® ® ADS-937 16-Bit, 1MHz, Low-Power Sampling A/D Converters FEATURES • • • • • • • • • 16-bit resolution 1MHz minimum 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 INPUT/OUTPUT CONNECTIONS 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 errorcorrection circuitry. Digital input and output levels are TTL. 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 +70°C) or PIN FUNCTION PIN FUNCTION 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ANALOG INPUT ANALOG GROUND UNIPOLAR OFFSET ADJUST +5V REFERENCE OUT GAIN ADJUST COMPENSATION –15V SUPPLY +15V SUPPLY +5V ANALOG SUPPLY –5V ANALOG SUPPLY ANALOG GROUND DIGITAL GROUND +5V DIGITAL 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) military (–55 to +125°C) operating temperature ranges. A proprietary, auto-calibrating, error-correcting circuit enables the device to achieve specified performance over the full military temperature range. UNIPOLAR 3 OFFSET ADJUST 4 32 BIT 1 (MSB) BUFFER 31 BIT 2 – FLASH ADC 1 S/H + GAIN ADJUST 6 GAIN CIRCUIT 30 BIT 3 29 BIT 4 DIGITAL CORRECTION LOGIC ANALOG INPUT 1 REF DAC Σ +5V REFERENCE OUT 5 COMPENSATION 7 28 BIT 5 27 BIT 6 26 BIT 7 25 BIT 8 24 BIT 9 23 BIT 10 22 BIT 11 21 BIT 12 20 BIT 13 FLASH ADC 2 AMP 19 BIT 14 18 BIT 15 17 BIT 16 (LSB) START CONVERT 16 TIMING AND CONTROL LOGIC EOC 15 10 11 2, 12 14 9 8 13 +5V ANALOG SUPPLY –5V ANALOG SUPPLY ANALOG GROUND +5V DIGITAL SUPPLY +15V SUPPLY –15V SUPPLY DIGITAL GROUND Figure 1. ADS-937 Functional Block Diagram DATEL, Inc., Mansfield, MA 02048 (USA) • Tel: (508) 339-3000, (800) 233-2765 Fax: (508) 339-6356 • Email: [email protected] • Internet: www.datel.com ® ® ADS-937 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) PHYSICAL/ENVIRONMENTAL 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 PARAMETERS MIN. TYP. MAX. UNITS 0 –55 — — +70 +125 °C °C — — –65 5 22 — — — +150 °C/Watt °C/Watt °C Operating Temp. Range, Case ADS-937MC ADS-937MM/883 Thermal Impedance θjc θca Storage Temperature Range Package Type Weight 32-pin,side-brazed, metal-sealed, ceramic TDIP 0.56 ounces (16 grams) FUNCTIONAL SPECIFICATIONS (TA = +25°C, ±VCC = ±15V, ±VDD = ±5V, 1MHz sampling rate, and a minimum 1 minute warm-up ➀ unless otherwise specified.) +25°C ANALOG INPUTS Input Voltage Ranges ➁ Bipolar Unipolar Input Resistance Input Capacitance 0 to +70°C –55 to +125°C MIN. TYP. MAX. MIN. TYP. MAX. MIN. TYP. MAX. UNITS — — — — ±5 0 to –10 1 7 — — — 15 — — — — ±5 0 to –10 1 7 — — — 15 — — — — ±5 0 to –10 1 7 — — — 15 Volts Volts kΩ pF +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 µA µA ns — — –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 — — –90 –88 –84 –81 — — –90 –88 –84 –81 — — –88 –87 –83 –80 dB dB — — –87 –86 –82 –81 — — –87 –86 –82 –81 — — –86 –85 –81 –80 dB dB 85 84 88 87 — — 85 84 88 87 — — 84 83 87 87 — — dB dB 81 80 — 85 84 110 — — — 81 80 — 85 84 110 — — — 80 78 — 84 83 110 — — — dB dB µVrms — –85 — — –85 — — –85 — dB — — — — — — 4.5 4 84 ±33 +20 5 — — — — — — — — — — — — 4.5 4 84 ±33 +20 5 — — — — — — — — — — — — 4.5 4 84 ±33 +20 5 — — — — — — MHz MHz dB V/µs ns ps rms — — 1 260 500 — 300 1000 — — — 1 260 500 — 300 1000 — — — 1 260 500 — 300 1000 — ns ns MHz DIGITAL INPUTS Logic Levels Logic "1" Logic "0" Logic Loading "1" Logic Loading "0" Start Convert Positive Pulse Width ➂ 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 ➃ (& 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 ➄ A/D Conversion Rate 2 ® ® ADS-937 +25°C 0 to +70°C –55 to +125°C ANALOG OUTPUT MIN. TYP. MAX. MIN. TYP. MAX. MIN. TYP. MAX. UNITS Internal Reference Voltage Drift External Current +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 +2.4 — — — — — — — — +0.4 –4 +4 — — — — — +0.4 –4 +4 Volts Volts mA mA +14.5 –14.5 +4.75 –4.75 +15.0 –15.0 +5.0 –5.0 +15.5 –15.5 +5.25 –5.25 +14.5 –14.5 +4.75 –4.75 +15.0 –15.0 +5.0 –5.0 +15.5 –15.5 +5.25 –5.25 +14.5 –14.5 +4.75 –4.75 +15.0 –15.0 +5.0 –5.0 +15.5 –15.5 +5.25 –5.25 Volts Volts Volts Volts — — — — — — +7 –8 +133 –72 1.25 — +9 –10 +145 –80 1.35 ±0.01 — — — — — — +7 –8 +133 –72 1.25 — +9 –10 +145 –80 1.35 ±0.01 — — — — — — +7 –8 +133 –72 1.25 — +9 –10 +145 –80 1.35 ±0.01 mA mA mA mA Watts %FSR/%V DIGITAL OUTPUTS Logic Levels Logic "1" Logic "0" Logic Loading "1" Logic Loading "0" Output Coding +2.4 — — +2.4 — — +0.4 — — — –4 — — — +4 — Complementary Binary / Complementary Offset Binary 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 Footnotes: ➃ Effective bits is equal to: ➀ 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. (SNR + Distortion) – 1.76 + ➁ Contact DATEL for other input voltage ranges. 20 log Full Scale Amplitude Actual Input Amplitude 6.02 ➄ This is the time required before the A/D output data is valid once the analog input is back within the specified range. ➂ 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. 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 analog and digital ground systems 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. 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 +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. Bypass all power supplies and the +5V REFERENCE OUTPUT (pin 5) to ground with 4.7µF tantalum capacitors in parallel with 0.1µF ceramic capacitors. Locate the bypass capacitors as close to the unit as possible. Tie a 47µF capacitor between COMPENSATION (pin 7) and ground (See figure 2.). 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. 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 ® ® ADS-937 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. 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. 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. 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. 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 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. For the ADS-937, offset adjusting is normally accomplished when the analog input is 0 minus ½LSB (–76.3µV). See Table 2 for the proper bipolar and unipolar output coding. 3. To confirm proper operation of the device, vary the applied input voltage to obtain the output coding listed in Table 2. Gain adjusting is accomplished when the analog input is at nominal full scale minus 1½LSB's (–9.999771V for unipolar and –4.999771V for bipolar). Table 1. Input Connections INPUT VOLTAGE RANGE Zero/Offset Adjust Procedure 1. Apply a train of pulses to the START CONVERT input (pin 16) so that the converter is continuously converting. ±5V 0 to –10V 2. For unipolar or bipolar zero/offset adjust, apply –76.3µV to the ANALOG INPUT (pin 1). INPUT PIN TIE TOGETHER Pin 1 Pin 1 Pins 2 and 3 Pins 3 and 5 Table 2. Output Coding COMPLEMENTARY BINARY UNIPOLAR SCALE INPUT VOLTAGE 0 to –10V –FS +1 LSB –7/8 FS –3/4 FS –1/2 FS –1/4 FS –1/8 FS –1 LSB 0 –9.999847 –8.750000 –7.500000 –5.000000 –2.500000 –1.250000 –0.000153 0.000000 COMPLEMENTARY OFFSET BINARY OUTPUT CODING MSB LSB MSB 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 LSB 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 4 INPUT RANGE ±5V BIPOLAR SCALE +4.999847 +3.750000 +2.500000 +0.000000 –2.500000 –3.750000 –4.999847 –5.000000 +FS –1 LSB +3/4 FS +1/2 FS 0 –1/2 FS –3/4 FS –FS +1 LSB –FS ® ® ADS-937 20kΩ Pin 5 (ADS-937) –15V +15V 10kΩ 15 6 EOC GAIN ADJUST 4.7µF 0.1µF 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 13 DIGITAL GROUND 8 4.7µF + 4.7µF 0.1µF + –15V 0.1µF 12 ANALOG GROUND ADS-937 9 10 +5V ANALOG + 4.7µF 0.1µF + –5V ANALOG OFFSET ADJUST 14 +5V DIGITAL +15V 4 4.7µF 0.1µF 2 ANALOG GROUND START CONVERT COMPENSATION 11 16 7 47µF + ANALOG INPUT 5 +5V REF. OUT 0.1µF 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) UNIPOLAR 1 3 4.7µF Figure 2. Typical