ADS-947/883 - Datel, Inc.

Figure 1. ADS-947 Functional Block Diagram

FEATURES

••

•14-bit resolution

••

•10MHz minimum sampling rate

••

•No missing codes over full military temperature range

••

•Ideal for both time and frequency-domain applications

••

•Excellent THD (–81dB) and SNR (76dB)

••

•Edge-triggered

••

•Small, 24-pin, ceramic DDIP or SMT

••

•Requires only +5V and –5.2V supplies

••

•Low-power, 2 Watts

••

•Low cost

GENERAL DESCRIPTION

The low-cost ADS-947 is a 14-bit, 10MHz sampling A/D

converter. This device accurately samples full-scale input

signals up to Nyquist frequencies with no missing codes.

Excellent differential nonlinearity error (DNL), signal-to-noise

ratio (SNR), and total harmonic distortion (THD) make the

ADS-947 the ideal choice for both time-domain (CCD/FPA

imaging, scanners, process control) and frequency-domain

(radar, telecommunications, spectrum analysis) applications.

The functionally complete ADS-947 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 ADS-947

only requires the rising edge of a start convert pulse to

operate.

Requiring only +5V and –5.2V supplies, the ADS-947 typically

dissipates just 2 Watts. 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.

INPUT/OUTPUT CONNECTIONS

PRELIMINARY PRODUCT DATA

REF DAC

OUTPUT REGISTER

16 BIT 14 (LSB)

15 BIT 13

12 BIT 12

11 BIT 11

10 BIT 10

9 BIT 9

8 BIT 8

7 BIT 7

6 BIT 6

5 BIT 5

4 BIT 4

3 BIT 3

2 BIT 2

1 BIT 1 (MSB)

TIMING AND

CONTROL LOGIC

OFFSET ADJUST 23

ANALOG INPUT 21

START CONVERT 18

DATA VALID 17

+5V ANALOG SUPPLY 22

+5V DIGITAL SUPPLY 13

–5.2V SUPPLY 20

ANALOG GROUND 19, 24

DIGITAL GROUND 14

–

+S/H

BUFFER

DIGITAL CORRECTION LOGIC

FLASH

ADC

FLASH

ADC

POWER AND GROUNDING

AMP

PIN FUNCTION PIN FUNCTION

1 BIT 1 (MSB) 24 ANALOG GROUND

2 BIT 2 23 OFFSET ADJUST

3 BIT 3 22 +5V ANALOG SUPPLY

4 BIT 4 21 ANALOG INPUT

5 BIT 5 20 –5.2V SUPPLY

6 BIT 6 19 ANALOG GROUND

7 BIT 7 18 START CONVERT

8 BIT 8 17 DATA VALID

9 BIT 9 16 BIT 14 (LSB)

10 BIT 10 15 BIT 13

11 BIT 11 14 DIGITAL GROUND

12 BIT 12 13 +5V DIGITAL SUPPLY

ADS-947

14-Bit, 10MHz

Sampling A/D Converters

DATEL, Inc., Mansfield, MA 02048 (USA) • Tel: (508) 339-3000, (800) 233-2765 Fax: (508) 339-6356 • Email: sales@datel.com • Inter net: www.datel.com

ADS-947

®®

+25°C 0 to +70°C –55 to +125°C

ANALOG INPUT MIN. TYP. MAX. MIN. TYP. MAX. MIN. TYP. MAX. UNITS

Input V oltage Range ➁— ±2 — — ±2 — — ±2 — Volts

Input Resistance — 250 — — 250 — — 250 — Ω

Input Capacitance — 6 15 — 6 15 — 6 15 pF

DIGITAL INPUT

Logic Levels

Logic "1" +2.0 — — +2.0 — — +2.0 — — Volts

Logic "0" — — +0.8 — — +0.8 — — +0.8 Volts

Logic Loading "1" — — +20 — — +20 — — +20 µA

Logic Loading "0" — — –20 — — –20 — — –20 µA

Start Convert Positive Pulse Width ➂10 20 — 10 20 — 10 20 — ns

STATIC PERFORMANCE

Resolution — 14 — — 14 — — 14 — Bits

Integral Nonlinearity (fin = 10kHz) — ±0.75 — — ±0.75 — — ±1 — LSB

Differential Nonlinearity (fin = 10kHz) –0.95 ±0.5 +1.25 –0.95 ±0.5 +1.25 –0.95 ±0.5 +1.5 LSB

