® ® ADS-927 14-Bit, 1MHz, Low-Power Sampling A/D Converters FEATURES • • • • • • • • 14-bit resolution 1MHz sampling rate Functionally complete No missing codes Small 24-pin DDIP or SMT package Low power, 1.9 Watts maximum Operates from ±15V or ±12V supplies Bipolar ±5V input range GENERAL DESCRIPTION INPUT/OUTPUT CONNECTIONS The ADS-927 is a high-performance, 14-bit, 1MHz sampling A/D converter. This device samples input signals up to Nyquist frequencies with no missing codes. The ADS-927 features outstanding dynamic performance including a THD of –80dB. Housed in a small 24-pin DDIP or SMT (gull-wing) package, the functionally complete ADS-927 contains a fast-settling sample-hold amplifier, a subranging (two-pass) A/D converter, a precise voltage reference, timing/control logic, and errorcorrection circuitry. Digital input and output levels are TTL. Requiring ±15V (or ±12V) and +5V supplies, the ADS-927 dissipates only 1.95W (1.65W for ±12V), maximum. The unit is offered with a bipolar input (–5V to +5V). Models are available for use in either commercial (0 to +70°C) or military (–55 to +125°C) operating temperature ranges. Applications include radar, sonar, spectrum analysis, and graphic/medical imaging. PIN FUNCTION PIN 1 2 3 4 5 6 7 8 9 10 11 12 BIT 14 (LSB) BIT 13 BIT 12 BIT 11 BIT 10 BIT 9 BIT 8 BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 24 23 22 21 20 19 18 17 16 15 14 13 FUNCTION –12V/–15V SUPPLY ANALOG GROUND +12V/+15V SUPPLY +10V REFERENCE OUT ANALOG INPUT ANALOG GROUND BIT 1 (MSB) BIT 2 START CONVERT EOC DIGITAL GROUND +5V SUPPLY DAC 18 BIT 1 (MSB) 17 BIT 2 REF 12 BIT 3 REGISTER S2 FLASH ADC S/H ANALOG INPUT 20 S1 BUFFER – REGISTER + 11 BIT 4 DIGITAL CORRECTION LOGIC +10V REF. OUT 21 10 BIT 5 9 BIT 6 8 BIT 7 7 BIT 8 6 BIT 9 5 BIT 10 4 BIT 11 3 BIT 12 2 BIT 13 1 BIT 14 (LSB) START CONVERT 16 TIMING AND CONTROL LOGIC EOC 15 13 14 22 19, 23 24 +5V SUPPLY DIGITAL GROUND +12V/+15V SUPPLY ANALOG GROUND –12V/–15V SUPPLY Figure 1. ADS-927 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-927 ABSOLUTE MAXIMUM RATINGS PARAMETERS +12V/+15V Supply (Pin 22) –12V/–15V Supply (pin 24) +5V Supply (Pin 13) Digital Input (Pin 16) Analog Input (Pin 20) Lead Temperature (10 seconds) PHYSICAL/ENVIRONMENTAL LIMITS UNITS 0 to +16 0 to –16 0 to +6 –0.3 to +VDD +0.3 ±15 +300 Volts Volts Volts Volts Volts °C PARAMETERS Operating Temp. Range, Case ADS-927MC, GC ADS-927MM, GM, 883 Thermal Impedance θjc θca Storage Temperature Package Type Weight MIN. TYP. MAX. UNITS 0 –55 — — +70 +125 °C °C 6 °C/Watt 24 °C/Watt –65 — +150 °C 24-pin, metal-sealed, ceramic DDIP or SMT 0.42 ounces (12 grams) FUNCTIONAL SPECIFICATIONS (TA = +25°C, ±VCC = ±15V (or ±12V), +VDD = +5V, 1MHz sampling rate, and a minimum 1 minute warmup ➀ unless otherwise specified.) +25°C ANALOG INPUT Input Voltage Range ➁ Input Resistance Input Capacitance 0 to +70°C MIN. TYP. MAX. — — — ±5 1 7 — — 15 +2.0 — — — 175 — — — — 200 — — — — — — — 14 MIN. –55 to +125°C TYP. MAX. — — — ±5 1 7 — — 15 — +0.8 +20 –20 225 +2.0 — — — 175 — — — — 200 14 ±0.5 ±0.5 ±0.08 ±0.05 ±0.05 ±0.1 — — — ±0.95 ±0.15 ±0.1 ±0.1 ±0.15 — — — — — — — — 