Figure 1. ADS-953 Functional Block Diagram
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
Σ
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
BLOCK DIAGRAM
The ADS-953 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
–95dB peak harmonic distortion (THD), makes the
ADS-953 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-953 contains a fast-settling sample-hold
amplifi er, 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-953 only requires the
rising edge of the start convert pulse to operate.
Requiring ±15V and ±5V supplies, the ADS-
953 typically dissipates 1.45 Watts. The device is
offered with a bipolar (±5V) analog input range.
Models are available for use in either commer-
cial (0 to +70°C) or extended (–40 to +110°C)
operating temperature ranges. A proprietary,
auto-calibrating, error-correcting circuit enables
the device to achieve specifi ed performance over
the full military temperature range.
PRODUCT OVERVIEW
FEATURES
■ 18-bit resolution
■ 1MHz minimum sampling rate
■ No missing codes over extended temperature
range
■ Very low power, 1.45 Watts
■ Small, 32-pin, side-brazed, ceramic TDIP
■ Edge-triggered
■ Excellent performance, –95dB peak harmonics
■ Ideal for both time and frequency-domain
applications
■ Low cost
INPUT/OUTPUT CONNECTIONS
PIN FUNCTION PIN FUNCTION
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)
ADS-953
18-Bit, 1MHz, Low-Distortion Sampling A/D Converters
®®
DATEL • 11 Cabot Boulevard, Mansfi eld, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: help@datel.com
01 Apr 2011 MDA_ADS-953.B02 Page 1 of 6
PHYSICAL/ENVIRONMENTAL
PARAMETERS MIN. TYP. MAX. UNITS
Operating Temp. Range, Case
ADS-953MC 0 — +70 °C
ADS-953ME –40 — +110 °C
Thermal Impedance
Tjc — 5 — °C/Watt
Tca — 22 — °C/Watt
Storage Temperature Range –65 — +150 °C
Package Type 32-pin,side-brazed, metal-sealed, ceramic TDIP
Weight 0.46 ounces (13 grams)
ABSOLUTE MAXIMUM RATINGS
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 +VDD +0.3 Volts
Analog Input (Pin 4) ±15 Volts
Lead Temperature (10 seconds) +300 °C
+25°C 0 TO +70°C –40 TO +110°C
ANALOG INPUT MIN. TYP. MAX. MIN. TYP. MAX. MIN. TYP. MAX. UNITS
Input Voltage Range d — ±5 — — ±5 — — ±5 — Volts
Input Resistance — 500 — — 500 — — 500 — :
Input Capacitance — 7 15 — 7 15 — 7 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 20 500 — 20 500 — 20 500 — ns
STATIC PERFORMANCE
Resolution — 18 — — 18 — — 18 — Bits
Integral Nonlinearity (fi n = 10kHz) — ±10 — — ±10 — — ±15 — LSB
Differential Nonlinearity (fi n = 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 (fi n = 10kHz) 18 — — 18 — — 18 — — Bits
DYNAMIC PERFORMANCE (500kHz SAMPLING RATE)
Peak Harmonics (–0.5dB)
dc to 1kHz — –95 –93 — –95 –93 — –82 — dB
dc to 100kHz — –87 —————–80—dB
Total Harmonic Distortion (–0.5dB)
dc to 100kHz — –85 –80 — –85 –80 — –81 — dB
Signal-to-Noise Ratio (w/o distortion, –0.5dB)
dc to 100kHz 91 93 — 91 93 — — 92 — dB
Signal-to-Noise Ratio f (& distortion, –0.5dB)
dc to 100kHz 76 84 — 76 84 — — 80 — dB
DC Noise — 76 — — 76 — — 76 — Vrms
Two-Tone Intermodulation Distortion
(fi n = 100kHz, 240kHz, fs = 500kHz, –0.5dB) — –85 — — –85 — — –81 — d
Input Bandwidth (–3dB)
Small Signal (–20dB input) — TBD — — TBD — — TBD — MHz
Large Signal (–0.5dB input) — TBD — — TBD — — TBD — MHz
Feedthrough Rejection (fi n = 500kHz) — 84 — — 84 — — 84 — dB
Slew Rate — TBD — — TBD — — TBD — V/s
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
ANALOG OUTPUT
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
FUNCTIONAL SPECIFICATIONS
(TA = +25°C, ±VCC = ±15V, ±VDD = ±5V, 1MHz sampling rate, and a minimum 1 minute warmup ➀ unless otherwise specifi ed.)