Full Scale Absolute Accuracy — ±0.15 ±0.4 — ±0.15 ±0.4 — ±0.4 ±0.8 %FSR

Bipolar Zero Error (Tech Note 2) — ±0.1 ±0.3 — ±0.1 ±0.3 — ±0.3 ±0.6 %FSR

Gain Error (Tech Note 2) — ±0.2 ±0.4 — ±0.2 ±0.4 — ±0.4 ±1.5 %

No Missing Codes (fin = 10kHz) 14 — — 14 — — 14 — — Bits

DYNAMIC PERFORMANCE

Peak Harmonics (–0.5dB)

dc to 1MHz — –83 –76 — –83 –75 — –79 –71 dB

1MHz to 2.5MHz — –78 –72 — –78 –72 — –73 –68 dB

2.5MHz to 5MHz — –76 –71 — –76 –71 — –71 –65 dB

Total Harmonic Distortion (–0.5dB)

dc to 1MHz — –81 –74 — –81 –74 — –77 –70 dB

1MHz to 2.5MHz — –76 –71 — –76 –71 — –72 –66 dB

2.5MHz to 5MHz — –74 –69 — –74 –69 — –69 –63 dB

Signal-to-Noise Ratio

(w/o distortion, –0.5dB)

dc to 1MHz 72 76 — 72 76 — 70 75 — dB

1MHz to 2.5MHz 72 76 — 72 76 — 70 75 — dB

2.5MHz to 5MHz 71 75 — 71 75 — 70 75 — dB

Signal-to-Noise Ratio ➃

(& distortion, –0.5dB)

dc to 1MHz 70 74 — 70 74 — 68 73 — dB

1MHz to 2.5MHz 70 74 — 70 74 — 66 71 — dB

2.5MHz to 5MHz 68 73 — 68 73 — 65 70 — dB

Noise — 150 — — 150 — — 150 — µVrms

Two-tone Intermodulation

Distortion (fin = 2.45MHz,

1.975MHz, fs = 10MHz, –0.5dB) — –82 — — –82 — — –82 — dB

Input Bandwidth (–3dB)

Small Signal (–20dB input) — 30 — — 30 — — 30 — MHz

Large Signal (–0.5dB input) — 10 — — 10 — — 10 — MHz

Feedthrough Rejection (fin = 5MHz) — 85 — — 85 — — 85 — dB

Slew Rate — ±400 — — ±400 — — ±400 — V/µs

Aperture Delay Time —+5——+5— —+5 —ns

Aperture Uncertainty — 2 — — 2 — — 2 — ps rms

FUNCTIONAL SPECIFICATIONS

(TA = +25°C , +VDD = +5V, –VDD = –5.2V, 10MHz sampling rate, and a minimum 3 minute warmup ➀ unless otherwise specified.)

P ARAMETERS MIN. TYP. MAX. UNITS

Operating Temp. Range, Case

ADS-947MC, GC 0 — +70 °C

ADS-947MM, GM, 883 –55 — +125 °C

Thermal Impedance

θjc — 6 — °C/Watt

θca — 23 — °C/Watt

Storage T emperature Range –65 — +150 °C

Package Type 24-pin, metal-sealed, ceramic DDIP or SMT

Weight 0.46 ounces (13 grams)

ABSOLUTE MAXIMUM RATINGS

PARAMETERS LIMITS UNITS

+5V Supply (Pins 13, 22) 0 to +6 Volts

–5.2V Supply (Pin 20) 0 to –5.5V Volts

Digital Input (Pin 18) –0.3 to +VDD +0.3 Volts

Analog Input (Pin 21) ±5 Volts

Lead T emperature (10 seconds) +300 °C

PHYSICAL/ENVIRONMENTAL

ADS-947

®®

+25°C 0 to +70°C –55 to +125°C

DYNAMIC PERFORMANCE (Cont.) MIN. TYP. MAX. MIN. TYP. MAX. MIN. TYP. MAX. UNITS

S/H Acquisition Time

( to ±0.003%FSR, 4V step) — 40 45 — 40 45 — 40 45 ns

Overvoltage Recovery Time ➄— — 100 — — 100 — — 100 ns

A/D Conversion Rate 10 — — 10 — — 10 — — MHz

DIGITAL OUTPUTS

Logic Levels

Logic "1" +2.4 — — +2.4 — — +2.4 — — Volts

Logic "0" — — +0.4 — — +0.4 — — +0.4 Volts

Logic Loading "1" — — –4 — — –4 — — –4 mA

Logic Loading "0" — — +4 — — +4 — — +4 mA

Output Coding Offset Binary

POWER REQUIREMENTS

Power Supply Ranges ➅

+5V Supply +4.75 +5.0 +5.25 +4.75 +5.0 +5.25 +4.9 +5.0 +5.25 Volts

–5.2V Supply –4.75 –5.2 –5.45 –4.75 –5.2 –5.45 –4.9 –5.2 –5.45 Volts

Power Supply Currents

+5V Supply — +250 +260 — +250 +260 — +250 +260 mA

–5.2V Supply — –200 –210 — –200 –210 — –200 –210 mA

Power Dissipation — 2.0 2.25 — 2.0 2.25 — 2.0 2.25 Watts

Power Supply Rejection — — ±0.1 — — ±0.1 — — ±0.1 %FSR/%V

Footnotes:

TECHNICAL NOTES

1. Obtaining fully specified performance from the ADS-947

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-947 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 gain

calibration hardware, make adjustments following warmup.

To avoid interaction, always adjust offset before gain.

3. Applying a star t 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.

Figure 2. Optional ADS-947 Gain Adjust Calibration Circuit

➀All power supplies should be on before applying a start convert pulse. All

supplies and the clock (start conv ert pulses) must be present during warmup

periods. The device must be continuously converting during this time.

➁Contact DATEL for other input voltage ranges.

➂A 10MHz clock with a 20ns positive pulse width is used for all production

testing. See Timing Diagram, figure 4, for more details.

To Pin 21

of ADS-947

–5V

SIGNAL

INPUT

GAIN

ADJUST

1.98k

Ω

+5V

Ω

➄This 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).

➅The minimum supply voltages of +4.9V and –5.1V for ±VDD are required for

–55°C operation only. The minimum limits are +4.75V and –4.95V when

operating at +125°C

➃Effective bits is equal to:

(SNR + Distortion) – 1.76 + 20 log Full Scale Amplitude

Actual Input Amplitude

6.02

ADS-947

®®

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-947’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-947 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.

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.

BIPOLAR INPUT V OL T A GE OFFSET BINARY

SCALE (±2V RANGE) MSB LSB

+FS –1 LSB +1.99976 11 1111 1111 1111

+3/4 FS +1.50000 11 1000 0000 0000

+1/2 FS +1.00000 11 0000 0000 0000

0 0.00000 10 0000 0000 0000

–1/2 FS –1.00000 01 0000 0000 0000

–3/4 FS –1.50000 00 1000 0000 0000

–FS +1 LSB –1.99976 00 0000 0000 0001

–FS –2.00000 00 0000 0000 0000

Tab le 2. Output Coding for Bipolar Operation

INPUT VOLTAGE ZERO ADJUST GAIN ADJUST

RANGE +½ LSB +FS –1½ LSB

±2V +122µV +1.99963V

Tab le 1. Gain and Zero Adjust

Figure 3. Typical ADS-947 Connection Dia gram

0.1µF0.1µF

4.7µF 4.7µF

22, 13

2019

ADS-947

–5.2V

20k

0.1µF

4.7µF

+5V

–5V

+5V

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)

DATA VALID

ANALOG

INPUT

START

CONVERT

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.

➀

+ + +

ZERO/

OFFSET

ADJUST

ADS-947

®®

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 AN8, "Heat Sinks for DIP Data Converters",

or contact DATEL directly, for additional information.

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 perf ormed 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.

Figure 4. ADS-947 Timing Diagram

START

CONVERT

OUTPUT

DATA

INTERNAL S/H

NN+1

DATA N-1 VALID

50ns typ.

(±5ns)

20ns

typ.

Acq uis itio n Ti m e

35ns

typ.

Hold

65ns typ.

10ns typ.

DATA N VALID

INVALID DATA

50ns typ.

Notes:

1. Scale is approximately 5ns per division. Sampling rate = 10MHz.

2. The start convert pulse must be between 20 and 50ns wide or between 80 and 100ns wide (when sampling at 10MHz)

to ensure proper operation. For sampling rates less than 10MHz, the start pulse can be wider than 85nsec, however a minimum

pulse width low of 15nsec should be maintained. A 10MHz clock with a 20nsec positive pulse width is used for all production testing.

INTERNAL EOC

25ns typ.

Conversion Time

70ns typ.

DATA N-1 VALID DATA N VALID

DATA

VALID 40ns typ.

(±5ns) 40ns typ.

(±5ns)

40ns max.

15ns

(61ns min., 68ns max.)

(22ns min., 28ns max.)

