ETC1 ADS-942AME 14-bit, 2mhz, low-power sampling a/d converter Datasheet

®
®
ADS-942A
14-Bit, 2MHz, Low-Power
Sampling A/D Converters
FEATURES
•
•
•
•
•
•
•
•
14-bit resolution
2MHz minimum throughput
Low-power, 2.2 Watts
Functionally complete
Internal reference and S/H amplifier
78dB signal-to-noise ratio
Full Nyquist-rate sampling
Small 32-pin TDIP
INPUT/OUTPUT CONNECTIONS
GENERAL DESCRIPTION
DATEL's ADS-942A is a functionally complete, 14-bit, 2MHz,
sampling A/D converter. Packaged in a 32-pin TDIP, the unit
contains a fast-settling sample/hold amplifier, a 14-bit
subranging (two-pass) A/D converter, a precision reference,
three-state output register, and all the timing/control logic
necessary to operate from a single start convert pulse.
The ADS-942A is optimized for wideband frequency-domain
applications and is fully FFT tested. The ADS-942A requires
±15V and ±5V supplies and typically consumes 2.2 Watts
PIN
FUNCTION
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
+10V REF. OUT
BIPOLAR
AVALOG INPUT
SIGNAL GROUND
OFFSET ADJUST
ANALOG GROUND
OVERFLOW
CODING SELECT
ENABLE
+5V SUPPLY
DIGITAL GROUND
+15V SUPPLY
–15V SUPPLY
–5V SUPPLY
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
S2
FLASH
ADC
BIPOLAR 2
BUFFER
S/H
REGISTER
ANALOG INPUT 3
S1
3-STATE OUTPUT REGISTER
OFFSET
CIRCUIT
OFFSET ADJUST 5
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
13
14
6, 15
8
SIGNAL
GROUND
+5V
SUPPLY
DIGITAL
GROUND
+15V
SUPPLY
–15V
SUPPLY
–5V
SUPPLY
ANALOG
GROUND
CODING
SELECT
Figure 1. ADS-942A 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-942A
ABSOLUTE MAXIMUM RATINGS
PARAMETERS
+15V Supply (Pin 12)
–15V Supply (Pin 13)
+5V Supply (Pin 10)
–5V Supply (Pin 14)
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 to –6
–0.3 to +VDD +0.3
±15
+300
Volts
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
—
—
2.3
—
0 to +10
±5
2.5
7
—
—
—
15
Volts
Volts
kΩ
pF
+2.0
—
—
—
—
—
—
—
—
+0.8
+10
–600
Volts
Volts
µA
µA
Total Harm. Distort. (0.5dB)
dc to 100kHz
100kHz to 500kHz
500kHz to 1MHz
Signal-to-Noise Ratio
(w/o distortion, –0.5dB
dc to 100kHz
100kHz to 500kHz
500kHz to 1MHz
Signal-to-Noise Ratio
(and distortion, –0.5dB) ➀
dc to 100kHz
100kHz to 500kHz
500kHz to 1MHz
Spurious Free Dyn. Range ➁
dc to 100kHz
100 to 500kHz
500kHz to 1MHz
Two-tone IMD ➂
Input Bandwidth (–3dB)
Small Signal (–20dB input)
Large Signal (–0.5dB input)
Slew Rate
Aperture Delay Time
Aperature Uncertainty
S/H Acq. Time, (to ±0.003%FSR)
Sinusoidal (fin = 1MHz)
Step input (10V)
Conversion Rate
Sinusoidal (fin = 1MHz)
Step input
Feedthrough Rejection
(fin = 1MHz)
Overvoltage Recovery, ±12V
Noise
DIGITAL INPUTS
Logic Levels
Logic "1"
Logic "0"
Logic Loading "1"
Logic Loading "0"
PERFORMANCE
Integral Non-Linearity
+25°C
0 to +70°C
–40 to +85°C
Differential Non-Linearity
+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
0 to +70°C
–40 to ±85°C
Bipolar Zero Error
+25°C
0 to +70°C
–40 to +85°C
