ADS-942ME - Datel, Inc. - Datasheet.Live

® ® ADS-942

14-Bit, 2MHz

Sampling A/D Converters

FEATURES

•14-bit resolution

•2MHz minimum throughput

•Functionally complete

•Internal reference and sample/hold

•-85dB total harmonic distortion

•78dB signal-to-noise ratio

•Full Nyquist-rate sampling

•Small 32-pin DIP

•Low-power, 2.9 Watts

GENERAL DESCRIPTION

DATEL's ADS-942 is a functionally complete, 14-bit, 2MHz,

sampling A/D converter. Its standard, 32-pin, triple-wide

ceramic DIP contains a fast-settling sample/hold amplifier, a

14-bit subranging (two-pass) A/D converter, a precision

reference, three-state output register and all the timing and

control logic necessary to operate from a single start

convert pulse.

The ADS-942 is optimized for wideband frequency-domain

applications and is fully FFT tested. The ADS-942 requires

±15V and +5V supplies and typically consumes 2.9 Watts.

INPUT/OUTPUT CONNECTIONS

1+10V REF. OUT 32 START CONVERT

2BIPOLAR 31 BIT 1 OUT (MSB)

3ANALOG INPUT 30 BIT 1 OUT (MSB)

4SIGNAL GROUND 29 BIT 2 OUT

5OFFSET ADJUST 28 BIT 3 OUT

6ANALOG GROUND 27 BIT 4 OUT

7OVERFLOW26 BIT 5 OUT

8CODING SELECT 25 BIT 6 OUT

9ENABLE 24 BIT 7 OUT

10 +5V SUPPLY23 BIT 8 OUT

11 DIGITAL GROUND 22 BIT 9 OUT

12 +15V SUPPLY21 BIT 10 OUT

13 –15V SUPPLY20 BIT 11 OUT

14 ANALOG GROUND 19 BIT 12 OUT

15 ANALOG GROUND 18 BIT 13 OUT

16 EOC 17 BIT 14 OUT (LSB)

PIN FUNCTION PIN FUNCTION

Figure 1. ADS-942 Functional Block Diagram

REF

REGISTERREGISTER

31 BIT 1 OUT (MSB)

30 BIT 1 OUT (MSB)

29 BIT 2 OUT

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)

TIMING AND

CONTROL LOGIC

+10V REF. OUT 1

START CONVERT 32

EOC 16

DIGITAL CORRECTION LOGIC

DAC

FLASH

ADC

BUFFER

ANALOG INPUT 3

SIGNAL

GROUND

DIGITAL

GROUND

+15V

SUPPLY

3-STATE OUTPUT REGISTER

S/H

OFFSET

CIRCUIT

BIPOLAR 2

OFFSET ADJUST 5

+5V

SUPPLY

6, 14, 15

ANALOG

GROUND

CODING

SELECT

–15V

SUPPLY

9 ENABLE

7 OVERFLOW

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-942

FUNCTIONAL SPECIFICATIONS

(TA = +25°C, ±VCC = ±15V, +VDD = +5V, 2MHz sampling rate, and a minimum 7 minute

warmup unless otherwise specified.)

ANALOG INPUTS MIN. TYP. MAX. UNITS

Input Voltage Range

Unipolar —0 to +10 —Volts

Bipolar —±5 —Volts

Input Impedence 4.9 5—kΩ

Input Capacitance —7 15 pF

DIGITAL INPUTS

Logic Levels

Logic "1" +2.0 — — Volts

Logic "0" — — +0.8 Volts

Logic Loading "1" — — +5 µA

Logic Loading "0" — — –600 µA

PERFORMANCE

Integral Non-Linearity

(fin = 1MHz)

+25°C —±1 ±2 LSB

0 to +70°C —±1 ±2 LSB

–40 to +85°C —±2 ±3 LSB

Differential Non-Linearity

(fin = 1MHz)

+25°C –0.75 ±0.5 ±0.75 LSB

0 to +70°C –0.95 ±0.75 ±1.25 LSB

–40 to +85°C –1 ±1 +2.5 LSB

Full Scale Absolute Accuracy

+25°C —±0.1 ±0.122 %FSR

0 to +70°C —±0.12 ±0.36 %FSR

–40 to +85°C —±0.45 ±0.85 %FSR

Unipolar Zero Error

+25°C (see Figure 3) —±0.05 ±0.122 %FSR

0 to +70°C —±0.1 ±0.2 %FSR

–40 to +85°C —±0.2 ±0.3 %FSR

Bipolar Zero Error

+25°C (see Figure 3) —±0.05 ±0.122 %FSR

0 to +70°C —±0.1 ±0.2 %FSR

–40 to +85°C —±0.2 ±0.3 %FSR

Bipolar Offset Error

+25°C (see Figure 3) —±0.1 ±0.2 %FSR

0 to +70°C —±0.12 ±0.3 %FSR

–40 to +85°C —±0.5 ±0.8 %FSR

Gain Error

+25°C (see Figure 3) —±0.018 ±0.122 %

0 to +70°C —±0.12 ±0.3 %

–40 to +85°C —±0.6 ±0.8 %

No Missing Codes (fin = 500kHz)

14 Bits 0 to +70°C

13 Bits –40 to +85°C

Resolution 14 Bits

OUTPUTS MIN. TYP. MAX. UNITS

Output Coding Staight Bin./Offset Bin./2's Comp.

