ADS-941

ADS-941
14-Bit, 1MHz Sampling A/D Converters
PRODUCT OVERVIEW
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 fastsettling 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.
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
The ADS-941 is optimized for wideband
frequency-domain applications and is fully FFT
tested. Total harmonic distortion (THD) and signalto-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.
INPUT/OUTPUT CONNECTIONS
PIN FUNCTION
PIN
FUNCTION
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
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)
BLOCK DIAGRAM
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 USA
• Tel: (508) 339-3000
•
www.datel.com
•
e-mail: help@datel.com
17 Aug 2015
MDA_ADS-941.B04 Page 1 of 5
ADS-941
14-Bit, 1MHz Sampling A/D Converters
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
0 to +16
0 to –16
0 to +6.0
–0.3 to +VDD +0.3
±25
300
UNITS
Volts
Volts
Volts
Volts
Volts
°C
FUNCTIONAL SPECIFICATIONS
(TA = +25°C, ±VCC = ±15V ±VDD = +5V, 1MHz sampling rate, and a minimum 7 minute
warmup ➀ unless otherwise specified.)
ANALOG INPUTS
Input Voltage Range
Unipolar
Bipolar
Input Impedence
Input Capacitance
DIGITAL INPUTS
Logic Levels
Logic "1"
Logic "0"
Logic Loading "1"
Logic Loading "0"
MIN.
TYP.
MAX.
UNITS
—
—
2.2
—
0 to +10
±5
2.5
7
—
—
—
15
Volts
Volts
kW
pF
+2.0
—
—
—
PERFORMANCE
Integral Non-Linearity (fin = 10KHz)
+25°C
0 to +70°C
–40 to +100°C
Differential Non-Linearity (fin = 10KHz)
+25°C
0 to +70°C
–40 to +100°C
Full Scale Absolute Accuracy
+25°C
0 to +70°C
–40 to +100°C
Unipolar Zero Error
+25°C (see Figure 3)
0 to +70°C
–40 to +100°C
Bipolar Zero Error
+25°C (see Figure 3)
0 to +70°C
–40 to +100°C
Bipolar Offset Error
+25°C (see Figure 3)
0 to +70°C
–40 to +100°C
Gain Error
+25°C (see Figure 3)
0 to +70°C
–40 to +100°C
No Missing Codes (fin = 500kHz)
14 Bits
Resolution
—
—
—
—
—
+0.5
+5
–600
Volts
Volts
μA
μA
—
—
—
±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
±0.5
±0.12
±0.3
±0.8
%FSR
%FSR
%FSR
—
—
—
±0.018
±0.12
±0.6
±0.122
±0.3
±0.8
%FSR
%FSR
%FSR
0 to +70°C
14 Bits
MIN.
TYP.
MAX.
UNITS
Staight Bin./Offset Bin./Two's Comp.
Comp. Bin./Comp. Offset Bin./C2C
Output Coding
Logic Level
Logic "1"
Logic "0"
Logic Loading "1"
Logic Loading "0"
Internal Reference
Voltage, +25°C
Drift
External Current
DYNAMIC PERFORMANCE
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 c
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
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, MC-C
ADS-941ME, ME-C
Storage Temperature Range
Package Type
Weight
+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
—
—
250
—
10
±10
350
V/μs
ns
ps
ns
–78
–77
–85
–80
—
—
dB
dB
—
76
90
85
—
—
dB
dB
74
72
80
75
—
—
dB
dB
78
77
86
83
—
—
dB
dB
—
–85
—
dB
—
—
—
—
1
—
6
1.75
87
1000
—
250
—
—
—
2000
—
—
MHz
MHz
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
—
—
—
—
—
+65
–80
+140
2.8
—
+87
–105
+185
3.5
±0.02
mA
mA
mA
Watts
%FSR%V
0
—
+70
°C
–40
—
+100
°C
–65
—
+150
°C
32-pin, metal-sealed, ceramic TDIP
0.46 ounces (13 grams)
Footnote: c Same specification as In-Band Harmonics and Peak Harmonics.
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA
• Tel: (508) 339-3000
•
www.datel.com
•
e-mail: help@datel.com
17 Aug 2015
MDA_ADS-941.B04 Page 2 of 5
ADS-941
14-Bit, 1MHz Sampling A/D Converters
TECHNICAL NOTES
THERMAL REQUIREMENTS
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.
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.
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.
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.
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 pullup 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).
Removing System Errors
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.
Use external potentiometers to remove system errors or to reduce the small
initial errors to zero. Use a 100W trimpot in series with the analog input for
gain adjustment. Use a fixed 50W resistor instead of the trimpot for operation without adjustment. Use a 20kW 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.
