Datasheet ADS-942AME, ADS-942AMC Datasheet (DATEL)

® ®

REGISTERREGISTER

DIGITAL CORRECTION LOGIC

GROUND

GROUND

SUPPLY

3-STATE OUTPUT REGISTER

SUPPLY

GROUND

SELECT

SUPPLY

SUPPLY

FEATURES

• 14-bit resolution

• 2MHz minimum throughput

• Low-power, 2.2 Watts

• Functionally complete

• Internal reference and S/H amplifier

• 78dB signal-to-noise ratio

• Full Nyquist-rate sampling

• Small 32-pin TDIP

ADS-942A

14-Bit, 2MHz, Low-Power

Sampling A/D Converters

GENERAL DESCRIPTION

DATEL's ADS-942A is a functionally complete, 14-bit, 2MHz,
sampling A/D converter. Packaged in a 32-pin TDIP, the unit
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/control logic
necessary to operate from a single start convert pulse.

The ADS-942A is optimized for wideband frequency-domain
applications and is fully FFT tested. The ADS-942A requires
±15V and ±5V supplies and typically consumes 2.2 Watts

+10V REF. OUT 1

OFFSET ADJUST 5

BIPOLAR 2

ANALOG INPUT 3

START CONVERT 32

EOC 16

OFFSET
CIRCUIT

S/H

TIMING AND

CONTROL LOGIC

4

SIGNAL

10

+5V

2

S

S1

DIGITAL

BUFFER

11

FLASH

12

+15V

REF

ADC

INPUT/OUTPUT CONNECTIONS

PIN FUNCTION PIN FUNCTION

1 +10V REF. OUT 32 START CONVERT
2 BIPOLAR 31 BIT 1 OUT (MSB)
3 AVALOG INPUT 30 BIT 1 OUT (MSB)
4 SIGNAL GROUND 29 BIT 2 OUT
5 OFFSET ADJUST 28 BIT 3 OUT
6 ANALOG GROUND 27 BIT 4 OUT
7 OVERFLOW 26 BIT 5 OUT
8 CODING SELECT 25 BIT 6 OUT

9 ENABLE 24 BIT 7 OUT
10 +5V SUPPLY 23 BIT 8 OUT
11 DIGITAL GROUND 22 BIT 9 OUT
12 +15V SUPPLY 21 BIT 10 OUT
13 –15V SUPPLY 20 BIT 11 OUT
14 –5V SUPPLY 19 BIT 12 OUT
15 ANALOG GROUND 18 BIT 13 OUT
16 EOC 17 BIT 14 OUT (LSB)

13

–15V

DAC

14

–5V

6, 15

ANALOG

8

CODING

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)

9 ENABLE
7 OVERFLOW

Figure 1. ADS-942A Functional Block Diagram

DATEL, Inc., 11 Cabot Boulevard, Mansfield, MA 02048-1151 (U.S.A.) • Tel: [phone] Fax: [phone] • For immediate assistance: [phone]

ADS-942A

® ®

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
–5V Supply (Pin 14) 0 to –6 Volts
Digital Inputs (Pin 8,9, 32) –0.3 to +V

DD +0.3 Volts

Analog Input (Pin 3) ±15 Volts
Lead Temp. (10 seconds) +300 °C

FUNCTIONAL SPECIFICATIONS

(TA = +25°C, ±VCC = ±15V, ±VDD = ±5V, 2MHz sampling rate, and a minimum 7 minute
warmup ➀ unless otherwise specified.)