Comp. Bin./Comp. Offset Bin./C2C

Logic Level

Logic "1" +2.4 — — Volts

Logic "0" — — +0.4 Volts

Logic Loading "1" — — –160 µA

Logic Loading "0" — — +6.4 mA

Internal Reference

Voltage, +25°C +9.98 +10.0 +10.02 Volts

Drift —±13 ±30 ppm/°C

External Current — — 5mA

DYNAMIC PERFORMANCE

Total Harm. Distort. (–0.5dB)

dc to 100kHz —–85 –76 dB

100kHz to 500kHz —–80 –75 dB

500kHz to 1MHz —–77 —dB

Signal-to-Noise Ratio

(w/o distortion, –0.5dB

dc to 100kHz 74 78 —dB

100kHz to 500kHz 73 75 —dB

500kHz to 1MHz —73 —dB

Signal-to-Noise Ratio

(and distortion, –0.5dB)

dc to 100kHz 73 78 —dB

100kHz to 500kHz 72 75 —dB

500kHz to 1MHz —72 —dB

Spurious Free Dyn. Range ➀

dc to 100kHz —–86 –77 dB

100 to 500kHz —–81 –75 dB

500kHz to 1MHz —–78 —dB

Two-tone IMD

Distortion (fin = 100kHz,

240kHz, fs = 2.0Mhz,

–0.5dB) –85 — — dB

Input Bandwidth (–3dB)

Small Signal (–20dB input) —6—MHz

Large Signal (–0.5dB input) —1.75 —MHz

Slew Rate —±250 —V/µs

Aperture Delay Time — — ±10 ns

Aperature Uncertainty — — 5ps, ms

S/H Acq. Time, (to ±0.003%FSR)

Sinusoidal (fin = 1MHz) —120 150 ns

Step input —250 450 ns

Conversion Rate

Sinusoidal (fin = 1MHz) 2— — MHz

Step input 1.3 — — MHz

Feedthrough Rejection

(fin = 1MHz) —85 —dB

Overvoltage Recovery, ±12V —1000 2000 ns

Noise —250 —µVrms

POWER REQUIREMENTS

Power Supply Ranges

+15V Supply +14.25 +15.0 +15.75 Volts

–15V Supply –14.25 –15.0 –15.75 Volts

+5V Supply +4.75 +5.0 +5.25 Volts

Power Supply Currents

+15V Supply —+65 +87 mA

–15V Supply —–80 –98 mA

+5V Supply —+150 +165 mA

Power Dissipation —2.9 3.4 Watts

Power Supply Rejection — — ±0.02 %FSR%V

PHYSICAL/ENVIRONMENTAL

Operating Temp. Range, Case

ADS-942MC 0—+70 °C

ADS-942ME –40 —+85 °C

Storage Temperature Range –65 —+150 °C

Package Type 32-pin, metal-sealed, ceramic TDIP

Weight 0.46 ounces (13 grams)

ABSOLUTE MAXIMUM RATINGS

PARAMETERS LIMITS UNITS

+15V Supply (Pin 12) 0 to +16 Volts

–15V Supply (Pin 13) 0 to –16 Volts

+5V Supply (Pin 10) 0 to +6 Volts

Digital Inputs (Pin 8,9, 32) –0.3 to +VDD +0.3 Volts

Analog Input (Pin 3) ±15 Volts

Lead Temp. (10 seconds) +300 °C

Footnote:

➀Same specification as In-Band Harmonics and Peak Harmonics.

® ® ADS-942

For unipolar, 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.

3. Full-Scale Adjustment

Set the output of the voltage reference used in step 2 to the

value shown in Table 2.

Table 2. Zero and Gain Adjustments

Input Zero Adjust Gain Adjust

Range +1/2 LSB FS – 1½ LSB

0 to +10V +305µV +9.999085V

±5V +305µV +4.999085V

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.

TECHNICAL NOTES

1. Rated performance requires using good high-frequency

circuit board layout techniques. Connect the digital and

analog grounds to one point, the analog ground plane

beneath the converter. Due to the inductance and resis-

tance of the power supply return paths, return the analog

and digital ground separately to the power supplies.

SIGNAL GROUND (pin 4) is not internally connected to

ANALOG GROUND (pins 6, 15).

2. Bypass the analog and digital supplies and the +10V REF.

OUT (pin 1) to ground with a 4.7µF, 25V tantalum electro-

lytic capacitor in parallel with a 0.1µF ceramic capacitor.