ADS-953
18-Bit, 1MHz, Low-Distortion Sampling A/D Converters
®®
DATEL • 11 Cabot Boulevard, Mansfi eld, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: help@datel.com
01 Apr 2011 MDA_ADS-953.B02 Page 2 of 6
+25°C 0 TO +70°C –40 TO +110°C
DIGITAL OUTPUTS MIN. TYP. MAX. MIN. TYP. MAX. MIN. TYP. MAX. UNITS
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 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
Footnotes:
➀ All power supplies should 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:
➄ This is the time required before the A/D output data is valid once the analog input
is back within the specifi ed range.
(SNR + Distortion) – 1.76 + 20 log Full Scale Amplitude
Actual Input Amplitude
6.02
ADS-953
18-Bit, 1MHz, Low-Distortion Sampling A/D Converters
®®
DATEL • 11 Cabot Boulevard, Mansfi eld, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: help@datel.com
01 Apr 2011 MDA_ADS-953.B02 Page 3 of 6
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-953'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 "fl icker" 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-953, offset adjusting is normally accomplished when the
analog input is 0 minus ½LSB (–19V). 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).
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 –19V to the ANALOG INPUT (pin 4).
3. Adjust the offset potentiometer until the output code fl ickers equally be-
tween 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 fl ick-
ers between 1 and 0.
3. To confi rm proper operation of the device, vary the applied input voltage to
obtain the output coding listed in Table 2.
Table 1. Input Connections
INPUT VOLTAGE
RANGE
ZERO ADJUST
(–½ LSB)
GAIN ADJUST
(–FS +1½ LSB)
±5V –19V –4.999943
Table 2. Output Coding
TECHNICAL NOTES
1. Obtaining fully specifi ed performance from the ADS-953 requires careful
attention to pc-card layout and power supply decoupling. The device's ana-
log 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 10F tantalum capacitors in parallel with 0.1F ceramic ca-
pacitors. Locate the bypass capacitors as close to the unit as possible. Tie a
47F capacitor between COMPENSATION (pin 7) and ground.
2. The ADS-953 achieves its specifi ed accuracies without the need for exter-
nal 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.
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.
THERMAL REQUIREMENTS
All DATEL sampling A/D converters are fully characterized and speci-
fi ed over operating temperature (case) ranges of 0 to +70°C and –40
to +110°C. All room-temperature (TA = +25°C) production testing is
performed without the use of heat sinks or forced-air cooling. Thermal
impedance fi gures for each device are listed in their respective specifi ca-
tion tables.
These devices do not normally require heat sinks, however, standard pre-
cautionary 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 fl ow over the surface can greatly help reduce the
package temperature.
COMPLEMENTARY OFFSET BINARY
BIPOLAR
SCALE
INPUT RANGE
±5V
OUTPUT CODING
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
ADS-953
18-Bit, 1MHz, Low-Distortion Sampling A/D Converters
®®
DATEL • 11 Cabot Boulevard, Mansfi eld, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: help@datel.com
01 Apr 2011 MDA_ADS-953.B02 Page 4 of 6
Figure 3. ADS-953 Timing Diagram
Scale is approximately 50ns per division.
START
CONVERT
INTERNAL S/H
NN+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
Figure 2. Typical ADS-953 Connection Diagram
3
11
ADS-953
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-953)
10k Ω
ADS-953
18-Bit, 1MHz, Low-Distortion Sampling A/D Converters
®®
DATEL • 11 Cabot Boulevard, Mansfi eld, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: help@datel.com
01 Apr 2011 MDA_ADS-953.B02 Page 5 of 6
MECHANICAL DIMENSIONS INCHES (mm)
ORDERING INFORMATION
MODEL
NUMBER
OPERATING
TEMP. RANGE
32-PIN
PACKAGE ACCESSORIES
ADS-953MC 0 to +70°C TDIP ADS-B951* Evaluation Board (without ADS-951)
ADS-953ME –40 to +110°C TDIP
Receptacles for PC 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.
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
* NOTE: The ADS-951 evalution board is used for the AD-953, as the ADS-951 and ADS-953, share a common pinout
ADS-953
18-Bit, 1MHz, Low-Distortion Sampling A/D Converters
. 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. Specifi cations are subject to change
without notice.
www.datel.com • e-mail: help@datel.com
®®
DATEL
11 Cabot Boulevard, Mansfi eld, MA 02048-1151 USA
ITAR and ISO 9001/14001 REGISTERED
01 Apr 2011 MDA_ADS-953.B02 Page 6 of 6