14 — — –91 –82 –83 –78 — — –90 –80 77 75 MIN. TYP. MAX. UNITS — — — ±5 1 7 — — 15 Volts kΩ pF — +0.8 +20 –20 225 +2.0 — — — 175 — — — — 200 — +0.8 +20 –20 225 Volts Volts µA µA ns 14 ±0.75 ±0.5 ±0.15 ±0.1 ±0.1 ±0.15 — — — ±0.95 ±0.25 ±0.25 ±0.25 ±0.25 — — — — — — — — 14 14 ±1.5 ±0.75 ±0.3 ±0.15 ±0.25 ±0.25 — — — ±0.99 ±0.5 ±0.3 ±0.4 ±0.4 — Bits LSB LSB %FSR %FSR %FSR % Bits — — –90 –82 — –78 — — –88 –80 — –77 dB dB –81 –76 — — –89 –80 — –76 — — –87 –79 — –74 dB dB 79 78 — — 74 74 78 78 — — 73 73 77 76 — — dB dB 76 73 78 76 — — 73 73 77 76 — — 71 71 76 75 — — dB dB — — –87 350 — — — — –86 350 — — — — –85 350 — — dB µVrms — — — — — — 7 5 84 ±60 ±20 5 — — — — — — — — — — — — 7 5 84 ±60 ±20 5 — — — — — — — — — — — — 7 5 84 ±60 ±20 5 — — — — — — MHz MHz dB V/µs ns ps rms 335 — 1 390 400 — 445 1000 — 335 — 1 390 400 — 445 1000 — 335 — 1 390 400 — 445 1000 — ns ns MHz DIGITAL INPUT Logic Levels Logic "1" Logic "0" Logic Loading "1" Logic Loading "0" Start Convert Positive Pulse Width ➂ STATIC PERFORMANCE Resolution Integral Nonlinearity (fin = 10kHz) 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) 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 Two-Tone Intermodulation Distortion (fin = 100kHz, 240kHz, fs = 1MHz, –0.5dB) Noise 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-927 +25°C 0 to +70°C ANALOG OUTPUT MIN. TYP. MAX. Internal Reference Voltage Drift External Current +9.95 — — +10.0 ±5 — +10.05 — 1.5 +2.4 — — — — — — — — — MIN. –55 to +125°C TYP. MAX. MIN. TYP. MAX. UNITS +9.95 — — +10.0 ±5 — +10.05 — 1.5 +9.95 — — +10.0 ±5 — +10.05 — 1.5 Volts ppm/°C mA — +0.4 –4 +4 +2.4 — — — — — — — — +0.4 –4 +4 +2.4 — — — — — — — — +0.4 –4 +4 Volts Volts mA mA 35 — — 35 — — 35 ns DIGITAL OUTPUTS Logic Levels Logic "1" Logic "0" Logic Loading "1" Logic Loading "0" Delay, Falling Edge of EOC to Output Data Valid Output Coding Offset Binary POWER REQUIREMENTS, ±15V Power Supply Ranges +15V Supply –15V Supply +5V Supply Power Supply Currents +15V Supply –15V Supply +5V Supply Power Dissipation Power Supply Rejection +14.5 –14.5 +4.75 +15.0 –15.0 +5.0 +15.5 –15.5 +5.25 +14.5 –14.5 +4.75 +15.0 –15.0 +5.0 +15.5 –15.5 +5.25 +14.5 –14.5 +4.75 +15.0 –15.0 +5.0 +15.5 –15.5 +5.25 Volts Volts Volts — — — — — +43 –25 +71 1.6 — +65 –45 +80 1.95 ±0.02 — — — — — +43 –25 +71 1.6 — +65 –45 +80 1.95 ±0.02 — — — — — +43 –25 +71 1.6 — +65 –45 +80 1.95 ±0.02 mA mA mA Watts %FSR/%V +11.5 –11.5 +4.75 +12.0 –12.0 +5.0 +12.5 –12.5 +5.25 +11.5 –11.5 +4.75 +12.0 –12.0 +5.0 +12.5 –12.5 +5.25 +11.5 –11.5 +4.75 +12.0 –12.0 +5.0 +12.5 –12.5 +5.25 Volts Volts Volts — — — — — +42 –25 +71 1.4 — +65 –45 +80 1.65 ±0.02 — — — — — +42 –25 +71 1.4 — +65 –45 +80 1.65 ±0.02 — — — — — +42 –25 +71 1.4 — +65 –45 +80 1.65 ±0.02 mA mA mA Watts %FSR/%V POWER REQUIREMENTS, ±12V Power Supply Ranges +12V Supply –12V Supply +5V Supply Power Supply Currents +12V Supply –12V Supply +5V Supply Power Dissipation Power Supply Rejection Footnotes: ➀ All power supplies must be on before applying a start convert pulse. All supplies and the clock (START CONVERT) must be present during warmup periods. The device must be continuously