference (pin 21) to ground with 4.7F, 25V tantalum
electrolytic capacitors in parallel with 0.1F ceramic
capacitors. Bypass the +10V reference (pin 21) to analog
ground (pin 23).
4. Obtain straight binary/offset binary output coding by tying
COMP BIN (pin 18) to +5V or leaving it open. The device
Figure 2. ADS-112 Timing Diagram
START
CONVERT
INTERNAL S/H
N
N+1
150ns, 25ns
Acquisition Time
250ns
10ns min.
20ns max.
EOC
20ns max.
Conversion Time
600ns max.
60ns max.
Note: Scale is approximately 50ns per division.
35ns max.
OUTPUT
DATA
DATA N-1 VALID
INVALID
DATA
DATA N VALID
800ns min.
INVALID
DATA
200ns max.
Hold
ADS-112
4
CALIBRATION PROCEDURE
1. Connect the converter per Figures 3 and 4 and Tables 1 and
3 for the appropriate input range. Apply a pulse of 150
nanoseconds to the START CONVERT input (pin 16) at a
rate of 250kHz. This rate is chosen to reduce the flicker if
LED's are used on the outputs for calibration purposes.
2. Zero Adjustments
Apply a precision voltage reference source between the
amplifier's analog input and ground. Adjust the output of the
reference source per Table 2. For unipolar, adjust the zero
trimming potentiometer so that the output code flickers
equally between 0000 0000 0000 and 0000 0000 0001 with
COMP BIN (pin 18) tied high (straight binary) or between
1111 1111 1111 and 1111 1111 1110 with pin 18 tied low
(complementary binary).
For bipolar operation, adjust the potentiometer such that the
code flickers equally between 1000 0000 0000 and 1000
0000 0001 with pin 18 tied high (offset binary) or between
0111 1111 1111 and 0111 1111 1110 with pin 18 tied low
(complementary offset binary).
3. Full-Scale Adjustment
Set the output of the voltage reference used in step 2 to the
value shown in Table 2. Adjust the gain trimming potentiom-
eter so that the output code flickers equally between 1111
1111 1110 and 1111 1111 1111 for pin 18 tied high or between
0000 0000 0001 and 0000 0000 0000 for pin 18 tied low.
To confirm proper operation of the device, vary the precision
reference voltage source to obtain the output coding listed
in Table 4.
Figure 3. Typical ADS-112 Connection Diagram
Table 1. Input Range Selection
INPUT RANGE
INPUT PIN
TIE TOGETHER
5v
Pin 19
Pin 20 to Pin 21
0 to +10V
Pin 19
Pin 20 to Ground
Table 3. Input Range (using external calibration)
INPUT RANGE
R1
R2
UNIT
0 to 10V, 5
2
2
k
0 to 5V, 2.5V
2
6
k
0 to +2.5V, 1.25V
2
14
k
To Pin19
of ADS-112
15V
+15V
For values of R1 and R2 refer to Table 3.
R2
R1
5k
50
10k
ZERO/
OFFSET
ADJUST
SIGNAL
INPUT
GAIN
ADJUST
5k
Figure 4. Optional Calibration Circuit
Table 2. Zero and Gain Adjust
Input
Zero Adjust
Gain Adjust
Range
+1/2 LSB
+FS 1 1/2 LSB
0 to +10V
+1.22mV
+9.9963V
5V
+1.22mV
+4.9963V
0.1F
4.7F
13
14
ADS-112
19
16
12
11
10
9
8
7
6
5
4
3
2
1
15
17
BIT 1 (MSB)
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
BIT 8
BIT 9
BIT 10
BIT 11
BIT 12 (LSB)
EOC
ENABLE (1-12)
ANALOG INPUT
START CONVERT
+
+5V
15V
+15V
+
+
0.1F
4.7F
23
22
0.1F
4.7F
24
20
COMP BIN
0.1F
+
4.7F
21 +10V REF.
UNIPOLAR
OPERATION
BIPOLAR
OPERATION
20
21
18
+5V
Note: Always bypass pin 21 to ground
ADS-112
5
Table 4. Output Coding
UNIPOLAR
INPUT RANGE
OUTPUT CODING
INPUT RANGE
BIPOLAR
SCALE
0 to +10V
MSB LSB
MSB
LSB
5V
SCALE
+FS 1 LSB
+9.9976
1111 1111 1111
0000 0000 0000
+4.9976
+FS 1 LSB
+7/8 FS
+8.7500
1110 0000 0000
0001 1111
1111
+3.7500
+3/4FS
+3/4 FS
+7.5000
1100 0000 0000
0011 1111
1111
+2.5000
+1/2FS
+1/2 FS
+5.0000
1000 0000 0000
0111
1111
1111
0.0000
0
+1/4 FS
+2.5000
0100 0000 0000
1011 1111
1111
2.5000
1/2FS
+1/8 FS
+1.2500
0010 0000 0000
1101 1111
1111
3.7500
3/4FS
+1 LSB
+0.0024
0000 0000 0001
1111
1111
1110
4.9976
FS+1LSB
0
0.0000
0000 0000 0000
1111
1111
1111
5.0000
FS
STRAIGHT BIN.
COMP. BINARY
OFF. BINARY
COMP. OFF. BIN.
Figure 5. FFT Analysis of ADS-112
0
10
20
30
40
50
60
70
80
90
100
110
120
130
0 50 100 150 200 250 300 350 400 450 500
Frequency (kHz)
(fs = 1MHz, fin = 485kHz, Vin = 0.5dB, 4,096-point FFT)
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