ADS-943MM

® ® ADS-943 14-Bit, 3MHz, Low-Distortion Sampling A/D Converters FEATURES • • • • • • • • • 14-bit resolution 3MHz minimum sampling rate Ideal for both frequency and time-domain applications Excellent peak harmonics, –83dB Excellent signal-to-noise ratio, 79dB No missing codes over full military temperature range ±5V supplies, 1.7 Watts Small, 24-pin ceramic DDIP or SMT Low cost PIN 1 2 3 4 5 6 7 8 9 10 11 12 INPUT/OUTPUT CONNECTIONS FUNCTION BIT1 (MSB) BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 BIT 8 BIT 9 BIT 10 BIT 11 BIT 12 PIN 24 23 22 21 20 19 18 17 16 15 14 13 FUNCTION ANALOG GROUND OFFSET ADJUST +5V ANALOG SUPPLY ANALOG INPUT –5V SUPPLY ANALOG GROUND START CONVERT EOC BIT 14 (LSB) BIT 13 DIGITAL GROUND +5V DIGITAL SUPPLY GENERAL DESCRIPTION The low-cost ADS-943 is a 14-bit, 3MHz sampling A/D converter optimized to meet the demanding dynamic-range and sampling-rate requirements of contemporary digital telecommunications applications. The ADS-943's outstanding dynamic performance is evidenced by a peak harmonic specification of –83dB and a signal-to-noise ratio (SNR) of 79dB. Additionally, the ADS-943 easily achieves the 2.2MHz minimum sampling rate required by digital receivers in certain ADSL, HDSL and ATM applications. The ADS-943 also addresses size and power constraints normally associated with these types of applications. This device requires just ±5V supplies, dissipates 1.7 Watts, and is packaged in a very small 24-pin DDIP. Although optimized for frequency-domain applications, the ADS-943's DNL and noise specifications are also outstanding, thereby making it an equally impressive device for time-domain applications (graphic and medical imaging, process control, etc.). In fact, the ADS-943 guarantees no missing codes to the 14-bit level over the full military operating temperature range. The functionally complete ADS-943 contains a fast-settling 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 unit is edge-triggered, requiring only the rising edge of a start convert pulse to initiate a conversion. The device is offered with a bipolar input range of ±2V. Models are available for use in either commercial (0 to +70°C) or military (–55 to +125°C) operating temperature ranges. A proprietary, auto-calibrating, error-correcting circuit allows the device to achieve specified performance over the full military temperature range. OFFSET ADJUST 23 BUFFER REGISTER ANALOG INPUT 21 – S/H + FLASH ADC 1 16 BIT 14 (LSB) 15 BIT 13 12 BIT 12 DIGITAL CORRECTION LOGIC 11 BIT 11 OUTPUT REGISTER 10 BIT 10 9 8 7 6 5 4 3 2 1 BIT 9 BIT 8 BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 (MSB) POWER AND GROUNDING REF +5V ANALOG SUPPLY +5V DIGITAL SUPPLY DIGITAL GROUND –5V SUPPLY ANALOG GROUND 22 13 14 20 19, 24 AMP FLASH ADC 2 REGISTER DAC Σ START CONVERT 18 EOC 17 TIMING AND CONTROL LOGIC Figure 1. ADS-943 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-943 ABSOLUTE MAXIMUM RATINGS PARAMETERS +5V Supply (Pins 13, 22) –5V Supply (Pin 20) Digital Input (Pin 18) Analog Input (Pin 21) Lead Temperature (10 seconds) LIMITS 0 to +6 0 to –6 –0.3 to +VDD +0.3 –5 to +5 +300 UNITS Volts Volts Volts Volts °C PHYSICAL/ENVIRONMENTAL PARAMETERS Operating Temp. Range, Case ADS-943MC, GC ADS-943MM, GM, 883, G/883 Thermal Impedance θjc θca Storage Temperature Range Package Type Weight MIN. 0 –55 TYP. — — MAX. +70 +125 UNITS °C °C — 6 — °C/Watt — 23 — °C/Watt –65 — +150 °C 24-pin,metal-sealed, ceramic DDIP or SMT 0.42 ounces (12 grams) FUNCTIONAL SPECIFICATIONS (TA = +25°C, ±VDD = ±5V, 3MHz sampling rate, and a minimum 3 minute warmup Œ unless otherwise specified.) +25°C ANALOG INPUT Input Voltage Range  Input Resistance Input Capacitance DIGITAL INPUT Logic Levels Logic "1" Logic "0" Logic Loading "1" Logic Loading "0" Start Convert Positive Pulse Width Ž STATIC PERFORMANCE Resolution Integral Nonlinearity (fin = 10kHz) Differential Nonlinearity (fin = 10kHz) Full Scale Absolute Accuracy Bipolar Zero Error (Tech Note 2) Gain Error (Tech Note 2) No Missing Codes (fin = 10kHz) DYNAMIC PERFORMANCE Peak Harmonics (–0.5dB) dc to 500kHz 500kHz to 1MHz 1MHz to 1.5MHz Total Harmonic Distortion (–0.5dB) dc to 500kHz 500kHz to 1MHz 1MHz to 1.5MHz Signal-to-Noise Ratio (w/o distortion, –0.5dB) dc to 500kHz 500kHz to 1MHz 1MHz to 1.5MHz Signal-to-Noise Ratio  (& distortion, –0.5dB) dc to 500kHz 500kHz to 1MHz 1MHz to 1.5MHz Noise Two-Tone Intermodulation Distortion (fin = 975kHz, 1.2MHz, fs = 3MHz, –0.5dB) Input Bandwidth (–3dB) Small Signal (–20dB input) Large Signal (–0dB input) Feedthrough Rejection (fin = 1.5MHz) Slew Rate Aperture Delay Time Aperture Uncertainty — — — — — — 76 76 75 73 73 73 — — — — — — — — –83 –83 –83 –80 –80 –80 79 79 78 77 77 77 125 –82 30 10 85 ±400 +5 2 –77 –77 –77 –76 –76 –76 — — — — — — — — — — — — — — — — — — — — 76 76 75 73 73 73 — — — — — — — — –83 –83 –83 –80 –80 –80 79 79 78 77 77 77 125 –82 30 10 85 ±400 +5 2 –77 –77 –77 –76 –76 –76 — — — — — — — — — — — — — — — — — — — — 75 74 74 71 71 71 — — — — — — — — –81 –81 –81 –78 –77 –77 78 77 77 75 75 74 125 –82 30 10 85 ±400 +5 2 –75 –75 –75 –74 –73 –73 — — — — — — — — — — — — — — dB dB dB dB dB dB dB dB dB dB dB dB µVrms dB MHz MHz dB V/µs ns ps rms — — –0.95 — — — 14 14 ±0.75 ±0.5 ±0.15 ±0.1 ±0.2 — — — +1.25 ±0.4 ±0.3 ±0.5 — — — –0.95 — — — 14 14 ±0.75 ±0.5 ±0.15 ±0.1 ±0.2 — — — +1.25 ±0.4 ±0.3 ±0.5 — — — –0.95 — — — 14 14 ±1 ±0.75 ±0.4 ±0.3 ±0.4 — — — +1.5 ±0.6 ±0.6 ±1.25 — Bits LSB LSB %FSR %FSR % Bits +2.0 — — — 10 — — — — 20 — +0.8 +20 –20 — +2.0 — — — 10 — — — — 20 — +0.8 +20 –20 — +2.0 — — — 10 — — — — 20 — +0.8 +20 –20 — Volts Volts µA µA ns MIN. — — — TYP. ±2 280 6 MAX. — — 15 MIN. — — — 0 to +70°C TYP. ±2 280 6 MAX. — — 15 MIN. — — — –55 to +125°C TYP. ±2 280 6 MAX. — — 15 UNITS Volts Ω pF 2 ® ® ADS-943 +25°C DYNAMIC PERFORMANCE cont. S/H Acquisition Time ( to ±0.003%FSR, 4V step) Overvoltage Recovery Time  A/D Conversion Rate DIGITAL OUTPUTS Logic Levels Logic "1" Logic "0" Logic Loading "1" Logic Loading "0" Output Coding POWER REQUIREMENTS Power Supply Ranges ‘ +5V