DATEL ADS-951MM, ADS-951MC, ADS-B951 Datasheet

FEATURES

••

••

• 18-bit resolution

••

••

• 1MHz minimum sampling rate

••

••

• No missing codes over full military temperature range

••

••

• Very low power, 1.45 Watts

••

••

• Small, 32-pin, side-brazed, ceramic TDIP

••

••

• Edge-triggered

••

••

• Excellent performance

••

••

• Ideal for both time and frequency-domain applications

••

••

• Low cost

operating temperature ranges. A proprietary, auto-calibrating,
error-correcting circuit enables the device to achieve specified
performance over the full military temperature range.

PRELIMINARY PRODUCT DATA

ADS-951

18-Bit, 1MHz, Low-Power

Sampling A/D Converters

GENERAL DESCRIPTION

The low-cost ADS-951 is an 18-bit, 1MHz sampling A/D
converter. This device accurately samples full-scale input
signals up to Nyquist frequencies with no missing codes. This
feature, combined with excellent signal-to-noise ratio (SNR)
and total harmonic distortion (THD), makes the ADS-951 the
ideal choice for both time-domain (medical imaging, scanners,
process control) and frequency-domain (radar, telecommunica­tions, spectrum analysis) applications.

Packaged in a 32-pin, side-brazed, metal-sealed, ceramic
TDIP, the functionally complete ADS-951 contains a fast­settling sample-hold amplifier, a subranging (two-pass) A/D
converter, an internal reference, timing/control logic, and error­correction circuitry. Digital input and output levels are TTL, and
the ADS-951 only requires the rising edge of the start convert
pulse to operate.

Requiring ±15V and ±5V supplies, the ADS-951 typically
dissipates 1.45 Watts. The device is offered with a bipolar
(±5V) analog input range. Models are available for use in
either commercial (0 to +70°C) or military (–55 to +125°C)

INPUT/OUTPUT CONNECTIONS

Figure 1. ADS-951 Functional Bloc k Diagram

1 BIT 2 32 BIT 3
2 BIT 1 (MSB) 31 BIT 4
3 ANALOG GROUND 30 BIT 5
4 ANALOG INPUT 29 BIT 6
5 +5V REFERENCE OUT 28 BIT 7
6 GAIN ADJUST 27 BIT 8
7 COMPENSATION 26 BIT 9
8 –15V SUPPLY 25 BIT 10

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

PIN FUNCTION PIN FUNCTION

DATEL, Inc., Mansfield, MA 02048 ( USA) • Tel: [phone] Fax: [phone] • Email: [e-mail] • Internet: www.datel.com

®®

REF

DAC

2 BIT 1 (MSB)
1 BIT 2
32 BIT 3
31 BIT 4
30 BIT 5
29 BIT 6
28 BIT 7
27 BIT 8
26 BIT 9
25 BIT 10
24 BIT 11
23 BIT 12
22 BIT 13
21 BIT 14
20 BIT 15
19 BIT 16
18 BIT 17
17 BIT 18 (LSB)

