ADS-941 14-Bit, 1MHz Sampling A/D Converters PRODUCT OVERVIEW 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 fastsettling 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. 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 The ADS-941 is optimized for wideband frequency-domain applications and is fully FFT tested. Total harmonic distortion (THD) and signalto-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. INPUT/OUTPUT CONNECTIONS PIN FUNCTION PIN FUNCTION 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 +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 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 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) BLOCK DIAGRAM DAC 31 BIT 1 OUT (MSB) 30 BIT 1 OUT (MSB) 29 BIT 2 OUT REGISTER OFFSET ADJUST 5 S2 FLASH ADC BIPOLAR 2 BUFFER S/H REGISTER ANALOG INPUT 3 S1 3-STATE OUTPUT REGISTER OFFSET CIRCUIT 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 6, 14, 15 13 8 SIGNAL GROUND +5V SUPPLY DIGITAL GROUND +15V SUPPLY ANALOG GROUND –5V SUPPLY CODING SELECT Figure 1. ADS-941 Functional Block Diagram DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: [email protected] 17 Aug 2015 MDA_ADS-941.B04 Page 1 of 5 ADS-941 14-Bit, 1MHz Sampling A/D Converters 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) OUTPUTS LIMITS 0 to +16 0 to –16 0 to +6.0 –0.3 to +VDD +0.3 ±25 300 UNITS Volts Volts Volts Volts Volts °C FUNCTIONAL SPECIFICATIONS (TA = +25°C, ±VCC = ±15V ±VDD = +5V, 1MHz sampling rate, and a minimum 7 minute warmup ➀ 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" MIN. TYP. MAX. UNITS — — 2.2 — 0 to +10 ±5 2.5 7 — — — 15 Volts Volts kW pF +2.0 — — — PERFORMANCE Integral Non-Linearity (fin = 10KHz) +25°C 0 to +70°C –40 to +100°C Differential Non-Linearity (fin = 10KHz) +25°C 0 to +70°C –40 to +100°C Full Scale Absolute Accuracy +25°C 0 to +70°C –40 to +100°C Unipolar Zero Error +25°C (see Figure 3) 0 to +70°C –40 to +100°C Bipolar Zero Error +25°C (see Figure 3) 0 to +70°C –40 to +100°C Bipolar Offset Error +25°C (see Figure 3) 0 to +70°C –40 to +100°C Gain Error +25°C (see Figure 3) 0 to +70°C –40 to +100°C No Missing Codes (fin = 500kHz) 14 Bits Resolution — — — — — +0.5 +5 –600 Volts Volts μA μA — — — ±1 ±1.5 ±2 ±2 ±2 ±3 LSB LSB LSB –0.75 –0.95 –1 ±0.5 ±0.75 ±0.95 ±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 ±0.12 ±0.3 ±0.8 %FSR %FSR %FSR — — — ±0.018 ±0.12 ±0.6 ±0.122 ±0.3 ±0.8 %FSR %FSR %FSR 0 to +70°C 14 Bits MIN. TYP. MAX. UNITS Staight Bin./Offset Bin./Two's Comp. Comp. Bin./Comp. Offset Bin./C2C Output Coding Logic Level Logic "1" Logic "0" Logic Loading "1" Logic Loading "0" Internal Reference Voltage, +25°C 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 c 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 Operating Temp. Range, Case ADS-941MC, MC-C ADS-941ME, ME-C Storage Temperature Range Package Type Weight +2.4 — — — — — — — — +0.4 –160 +6.4 Volts Volts μA mA +9.98 — — +10.0 ±13 — +10.02 ±30 5 Volts ppm/°C mA — — — — ±250 — — 250 — 10 ±10 350 V/μs ns ps ns –78 –77 –85 –80 — — dB dB — 76 90 85 — — dB dB 74 72 80 75 — — dB dB 78 77 86 83 — — dB dB — –85 — dB — — — — 1 — 6 1.75 87 1000 — 250 — — — 2000 — — MHz MHz dB ns MHz μVrms +14.25 –14.25 +4.75 +15.0 –15.0 +5.0 +15.75 –15.75 +5.25 Volts Volts Volts — — — — — +65 –80 +140 2.8 — +87 –105 +185 3.5 ±0.02 mA mA mA Watts %FSR%V 0 — +70 °C –40 — +100 °C –65 — +150 °C 32-pin, metal-sealed, ceramic TDIP 0.46 ounces (13 grams) Footnote: c Same specification as In-Band Harmonics and Peak Harmonics. DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: [email protected] 17 Aug 2015 MDA_ADS-941.B04 Page 2 of 5 ADS-941 14-Bit, 1MHz Sampling A/D Converters TECHNICAL NOTES THERMAL REQUIREMENTS 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. 