CANDD HS-32

®
®
ADS-941
14-Bit, 1MHz
Sampling A/D Converters
FEATURES
•
•
•
•
•
•
•
•
•
14-bit resolution
1MHz minimum sampling rate
Functionally complete
Internal reference and sample/hold
No missing codes
Excellent performance
Full Nyquist-rate sampling
Small 32–pin DIP
Low power, 2.8 Watts
INPUT/OUTPUT CONNECTIONS
GENERAL DESCRIPTION
DATEL's ADS-941 is a functionally complete, 14-bit, 1MHz,
sampling A/D converter. Its standard, 32-pin, triple-wide
ceramic DIP contains a fast-settling sample/hold amplifier, a
14-bit subranging (two-pass) A/D converter, a precision
reference, a three-state output register, and all the timing and
control logic necessary to operate from a single start convert
pulse.
The ADS-941 is optimized for wideband frequency-domain
applications and is fully FFT tested. Total harmonic distortion
(THD) and signal-to-noise ratio (including distortion) typically
run at –85dB and 80dB, respectively, with full-scale inputs up
to 100kHz.
The ADS-941 requires ±15V and +5V supplies and typically
consumes 2.8 Watts.
PIN
FUNCTION
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
+10V REF. OUT
BIPOLAR
ANALOG INPUT
SIGNAL GROUND
OFFSET ADJUST
ANALOG GROUND
OVERFLOW
CODING SELECT
ENABLE
+5V SUPPLY
DIGITAL GROUND
+15V SUPPLY
–15V SUPPLY
ANALOG GROUND
ANALOG GROUND
EOC
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
FUNCTION
START CONVERT
BIT 1 OUT (MSB)
BIT 1 OUT (MSB)
BIT 2 OUT
BIT 3 OUT
BIT 4 OUT
BIT 5 OUT
BIT 6 OUT
BIT 7 OUT
BIT 8 OUT
BIT 9 OUT
BIT 10 OUT
BIT 11 OUT
BIT 12 OUT
BIT 13 OUT
BIT 14 OUT (LSB)
DAC
31 BIT 1 OUT (MSB)
30 BIT 1 OUT (MSB)
29 BIT 2 OUT
REGISTER
OFFSET ADJUST 5
S2
FLASH
ADC
BIPOLAR 2
BUFFER
S/H
REGISTER
ANALOG INPUT 3
S1
3-STATE OUTPUT REGISTER
OFFSET
CIRCUIT
DIGITAL CORRECTION LOGIC
REF
+10V REF. OUT 1
28 BIT 3 OUT
27 BIT 4 OUT
26 BIT 5 OUT
25 BIT 6 OUT
24 BIT 7 OUT
23 BIT 8 OUT
22 BIT 9 OUT
21 BIT 10 OUT
20 BIT 11 OUT
19 BIT 12 OUT
18 BIT 13 OUT
17 BIT 14 OUT (LSB)
START CONVERT 32
TIMING AND
CONTROL LOGIC
9 ENABLE
EOC 16
7 OVERFLOW
4
10
11
12
6, 14, 15
13
8
SIGNAL
GROUND
+5V
SUPPLY
DIGITAL
GROUND
+15V
SUPPLY
ANALOG
GROUND
–5V
SUPPLY
CODING
SELECT
Figure 1. ADS-941 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-941
ABSOLUTE MAXIMUM RATINGS
PARAMETERS
+15V Supply (Pin 12)
–15V Supply (Pin 13)
+5V Supply (Pin 10)
Digital Inputs (Pin 8,9, 32)
Analog Input (Pin 3)
Lead Temp. (10 seconds)
OUTPUTS
LIMITS
UNITS
0 to +16
0 to –16
0 to +6.0
–0.3 to +VDD +0.3
±15
300
Volts
Volts
Volts
Volts
Volts
°C
Output Coding
Logic Level
Logic "1"
Logic "0"
Logic Loading "1"
Logic Loading "0"
Internal Reference
Voltage, +25°C
Drift
External Current
FUNCTIONAL SPECIFICATIONS
MIN.
TYP.
MAX.