Bipolar Offset Error
+25°C
0 to +70°C
–40 to +85°C
Gain Error
+25°C
0 to +70°C
–40 to +85°C
No Missing Codes (fin = 500kHz)
14 Bits
13 Bits
Resolution
—
—
—
±1
±1
±2
±2
±2
±3
LSB
LSB
LSB
—
–0.95
–1
±0.5
±0.75
±1
±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
±0.2
±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./2'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
—
—
—
–85
–80
–77
–76
–75
—
dB
dB
dB
74
73
—
78
75
73
—
—
—
dB
dB
dB
73
72
—
78
75
72
—
—
—
dB
dB
dB
—
—
—
—
–86
–81
–78
85
–77
–75
—
—
dB
dB
dB
dB
—
—
—
—
—
6
1.75
±250
—
—
—
—
—
±10
5
MHz
MHz
V/µs
ns
ps, ms
—
—
—
250
150
450
ns
ns
2
1.3
—
—
—
—
MHz
MHz
—
—
—
85
1000
250
—
2000
—
dB
ns
µVrms
+14.25
–14.25
+4.75
–4.75
+15.0
–15.0
+5.0
–5.0
+15.75
–15.75
+5.25
–5.25
Volts
Volts
Volts
Volts
—
—
—
—
—
—
+65
–19
+150
–55
2.2
—
+80
–35
+175
–65
2.6
±0.03
mA
mA
mA
mA
Watts
%FSR%V
DYNAMIC PERFORMANCE
(TA = +25°C, ±VCC = ±15V, ±VDD = ±5V, 2MHz sampling rate, and a minimum 7 minute
warmup ➀ unless otherwise specified.)
ANALOG INPUTS
MIN.
POWER REQUIREMENTS
Power Supply Ranges
+15V Supply
–15V Supply
+5V Supply
–5V Supply
Power Supply Currents
+15V Supply
–15V Supply
+5V Supply
–5V Supply
Power Dissipation
Power Supply Rejection
0 to +70°C
–40 to +85°C
14 Bits
PHYSICAL/ENVIRONMENTAL
Footnote:
➀ Effective Bits is equal to:
(SNR + Distortion) – 1.76 +
Operating Temp. Range, Case
ADS-942AMC
ADS-942AME
Storage Temperature Range
Package Type
Full Scale Amplitude
20 log
Actual Input Amplitude
6.02
➁ Same specification as In-Band Harmonics and Peak Harmonics.
Weight
➂ Two-tone Intermodulation Distortion (IMD) conditions:
fin = 100kHz, 240kHz, fs = 2MHz, –0.5dB
2
0
—
+70
°C
–40
—
+85
°C
–65
—
+150
°C
32-pin, metal-sealed, ceramic TDIP
0.46 ounces (13 grams)
®
®
ADS-942A
TECHNICAL NOTES
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).
1. Rated performance requires using good high-frequency
circuit board layout techniques. Connect the digital and
analog grounds to one point, the analog 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.
SIGNAL GROUND (pin 4) is not internally connected to
ANALOG GROUND (pins 6, 15).
Two's complement coding requires using pin 31 (MSB).
With pin 8 tied low, adjust the trimpot until the code flickers
between 00 0000 0000 0000 and 00 0000 0000 0001.
3. Full-Scale (Gain) Adjustment
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.
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 (straight binary/offset binary) or between 00 0000
0000 0000 and 00 0000 0000 0001 with pin 8 tied high
(complementary binary/complementary offset binary).
3. CODING SELECT(pin 8) is compatible with CMOS/TTL
logic levels for those users desiring logic control of this
function. There is an internal pull-up resistor on this pin;
connect to +5V or leave open for logic 1. See the Calibration Procedure for selecting an output coding.
Two's complement coding requires using pin 31 (MSB).