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. 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. 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. 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 pullup 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). Removing System Errors 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. Use external potentiometers to remove system errors or to reduce the small initial errors to zero. Use a 100W trimpot in series with the analog input for gain adjustment. Use a fixed 50W resistor instead of the trimpot for operation without adjustment. Use a 20kW 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. 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. INPUT RANGE ZERO ADJUST +½ LSB GAIN ADJUST FS –1½ LSB 0 to +10V +305μV +9.999085V ±5V +305μV +4.999085V Table 2. Zero and Gain Adjustments N+1 N START CONVERT 50ns min., 100ns max 35ns max. 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 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. Conversion Time 600ns typ. EOC 10ns typ. Aquisition Time INTERNAL S/H Hold OUTPUT DATA DATA N-1 VALID 350ns max. 30ns max. INVALID DATA DATA N VALID 400ns max. 600ns min. Scale is approximately 50ns per division. Figure 2. ADS-941 Timing Diagram INPUT RANGE INPUT PIN TIE TOGETHER 0 +10V Pin 3 Pins 2 and 4 ±5V Pin 3 Pins 1 and 2 Table 1. Input Connections DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: [email protected] 17 Aug 2015 MDA_ADS-941.B04 Page 3 of 5 ADS-941 14-Bit, 1MHz Sampling A/D Converters ZERO/OFFSET ADJUST 20kΩ +5V +5V 0.1μF 4.7μF 4.7μF 4.7μF 0.1μF 6, 14, 15 ANALOG GROUND 13 GAIN ADJUST ADS-941 7 OVERFLOW 16 EOC ANALOG INPUT 3 0 to +10V 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) 12 0.1μF + –15V 5 OFFSET ADJUST 10 DIGITAL 11 GROUND + +15V –5V 100Ω 4 SIGNAL GROUND 8 CODING SELECT 1 +10V REF. OUT 0.1μF START CONVERT 32 ENABLE 9 BIPOLAR 2 4.7μF Figure 3. Typical ADS-941 Connection Diagram 0 Amplitude Relative to Full Scale (dB) –10 –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) Figure 4. ADS-941 FFT Analysis DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: [email protected] 17 Aug 2015 MDA_ADS-941.B04 Page 4 of 5 ADS-941 14-Bit, 1MHz Sampling A/D Converters STRAIGHT 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 RANGE 0 to +10V +9.999390 +8.750000 +7.500000 +5.000000 +2.500000 +1.250000 +0.000610 0.000000 COMP. BINARY OUTPUT CODING MSB LSB MSB LSB MSB LSB 11 1111 1111 1111 00 0000 0000 0000 01 1111 1111 1111 11 1000 0000 0000 00 0111 1111 1111 01 1000 0000 0000 11 0000 0000 0000 00 1111 1111 1111 01 0000 0000 0000 10 0000 0000 0000 01 1111 1111 1111 00 0000 0000 0000 01 0000 0000 0000 10 1111 1111 1111 11 0000 0000 0000 00 1000 0000 0000 11 0111 1111 1111 10 1000 0000 0000 00 0000 0000 0001 11 1111 1111 1110 10 0000 0000 0001 00 0000 0000 0000 11 1111 1111 1111 10 0000 0000 0000 OFFSET BINARY COMP. OFF. BIN. TWO'S COMP. Table 3. Output Coding INPUT RANGE ±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 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 1.11 MAX. (28.19) 1 Lead Finish: 50 microinches (minimum) gold plating over 100 microinches (nominal) nickel plating 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 ADS-941MC ADS-941MC-C ADS-941ME ADS-941ME-C OPERATING TEMP. RANGE 0 to +70°C 0 to +70°C –40 to +100°C –40 to +100°C PACKAGE ROHS ACCESSORIES TDIP TDIP TDIP TDIP No Yes No Yes 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. DATEL is a registered trademark of DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA DATEL, 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. ITAR and ISO 9001/14001 REGISTERED © 2015 DATEL, Inc. www.datel.com • e-mail: [email protected] 17 Aug 2015 MDA_ADS-941.B04 Page 5 of 5