UNITS
Input Voltage Range
Unipolar
Bipolar
Input Impedence
Input Capacitance
—
—
2.2
—
0 to +10
±5
2.5
7
—
—
—
15
Volts
Volts
kΩ
pF
Slew Rate
Aperature Delay Time
Aperature Uncertainty
S/H Aquisition TIme
(to ±0.003%FS, 10V step)
Total Harm. Distort. (–0.5dB)
dc to 100kHz
100kHz to 500kHz
Signal-to-Noise Ratio
(w/o distortion, –0.5dB
dc to 100kHz
100kHz to 500kHz
Signal-to-Noise Ratio
(and distortion, –0.5dB)
dc to 100kHz
100kHz to 500kHz
Spurious Free Dyn. Range ➀
dc to 100kHz78
100 to 500kHz
Two-tone IMD
Distortion (fin = 100kHz,
240kHz, fs = 2.0Mhz,
–0.5dB)
Input Bandwidth (–3dB)
Small Signal (–20dB input)
Large Signal (–0dB input)
Feedthrough Rejection
(fin = 500KHz)
Overvoltage Recovery, ±12V
A/D Conversion Rate
Noise
DIGITAL INPUTS
Logic Levels
Logic "1"
Logic "0"
Logic Loading "1"
Logic Loading "0"
+2.0
—
—
—
—
—
—
—
—
+0.8
+10
–600
Volts
Volts
µA
µA
PERFORMANCE
Integral Non-Linearity
(fin = 10KHz)
+25°C
0 to +70°C
–40 to +85°C
Differential Non-Linearity
(fin = 10KHz)
+25°C
0 to +70°C
–40 to +85°C
Full Scale Absolute Accuracy
+25°C
0 to +70°C
–40 to +85°C
Unipolar Zero Error
+25°C (see Figure 3)
0 to +70°C
–40 to +85°C
Bipolar Zero Error
+25°C (see Figure 3)
0 to +70°C
–40 to +85°C
Bipolar Offset Error
+25°C (see Figure 3)
0 to +70°C
–40 to +85°C
Gain Error
+25°C (see Figure 3)
0 to +70°C
–40 to +85°C
No Missing Codes (fin = 500kHz)
14 Bits
Resolution
—
—
—
±1
±1.5
±2
±2
±2
±3
LSB
LSB
LSB
–0.75
–0.95
–1
±0.5
±0.75
±0.95
±0.75
±0.95
+2.5
LSB
LSB
LSB
—
—
—
±0.1
±0.12
±0.45
±0.122
±0.36
±0.85
%FSR
%FSR
%FSR
—
—
—
±0.05
±0.1
±0.2
±0.122
±0.2
±0.3
%FSR
%FSR
%FSR
—
—
—
±0.05
±0.1
±0.2
±0.122
±0.2
±0.3
%FSR
%FSR
%FSR
—
—
—
±0.1
±0.12
±0.6
±0.12
±0.3
±0.8
%FSR
%FSR
%FSR
—
—
—
±0.018
±0.12
±0.6
±0.122
±0.3
±0.8
%
%
%
TYP.
MAX.
UNITS
Staight Bin./Offset Bin./Two's Comp.
Comp. Bin./Comp. Offset Bin./C2C
+2.4
—
—
—
—
—
—
—
—
+0.4
–160
+6.4
Volts
Volts
µA
mA
+9.98
—
—
+10.0
±13
—
+10.02
±30
5
Volts
ppm/°C
mA
—
—
—
±250
—
—
1
10
±5
V/µs
ns
ps
—
250
350
ns
–78
–77
–85
–80
—
—
dB
dB
75
74
80
77
—
—
dB
dB
74
73
80
78
—
—
dB
dB
78
77
86
83
—
—
dB
dB
—
–85
—
dB
—
—
6
1.75
—
—
MHz
MHz
—
—
1
—
87
1000
—
250
—
2000
—
—
dB
ns
MHz
µVrms
+14.25
–14.25
+4.75
+15.0
–15.0
+5.0
+15.75
–15.75
+5.25
Volts
Volts
Volts
—
—
—
—
—
+62
–80
+140
2.8
—
+85
–95
+160
3.3
±0.02
mA
mA
mA
Watts
%FSR%V
DYNAMIC PERFORMANCE
(TA = +25°C, ±VCC = ±15V, ±VDD = ±5V, 1MHz sampling rate, and a minimum 7 minute
warmup unless otherwise specified.)
ANALOG INPUTS
MIN.
POWER REQUIREMENTS
Power Supply Ranges
+15V Supply
–15V Supply
+5V Supply
Power Supply Currents
+15V Supply
–15V Supply
+5V Supply
Power Dissipation
Power Supply Rejection
PHYSICAL/ENVIRONMENTAL
Operating Temp. Range, Case
ADS-941MC
ADS-941ME
Storage Temperature Range
Package Type
0 to +70°C
14 Bits
Weight
0
—
+70
°C
–40
—
+85
°C
–65
—
+150
°C
32-pin, metal-sealed, ceramic TDIP
0.46 ounces (13 grams)
Footnote:
➀ Same specification as In-Band Harmonics and Peak Harmonics.
2
®
®
ADS-941
TECHNICAL NOTES
1. Rated performance requires using good high-frequency
circuit board layout techniques. The analog and digital
grounds are not connected to each other internally. Avoid
ground-related problems by connecting the digital and
analog 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.
tied low for straight binary/offset binary or between 00 0000
0000 0000 and 00 0000 0000 0001 with pin 8 tied high for
complementary binary/complementary offset binary.