converting during this time. There is a slight degradation in performance when using ±12V supplies. ➃ Effective bits is equal to: (SNR + Distortion) – 1.76 + Full Scale Amplitude 20 log Actual Input Amplitude 6.02 ➁ See Ordering Information for 0 to +10V input range. Contact DATEL for availability of other input voltage ranges. ➄ This is the time required before the A/D output data is valid after the analog input is back within the specified range. ➂ A 1MHz clock with a 200ns wide start convert pulse is used for all production testing. For applications requiring less than a 1MHz sampling rate, wider start convert pulses can be used. See Timing Diagram for more details. need for external calibration. If required, the device's small initial offset and gain errors can be reduced to zero using the input circuit of Figure 2. When using this circuit, or any similar offset and gain-calibration hardware, make adjustments following warmup. To avoid interaction, always adjust offset before gain. TECHNICAL NOTES 1. Obtaining fully specified performance from the ADS-927 requires careful attention to pc-card layout and power supply decoupling. The device’s analog and digital ground systems are connected to each other internally. For optimal performance, tie all ground pins (14, 19 and 23) directly to a large analog ground plane below the package. 3. When operating the ADS-927 from ±12V supplies, do not drive external circuitry with the REFERENCE OUTPUT. The reference's accuracy and drift specifications may not be met, and loading the circuit may cause accuracy errors within the converter. Bypass all power supplies and the REFERENCE OUTPUT (pin 21) 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. If the user-installed offset and gain adjusting circuit in Figure 2 is used, also locate it as close to the ADS-927 as possible. 4. Applying a start convert pulse while a conversion is in progress (EOC = logic "1") initiates a new and inaccurate conversion cycle. Data for the interrupted and subsequent conversions will be invalid. 2. The ADS-927 achieves its specified accuracies without the 3 ® ® ADS-927 CALIBRATION PROCEDURE Zero/Offset Adjust Procedure (Refer to Figures 2 and 3) 1. Apply a train of pulses to the START CONVERT input (pin 16) so the converter is continuously converting. If using LED's on the outputs, a 200kHz conversion rate will reduce flicker. Any offset and/or gain calibration procedures should not be implemented until devices are fully warmed up. To avoid interaction, offset must be adjusted before gain. The ranges of adjustment for the circuit of Figure 2 are guaranteed to compensate for the ADS-927's initial accuracy errors and may not be able to compensate for additional system errors. 2. Apply +305µV to the ANALOG INPUT (pin 20). 3. Adjust the offset potentiometer until the output bits are a 1 and all 0's and the LSB flickers between 0 and 1. All fixed resistors in Figure 2 should be metal-film types, and multiturn potentiometers should have TCR’s of 100ppm/°C or less to minimize drift with temperature. Gain Adjust Procedure 1. Apply +4.999085V to the ANALOG INPUT (pin 20). A/D converters are calibrated by positioning their digital outputs exactly on the transition point between two adjacent digital output codes. This can be accomplished by connecting LED's to the digital outputs and adjusting 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. 