DATEL ADS-947MM, ADS-947MC, ADS-947GM, ADS-B947, ADS-947GC Datasheet

Figure 1. ADS-947 Functional Block Diagram

FEA TURES

••

••

• 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, error­correcting circuit allows the device to achieve specified
performance over the full military temperature range.

INPUT/OUTPUT CONNECTIONS

PRELIMINARY PRODUCT DATA

REF

DAC

REGISTER

REGISTER

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

1

FLASH

ADC

2

POWER AND GROUNDING

S

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: [phone] Fax: [phone] • Email: [e-mail] • Internet: www.datel.com

ADS-947

2

®®

+25°C 0 to +70°C –55 to +125°C

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

Input Voltage 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 ➂ 10 20 — 10 20 — 10 20 — ns

STATIC PERFORMANCE

Resolution — 14 — — 1 4 — — 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 Temperature 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 Temperature (10 seconds) +300 °C

PHYSICAL/ENVIRONMENTAL

ADS-947

3

®®

+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 f ollowing warmup.
To avoid interaction, always adjust offset before gain.

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.

Figure 2. Optional ADS-947 Gain Adjust Calibration Circuit

➀ 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.

➁ Contact DATEL for other input voltage ranges.
➂ A 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

50

Ω

+5V

2k

Ω

➄ 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).

➅ The 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

➃ Effective bits is equal to:

(SNR + Distortion) – 1.76 + 20 log

Full Scale Amplitude

Actual Input Amplitude

6.02

ADS-947

4

®®

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 BINAR Y

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

Table 2. Output Coding for Bipolar Operation

INPUT VOLTAGE ZERO ADJUST GAIN ADJUST

RANGE +½ LSB +FS –1½ LSB

±2V +122µV +1.99963V

Table 1. Gain and Zero Adjust

Figure 3. T ypical ADS-947 Connection Dia gram

0.1µF0.1µF

4.7µF 4.7µF

22, 13

24

2019

ADS-947

–5.2V

20k

W

0.1µF

4.7µF

+5V

14

–5V

+5V

21

23

18

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)
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

➀

+ + +

ZERO/
OFFSET
ADJUST

ADS-947

5

®®

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 character ized
and specified over operating temperature (case) ranges of
0 to +70°C and –55 to +125°C. All room temperature
(T

A = +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.

Figure 4. ADS-947 Timing Diagram

START

CONVERT

OUTPUT

DATA

INTERNAL S/H

NN+1

DATA N-1 VALID

50ns typ.
(±5ns)

20ns

typ.

Acquisition Time

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

6

®®

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

7

®®

Figure 7. ADS-947 Evaluation Board Sc hematic (ADS-B947)

GND

Q

CLR

CKDPR

+5VF

+5VA

+15V

–15V

-15V

+15V

–5VA

+5V

–5V

+5VF

–15V

–5VA

OPTION

+5VF

Q

PRDCK

CLR

+5VF

+5VF

+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

Q1Q2Q3Q4Q5Q6Q7

Q8

8D7D6D5D4D3D2D

1D

+

+

+

+

+

+

+

–

+5VA+15V

+

+

+

+

+

C15

U6

P2

SG10

SG3

SG2

SG1

C14

C7

C13

C6

C12C5

L7

L6

R1

C20

C4 C11

L5

L4

L3

C3

C10

C2

C9

L2

C8C1

L1

P4

C19

SG8SG7

U4

R2

C18

SG5

SG6

SG4

R3

C26 C27

C25

SG9

C24

C23

C16

C22

C17

C21

X1

U6

P3

JPR1

U5

P1

JPR2

U5

U1

U3

OFFSET

ADJUST

ANA. IN

IN

ANA.

CLC402

HI2541

ANA. IN

START CONVERT

7

8

14

CONVERT

START

74HCT86

B14

B13

B12

B11

B10

B9B8B7B6B5B4B3

B2

B1

TRIG

74HCT86

74HCT573

74HCT573

74HCT86

HCT7474

20k

20µH

HCT7474

10MHz

CRYSTAL

15pF

3.2k

2.2µF

4

5

6

13

12

14

11

7

9

8

131112

10

262422

25232119171513

11

97531

2018161412

10

864

2

2

5

4

11

10

14

5

6

423

1

7

2

31

2

1

3

33

31

34

32302826242220

1816141210

8

6

4

2

29

27

25

23

211917

15

13

11

9

7

5

3

1

2

3

1

9

10

8

123456789

101112

2423222120191817161514

13

10

1

12131415161718

19

20

2345678

9

11

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:

OE

CE

Q1Q2Q3Q4Q5Q6Q7

Q8

8D7D6D5D4D3D2D

1D

U2

10

12131415161718

19

20

2345678

9

11

OE

CE

1

CE

0.1µF

0.1µF

0.1µF

0.1µF

0.1µF

2.2µF

0.1µF

2.2µF

2.2µF

0.1µF

2.2µF

2.2µF

2.2µF

2.2µF

2.2µF

2.2µF

2.2µF

6

+5VF

(Optional)

(Optional)

(Optional)

(Optional)

0.01µF

0.01µF

0.01µF

0.01µF

0.01µF

0.01µF

0.01µF

0.1µF

U5

U5

20µH

20µH

20µH

20µH

20µH

20µH

Q

ADS-947

®

®

INNOV A TION and EX CELLENCE

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 D ATEL logo is a registered DATEL, Inc. trademark.

DS-0346 01/97

OPERATING 24-PIN

MODEL TEMP . RANGE PA CKAGE
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

13

24

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

®®

ISO 9001

I

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 Boulevard, Mansfield, MA 02048-1151
Tel: [phone] [phone] Fax: [phone]
Internet: www.datel.com Email: [e-mail]
Data Sheet Fax Back: [phone]

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]