ADS-937 Connection Diagram N START CONVERT N+1 500ns typ. 5ns typ. INTERNAL S/H Acquisition Time 740ns typ. 260ns typ. Hold 65ns typ. EOC Conversion Time 730ns typ. 20ns typ. OUTPUT DATA Invalid Data 20ns Data N-1 Valid Data N-2 Valid 980ns typ. Scale is approximately 50ns per division. Note: Scale is approximately 50ns per division. Sampling Rate = 1MHz. Figure 3. ADS-937 Timing Diagram 5 N ® ® ADS-937 0 –10 –30 –40 –50 –60 –70 –80 –90 –100 –110 –120 –130 –140 –150 0 50 kHz 100 kHz 150 kHz 200 kHz 250 kHz 300 kHz 350 kHz 400 kHz Frequency (fs = 1MHz, fin = 480kHz, Vin = – 0.5dB, 16,384-point FFT) Figure 4. FFT Analysis of ADS-937 DNL (LSB's) 0.63 Number of Occurrences Amplitude Relative to Full Scale (dB) –20 – 0.50 0 0 Codes 65,536 Digital Output Code Figure 5. ADS-937 Histogram and Differential Nonlinearity 6 65,536 450 kHz 500 kHz 7 P4 AIN R1 23 21 19 17 15 13 11 9 7 5 3 1 22 20 18 16 14 12 10 8 6 4 2 25 3 + 2 – –15V 24 26 P1 OPT AMPLIFIER OPTION SG2 +15V R2 AR1 OPT C12 OPT + +5V +15V –15V –5V +5VD N.C. N.C. N.C. 6 C22 OPT 4 C23 OPT 7 OPT C11 OPT 1 REF C18 + 1 X1 14 7 8 3 1 2 51 R6 EXT CLK P3 JPR3 5 4 U3 10 9 C10 0.1uF U3 13 12 6 0.1uF 10uF + C21 10uF +5VD C9 C6 0.1uF + C14 22uF C5 0.1uF + C16 22uF C4 0.1uF C28 0.1uF C20 10uF C17 C8 0.1uF –15V C15 10uF R4 20K SG1 8 U3 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 11 (LSB) BIT16 BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 (MSB) BIT1 ADS-937 UUT START CONVERT EOC +5VD DGND AGND -5VA +5VA +15VA –15VA COMP. GAIN ADJ REF. OUT OFFSET ADJ. UNIPOLAR AGND AIN Figure 6. ADS-937 Evaluation Board 10uF C24 R3 C25 +15V –15V 0.1uF 10 C19 10uF +5VD C26 0.1uF C7 0.1uF +5VA R5 20K "OFFSET ADJ." "GAIN ADJ." 10uF 2 JPR2 3 +15V JPR2 SG4 SG3 + C27 + OPT + + + 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 +5VD 10 U2 10 U1 2 1 10uF C3 1Q 1Q 1 OC 8Q 7Q 6Q 5Q 4Q 3Q 2Q 20 OC 8Q 7Q 6Q 5Q 4Q 3Q 2Q 20 7 2 14 U3 C29 + LE 8D 7D 6D 5D 4D 3D 2D 1D LE 8D 7D 6D 5D 4D 3D 2D 1D 0.1uF 11 9 8 7 6 5 4 3 2 +5VD 11 9 8 7 6 5 4 3 2 +5VD BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 0.1uF 3 74HCT573 1 START CONVERT 12 (LSB) BIT16 13 14 15 16 17 18 19 C2 74HCT573 1 12 13 14 15 16 17 18 19 (MSB) BIT1 C1 0.1uF 34 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 P2 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 EOC ® ® ADS-937 + ® ® ADS-937 5000 4000 3000 2000 This histogram represents the typical peak-to- peak noise (including quantization noise) associated with the ADS-937. 1000 0.00 Digital Output Code Figure 7. ADS-937 Grounded Input Histogram MECHANICAL DIMENSIONS INCHES (mm) 1.62 MAX. (41.15) Dimension Tolerances (unless otherwise indicated): 2 place decimal (.XX) ±0.010 (±0.254) 3 place decimal (.XXX) ±0.005 (±0.127) 0.92 MAX. (23.37) Lead Material: Kovar Alloy Lead Finish: 50 microinches (minimum) gold plating over 100 microinches (nominal) nickel plating 1.50 TYP (38.10) SEATING PLANE 0.05 TYP. (1.27) 0.220 TYP. (6.86) PIN 1 INDEX 0.010 TYP. (0.254) 0.05 TYP. (1.27) 0.018 TYP. (0.46) 0.100 TYP. (2.54) 0.90 TYP. (22.86) 0.175 TYP (4.45) 0.05 TYP. (1.27) ORDERING INFORMATION MODEL NUMBER OPERATING TEMP. RANGE 32-PIN PACKAGE ADS-937MC ADS-937MM ADS-937/883 0 to +70°C –55 to +125°C –55 to +125°C TDIP TDIP TDIP ACCESSORIES ADS-B937 Evaluation Board (without ADS-937) Receptacles for pc board mounting can be ordered through AMP, Inc., Part # 3-331272-8 (Component Lead Socket), 32 required. For availability of MIL-STD-883 product, contact DATEL. ® ® ISO 9001 R E G I S T E R E D DS-0306C DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356 Internet: www.datel.com Email: [email protected] Data Sheet Fax Back: (508) 261-2857 5/99 DATEL (UK) LTD. Tadley, England Tel: (01256)-880444 DATEL S.A.R.L. Montigny Le Bretonneux, France Tel: 01-34-60-01-01 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.