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ADS-937
16-Bit, 1MHz Sampling A/D Converters
FEATURES 16-bit resolution 1MHz sampling rate No missing codes over full military temperature range Very low power, 1.25 Watts Small, 32-pin, side-brazed ceramic TDIP Edge-triggered Excellent performance Ideal for both time and frequency-domain applications Low cost GENERAL DESCRIPTION
The low-cost ADS-937 is a 16-bit, 1MHz sampling A/D converter. This device accurately samples full-scale input signals up to Nyquist frequencies with no missing codes. This feature, combined with excellent signal-to-noise ratio (SNR) and total harmonic distortion (THD), makes the ADS-937 the ideal choice for both time-domain (CCD/medical imaging, scanners, process control) and frequency-domain (radar, telecommunications, spectrum analysis) applications. Packaged in a 32-pin, side-brazed, metal-sealed, ceramic TDIP, the functionally complete ADS-937 contains a fastsettling sample-hold amplifier, a subranging (two-pass) A/D converter, an internal reference, timing/control logic, and error correction circuitry. Digital input and output levels are TTL. The ADS-937 only requires the rising edge of the start convert pulse to operate. Requiring 15V and 5V supplies, the ADS-937 typically dissipates 1.25 Watts. The device is offered with both bipolar (5V) and unipolar (0 to -10V) analog input ranges. Models are available for use in either commercial (0 to +70C) or military (-55 to +125C) operating temperature ranges. A proprietary, auto-calibrating, error-correcting circuit enables the device to achieve specified performance over the full military temperature range.
INPUT/OUTPUT CONNECTIONS
PIN FUNCTION PIN FUNCTION
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
ANALOG INPUT GROUND UNIPOLAR OFFSET ADJUST +5V REFERENCE OUT GAIN ADJUST COMPENSATION -15V SUPPLY +15V SUPPLY +5V SUPPLY -5V SUPPLY GROUND GROUND +5V SUPPLY EOC START CONVERT
32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 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 BIT 13 BIT 14 BIT 15 BIT 16 (LSB)
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Figure 1. ADS-937 Functional Block Diagram
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MDA_ADS-937.A01 Page 1 of 8
ADS-937
16-Bit, 1MHz Sampling A/D Converters
ABSOLUTE MAXIMUM RATINGS
PARAMETERS +15V Supply (Pin 9) -15V Supply (Pin 8) +5V Supply (Pins 10, 14) -5V Supply (Pin 11) Digital Input (Pin 16) Analog Input (Pin 1) Lead Temperature (10 seconds) LIMITS 0 to +16 0 to -16 0 to +6 0 to -6 -0.3 to +VDD +0.3 15 +300 UNITS Volts Volts Volts Volts Volts Volts C
PHYSICAL/ENVIRONMENTAL
PARAMETERS Operating Temp. Range, Case ADS-937MC ADS-937MM/883 Thermal Impedance jc ca Storage Temperature Range Package Type Weight unless otherwise specified.) 0 to +70C MAX. -- -- -- 15 MIN. -- -- -- -- TYP. 5 0 to -10 1 7 MAX. -- -- -- 15 -55 to +125C MIN. -- -- -- -- TYP. 5 0 to -10 1 7 MAX. -- -- -- 15 UNITS Volts Volts k pF MIN. 0 -55 TYP. -- -- MAX. +70 +125 UNITS C C
-- 5 -- C/Watt -- 22 -- C/Watt -65 -- +150 C 32-pin, side-brazed, metal-sealed, ceramic TDIP 0.56 ounces (16 grams)
FUNCTIONAL SPECIFICATIONS
(TA = +25C, VCC = 15V, +VDD = 5V, 1MHz sampling rate, and a minimum 1 minute warm-up +25C ANALOG INPUT Input Voltage Range Bipolar Unipolar Input Resistance Input Capacitance DIGITAL INPUTS Logic Levels Logic "1" Logic "0" Logic Loading "1" Logic Loading "0" Start Convert Positive Pulse Width STATIC PERFORMANCE Resolution Integral Nonlinearity Differential Nonlinearity (fin = 10kHz) Full Scale Absolute Accuracy Bipolar Zero Error (Tech Note 2) Bipolar Offset Error (Tech Note 2) Gain Error (Tech Note 2) Unipolar Offset Error (Tech Note 2) No Missing Codes (fin = 10kHz) DYNAMIC PERFORMANCE Peak Harmonics (-0.5dB) dc to 100kHz 100kHz to 500kHz Total Harmonic Distortion (-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 (& distortion, -0.5dB) dc to 100kHz 100kHz to 500kHz Noise Two-Tone Intermodulation Distortion (fin = 100kHz, 240kHz, fs = 1MHz, -0.5dB) Input Bandwidth (-3dB) Small Signal (-20dB input) Large Signal (-0.5dB input) Feedthrough Rejection (fin = 500kHz) Slew Rate Aperture Delay Time Aperture Uncertainty S/H Acquisition Time ( to 0.003%FSR, 10V step) Overvoltage Recovery Time A/D Conversion Rate -- -- -- -- 85 84 81 80 -- -- -- -- -- -- -- -- -- -- 1 -90 -88 -87 -86 88 87 85 84 110 -85 4.5 4 84 33 +20 5 260 500 -- -84 -81 -82 -81 -- -- -- -- -- -- -- -- -- -- -- -- 300 1000 -- -- -- -- -- 85 84 81 80 -- -- -- -- -- -- -- -- -- -- 1 -90 -88 -87 -86 88 87 85 84 110 -85 4.5 4 84 33 +20 5 260 500 -- -84 -81 -82 -81 -- -- -- -- -- -- -- -- -- -- -- -- 300 1000 -- -- -- -- -- 84 83 80 78 -- -- -- -- -- -- -- -- -- -- 1 -88 -87 -86 -85 87 87 84 83 110 -85 4.5 4 84 33 +20 5 260 500 -- -83 -80 -81 -80 -- -- -- -- -- -- -- -- -- -- -- -- 300 1000 -- dB dB dB dB dB dB dB dB Vrms dB MHz MHz dB V/s ns ps rms ns ns MHz -- -- -0.95 -- -- -- -- -- 16 16 0.75 0.5 0.1 0.1 0.1 0.1 0.1 -- -- -- +1 0.25 0.15 0.2 0.3 0.15 -- -- -- -0.95 -- -- -- -- -- 16 16 1.5 0.5 0.2 0.1 0.15 0.25 0.1 -- -- -- +1 0.4 0.25 0.3 0.5 0.25 -- -- -- -0.95 -- -- -- -- -- 16 16 2 0.5 0.25 0.15 0.2 0.4 0.15 -- -- -- +1.5 0.5 0.5 0.5 0.7 0.5 -- Bits LSB LSB %FSR %FSR %FSR % %FSR Bits +2.0 -- -- -- 20 -- -- -- -- 500 -- +0.8 +20 -20 -- +2.0 -- -- -- 20 -- -- -- -- 500 -- +0.8 +20 -20 -- +2.0 -- -- -- 20 -- -- -- -- 500 -- +0.8 +20 -20 -- Volts Volts A A ns MIN. -- -- -- -- TYP. 5 0 to -10 1 7
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MDA_ADS-937.A01 Page 2 of 8
ADS-937
16-Bit, 1MHz Sampling A/D Converters
MIN. ANALOG OUTPUT Internal Reference Voltage Drift External Current DIGITAL OUTPUTS Logic Levels Logic "1" Logic "0" Logic Loading "1" Logic Loading "0" Output Coding 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 +14.5 -14.5 +4.75 -4.75 -- -- -- -- -- -- +15.0 -15.0 +5.0 -5.0 +7 -8 +133 -72 1.25 -- +15.5 -15.5 +5.25 -5.25 +9 -10 +145 -80 1.35 0.01 +14.5 -14.5 +4.75 -4.75 -- -- -- -- -- -- +15.0 -15.0 +5.0 -5.0 +7 -8 +133 -72 1.25 -- +15.5 -15.5 +5.25 -5.25 +9 -10 +145 -80 1.35 0.01 +14.5 -14.5 +4.75 -4.75 -- -- -- -- -- -- +15.0 -15.0 +5.0 -5.0 +7 -8 +133 -72 1.25 -- +15.5 -15.5 +5.25 -5.25 +9 -10 +145 -80 1.35 0.01 Volts Volts Volts Volts mA mA mA mA Watts %FSR/%V +2.4 -- -- +2.4 -- -- +0.4 -- -- -- -4 -- -- -- +4 -- (Offset) Binary / Complementary (Offset) Binary -- -- -- -- -- +0.4 -4 +4 +2.4 -- -- -- -- -- -- -- -- +0.4 -4 +4 Volts Volts mA mA +4.95 -- -- +5.0 30 1 +5.05 -- -- +4.95 -- -- +5.0 30 1 +5.05 -- -- +4.95 -- -- +5.0 30 1 +5.05 -- -- Volts ppm/C mA +25C TYP. MAX. MIN. 0 TO +70C TYP. MAX. MIN. -55 TO +125C TYP. MAX. UNITS
Footnotes:
All power supplies must be on before applying a start convert pulse. All supplies and the clock (START CONVERT) must be present during warm-up periods. The device must be continuously converting during this time. Contact Murata-PS for other input voltage ranges. A 1MHz clock with a 500nsec positive pulse width (50% duty cycle) is used for all production testing. Any duty cycle may be used as long as a minimum positive pulse width of 20nsec is maintained. For applications requiring lower sampling rates, clock frequencies less than 1MHz may be used. Effective bits is equal to:
(SNR + Distortion) - 1.76 + 20 log 6.02 Full Scale Amplitude Actual Input Amplitude
This is the time required before the A/D output data is valid once the analog input is back within the specified range.