TIMING AND

CONTROL LOGIC

ANALOG INPUT 4

START CONVERT 16

EOC 15

–

+

S/H

BUFFER

DIGITAL CORRECTION LOGIC

FLASH

ADC

1

FLASH

ADC

2

5

AMP

GAIN

CIRCUIT

COMPENSATION 7

+

5V REFERENCE OUT 5

10

+5V ANALOG

SUPPLY

11

–5V ANALOG

SUPPLY

3, 12

ANALOG

GROUND

14

+5V DIGITAL

SUPPLY

9

+15V

SUPPLY

8

–15V

SUPPLY

13

DIGITAL

GROUND

GAIN ADJUST 6

ADS-951

2

®®

+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

— ±5 ——±5 ——±5 — Volts

Input Resistance — 500 ——500 ——500 —

Ω

Input Capacitance — 715— 715— 715pF

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

20 500 — 20 500 — 20 500 — ns

STATIC PERFORMANCE

Resolution — 18 ——18 ——18 — Bits
Integral Nonlinearity (fin = 10kHz) — ±0.75 ——±1.5 ——±2 — LSB
Differential Nonlinearity (fin = 10kHz) –0.95 ±0.5 +1 –0.95 ±0.5 +1 –0.95 ±0.50 +1.25 LSB
Full Scale Absolute Accuracy — ±0.1 ±0.25 — ±0.25 ±0.4 — ±0.4 ±0.8 %FSR
Bipolar Zero Error (Tech Note 2) — ±0.1 ±0.15 — ±0.15 ±0.25 — ±0.25 ±0.5 %FSR
Bipolar Offset Error (Tech Note 2) — ±0.1 ±0.2 — ±0.2 ±0.3 — ±0.3 ±0.6 %FSR
Gain Error (Tech Note 2) — ±0.1 ±0.25 — ±0.25 ±0.4 — ±0.4 ±0.9 %
No Missing Codes (fin = 10kHz) 18 ——18 ——18 ——Bits

DYNAMIC PERFORMANCE

Peak Harmonics (–0.5dB)

dc to 100kHz —–90 ——–90 ——–86 — dB
100kHz to 500kHz —–89 ——–89 ——–85 — dB

Total Harmonic Distortion (–0.5dB)

dc to 100kHz —–89 ——–89 ——–85 — dB
100kHz to 500kHz —–88 ——–88 ——–84 — dB

Signal-to-Noise Ratio

(w/o distortion, –0.5dB)
dc to 100kHz — 89 ——89 ——86 — dB
100kHz to 500kHz — 88 ——88 ——85 — dB

Signal-to-Noise Ratio

➃

(& distortion, –0.5dB)
dc to 100kHz — 86 ——86 ——82 — dB
100kHz to 500kHz — 84 ——84 ——81 — dB

Noise — 25 ——25 ——25 — µVrms
Two-Tone Intermodulation

Distortion (fin = 100kHz,

240kHz, fs = 1MHz, –0.5dB) —–85 ——–85 ——–85 — dB

Input Bandwidth (–3dB)

Small Signal (–20dB input) — TBD ——TBD ——TBD — MHz
Large Signal (–0.5dB input) — TBD ——TBD ——TBD — MHz

Feedthrough Rejection (fin = 500kHz) — 84 ——84 ——84 — dB
Slew Rate — TBD ——TBD ——TBD — V/µs
Aperture Delay Time — +20 ——+20 ——+20 — ns
Aperture Uncertainty — 5 ——5 —— 5 — ps rms
S/H Acquisition Time

( to ±0.003%FSR, 10V step) — 260 ——260 ——260 — ns

Overvoltage Recovery Time

➄

— 500 ——500 ——500 — ns

A/D Conversion Rate 1 —— 1 —— 1 ——MHz

PARAMETERS LIMITS UNITS
+15V Supply (Pin 9) 0 to +16 Volts

–15V Supply (Pin 8) 0 to –16 Volts
+5V Supply (Pins 10, 14) 0 to +6 Volts
–5V Supply (Pin 11) 0 to –6 Volts
Digital Input (Pin 16) –0.3 to +V

DD +0.3 Volts

Analog Input (Pin 4) ±15 Volts
Lead Temperature (10 seconds) +300 °C

P ARAMETERS MIN. TYP. MAX. UNITS
Operating Temp. Range, Case

ADS-951MC 0 — +70 °C
ADS-951MM –55 — +125 °C

Thermal Impedance

θ

jc — 5 —°C/Watt

θ

ca — 22 —°C/Watt

Storage Temperature Range –65 — +150 °C
Package T ype 32-pin,side-braz ed, metal-sealed, ceramic TDIP

Weight 0.46 ounces (13 grams)

ABSOLUTE MAXIMUM RATINGS

PHYSICAL/ENVIRONMENTAL

FUNCTIONAL SPECIFICATIONS

(TA = +25°C, ±VCC = ±15V, ±VDD = ±5V , 1MHz sampling rate, and a minimum 1 minute warmup ➀ unless otherwise specified.)

