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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
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 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
INPUT/OUTPUT CONNECTIONS
FUNCTION +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 PIN 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) +10V REF. OUT 1 OFFSET CIRCUIT S2 FLASH ADC BIPOLAR 2 S1 BUFFER REF DIGITAL CORRECTION LOGIC 3-STATE OUTPUT REGISTER 29 BIT 2 OUT 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 EOC 16 9 ENABLE 7 OVERFLOW 4 SIGNAL GROUND 10 +5V SUPPLY 11 DIGITAL GROUND 12 +15V SUPPLY 6, 14, 15 ANALOG GROUND 13 -5V SUPPLY 8 CODING SELECT
OFFSET ADJUST 5
ANALOG INPUT 3
S/H REGISTER
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
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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) LIMITS 0 to +16 0 to -16 0 to +6.0 -0.3 to +VDD +0.3 15 300 UNITS Volts Volts Volts Volts Volts C OUTPUTS Output Coding Logic Level Logic "1" Logic "0" Logic Loading "1" Logic Loading "0" Internal Reference Voltage, +25C 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 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 -- -- -- 0.018 0.12 0.6 0 to +70C 14 Bits 0.122 0.3 0.8 % % % Operating Temp. Range, Case ADS-941MC ADS-941ME Storage Temperature Range Package Type Weight 0 -- +70 C -40 -- +85 C -65 -- +150 C 32-pin, metal-sealed, ceramic TDIP 0.46 ounces (13 grams) +14.25 -14.25 +4.75 -- -- -- -- -- +15.0 -15.0 +5.0 +62 -80 +140 2.8 -- +15.75 -15.75 +5.25 +85 -95 +160 3.3 0.02 Volts Volts Volts mA mA mA Watts %FSR%V -- -- -- -- -78 -77 75 74 74 73 78 77 250 -- -- 250 -85 -80 80 77 80 78 86 83 1 10 5 350 -- -- -- -- -- -- -- -- V/s ns ps ns dB dB dB dB dB dB dB dB MIN. TYP. MAX. UNITS
Staight Bin./Offset Bin./Two's Comp. Comp. Bin./Comp. Offset Bin./C2C +2.4 -- -- -- +9.98 -- -- -- -- -- -- +10.0 13 -- -- +0.4 -160 +6.4 +10.02 30 5 Volts Volts A mA Volts ppm/C mA
FUNCTIONAL SPECIFICATIONS
(TA = +25C, VCC = 15V, VDD = 5V, 1MHz sampling rate, and a minimum 7 minute warmup 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" PERFORMANCE Integral Non-Linearity (fin = 10KHz) +25C 0 to +70C -40 to +85C Differential Non-Linearity (fin = 10KHz) +25C 0 to +70C -40 to +85C Full Scale Absolute Accuracy +25C 0 to +70C -40 to +85C Unipolar Zero Error +25C (see Figure 3) 0 to +70C -40 to +85C Bipolar Zero Error +25C (see Figure 3) 0 to +70C -40 to +85C Bipolar Offset Error +25C (see Figure 3) 0 to +70C -40 to +85C Gain Error +25C (see Figure 3) 0 to +70C -40 to +85C No Missing Codes (fin = 500kHz) 14 Bits Resolution +2.0 -- -- -- -- -- -- -- -- +0.8 +10 -600 Volts Volts A A MIN. -- -- 2.2 -- TYP. 0 to +10 5 2.5 7 MAX. -- -- -- 15 UNITS Volts Volts k pF
-- -- -- -0.75 -0.95 -1 -- -- -- -- -- -- -- -- -- -- -- --
1 1.5 2 0.5 0.75 0.95 0.1 0.12 0.45 0.05 0.1 0.2 0.05 0.1 0.2 0.1 0.12 0.6
2 2 3 0.75 0.95 +2.5 0.122 0.36 0.85 0.122 0.2 0.3 0.122 0.2 0.3 0.12 0.3 0.8
LSB LSB LSB LSB LSB LSB %FSR %FSR %FSR %FSR %FSR %FSR %FSR %FSR %FSR %FSR %FSR %FSR
-- -- -- -- -- 1 --
-85 6 1.75 87 1000 -- 250
-- -- -- -- 2000 -- --
dB MHz MHz dB ns MHz Vrms
Footnote:
Same specification as In-Band Harmonics and Peak Harmonics.