2. Adjust the gain potentiometer until the output bits are all 1's and the LSB flickers between 1 and 0. Table 1. Zero and Gain Adjust INPUT VOLTAGE RANGE For the ADS-927, offset adjusting is normally accomplished at the point where the MSB is a 1 and all other output bits are 0's and the LSB just changes from a 0 to a 1. This digital output transition ideally occurs when the applied analog input is +½LSB (+305µV). ±5V OUTPUT CODING MSB LSB 11 11 11 10 01 00 00 00 +15V 20kΩ –15V SIGNAL INPUT 1.2MΩ 2kΩ GAIN ADJUST +15V 1.98kΩ To Pin 20 of ADS-927 50Ω GAIN ADJUST +FS –1½ LSB +305µV +4.999085V Table 2. Output Coding Gain adjusting is accomplished when all bits are 1's and the LSB just changes from a 1 to a 0. This transition ideally occurs when the analog input is at +full scale minus 1½ LSB's (+4.999085V). ZERO/ OFFSET ADJUST ZERO ADJUST +½ LSB 1111 1000 0000 0000 0000 1000 0000 0000 1111 0000 0000 0000 0000 0000 0000 0000 1111 0000 0000 0000 0000 0000 0001 0000 INPUT RANGE ±5V BIPOLAR SCALE +4.99939 +3.75000 +2.50000 0.00000 –2.50000 –3.75000 –4.99939 –5.00000 +FS –1 LSB +3/4 FS +1/2FS 0 –1/2FS –3/4FS –FS +1 LSB –FS Coding is offset binary; 1LSB = 610µV. –15V Figure 2. ADS-927 Calibration Circuit 18 BIT 1 (MSB) +5V + 4.7µF 13 17 BIT 2 12 BIT 3 14 DIGITAL GROUND 11 BIT 4 10 BIT 5 9 BIT 6 0.1µF ADS-927 24 –12V/–15V 4.7µF + 4.7µF 0.1µF 19, 23 6 BIT 9 5 BIT 10 4 BIT 11 ANALOG GROUND 0.1µF + 22 +12V/+15V 3 BIT 12 2 BIT 13 ANALOG 20 INPUT 0 to +10V 1 BIT 14 (LSB) 15 EOC 21 +10V REF. OUT 0.1µF + START 16 CONVERT 4.7µF Figure 3. Typical ADS-927 Connection Diagram 4 8 BIT 7 7 BIT 8 ® ® ADS-927 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. N START CONVERT 200ns ±25ns 10ns typ. INTERNAL S/H N+1 Acquisition Time Hold 610ns typ. 390ns ±55ns 10ns typ. 70ns ±10ns Conversion Time EOC 480ns ±20ns 35ns max. 150ns max. OUTPUT DATA Data (N – 1) Valid Data N Valid (850ns min.) Invalid Data Notes: 1. fs = 1MHz. 2. The ADS-927 is a pulse-triggered device. Its internal operations are triggered by both the rising and falling edges of the start convert pulse. When sampling at 1MHz, the start pulse must be between 175 and 225nsec wide. For lower sampling rates, wider start pulses may be used, however, a minimum pulse width low of 50nsec must be maintained. Figure 4. ADS-927 Timing Diagram 5 ANALOG INPUT 3 5 7 9 11 13 15 17 19 21 23 4 6 8 10 12 14 16 18 20 22 24 6 SG1 26 50 +15V 3 2 C11 2.2MF P3 +15V -15V C10 0.1MF +5V .1% R4 1.98K 1.2M 5% START CONVERT GAIN ADJ R1 C1 0.1MF + - 0.1% 2 1 -15V C12 0.1MF C9 2.2MF 6 AD845 C6 2.2MF 4 -15V U5 C4 7 2.2MF +15V R5 2K C2 15pF 3 74LS86 2.2MF C14 C15 0.1MF +5V 13 12 10 9 24 23 22 21 20 19 18 17 16 15 14 13 5 4 2 3 4 5 6 7 8 9 10 11 12 74LS86 U4 B14 1 B13 B12 ADS-926/927 -15V AGND +15V B11 B10 B9 B8 B7 B6 B5 B4 B3 C8 2.2MF U1 +10VREF INPUT AGND B1 B2 11 8 74LS86 STRTCONV EOC' DGND +5V C7 0.1MF U4 U4 74LS86 6 Figure 5. ADS-927 Evaluation Board Schematic U4 7 14 +5V C5 0.1 MF C3 0.1MF COG C13 0.1MF + 25 1 2 P1 P4 -15V R2 20K R3 + + + OFFSET ADJ + + +15V 11 18 17 14 13 8 7 4 3 CLK 8D 7D 6D 5D 4D 3D 2D 1D OC 8Q 7Q 6Q 5Q 4Q 10 OC 8Q 7Q 6Q 5Q 4Q 3Q 2Q 1Q 20 U3 1 19 16 15 12 9 6 5 1 19 16 15 12 9 6 5 2 C17 0.1MF 10 U2 3Q 2Q 1Q 2 C16 0.1MF 20 +5V CLK 8D 7D 6D 5D 4D 3D 2D 1D 74ALS534 11 18 17 14 13 8 7 4 3 74ALS534 +5V N/C N/C B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 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 ® ® ADS-927 ® ® ADS-927 0 –20 –30 –40 –50 –60 –70 –80 –90 –100 –110 –120 –130 –140 –150 0 50 100 150 200 250 300 350 400 450 Frequency (kHz) (fs = 1MHz, fin = 480kHz, Vin = –0.5dB, 16,384-point FFT) Figure 6. ADS-927 FFT Analysis DNL (LSB's) +0.71 Number of Occurrences Amplitude Relative to Full Scale (dB) –10 0 –0.49 0 0 Digital Output Code 16,384 Digital Output Code Figure 7. ADS-927 Histogram and Differential Nonlinearity 7 16,384 500 ® ® ADS-927 MECHANICAL DIMENSIONS INCHES (mm) 1.31 MAX. (33.27) 24-Pin DDIP Versions 24 Dimension Tolerances (unless otherwise indicated): 2 place decimal (.XX) ±0.010 (±0.254) 3 place decimal (.XXX) ±0.005 (±0.127) 13 Lead Material: Kovar alloy 0.80 MAX. (20.32) ADS-927MC ADS-927MM ADS-927/883 ADS-917MC ADS-917MM 1 Lead Finish: 50 microinches (minimum) gold plating over 100 microinches (nominal) nickel plating 12 0.100 TYP. (2.540) 1.100 (27.940) 0.235 MAX. (5.969) PIN 1 INDEX 0.200 MAX. (5.080) 0.010 (0.254) 0.190 MAX. (4.826) 0.100 (2.540) 0.600 ±0.010 (15.240) SEATING PLANE 0.025 (0.635) 0.040 (1.016) 0.018 ±0.002 (0.457) +0.002 –0.001 0.100 (2.540) 1.31 MAX. (33.02) 24-Pin Surface Mount Versions Dimension Tolerances (unless otherwise indicated): 2 place decimal (.XX) ±0.010 (±0.254) 3 place decimal (.XXX) ±0.005 (±0.127) 13 24 0.80 MAX. (20.32) ADS-927GC ADS-927GM ADS-917GC ADS-917GM 1 0.190 MAX. (4.826) Lead Material: Kovar alloy Lead Finish: 50 microinches (minimum) gold plating over 100 microinches (nominal) nickel plating 12 0.020 TYP. (0.508) 0.060 TYP. (1.524) 0.130 TYP. (3.302) PIN 1 INDEX 0.100 (2.540) 0.100 TYP. (2.540) 0.020 (0.508) 0.015 (0.381) MAX. radius for any pin 0.010 TYP. (0.254) 0.040 (1.016) ORDERING INFORMATION MODEL NUMBER ADS-927MC ADS-927MM ADS-927/883 ADS-927GC ADS-927GM ADS-917MC ADS-917MM ADS-917GC ADS-917GM ® OPERATING TEMP. RANGE 0 to +70°C –55 to +125°C –55 to +125°C 0 to +70°C –55 to +125°C 0 to +70°C –55 to +125°C 0 to +70°C –55 to +125°C ® ANALOG INPUT Bipolar (±5V) Bipolar (±5V) Bipolar (±5V) Bipolar (±5V) Bipolar (±5V) Unipolar (0 to +10V)* Unipolar (0 to +10V)* Unipolar (0 to +10V)* Unipolar (0 to +10V)* ACCESSORIES ADS-B926/927 HS-24 Receptacles for PC board mounting can be ordered through AMP Inc. Part #3-331272-8 (Component Lead Socket), 24 required. For MIL-STD-883 product specifications, contact DATEL. * For information, see ADS-917 data sheet. 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 Evaluation Board (without ADS-927) Heat Sinks for all ADS-917/927 DDIP models I S T E R E D DS-0246E 11/96 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.