Two's complement coding requires using pin 31. With pin 8
tied low, adjust the gain trimpot until the output code flickers
equally between 01 1111 1111 1110 and 01 1111 1111 1111.
4. To confirm proper operation of the device, vary the precision
reference voltage source to obtain the output coding listed
in Table 3.
2. Bypass the analog and digital supplies and the +10V REF.
OUT (pin 1) to ground with a 4.7µF, 25V tantalum electrolytic capacitor in parallel with a 0.1µF ceramic capacitor.
Table 1. Input Connections
3. CODING SELECT (pin 8) is compatible with CMOS/TTL
logic levels for those users desiring logic control of this
function. The device has an internal pull-up resistor on this
pin, allowing pin 8 to be connected to +5V or left open when
a logic 1 is needed. See the Calibration Procedure for
selecting an output coding.
4. To enable the three-state outputs, connect ENABLE (pin 9)
to a logic "0" (low). To disable, connect pin 9 to a logic "1"
(high).
INPUT RANGE
INPUT PIN
TIE TOGETHER
0 +10V
±5V
Pin 3
Pin 3
Pins 2 and 4
Pins 1 and 2
Table 2. Zero and Gain Adjustments
CALIBRATION PROCEDURE
1. Connect the converter per Figure 3 and Table 1 for the
appropriate input range. Apply a pulse of 50 nanoseconds
minimum to START CONVERT (pin 32) at a rate of 200kHz.
This rate is chosen to reduce flicker if LED's are used on
the outputs for calibration purposes.
Input
Range
Zero Adjust
+1/2 LSB
Gain Adjust
FS – 1 1/2 LSB
0 to +10V
±5V
+305µV
+305µV
+9.999085V
+4.999085V
THERMAL REQUIREMENTS
2. Zero Adjustments
All DATEL sampling A/D converters are fully characterized and
specified over operating temperature (case) ranges of 0 to
+70°C and –55 to +125°C. All room-temperature (TA = +25°C)
production testing is performed without the use of heat sinks or
forced-air cooling. Thermal impedance figures for each device
are listed in their respective specification tables.
Apply a precision voltage reference source between
ANALOG INPUT (pin 3) and SIGNAL GROUND (pin 4),
then adjust the reference source output per Table 2.
For unipolar operation, adjust the zero trimpot so that the
output code flickers equally between 00 0000 0000 0000
and 00 0000 0000 0001 with CODING SELECT (pin 8) tied
low (straight binary) or between 11 1111 1111 1111 and 11
1111 1111 1110 with pin 8 tied high (complementary binary).
These devices do not normally require heat sinks, however,
standard precautionary design and layout procedures should
be used to ensure devices do not overheat. The ground and
power planes beneath the package, as well as all pcb signal
runs to and from the device, should be as heavy as possible to
help conduct heat away from the package. Electricallyinsulating, thermally-conductive "pads" may be installed
underneath the package. Devices should be soldered to
boards rather than "socketed", and of course, minimal air flow
over the surface can greatly help reduce the package
temperature.
For bipolar operation, adjust the trimpot until the code
flickers equally between 10 0000 0000 0000 and 10 0000
0000 0001 with pin 8 tied low (offset binary) or between 01
1111 1111 1111 and 01 1111 1111 1110 with pin 8 tied high
(complementary offset binary).
Two's complement coding requires using BIT 1 OUT (MSB)
(pin 31). With pin 8 tied low, adjust the trimpot until the
code flickers between 00 0000 0000 0000 and 00 0000
0000 0001.
In more severe ambient conditions, the package/junction
temperature of a given device can be reduced dramatically
(typically 35%) by using one of DATEL's HS Series heat sinks.
See Ordering Information for the assigned part number. See
page 1-183 of the DATEL Data Acquisition Components
Catalog for more information on the HS Series. Request
DATEL Application Note AN-8, "Heat Sinks for DIP Data
Converters", or contact DATEL directly, for additional
information.
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 trimpot until the output code flickers equally
between 11 1111 1111 1110 and 11 1111 1111 1111 with pin 8
3
®
®
ADS-941
N+1
N
START
CONVERT
50ns min., 100ns max
35ns max.
Conversion Time
600ns typ.
EOC
10ns typ.
Aquisition Time
INTERNAL S/H
Hold
350ns max.
30ns max.
OUTPUT
DATA DATA N-1 VALID
INVALID DATA
DATA N VALID
400ns max.
600ns min.
Scale is approximately 50ns per division.
Figure 2. ADS-941 Timing Diagram
Removing System Errors
adjustment. Use a 20kΩ trimpot with the wiper tied to OFFSET
ADJUST (pin 5) for zero/offset adjustment. Connect pin 5 to
ANALOG GROUND (pin 6) for operation without zero/offset
adjustment.