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 enable the three-state outputs, connect ENABLE (pin 9)
to a logic "0" (low). To disable, connect pin 9 to a logic "1"
(high).
5. OVERFLOW (pin 7) changes from low (logic "0") to high
(logic "1") when the input voltage exceeds the input voltage
range limits by 1LSB (610µV).
4. To confirm proper operation of the device, vary the precision
reference voltage source to obtain the output coding listed
in Table 3.
Table 1. Input Connections
CALIBRATION PROCEDURE
1. Connect the converter per Figure 3 and Table 1 for the
appropriate input voltage range. Apply a pulse of 35
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
INPUT PIN
TIE TOGETHER
0 +10V
±5V
Pin 3
Pin 3
Pins 2 and 4
Pins 1 and 2
2. Zero Adjustments
Table 2. Zero and Gain 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.
Input Zero Adjust
Range
0 to +10V
±5V
For unipolar, 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).
START
CONVERT
N
Gain Adjust
+½ LSB
35ns min., 50ns typ., 60 ns max
+305µV
+305µV
N+1
35ns max..
Conversion Time
300ns typ., 325ns max.
EOC
10ns typ.
15ns max.
INTERNAL S/H
35ns typ.
Hold
150ns max.
Aquisition Time
350ns min.
30ns max.
OUTPUT
DATA
DATA N VALID
DATA N-1 VALID
INVALID DATA
200ns max.
300ns min.
Note: Scale is approximately 25ns per division.
Figure 2. ADS-942A Timing Diagram
3
FS – 1½ LSB
+9.999085V
+4.999085V
®
®
ADS-942A
Use external trimpots to remove system errors or to reduce
small initial errors to zero. Use a 100Ω trimpot in series
with the analog input for gain adjustment; use a fixed 50Ω
resistor in its place for operation without 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.
ZERO/OFFSET
ADJUST
20kΩ
–15V
+15V
4.7µF
+
0.1µF
4.7µF
0.1µF
–5V
+
+15V
4.7µF
+
0.1µF
4.7µF
0.1µF
–15V
5
OFFSET
ADJUST
10
+
+5V
31 BIT 1 OUT(MSB)
30 BIT 1 OUT(MSB)
DIGITAL
11 GROUND
29 BIT 2 OUT
28 BIT 3 OUT
14
27 BIT 4 OUT
26 BIT 5 OUT
25 BIT 6 OUT
12
24 BIT 7 OUT
23 BIT 8 OUT
22 BIT 9 OUT
6, 15 ANALOG
GROUND
21 BIT 10 OUT
20 BIT 11 OUT
19 BIT 12 OUT
13
ADS-942A
18 BIT 13 OUT
17 BIT 14 OUT (LSB)
GAIN ADJUST
7 OVERFLOW
16 EOC
0 to +10V
100Ω
3 ANALOG INPUT
CODING SELECT
8
+5V
4 SIGNAL GROUND
START CONVERT 32
1 +10V REF. OUT
0.1µF
4.7µF
ENABLE
9
BIPOLAR
2
Figure 3. ADS-942A Connection Diagram (Unipolar Input)
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
4
LSB
INPUT VOLT.
±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
®
®
ADS-942A
THERMAL REQUIREMENTS
Electrically-insulating, 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.
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.
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.
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.
0
Amplitude Relative to Full Scale (dB)
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–110
–120
–130
–140
–150
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Frequency (MHz)
(fs = 2MHz, fin = 490kHz, Vin = –0.5dB, 16,384-point FFT)
Figure 4. FFT Analysis of ADS-942A
5
0.9
1
®
®
ADS-942A
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
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
ACCESSORIES
OPERATING TEMP. RANGE
ADS-942AMC
0 to +70°C
ADS-942AME
–40 to +85°C
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:[email protected]
Data Sheet Fax Back: (508) 261-2857
E
G
I
S
T
E
R
E
D
DS-0204B
10/96
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.
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