Supply –5V Supply Power Supply Currents +5V Supply –5V Supply Power Dissipation Power Supply Rejection +4.75 –4.75 — — — — +5.0 –5.0 +210 –125 1.7 — +5.25 –5.25 +230 –145 1.9 ±0.05 +4.75 –4.75 — — — — +5.0 –5.0 +210 –125 1.7 — +5.25 –5.25 +230 –145 1.9 ±0.05 +4.9 –4.9 — — — — +5.0 –5.0 +210 –125 1.7 — +5.25 –5.25 +230 –145 1.9 ±0.05 Volts Volts mA mA Watts %FSR/%V +2.4 — — — — — — — — +0.4 –4 +4 +2.4 — — — — — — +0.4 — –4 — +4 Offset Binary +2.4 — — — — — — — — +0.4 –4 +4 Volts Volts mA mA MIN. — — 3 TYP. 208 100 — MAX. 215 333 — MIN. — — 3 0 to +70°C TYP. 208 100 — MAX. 215 333 — MIN. — — 3 –55 to +125°C TYP. 208 100 — MAX. 215 333 — UNITS ns ns MHz Footnotes: Œ All power supplies should be on before applying a start convert pulse. All supplies and the clock (start convert pulses) must be present during warmup periods. The device must be continuously converting during this time.  Contact DATEL for other input voltage ranges. Ž A 3MHz clock with a 20nsec positive pulse width is used for all production testing. When sampling at 3MHz, the start convert pulse must be between 10 and 110nsec wide or between 160 and 300nsec wide. The falling edge must not occur between 110 and 160nsec. For lower sampling rates, wider start pulses 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. This time is only guaranteed if the input does not exceed ±2.2V (S/H Saturation Voltage). ‘ The minimum supply voltages of +4.9V and –4.9V for ±VDD are required for –55°C operation only. The minumum limits are +4.75V and –4.75V when operating at +125°C. TECHNICAL NOTES 1. Obtaining fully specified performance from the ADS-943 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 24) directly to a large analog ground plane beneath the package. Bypass all power supplies 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. 2. The ADS-943 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 Figures 2 and 3. When using this circuitry, or any similar offset and gaincalibration hardware, make adjustments following warmup. To avoid interaction, always adjust offset before gain. GAIN ADJUST +5V SIGNAL INPUT 1.98kΩ 50Ω To Pin21 of ADS-943 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. 4. A passive bandpass filter is used at the input of the A/D for all production testing. 2k Ω –5V Figure 2. Optional ADS-943 Gain Adjust Calibration Circuit 3 ® ® ADS-943 CALIBRATION PROCEDURE 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 circuits in Figures 2 and 3 are guaranteed to compensate for the ADS-943'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 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. Offset adjusting for the ADS-943 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 +½ LSB (+122µV). 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 (+1.99963V). Zero/Offset Adjust Procedure 1. Apply a train of pulses to the START CONVERT input (pin 18) so the converter is continuously converting. 2. Apply +122µV to the ANALOG INPUT (pin 21). 