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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. 2. Bypass the analog and digital supplies and the +10V REF. OUT (pin 1) to ground with a 4.7F, 25V tantalum electrolytic capacitor in parallel with a 0.1F ceramic capacitor. 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). 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.
Table 1. Input Connections
INPUT RANGE 0 +10V 5V
INPUT PIN Pin 3 Pin 3
TIE TOGETHER Pins 2 and 4 Pins 1 and 2
Table 2. Zero and Gain Adjustments
Input Range 0 to +10V 5V
Zero Adjust +1/2 LSB +305V +305V
Gain Adjust FS - 1 1/2 LSB +9.999085V +4.999085V
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. 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. 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
THERMAL REQUIREMENTS
All DATEL sampling A/D converters are fully characterized and specified over operating temperature (case) ranges of 0 to +70C and -55 to +125C. All room-temperature (TA = +25C) 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. 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. 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.
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N START CONVERT 50ns min., 100ns max 35ns max.
N+1
EOC
Conversion Time 600ns typ. 10ns typ.
INTERNAL S/H
Aquisition Time Hold 350ns max. 30ns max.
OUTPUT DATA DATA N-1 VALID
INVALID DATA 400ns max.
DATA N VALID 600ns min.
Scale is approximately 50ns per division.
Figure 2. ADS-941 Timing Diagram
Removing System Errors Use external potentiometers to remove system errors or to reduce the small initial errors to zero. Use a 100 trimpot in series with the analog input for gain adjustment. Use a fixed 50 resistor instead of the trimpot for operation without adjustment. Use a 20k 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 20k +5V -5V
+5V 4.7F
0.1F
10 DIGITAL 11 GROUND
5 OFFSET ADJUST
4.7F +
+
+15V
12 0.1F 6, 14, 15 ANALOG GROUND 13 ADS-941
4.7F -15V
0.1F
GAIN ADJUST
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) 7 OVERFLOW 16 EOC
0 to +10V
100
3 ANALOG INPUT
4 SIGNAL GROUND CODING SELECT 1 +10V REF. OUT 4.7F 8
0.1F
START CONVERT 32 ENABLE BIPOLAR 9 2
Figure 3. ADS-941 Connection Diagram
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0 -10 Amplitude Relative to Full Scale (dB) -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 INPUT VOLT. 0 TO +10V MSB LSB COMP. BINARY OUTPUT CODING MSB LSB MSB LSB INPUT VOLT. 5V BIPOLAR SCALE
+FS - 1 LSB +7/8 FS +3/4 FS +1/2 FS +1/4 FS +1/8 FS +1 LSB 0
+9.999390 +8.750000 +7.500000 +5.000000 +2.500000 +1.250000 +0.000610 0.000000
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
OFF. BINARY
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
COMP. OFF. BIN.
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
TWO'S COMP.
+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
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MECHANICAL DIMENSIONS INCHES (mm)
1.72 MAX. (43.69)
32
17
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
1.11 MAX. (28.19)
Lead Finish: 50 microinches (minimum) gold plating over 100 microinches (nominal) nickel plating
1
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0.235 MAX. (5.969)
0.100 TYP. (2.540) 1.500 (38.100) 0.200 MAX. (5.080)
0.010 -0.001 (0.254) 0.190 MAX. (4.826) 0.018 0.002 (0.457) 0.100 (2.540) 0.040 (1.016) SEATING PLANE 0.025 (0.635)
+0.002
0.900 0.010 (22.860)
0.100 (2.540)
ORDERING INFORMATION
MODEL NUMBER ADS-941MC ADS-941ME OPERATING TEMP. RANGE 0 to +70C -40 to +85C 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.
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ISO 9001
R E G I S T E R E D
DS-0227B
11/96
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
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 Munchen, 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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