Use external potentiometers to remove system errors or to
reduce the small initial errors to zero. Use a 100Ω trimpot in
series with the analog input for gain adjustment. Use a fixed
50Ω resistor instead of the trimpot for operation without
ZERO/OFFSET
ADJUST
20kΩ
+5V
+5V
0.1µF
4.7µF
4.7µF
+
4.7µF
0.1µF
6, 14, 15 ANALOG
GROUND
13
GAIN ADJUST
0 to +10V
31 BIT 1 (MSB)
30 BIT 1 (MSB)
29 BIT2
28 BIT 3
27 BIT 4
26 BIT 5
25 BIT 6
24 BIT 7
23 BIT 8
22 BIT 9
21 BIT 10
20 BIT 11
19 BIT 12
18 BIT 13
17 BIT 14 (LSB)
12
0.1µF
–15V
5
OFFSET
ADJUST
10
DIGITAL
11 GROUND
+
+15V
–5V
ADS-941
7 OVERFLOW
16 EOC
3 ANALOG INPUT
100Ω
4 SIGNAL GROUND
CODING SELECT
1 +10V
REF. OUT
0.1µF
8
START CONVERT 32
4.7µF
ENABLE
9
BIPOLAR
2
Figure 3. ADS-941 Connection Diagram
4
®
®
ADS-941
0
Amplitude Relative to Full Scale (dB)
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–110
–120
–130
–140
–150
0
50
100
150
200
250
300
350
400
450
500
Frequency (kHz)
(fs = 1MHz, fin = 480kHz, Vin = –0.5dB, 16,384-point FFT)
Table 3. Output Coding
STRAIGHT BIN.
UNIPOLAR
SCALE
+FS – 1 LSB
+7/8 FS
+3/4 FS
+1/2 FS
+1/4 FS
+1/8 FS
+1 LSB
0
INPUT VOLT.
0 TO +10V
+9.999390
+8.750000
+7.500000
+5.000000
+2.500000
+1.250000
+0.000610
0.000000
COMP. BINARY
LSB
OUTPUT CODING
MSB
LSB
MSB
11 1111 1111 1111
11 1000 0000 0000
11 0000 0000 0000
10 0000 0000 0000
01 0000 0000 0000
00 1000 0000 0000
00 0000 0000 0001
00 0000 0000 0000
00 0000 0000 0000
00 0111 1111 1111
00 1111 1111 1111
01 1111 1111 1111
10 1111 1111 1111
11 0111 1111 1111
11 1111 1111 1110
11 1111 1111 1111
01 1111 1111 1111
01 1000 0000 0000
01 0000 0000 0000
00 0000 0000 0000
11 0000 0000 0000
10 1000 0000 0000
10 0000 0000 0001
10 0000 0000 0000
OFF. BINARY
COMP. OFF. BIN.
TWO'S COMP.
MSB
5
LSB
INPUT VOLT.
±5V
BIPOLAR
SCALE
+4.999390
+3.750000
+2.500000
0.000000
–2.500000
–3.750000
–4.999390
–5.000000
+FS – 1LSB
+3/4FS
+1/2FS
0
–1/2FS
–3/4FS
–FS+1LSB
–FS
®
®
ADS-941
MECHANICAL DIMENSIONS INCHES (mm)
1.72 MAX.
(43.69)
32
Dimension Tolerances (unless otherwise indicated):
2 place decimal (.XX) ±0.010 (±0.254)
3 place decimal (.XXX) ±0.005 (±0.127)
17
Lead Material: Kovar alloy
Lead Finish: 50 microinches (minimum) gold plating
over 100 microinches (nominal) nickel plating
1.11 MAX.
(28.19)
1
0.235 MAX.
(5.969)
16
0.100 TYP.
(2.540)
1.500
(38.100)
0.200 MAX.
(5.080)
+0.002
0.010 –0.001
(0.254)
0.190 MAX.
(4.826)
0.018 ±0.002
(0.457)
SEATING
PLANE
0.025
(0.635)
0.100
(2.540)
0.040
(1.016)
0.900 ±0.010
(22.860)
0.100
(2.540)
ORDERING INFORMATION
MODEL NUMBER
OPERATING TEMP. RANGE
ADS-941MC
0 to +70°C
ADS-941ME
–40 to +85°C
ACCESSORIES
ADS-EVAL4
HS-32
Evaluation Board (without ADS-942)
Heat Sink for all ADS-942 models
Receptacles for PC mounting can be ordered through AMP Inc., Part # 3-331272-8 (Component Lead Socket), 32 required.
®
®
ISO 9001
R
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
E
G
I
S
T
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D
DS-0227B
11/96
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 München, Germany Tel: 89-544334-0
DATEL KK Tokyo, Japan Tel: 3-3779-1031, Osaka Tel: 6-354-2025
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.