TECHNICAL NOTES
1. Obtaining fully specified performance from the ADS-937 requires careful attention to pc-card layout and power supply decoupling. The device's ground pins are not connected to each other internally. For optimal performance, tie all ground pins (2, 12 and 13) directly to a large analog ground plane beneath the package. The device's +5V supply pins are not connected to each other internally and should be connected to a clean analog +5V supply. Bypass all power supplies and the +5V REFERENCE OUTPUT (pin 5) to ground with 4.7F tantalum capacitors in parallel with 0.1F ceramic capacitors. Locate the bypass capacitors as close to the unit as possible. Tie a 47F capacitor between COMPENSATION (pin 7) and ground (See figure 2.). 2. The ADS-937 achieves its specified accuracies without the need for external calibration. If required, the device's small initial offset and gain errors can be reduced to zero using the adjustment circuitry shown in Figure 2. When using this circuitry, or any similar offset and gain calibration hardware, make adjustments following warm-up. To avoid interaction, always adjust offset before gain. Float pins 4 and 6 if not using offset and gain adjust circuits.
3. Applying a start convert pulse while a conversion is in progress (EOC = logic "1") will initiate a new and inaccurate conversion cycle. Data for the interrupted and subsequent conversions will be invalid.
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. 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.
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MDA_ADS-937.A01 Page 3 of 8
ADS-937
16-Bit, 1MHz Sampling A/D Converters
CALIBRATION PROCEDURE
Connect the converter per Table 1 for the appropriate input voltage range. Any offset/gain calibration procedures should not be implemented until the device is fully warmed up. To avoid interaction, adjust offset before gain. The ranges of adjustment for the circuits in Figure 2 are guaranteed to compensate for the ADS-937's initial accuracy errors and may not be able to compensate for additional system errors. A/D converters are calibrated by positioning their digital outputs exactly on the transition point between two adjacent digital output codes. This is accomplished by connecting LED's to the digital outputs and performing adjustments until certain LED's "flicker" equally between on and off. Other approaches employ digital comparators or microcontrollers to detect when the outputs change from one code to the next. For the ADS-937, offset adjusting is normally accomplished when the analog input is 0 minus 1/2LSB (-76.3V). See Table 2 for the proper bipolar and unipolar output coding. Gain adjusting is accomplished when the analog input is at nominal full scale minus 11/2LSB's (-9.999771V for unipolar and -4.999771V for bipolar). 3. For a bipolar input - Adjust the offset potentiometer until the output code flickers equally between 1000 0000 0000 0000 and 0111 1111 1111 1111. For a unipolar input - Adjust the offset potentiometer until all output bits are 0's and the LSB flickers between 0 and 1.
Gain Adjust Procedure
1. Apply -4.999771V to the ANALOG INPUT (pin 1) for bipolar gain adjust or apply -9.999771V to pin 1 for unipolar gain adjust. 2. For a unipolar input - Adjust the gain potentiometer until all output bits are 1's and the LSB flickers between 1 and 0. For a bipolar input - Adjust the gain potentiometer until all output bits are 1's and the LSB flickers between 1 and 0. 3. To confirm proper operation of the device, vary the applied input voltage to obtain the output coding listed in Table 2.
