ADS-950MC - Datel, Inc. - Product.Network

FEATURES

·18-bit resolution

·500kHz 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 DA T A

ADS-950

18-Bit, 500kHz, Low-Power

Sampling A/D Converters

GENERAL DESCRIPTION

The low-cost ADS-950 is an 18-bit, 500kHz 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-950 the

ideal choice for both time-domain (medical imaging, scanners,

process control) and frequency-domain (radar, telecommunica-

tions, spectrum analysis) applications.

Packaged in a 32-pin, side-brazed, metal-sealed, ceramic

TDIP, the functionally complete ADS-950 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, and

the ADS-950 only requires the rising edge of the start convert

pulse to operate.

Requiring ±15V and ±5V supplies, the ADS-950 typically

dissipates 1.45 W atts. 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-950 Functional Block 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 SUPPL Y 25 BIT 10

9 +15V SUPPL Y 24 BIT 11

10 +5V ANALOG SUPPLY 23 BIT 12

11 –5V ANALOG SUPPL Y 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: (508) 339-3000, (800) 233-2765 Fax: (508) 339-6356 · Email: sales@datel.com · 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

FLASH

ADC

AMP

GAIN

CIRCUIT

COMPENSATION 7

5V REFERENCE OUT 5

+5V ANALOG

SUPPLY

–5V ANALOG

SUPPLY

3, 12

ANALOG

GROUND

+5V DIGITAL

SUPPLY

+15V

SUPPLY

–15V

SUPPLY

DIGITAL

GROUND

GAIN ADJUST 6

ADS-950

®®

+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— ±5 — — ±5 — — ±5 — Volts

Input Resistance — 500 — — 500 — — 500 — W

Input Capacitance — 7 15 — 7 15 — 7 15 pF

DIGIT AL 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 ➂20 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

Total Harmonics Distortion (–0.5dB)

dc to 100kHz — –89 — — –89 — — –85 — dB

Signal-to-Noise Ratio

(w/o distortion, –0.5dB)

dc to 100kHz 92 94 — 92 94 — — 92 — dB

Signal-to-Noise Ratio ➃

(& distortion, –0.5dB)

dc to 100kHz — 86 — — 86 — — 82 — dB

Noise — 38 48 — 38 48 — 38 — 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—1——1——1—µs

A/D Conversion Rate 500 — — 500 — — 500 — — kHz

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 V olts

–5V Supply (Pin 11 ) 0 to –6 Volts

Digital Input (Pin 16) –0.3 to +VDD +0.3 Volts

Analog Input (Pin 4) ±15 Volts

Lead Temperature (10 seconds) +300 °C

P ARAMETERS MIN. TYP. MAX. UNITS

Operating T emp. Range, Case

ADS-951MC 0 — +70 °C

ADS-951MM –55 — +125 °C

Thermal Impedance

qjc — 5 — °C/Watt

qca — 22 — °C/Watt

Storage Temperature Range –65 — +150 °C

Package T ype 32-pin,side-brazed, metal-sealed, ceramic TDIP

Weight 0.46 ounces (13 grams)

ABSOLUTE MAXIMUM RATINGS PHYSICAL/ENVIRONMENTAL

FUNCTIONAL SPECIFICATIONS

(TA = +25°C, ±VCC = ±15V, ±VDD = ±5V, 500kHz sampling rate, and a minimum 1 minute warmup ➀ unless otherwise specified.)

ADS-950

®®

+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 — — –4 mA

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 V olts

–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 V olts

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 (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.

TECHNICAL NOTES

1. Obtaining fully specified performance from the ADS-950

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-950 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 adjust-

ments following warmup. To avoid interaction, always adjust

offset before gain. Float pin 6 if not using gain adjust

circuits.

Footnotes:

➄This 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

➀All 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.

➁Contact DATEL for other input voltage ranges.

➂A 500kHz clock with a 1µsec 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.

➃Effective 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-950

®®

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 VOL T AGE

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-950'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-950, 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 VOL T AGE ZERO ADJUST GAIN ADJUST

RANGE (–½ LSB) (–FS +1½ LSB)

±5V –19µV –4.999943

Table 1. Input Connections

ADS-950

®®

Figure 3. ADS-950 Timing Diagram

Figure 2. Typical ADS-950 Connection Diagram

Scale is approxim ately 100ns per division.

START

CONVERT

INTERNAL S/H

NN+1

1000ns typ.

Acquisition Tim e

5ns typ.

EOC

OUTPUT

DATA D a ta N -2 V a lid

1980ns typ.

Hold

20ns typ. 20ns

800ns typ.

810ns typ.

65ns typ.

C onversion Tim e

800ns typ.

D a ta N -1 V a lid

ADS-950

BIT 1 (M SB)

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

ANALO G

GROUND

ANALO G

GROUND

DIGITAL

GROUND

0.1µF

10µF

0.1µF

10µF

+5V

REF. OUT

COM PENSATION 47µF

START CONVERT

+5V D IG ITAL

GAIN

ADJUST

0.1µF

10µF

0.1µF

10µF

0.1µF

10µF 0.1µF

10µF

EOC

5V ANALOG

+15V

15V

ANALO G INPUT 4

Pin 5 (A D S-951)

10k9

ADS-950

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-0???? 07/2000

MECHANICAL DIMENSIONS INCHES (mm)

ORDERING INFORMATION

OPERATING 32-PIN

MODEL NUMBER TEMP. RANGE PACKAGE

ADS-950MC 0 to +70°C TDIP

ADS-950MM –55 to +125°C TDIP

ACCESSORIES

ADS-B950 Evaluation Board (without ADS-950)

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 DA TEL.

ISO 9001

REGISTERED

DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151

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

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

DA TEL (UK) L TD. T adley, England Tel: (01256)-880444

DA TEL S.A.R.L. Montigny Le Bretonneux, France Tel: 01-34-60-01-01

DA TEL GmbH München, Germany Tel: 89-544334-0

DATEL KK Tokyo, Japan Tel: 3-3779-1031, Osaka Tel: 6-6354-2025

®®

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