ADS-951

3

®®

+25°C 0 to +70°C –55 to +125°C

ANALOG OUTPUT MIN. TYP. MAX. MIN. TYP. MAX. MIN. TYP. MAX. UNITS
Internal Reference

Voltage +4.95 +5.0 +5.05 +4.95 +5.0 +5.05 +4.95 +5.0 +5.05 Volts
Drift — ±30 ——±30 ——±30 — ppm/°C

External Current — 1 —— 1 ——1 — mA
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 —— –4mA
Logic Loading "0" ——+4 ——+4 —— +4 mA

Output Coding

Complementary Offset Binary

POWER REQUIREMENTS
Power Supply Ranges

+15V Supply +14.5 +15.0 +15.5 +14.5 +15.0 +15.5 +14.5 +15.0 +15.5 Volts
–15V Supply –14.5 –15.0 –15.5 –14.5 –15.0 –15.5 –14.5 –15.0 –15.5 Volts
+5V Supply +4.75 +5.0 +5.25 +4.75 +5.0 +5.25 +4.75 +5.0 +5.25 Volts
–5V Supply –4.75 –5.0 –5.25 –4.75 –5.0 –5.25 –4.75 –5.0 –5.25 Volts

Power Supply Currents

+15V Supply — +29 ——+29 ——+29 — mA
–15V Supply —–15 ——–15 ——–15 — mA
+5V Supply — +104 ——+104 ——+104 — mA
–5V Supply —–54 ——–54 ——–54 — mA

Power Dissipation — 1.45 1.65 — 1.45 1.65 — 1.45 1.65 Watts
Power Supply Rejection ——±0.05 ——±0.05 ——±0.05 %FSR/%V

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

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. 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.

TECHNICAL NOTES

1. Obtaining fully specified performance from the ADS-951
requires careful attention to pc-card layout and power
supply decoupling. The device's analog and digital ground
systems are not connected to each other internally. For
optimal performance, tie all ground pins (3, 12 and 13)
directly to a large

analog

ground plane beneath the

package.
Bypass all power supplies and the +5V REFERENCE

OUTPUT (pin 5) to ground with 10µF tantalum capacitors in
parallel with 0.1µF ceramic capacitors. Locate the bypass
capacitors as close to the unit as possible. Tie a 47µF
capacitor between COMPENSATION (pin 7) and ground.

2. The ADS-951 achieves its specified accuracies without the
need for external calibration. If required, the device's small
initial errors can be reduced to zero using the adjustment
circuitry shown in Figure 2. When using this circuitry, or any
similar offset and gain calibration hardware, make adjust­ments following warmup. To avoid interaction, always adjust
offset before gain. Float pin 6 if not using gain adjust
circuits.

Footnotes:

➄

This is the time required before the A/D output data is valid once the analog input
is back within the specified range.

6.02

(SNR + Distortion) – 1.76 + 20 log

Full Scale Amplitude

Actual Input Amplitude

➀

All power supplies must be on before applying a start convert pulse. All supplies
and the clock (START CONVERT) 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 1MHz clock with a 500nsec positive pulse width (50% duty cycle) is used for
all production testing. Any duty cycle may be used as long as a minimum
positive pulse width of 20nsec is maintained. For applications requiring lower
sampling rates, clock frequencies lower than 1MHz may be used.

➃

Effective bits is equal to:

3. Applying a start convert pulse while a conversion is in
progress (EOC = logic "1") will initiate a new and probably
inaccurate conversion cycle. Data for the interrupted and
subsequent conversions will be invalid.

ADS-951

4

®®

Zero/Offset Adjust Procedure

1. Apply a train of pulses to the START CONVERT input
(pin 16) so that the converter is continuously converting.

2. For bipolar zero/offset adjust, apply –19µV to the ANALOG
INPUT (pin 4).

3. Adjust the offset potentiometer until the output code flickers
equally between 01 1111 1111 1111 1111 and 10 0000
0000 0000 0000.

Gain Adjust Procedure

1. Apply –4.999943V to the ANALOG INPUT (pin 4).

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 applied
input voltage to obtain the output coding listed in Table 2.