3. CODING SELECT(pin 8) is compatible with CMOS/TTL

logic levels for those users desiring logic control of this

function. There is an internal pull-up resistor on this pin;

connect to +5V or leave open for logic 1. See the Calibra-

tion 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).

Figure 2. ADS-942 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

CALIBRATION PROCEDURE

1. Connect the converter per Figure 3 and Table 1 for the

appropriate input voltage range. Apply a pulse of 35

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.

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.

Note: Scale is approximately 25ns per division.

START

CONVERT

INTERNAL S/H

NN+1

35ns max..

EOC

10ns typ.

15ns max.

OUTPUT

DATA DATA N VALID

300ns min.

Hold

DATA N-1 VALID

30ns max.

35ns min., 50ns typ., 60 ns max

35ns typ.

350ns min. 150ns max.

Aquisition Time

INVALID DATA

200ns max.

Conversion Time

300ns typ., 325ns max.

® ®

ADS-942

Removing System Errors

Use external potentiometers to remove system errors or to

reduce the small initial errors to zero. Use a 100Ω trimpot in

series with the analog input for gain adjustment. Use a fixed

50Ω resistor instead of the trimpot for operation without

adjustment. Use a 20kΩ 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.

Figure 3. ADS-942 Connection Diagram

ADS-942

20kΩ

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)

OVERFLOW

EOC

ANALOG

GROUND

DIGITAL

GROUND

0.1µF

4.7µF

0.1µF ENABLE

4.7µF

+10V REF. OUT

CODING SELECT

+5V

–15V+15V

OFFSET

ADJUST

0.1µF

4.7µF

6, 14, 15

0.1µF

4.7µF

+ +

–15V

+15V

32START CONVERT

ANALOG INPUT

100Ω

2BIPOLAR

4SIGNAL GROUND

ZERO/OFFSET

ADJUST

0 to +10V

GAIN ADJUST

+5V

Table 3. Output Coding

UNIPOLAR INPUT VOLT.OUTPUT CODING INPUT VOLT.BIPOLAR

SCALE 0 TO +10V MSB LSB MSB LSB MSB LSB ±5V SCALE

+FS – 1 LSB +9.999390 11 1111 1111 1111 00 0000 0000 0000 01 1111 1111 1111 +4.999390 +FS – 1LSB

+7/8 FS +8.750000 11 1000 0000 0000 00 0111 1111 1111 01 1000 0000 0000 +3.750000 +3/4FS

+3/4 FS +7.500000 11 0000 0000 0000 00 1111 1111 1111 01 0000 0000 0000 +2.500000 +1/2FS

+1/2 FS +5.000000 10 0000 0000 0000 01 1111 1111 1111 00 0000 0000 0000 0.000000 0

+1/4 FS +2.500000 01 0000 0000 0000 10 1111 1111 1111 11 0000 0000 0000 –2.500000 –1/2FS

+1/8 FS +1.250000 00 1000 0000 0000 11 0111 1111 1111 10 1000 0000 0000 –3.750000 –3/4FS

+1 LSB +0.000610 00 0000 0000 0001 11 1111 1111 1110 10 0000 0000 0001 –4.999390 –FS+1LSB

00.000000 00 0000 0000 0000 11 1111 1111 1111 10 0000 0000 0000 –5.000000 –FS

STRAIGHT BIN. COMP. BINARY

OFF. BINARYCOMP. OFF. BIN. TWO'S COMP.

® ® ADS-942

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.

Figure 4. FFT Analysis of ADS-942

–10

–20

–30

–40

–50

–60

–70

–80

–90

–100

–110

–120

–130

–140

–150

Frequency (MHz)

(fs = 2MHz, fin = 490kHz, Vin = –0.5dB, 16,384-point FFT)

Amplitude Relative to Full Scale (dB)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

® ®

ADS-942

® ®

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.

DS-0228B 10/96

MODEL NUMBER OPERATING TEMP. RANGE

ADS-942MC 0 to +70°C

ADS-942ME –40 to +85°C

ACCESSORIES

ADS-EVAL4 Evaluation Board (without ADS-942)

HS-32 Heat Sink for all ADS-942 models

ORDERING INFORMATION

Receptacles for PC mounting can be ordered through AMP Inc., Part # 3-331272-8 (Component Lead Socket), 32 required.

MECHANICAL DIMENSIONS INCHES (mm)

0.040

(1.016)

SEATING

PLANE

0.025

(0.635)

0.200 MAX.

(5.080)

0.235 MAX.

(5.969)

0.190 MAX.

(4.826) 0.900 ±0.010

(22.860)

1.11 MAX.

(28.19)

0.100 TYP.

(2.540)

1.72 MAX.

(43.69)

116

1732

1.500

(38.100)

0.100

(2.540) 0.100

(2.540)

0.018 ±0.002

(0.457)

0.010

(0.254)

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

+0.002

–0.001

ISO 9001

ISO

9001

REGISTERED

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