ANALOG INPUTS MIN. TYP. MAX. UNITS

Input Voltage Range

Unipolar — 0 to +10 — Volts
Bipolar — ±5 — Volts

Input Impedence 2.3 2.5 — kΩ
Input Capacitance — 7 15 pF

DIGITAL INPUTS

Logic Levels

Logic "1" +2.0 — — Volts
Logic "0" — — +0.8 Volts
Logic Loading "1" — — +10 µA
Logic Loading "0" — — –600 µA

PERFORMANCE

Integral Non-Linearity

+25°C — ±1 ±2 LSB
0 to +70°C — ±1 ±2 LSB
–40 to +85°C — ±2 ±3 LSB

Differential Non-Linearity

+25°C — ±0.5 ±0.75 LSB
0 to +70°C –0.95 ±0.75 ±0.95 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 — ±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 — ±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 — ±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 — ±0.018 ±0.122 %
0 to +70°C — ±0.12 ±0.3 %
–40 to +85°C — ±0.6 ±0.8 %

No Missing Codes (f

14 Bits 0 to +70°C
13 Bits –40 to +85°C

Resolution 14 Bits

Footnote:

➀ Effective Bits is equal to:

➁ Same specification as In-Band Harmonics and Peak Harmonics.
➂ Two-tone Intermodulation Distortion (IMD) conditions:

in = 100kHz, 240kHz, fs = 2MHz, –0.5dB

f

in = 500kHz)

(SNR + Distortion) – 1.76 + 20 log

6.02

Full Scale Amplitude

Actual Input Amplitude

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 — — 5 mA

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) ➀
dc to 100kHz 73 78 — dB
100kHz to 500kHz 72 75 — dB
500kHz to 1MHz — 72 — dB

Spurious Free Dyn. Range ➁

dc to 100kHz — –86 –77 dB
100 to 500kHz — –81 –75 dB
500kHz to 1MHz — –78 — dB

Two-tone IMD ➂ — 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 — — 5 ps, ms
S/H Acq. Time, (to ±0.003%FSR)

Sinusoidal (fin = 1MHz) — — 150 ns

Step input (10V) — 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

–5V Supply –4.75 –5.0 –5.25 Volts

Power Supply Currents

+15V Supply — +65 +80 mA

–15V Supply — –19 –35 mA

+5V Supply — +150 +175 mA

–5V Supply — –55 –65 mA

Power Dissipation — 2.2 2.6 Watts
Power Supply Rejection — — ±0.03 %FSR%V

PHYSICAL/ENVIRONMENTAL

Operating Temp. Range, Case

ADS-942AMC 0 — +70 °C

ADS-942AME –40 — +85 °C

Storage Temperature Range –65 — +150 °C
Package Type 32-pin, metal-sealed, ceramic TDIP
Weight 0.46 ounces (13 grams)

2

® ®

Note: Scale is approximately 25ns per division.

ADS-942A

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 resis­tance 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 electro­lytic 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 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).

5. OVERFLOW (pin 7) changes from low (logic "0") to high
(logic "1") when the input voltage exceeds the input voltage
range limits by 1LSB (610µV).

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.

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 pin 31 (MSB).
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 (Gain) 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 (straight binary/offset binary) or between 00 0000
0000 0000 and 00 0000 0000 0001 with pin 8 tied high
(complementary binary/complementary offset binary).

Two's complement coding requires using pin 31 (MSB).
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.

Table 1. Input Connections

INPUT RANGE INPUT PIN TIE TOGETHER

0 +10V Pin 3 Pins 2 and 4

±5V Pin 3 Pins 1 and 2

Table 2. Zero and Gain Adjustments

Input Zero Adjust Gain Adjust

Range +½ LSB FS – 1½ LSB

0 to +10V +305µV +9.999085V

±5V +305µV +4.999085V

START

CONVERT

EOC

INTERNAL S/H

OUTPUT

DATA

N

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

35ns max..

Conversion Time

300ns typ., 325ns max.

10ns typ.
15ns max.

Hold

350ns min.

DATA N-1 VALID

300ns min.

Figure 2. ADS-942A Timing Diagram

INVALID DATA

200ns max.

3

N+1

35ns typ.

150ns max.

Aquisition Time

30ns max.