3. Adjust the offset potentiometer until the output bits are 10 0000 0000 0000 and the LSB flickers between 0 and 1. –5V Gain Adjust Procedure 1. Apply +1.99963V to the ANALOG INPUT (pin 21). 2. 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 input signal to obtain the output coding listed in Table 2. Table 1. Gain and Zero Adjust INPUT VOLTAGE RANGE ±2V ZERO ADJUST +1/2 LSB +122µV GAIN ADJUST +FS –1½ LSB +1.99963V Table 2. Output Coding for Bipolar Operation BIPOLAR SCALE INPUT VOLTAGE (±2V RANGE) OFFSET BINARY MSB LSB +FS – 1 LSB +3/4FS +1/2FS 0 –1/2 FS –3/4 FS –FS +1 LSB –FS +1.99976 +1.50000 +1.00000 0.00000 –1.00000 –1.50000 1.99976 –2.00000 11 11 11 10 01 00 00 00 1111 1000 0000 0000 0000 1000 0000 0000 1111 0000 0000 0000 0000 0000 0000 0000 1111 0000 0000 0000 0000 0000 0001 0000 +5V Œ 4.7µF + 4.7µF 4.7µF ++ 0.1µF 0.1µF 0.1µF 19 ANALOG INPUT +5V ZERO/ OFFSET ADJUST –5V START CONVERT 18 20 24 22, 13 14 21 23 20kΩ ADS-943 1 2 3 4 5 6 7 8 9 10 11 12 15 16 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 (LSB) EOC Œ A single +5V supply should be used for both the +5V analog and +5V digital. If separate supplies are used, the difference between the two cannot exceed 100mV. Figure 3. Connection Diagram 4 ® ® ADS-943 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. 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. 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. N START CONVERT 20ns typ. 333nsec 10ns typ. INTERNAL S/H 125ns typ. Hold Acquisition Time 208ns typ. 215ns max. N+1 125ns typ. 35ns typ. EOC 130ns Conversion Time 120ns min., 130ns typ., 140ns max. 30ns typ. 10ns max. OUTPUT DATA Data N-1 Valid Data N Valid 283ns typ. Invalid Data Data N+1 Valid 50ns typ. Note: 1. Scale is approximately 20ns per division. Sampling rate = 3MHz. 2. The start convert positive pulse width must be between either 10 and 110nsec or 160 and 300nsec (when sampling at 3MHz) to ensure proper operation. For sampling rates lower than 3MHz, the start pulse can be wider than 300nsec, however a minimum pulse width low of 30nsec should be maintained. A 3MHz clock with a 20nsec positive pulse width is used for all production testing. Figure 4. ADS-943 Timing Diagram 5 OPTION +15V +5VA ADS-943 SG5 SG6 C18 R2 0.1µF (Optional) 11 U4 +5VF (Optional) C19 0.1µF (Optional) +5VF C17 0.1µF + 1 3 U5 20 74HCT86 74HCT573 2.2µF 2 C21 SG9 14 -5VA X1 + P4 P3 C23 +5VF 3MHz CRYSTAL 0.1µF C24 + 5 (Optional) 4 – START CONV. 10 CLC402 HI2541 ANA. IN 6 + ANA. IN SG7 +5VF -15V C26 C25 7 3.2k HCT7474 15pF 0.1µF 2.2µF C27 7 8 SG8 L1 + 20µH C8 0.01µF 2.2µF 14 4 JPR1 PR 5 2 D U6 Q 6 3 1 23 CK Q 1 R3 CLR C1 2.2µF L2 20µH C9 –5V –5V ANA. IN +5VA U1 OFFSET ADJUST +15V R1 C10 0.01µF -15V 2 20k C22 + 2.2µF C16 0.1µF 0.01µF +5V START CONVERT SG4 C2 + 2.2µF L3 2 3 4 5 6 7 8 9 11 Q1 1D 2D Q2 Q3 3D 4D Q4 5D U3 Q5 6D Q6 Q7 7D Q8 8D OE CE 10 19 18 17 16 15 14 13 12 1 20µH + C3 +5VF 2.2µF L4 C20 C11 –5VA 0.1µF 0.01µF ADS-943 + + + + 6 +5V C12 –15V 0.01µF +15V SPARE GATES C13 +5VF 0.01µF +5VA U6 12 13 7 GND 74HCT86 4 5 U5 6 U5 11 Q 9 8 C14 0.01µF HCT7474 14 0.1µF +5VF C15 9 U5 10 8 10 12 11 13 PR D CK CLR 20 20µH C4 2.2µF 24 23 22 21 20 19 18 17 16 15 14 13 AGND BIT1 1 OFFSET BIT2 2 +5VA BIT3 3 AIN BIT4 4 -5V BIT5 5 AGND BIT6 6 TRIG BIT7 7 EOC BIT8 8 BIT14 BIT9 9 BIT13 BIT10 10 DGND BIT11 11 +5VD BIT12 12 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 TRIG JPR2 1 23 CE 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 P1 33 31 29 27 25 23 21 19 17 15 13 11 9 7 5 3 1 L5 20µH C5 2 3 4 5 6 7 8 9 11 2.2µF Q1 1D 2D Q2 Q3 3D 4D Q4 U2 Q5 5D 6D Q6 Q7 7D Q8 8D OE CE 10 19 18 17 16 15 14 13 12 1 74HCT573 26 24 22 20 18 16 14 12 10 8 6 4 2 25 23 21 19 17 15 13 11 9 7 5 3 1 L6 P2 20µH C6 74HCT86 SG1 2.2µF L7 SG2 20µH C7 NOTES: 1. UNLESS OTHERWISE SPECIFIED ALL CAPACITORS ARE 50V. C1 - C7 ARE 20V. ALL RESISTORS ARE IN OHMS. SG3 2.2µF SG10 ® 2. CLOSE SG1-SG3, SG9, SG10. 3. SEE DATEL DWG A-24546 FOR ADDITIONAL INFORMATION ON ADS-B946 EVALUATION BOARD. Figure 5. ADS-943 Evaluation Board Schematic ® ® ® ADS-943 0 –10 Amplitude Relative to Full Scale (dB) –20 –30 –40 –50 –60 –70 –80 –90 –100 –110 –120 –130 –140 –150 0 150 kHz 300 kHz 450 kHz 600 kHz 750 kHz 900 kHz 1.05 MHz 1.20 MHz 1.35 MHz 1.5 MHz Frequency (fs = 3MHz, fin = 1.485MHz, Vin = –0.5dB, 16,384-point FFT) Figure 6. FFT Analysis of ADS-943 +0.60 DNL (LSB's) 0.00 Number of Occurences –0.58 0 Digital Output Code 16,384 0 Digital Output Code 16,384 Figure 7. ADS-943 Histogram and Differential Nonlinearity 7 ® ® ADS-943 MECHANICAL DIMENSIONS INCHES (mm) 1.31 MAX. (33.27) 24-Pin DDIP Versions ADS-943MC ADS-943MM ADS-943/883 24 13 0.80 MAX. (20.32) 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 Lead Finish: 50 microinches (minimum) gold plating over 100 microinches (nominal) nickel plating 1 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) 0.018 ±0.002 (0.457) 0.100 (2.540) 0.040 (1.016) +0.002 –0.001 SEATING PLANE 0.025 (0.635) 0.600 ±0.010 (15.240) 0.100 (2.540) 1.31 MAX. (33.02) 24-Pin Surface Mount Versions ADS-943GC ADS-943GM ADS-943G/883 24 13 Dimension Tolerances (unless otherwise indicated): 2 place decimal (.XX) ±0.010 (±0.254) 3 place decimal (.XXX) ±0.005 (±0.127) 0.80 MAX. (20.32) Lead Material: Kovar alloy Lead Finish: 50 microinches (minimum) gold plating over 100 microinches (nominal) nickel plating 1 12 0.190 MAX. (4.826) 0.020 TYP. (0.508) PIN 1 INDEX 0.060 TYP. (1.524) 0.130 TYP. (3.302) 0.015 (0.381) MAX. radius for any pin 0.100 (2.540) 0.100 TYP. (2.540) 0.040 (1.016) 0.020 (0.508) 0.010 TYP. (0.254) ORDERING INFORMATION MODEL ADS-943MC ADS-943MM ADS-943/883 ADS-943GC ADS-943GM ADS-943G/883 OPERATING TEMP. RANGE 0 to +70°C –55 to +125°C –55 to +125°C 0 to +70°C –55 to +125°C –55 to +125°C 24-PIN PACKAGE DDIP DDIP DDIP SMT SMT SMT ACCESSORIES ADS-B943 HS-24 Evaluation Board (without ADS-943) Heat Sink for all ADS-943 DDIP models 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 specifcation, contact DATEL. ® ® ISO 9001 R E G I S T E R E D DS-0333A 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 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.