BIPLOAR INPUT VOLTAGE

SCALE ±5V MSB LSB

+FS –1 LSB +4.999962 00 0000 0000 0000 0000

+3/4 FS +3.750000 00 0111 1111 1111 1111
+1/2 FS +2.500000 00 1111 1111 1111 1111

0 +0.000000 01 1111 1111 1111 1111

–1/2 FS –2.500000 10 1111 1111 1111 1111
–3/4 FS –3.750000 11 0111 1111 1111 1111

–FS +1 LSB –4.999962 11 1111 1111 1111 1110

–FS –5.000000 11 1111 1111 1111 1111

OUTPUT CODING

COMPLEMENTARY

OFFSET BINARY

Table 2. Output Coding

CALIBRATION PROCEDURE

Connect the converter per Table 1 for the appropriate input
voltage range. Any offset/gain calibration procedures should
not be implemented until the device is fully warmed up. To
avoid interaction, adjust offset before gain. The ranges of
adjustment for the circuits in Figure 2 are guaranteed to
compensate for the ADS-951'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 is accomplished by connecting LED's to the
digital outputs and performing adjustments 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.

For the ADS-951, offset adjusting is normally accomplished
when the analog input is 0 minus ½LSB (–19µV). See Table 2
for the proper bipolar output coding.

Gain adjusting is accomplished when the analog input is at
nominal full scale minus 1½LSB's (–4.999943V).

INPUT VOLTAGE ZERO ADJUST GAIN ADJUST

RANGE (–½ LSB) (–FS +1½ LSB)

±5V –19µV –4.999943

Table 1. Input Connections

ADS-951

5

®®

Figure 3. ADS-951 Timing Diagram

Figure 2. Typical ADS-951 Connection Diagram

Scale is approximately 50ns per division.

START

CONVERT

INTERNAL S/H

N

N+1

500ns typ.

Acquisition Time

260ns typ.

740ns typ.

5ns typ.

EOC

65ns typ.

Conversion Time

730ns typ.

OUTPUT

DATA

Data N-2 Valid

980ns typ.

Hold

Data N-1 Valid

20ns typ.

20ns

Invalid Data

N

3

11

ADS-951

10

2

1
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
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
BIT 15
BIT 16
BIT 17
BIT 18 (LSB)

+5V ANALOG

15

ANALOG
GROUND

ANALOG
GROUND

DIGITAL
GROUND

0.1µF

10µF

0.1µF

+

10µF

+5V
REF. OUT

COMPENSATION

47µF

14

13

5

7

START CONVERT

+5V DIGITAL

GAIN

ADJUST

6

16

0.1µF

10µF

12

9

0.1µF

10µF

8

++

0.1µF

10µF

0.1µF

10µF

+

+

EOC

–5V ANALOG

+15V

–15V

ANALOG INPUT

4

Pin 5 (ADS-951)

10k

9

ADS-951

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-0366P 5/27/99

MECHANICAL DIMENSIONS INCHES (mm)

ORDERING INFORMATION

OPERATING 32-PIN

MODEL NUMBER TEMP. RANGE PACKAGE
ADS-951MC 0 to +70°C TDIP

ADS-951MM –55 to +125°C TDIP

ACCESSORIES
ADS-B951 Evaluation Board (without ADS-951)

Receptacles for PC board mounting can be ordered through AMP, Inc., Part # 3-331272-8
(Component Lead Socket), 32 required. For availability of MIL-STD-883 product, contact DATEL.

ISO 9001

ISO 9001

REGISTERED

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

®®

®®

1.62 MAX.
(41.15)

0.92 MAX.
(23.37)

0.018 TYP.
(0.46)

1.50 TYP
(38.10)

0.100 TYP.
(2.54)

0.05 TYP.
(1.27)

0.175 TYP
(4.45)

0.05 TYP.
(1.27)

0.220 TYP.
(6.86)

0.90 TYP.
(22.86)

0.010 TYP.
(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

PIN 1 INDEX

0.05 TYP.

(

1.27

)

SEATING PLANE