DATA N VALID

ADS-942A

+ +

+ +

® ®

Use external trimpots to remove system errors or to reduce
small initial errors to zero. Use a 100Ω trimpot in series
with the analog input for gain adjustment; use a fixed 50Ω
resistor in its place for operation without adjustment.

+5V

–5V

+15V

–15V

0 to +10V

4.7µF

4.7µF

4.7µF

4.7µF

GAIN ADJUST

0.1µF

0.1µF

0.1µF

0.1µF

100

Ω

10

DIGITAL

11

GROUND

14

12

ANALOG

6, 15

GROUND

13

3

ANALOG INPUT

4

SIGNAL GROUND

ZERO/OFFSET

ADJUST

20k

+15V

OFFSET
ADJUST

ADS-942A

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.

Ω

–15V

5

CODING SELECT

START CONVERT

8

32

BIT 1 OUT(MSB)

31

BIT 1 OUT(MSB)

30

BIT 2 OUT

29

BIT 3 OUT

28

BIT 4 OUT

27
26

BIT 5 OUT
BIT 6 OUT

25

BIT 7 OUT

24

BIT 8 OUT

23

BIT 9 OUT

22

BIT 10 OUT

21
20

BIT 11 OUT
BIT 12 OUT

19

BIT 13 OUT

18

BIT 14 OUT (LSB)

17

OVERFLOW

7

EOC

16

+5V

0.1µF

1

4.7µF

ENABLE

9
2BIPOLAR

+10V REF. OUT

Figure 3. ADS-942A Connection Diagram (Unipolar Input)

Table 3. Output Coding

STRAIGHT BIN. COMP. BINARY

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

0 0.000000 00 0000 0000 0000 11 1111 1111 1111 10 0000 0000 0000 –5.000000 –FS

OFF. BINARY COMP. OFF. BIN. TWO'S COMP.

4

® ®

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

Amplitude Relative to Full Scale (dB)

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 (T
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.

0
–10
–20
–30
–40
–50
–60
–70
–80
–90

–100
–110
–120
–130
–140
–150

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

A = +25°C)

ADS-942A

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.

Frequency (MHz)

Figure 4. FFT Analysis of ADS-942A

5

ADS-942A

ISO 9001

REGISTERED

® ®

MECHANICAL DIMENSIONS

INCHES (mm)

1.72 MAX.
(43.69)

Dimension Tolerances

32

17

1.11 MAX.
(28.19)

2 place decimal (.XX) ±0.010 (±0.254)
3 place decimal (.XXX) ±0.005 (±0.127)

Lead Material:
Lead Finish:

over 100 microinches (nominal) nickel plating

(unless otherwise indicated):

Kovar alloy

50 microinches (minimum) gold plating

1

0.018 ±0.002
(0.457)

0.100 TYP.
(2.540)

1.500

(38.100)

0.040

(1.016)

0.100

(2.540)

0.235 MAX.
(5.969)

0.190 MAX.
(4.826)

ORDERING INFORMATION

MODEL NUMBER OPERATING TEMP. RANGE
ADS-942AMC 0 to +70°C
ADS-942AME –40 to +85°C

16

0.200 MAX.
(5.080)

+0.002

0.010

–0.001

(0.254)

SEATING

PLANE

0.025

(0.635)

0.900 ±0.010
(22.860)

ACCESSORIES
ADS-EVAL4 Evaluation Board (without ADS-942)
HS-32 Heat Sink for all ADS-942 models

0.100

(2.540)

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

® ®

DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151
Tel: [phone] [phone] Fax: [phone]
Internet: www.datel.com E-mail:[e-mail]
Data Sheet Fax Back: [phone]

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.

ISO 9001

DS-0204B 10/96

DATEL (UK) LTD. Tadley, England Tel: [phone]
DATEL S.A.R.L. Montigny Le Bretonneux, France Tel: [phone]
DATEL GmbH München, Germany Tel: [phone]
DATEL KK Tokyo, Japan Tel: [phone], Osaka Tel: [phone]