2. Zero Adjustments
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). 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.
INPUT RANGE
ZERO ADJUST
+½ LSB
GAIN ADJUST
FS –1½ LSB
0 to +10V
+305μV
+9.999085V
±5V
+305μV
+4.999085V
Table 2. Zero and Gain Adjustments
N+1
N
START
CONVERT
50ns min., 100ns max
35ns max.
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 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.
Conversion Time
600ns typ.
EOC
10ns typ.
Aquisition Time
INTERNAL S/H
Hold
OUTPUT
DATA DATA N-1 VALID
350ns max.
30ns max.
INVALID DATA
DATA N VALID
400ns max.
600ns min.
Scale is approximately 50ns per division.
Figure 2. ADS-941 Timing Diagram
INPUT RANGE
INPUT PIN
TIE TOGETHER
0 +10V
Pin 3
Pins 2 and 4
±5V
Pin 3
Pins 1 and 2
Table 1. Input Connections
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA
• Tel: (508) 339-3000
•
www.datel.com
•
e-mail: help@datel.com
17 Aug 2015
MDA_ADS-941.B04 Page 3 of 5
ADS-941
14-Bit, 1MHz Sampling A/D Converters
ZERO/OFFSET
ADJUST
20kΩ
+5V
+5V
0.1μF
4.7μF
4.7μF
4.7μF
0.1μF
6, 14, 15 ANALOG
GROUND
13
GAIN ADJUST
ADS-941
7 OVERFLOW
16 EOC
ANALOG INPUT
3
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
100Ω
4 SIGNAL GROUND
8
CODING SELECT
1 +10V
REF. OUT
0.1μF
START CONVERT 32
ENABLE
9
BIPOLAR
2
4.7μF
Figure 3. Typical ADS-941 Connection Diagram
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)
Figure 4. ADS-941 FFT Analysis
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA
• Tel: (508) 339-3000
•
www.datel.com
•
e-mail: help@datel.com
17 Aug 2015
MDA_ADS-941.B04 Page 4 of 5
ADS-941
14-Bit, 1MHz Sampling A/D Converters
STRAIGHT BINARY
UNIPOLAR
SCALE
+FS – 1 LSB
+7/8 FS
+3/4 FS
+1/2 FS
+1/4 FS
+1/8 FS
+1 LSB
0
INPUT RANGE
0 to +10V
+9.999390
+8.750000
+7.500000
+5.000000
+2.500000
+1.250000
+0.000610
0.000000
COMP. BINARY
OUTPUT CODING
MSB
LSB MSB
LSB MSB
LSB
11 1111 1111 1111
00 0000 0000 0000
01 1111 1111 1111
11 1000 0000 0000
00 0111 1111 1111
01 1000 0000 0000
11 0000 0000 0000
00 1111 1111 1111
01 0000 0000 0000
10 0000 0000 0000
01 1111 1111 1111
00 0000 0000 0000
01 0000 0000 0000
10 1111 1111 1111
11 0000 0000 0000
00 1000 0000 0000
11 0111 1111 1111
10 1000 0000 0000
00 0000 0000 0001
11 1111 1111 1110
10 0000 0000 0001
00 0000 0000 0000
11 1111 1111 1111
10 0000 0000 0000
OFFSET BINARY
COMP. OFF. BIN.
TWO'S COMP.
Table 3. Output Coding
INPUT RANGE
±5V
+4.999390
+3.750000
+2.500000
0.000000
–2.500000
–3.750000
–4.999390
–5.000000
BIPOLAR
SCALE
+FS – 1LSB
+3/4FS
+1/2FS
0
–1/2FS
–3/4FS
–FS+1LSB
–FS
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
1.11 MAX.
(28.19)
1
Lead Finish: 50 microinches (minimum) gold plating
over 100 microinches (nominal) nickel plating
16
0.100 TYP.
(2.540)
0.235 MAX.
(5.969)
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
ADS-941MC
ADS-941MC-C
ADS-941ME
ADS-941ME-C
OPERATING
TEMP. RANGE
0 to +70°C
0 to +70°C
–40 to +100°C
–40 to +100°C
PACKAGE
ROHS
ACCESSORIES
TDIP
TDIP
TDIP
TDIP
No
Yes
No
Yes
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.
DATEL is a registered trademark of DATEL, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 USA
DATEL, Inc. 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.
ITAR and ISO 9001/14001 REGISTERED
© 2015 DATEL, Inc.
www.datel.com • e-mail: help@datel.com
17 Aug 2015
MDA_ADS-941.B04 Page 5 of 5