Table 1. Setting Output Coding Selection (Pin 35)
Zero/Offset Adjust Procedure
1. Apply a train of pulses to the START CONVERT input (pin 16) so that the converter is continuously converting. 2. For unipolar or bipolar zero/offset adjust, apply -76.3V to the ANALOG INPUT (pin 1).
INPUT VOLTAGE RANGE 5V 0 to -10V
INPUT PIN Pin 1 Pin 1
TIE TOGETHER Pins 2 and 3 Pins 3 and 5
Table 2. Output Coding COMPLEMENTARY 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 VOLTAGE 0 to -10V -9.999847 -8.750000 -7.500000 -5.000000 -2.500000 -1.250000 -0.000153 0.000000 COMPLEMENTARY OFFSET BINARY INPUT RANGE 5V +4.999847 +3.750000 +2.500000 +0.000000 -2.500000 -3.750000 -4.999847 -5.000000 BIPOLAR SCALE +FS -1 LSB +3/4 FS +1/2 FS 0 -1/2 FS -3/4 FS -FS +1 LSB -FS
OUTPUT CODING MSB LSB MSB LSB 1111 1111 1111 1111 1110 0000 0000 0000 1100 0000 0000 0000 1000 0000 0000 0000 0100 0000 0000 0000 0010 0000 0000 0000 0000 0000 0000 0001 0000 0000 0000 0000 0000 0000 0000 0000 0001 1111 1111 1111 0011 1111 1111 1111 0111 1111 1111 1111 1011 1111 1111 1111 1101 1111 1111 1111 1111 1111 1111 1110 1111 1111 1111 1111
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MDA_ADS-937.A01 Page 4 of 8
ADS-937
16-Bit, 1MHz Sampling A/D Converters
Figure 2. Typical ADS-937 Connection Diagram
Figure 3. ADS-937 Timing Diagram
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MDA_ADS-937.A01 Page 5 of 8
ADS-937
16-Bit, 1MHz Sampling A/D Converters
Figure 4. FFT Analysis of ADS-937
Figure 5. ADS-937 Histogram and Differential Nonlinearity
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MDA_ADS-937.A01 Page 6 of 8
ADS-937
16-Bit, 1MHz Sampling A/D Converters
Figure 6. ADS-937 Evaluation Board.
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MDA_ADS-937.A01 Page 7 of 8
ADS-937
16-Bit, 1MHz Sampling A/D Converters
This histogram represents the typical peak-to-peak noise (including quantization noise) associated with the ADS-937.
Figure 7. ADS-937 Grounded Input Histogram
MECHANICAL DIMENSIONS INCHES (mm)
ORDERING INFORMATION
MODEL NUMBER ADS-937MC ADS-937MM ADS-937/883 OPERATING TEMPERATURE RANGE 0 to +70C -55 to +125C -55 to +125C 32-PIN PACKAGE TDIP TDIP TDIP ADS-B937 Evaluation Board (without ADS937)
ACCESSORIES
Receptacles for PC board mounting can be ordered through AMP, Inc., Part # 3-331272-8 (Component Lead Socket), 32 required. For availabilty of MIL-STD-883 product, contact Murata Power Solutions.
USA: UK: France: Japan: Mansfield (Ma), Tel: (508) 339-3000, email: sales@murata-ps.com Milton Keynes, Tel: +44 (0)1908 615232, email: mk@murata-ps.com Montigny Le Bretonneux, Tel: +33 (0)1 34 60 01 01, email: france@murata-ps.com Tokyo, Tel: 3-3779-1031, email: sales_tokyo@murata-ps.com Osaka, Tel: 6-6354-2025, email: sales_osaka@murata-ps.com Website: www.murata-ps.jp Shanghai, Tel: +86 215 027 3678, email: shanghai@murata-ps.com Guangzhou, Tel: +86 208 221 8066, email: guangzhou@murata-ps.com
Canada: Toronto, Tel: (866) 740 1232, email: toronto@murata-ps.com
Murata Power Solutions, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A. Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356
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Murata Power Solutions, 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. (c) 2008 Murata Power Solutions, Inc.
Germany: Munchen, Tel: +49 (0)89-544334-0, email: munich@murata-ps.com
China:
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