ADS-947

®®

Figure 5. FFT Analysis of ADS-947

(fs = 8MHz, fin = 3.85MHz, Vin = –0.5dB, 16,384 point FFT)

Figure 6. ADS-947 Histogram and Differential Nonlinearity

ADS-947

®®

Figure 7. ADS-947 Evaluation Board Schematic (ADS-B947)

GND

CLR

+5VF

+5VA

+15V

–15V

-15V

+15V

–5VA

+5V

–5V

+5VF

–15V

–5VA

OPTION

+5VF

CLR

+5VF

+5V

–5.2V

+5VA

BIT12

BIT11

BIT10

BIT9

BIT8

BIT7

BIT6

BIT5

BIT4

BIT3

BIT2

BIT1

ADS-947

+5VD

DGND

BIT13

BIT14

DATA VALID

START

AGND

–5.2V

AIN

+5VA

OFFSET

AGND

–

+5VA+15V

C15

SG10

SG3

SG2

SG1

C14

C13

C12C5

C20

C4 C11

C3 C10

C2 C9

C8C1

C19

SG8SG7

R2 C18

SG5 SG6

SG4

C26 C27 C25

SG9

C24

C23

C16

C22

C17

C21

JPR1

JPR2

OFFSET

ADJUST

ANA. IN

ANA. CLC402

HI2541

ANA. IN

START CONVERT

CONVERT

START

74HCT86

B14

B13

B12

B11

B10

TRIG

74HCT86

74HCT573

74HCT86

HCT7474

20k

20µH

HCT7474

10MHz

CRYSTAL

15pF

3.2k

2.2µF

12 14 11

411 10

231

SPARE GATES

C1 - C7 ARE 20V.

2. CLOSE SG1-SG3, SG9, SG10.

ALL RESISTORS ARE IN OHMS.

1. UNLESS OTHERWISE SPECIFIED ALL CAPACITORS ARE 50V.

NOTES:

11 OE

CE 1

0.1µF

2.2µF

0.1µF

2.2µF

0.1µF

2.2µF

+5VF

(Optional) (Optional)

(Optional)

0.01µF

0.1µF

20µH

ADS-947

®®

INNOV A TION and EX CELLENCE

D ATEL 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 there with. Specifications are subject to change without notice. The D ATEL logo is a registered DATEL, Inc. trademark.

DS-0346 01/97

OPERATING 24-PIN

MODEL TEMP . RANGE P ACKAGE

ADS-947MC 0 to +70°C DDIP

ADS-947MM –55 to +125°C DDIP

ADS-947/883 –55 to +125°C DDIP

ADS-947GC 0 to +70°C SMT

ADS-947GM –55 to +125°C SMT

MECHANICAL DIMENSIONS INCHES (mm)

24-Pin DDIP

Versions

ADS-947MC

ADS-947MM

0.200 MAX.

(5.080)

0.235 MAX.

(5.969)

0.600 ±0.010

(15.240)

0.80 MAX.

(20.32)

0.100 TYP.

(2.540)

0.100

(2.540)

0.018 ±0.002

(0.457)

0.100

(2.540)

0.040

(1.016)

1.31 MAX.

(33.27)

112

1.100

(27.940)

0.190 MAX.

(4.826)

0.010

(0.254)

+0.002

–0.001

SEATING

PLANE

0.025

(0.635)

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

PIN 1 INDEX

ORDERING INFORMATION

ACCESSORIES

ADS-B947 Evaluation Board (without ADS-947)

HS-24 Heat Sink for all ADS-947 DDIP models

24-Pin

Surface Mount

Versions

ADS-947GC

ADS-947GM

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

Sock et), 24 required. For MIL-STD-883 product specifcation, contact DATEL.

®®

ISO 9001

SO 9001

REGISTERED

0.80 MAX.

(20.32)

0.015

(0.381)

MAX. radius

for any pin

1.31 MAX.

(33.02)

0.100 TYP.

(2.540)

0.100

(2.540)

0.190 MAX.

(4.826)

0.040

(1.016)

0.020 TYP.

(0.508)

0.020

(0.508)

24 13

121

PIN 1

INDEX 0.130 TYP.

(3.302)

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

0.060 TYP.

(1.524)

0.010 TYP.

(0.254)

DATEL, Inc. 11 Cabot Boule vard, Mansfield, MA 02048-1151

Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356

Internet: www.datel.com Email: sales@datel.com

Data Sheet Fax Back: (508) 261-2857

DATEL (UK) LTD . Tadley, England Tel: (01256)-880444

DATEL S.A.R.L. Montign y Le Bretonneux, France Tel: 01-34-60-01-01

DATEL GmbH München, Germany Tel: 89-544334-0

DATEL KK Tokyo, Japan Tel: 3-3779-1031, Osaka Tel: 6-354-2025