DATEL ADS-937MM, ADS-937MC, ADS-937-883, ADS-B937 Datasheet

FEATURES

• 16-bit resolution

• 1MHz minimum sampling rate

• No missing codes over full military temperature range

• Very low power, 1.25 Watts

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

• Edge-triggered

• Excellent performance

• Ideal for both time and frequency-domain applications

• Low cost

military (–55 to +125°C) operating temperature ranges. A
proprietary, auto-calibrating, error-correcting circuit enables
the device to achieve specified performance over the full
military temperature range.

ADS-937

16-Bit, 1MHz, Low-Power

Sampling A/D Converters

GENERAL DESCRIPTION

The low-cost ADS-937 is a 16-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-937 the ideal
choice for both time-domain (CCD/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-937 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.
ADS-937 only requires the rising edge of the start convert
pulse to operate.

Requiring ±15V and ±5V supplies, the ADS-937 typically
dissipates 1.25 Watts. The device is offered with both bipolar
(±5V) and unipolar (0 to –10V) analog input ranges. Models
are available for use in either commercial (0 to +70°C) or

INPUT/OUTPUT CONNECTIONS

Figure 1. ADS-937 Functional Block Diagram

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

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

PIN FUNCTION PIN FUNCTION

REF

DAC

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

17 BIT 16 (LSB)

TIMING AND

CONTROL LOGIC

ANALOG INPUT 1

START CONVERT 16

EOC 15

–

+

S/H

BUFFER

DIGITAL CORRECTION LOGIC

FLASH

ADC

1

FLASH

ADC

2

Σ

AMP

GAIN

CIRCUIT

COMPENSATION 7

+5V REFERENCE OUT 5

10

+5V ANALOG

SUPPLY

11

–5V ANALOG

SUPPLY

2, 12

ANALOG

GROUND

14

+5V DIGITAL

SUPPLY

9

+15V

SUPPLY

8

–15V

SUPPLY

13

DIGITAL

GROUND

OFFSET ADJUST 4

UNIPOLAR 3

GAIN ADJUST 6

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

® ®

ADS-937

2

® ®

+25°C 0 to +70°C –55 to +125°C

ANALOG INPUTS MIN. TYP. MAX. MIN. TYP. MAX. MIN. TYP. MAX. UNITS

Input Voltage Ranges ➁

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

Input Resistance — 1 — — 1 — — 1 — kΩ
Input Capacitance — 7 15 — 7 15 — 7 15 pF

DIGITAL INPUTS

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 — 16 — — 16 — — 16 — Bits
Integral Nonlinearity — ±0.75 — — ±1.5 — — ±2 — LSB
Differential Nonlinearity (f

in = 10kHz) –0.95 ±0.5 +1 –0.95 ±0.5 +1 –0.95 ±0.5 +1.5 LSB

Full Scale Absolute Accuracy — ±0.1 ±0.25 — ±0.2 ±0.4 — ±0.25 ±0.5 %FSR
Bipolar Zero Error (Tech Note 2) — ±0.1 ±0.15 — ±0.1 ±0.25 — ±0.15 ±0.5 %FSR
Bipolar Offset Error (Tech Note 2) — ±0.1 ±0.2 — ±0.15 ±0.3 — ±0.2 ±0.5 %FSR
Gain Error (Tech Note 2) — ±0.1 ±0.3 — ±0.25 ±0.5 — ±0.4 ±0.7 %
Unipolar Offset Error (Tech Note 2) — ±0.1 ±0.15 — ±0.1 ±0.25 — ±0.15 ±0.5 %FSR
No Missing Codes (f

in = 10kHz) 16 — — 16 — — 16 — — Bits

DYNAMIC PERFORMANCE

Peak Harmonics (–0.5dB)

dc to 100kHz — –90 –84 — –90 –84 — –88 –83 dB
100kHz to 500kHz — –88 –81 — –88 –81 — –87 –80 dB

Total Harmonic Distortion (–0.5dB)

dc to 100kHz — –87 –82 — –87 –82 — –86 –81 dB
100kHz to 500kHz — –86 –81 — –86 –81 — –85 –80 dB

Signal-to-Noise Ratio

(w/o distortion, –0.5dB)
dc to 100kHz 85 88 — 85 88 — 84 87 — dB
100kHz to 500kHz 84 87 — 84 87 — 83 87 — dB

Signal-to-Noise Ratio ➃

(& distortion, –0.5dB)
dc to 100kHz 81 85 — 81 85 — 80 84 — dB
100kHz to 500kHz 80 84 — 80 84 — 78 83 — dB

Noise — 110 — — 110 — — 110 — µVrms
Two-Tone Intermodulation
Distortion (f

in = 100kHz,

240kHz, f

s = 1MHz, –0.5dB) — –85 — — –85 — — –85 — dB

Input Bandwidth (–3dB)

Small Signal (–20dB input) — 4.5 — — 4.5 — — 4.5 — MHz
Large Signal (–0.5dB input) — 4 — — 4 — — 4 — MHz

Feedthrough Rejection (f

in = 500kHz) — 84 — — 84 — — 84 — dB

Slew Rate — ±33 — — ±33 — — ±33 — 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) — 260 300 — 260 300 — 260 300 ns

Overvoltage Recovery Time ➄ — 500 1000 — 500 1000 — 500 1000 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 1) ±15 Volts
Lead Temperature (10 seconds) +300 °C

PARAMETERS MIN. TYP. MAX. UNITS

Operating Temp. Range, Case

ADS-937MC 0 — +70 °C
ADS-937MM/883 –55 — +125 °C

Thermal Impedance

θjc — 5 — °C/Watt
θca — 22 — °C/Watt

Storage Temperature Range –65 — +150 °C
Package Type 32-pin,side-brazed, metal-sealed, ceramic TDIP

Weight 0.56 ounces (16 grams)

ABSOLUTE MAXIMUM RATINGS

PHYSICAL/ENVIRONMENTAL

FUNCTIONAL SPECIFICATIONS

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

ADS-937

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

Output Coding

Complementary Binary / 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 — +7 +9 — +7 +9 — +7 +9 mA
–15V Supply — –8 –10 — –8 –10 — –8 –10 mA
+5V Supply — +133 +145 — +133 +145 — +133 +145 mA
–5V Supply — –72 –80 — –72 –80 — –72 –80 mA

Power Dissipation — 1.25 1.35 — 1.25 1.35 — 1.25 1.35 Watts
Power Supply Rejection — — ±0.01 — — ±0.01 — — ±0.01 %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-937
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 (2, 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 4.7µF 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
(See figure 2.).

2. The ADS-937 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 Figure 2. When using this
circuitry, or any similar offset and gain calibration hardware,
make adjustments following warm-up. To avoid interaction,
always adjust offset before gain. Float pins 4 and 6 if not
using offset and 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 warm-up
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 less 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 inaccurate
conversion cycle. Data for the interrupted and subsequent
conversions will be invalid.