Figure 1. ADS-928 Functional Block Diagram
REF
REGISTERREGISTER
FLASH
ADC
BUFFER
–
+
S/H
LOGIC
CONTROL
AND
TIMING
OFFSET
CIRCUIT
START CONVERT 32
ANALOG INPUT 3
BIPOLAR 2
OFFSET ADJUST 5
+10V REF. OUT 1
GAIN ADJUST 6
DIGITAL
CORRECTION
LOGIC
DAC
30 BIT 1 OUT (MSB)
29 BIT 2 OUT
28 BIT 3 OUT
27 BIT 4 OUT
26 BIT 5 OUT
25 BIT 6 OUT
24 BIT 7 OUT
23 BIT 8 OUT
22 BIT 9 OUT
21 BIT 10 OUT
20 BIT 11 OUT
19 BIT 12 OUT
18 BIT 13 OUT
17 BIT 14 OUT (LSB)
7 OVERFLOW
3-STATE
OUTPUT
REGISTER
11
DIGITAL
GROUND
15
ANALOG
GROUND
4
SIGNAL
GROUND
10
+5V
SUPPLY
12
+15V
SUPPLY
13
-15V
SUPPLY
S
2
S
1
8
COMP BIN
EOC 16
31 BIT 1 OUT (MSB)
9 ENABLE
BLOCK DIAGRAM
DATEL's ADS-928 is a 14-bit, 500kHz sampling rate, functionally complete AID converter. The ADS-928
samples up to Nyquist with no missing codes.
Packaged in a small 32-pin DIP, power requirements are ±15V and +5V with 3.4 Watts power dissipation.
Please contact DATEL for availability.
PRODUCT OVERVIEW
FEATURES
■ 14-bit resolution
■ 500kHz sampling rate
■ Functionally complete
■ Small 32-pin DIP
■ Low-power, 3.1 Watts
■ Excellent dynamic performance
■ Samples up to Nyquist
INPUT/OUTPUT CONNECTIONS
PIN FUNCTION PIN FUNCTION
1 +10V REF. OUT 17 BIT 14 OUT (LSB)
2 BIPOLAR 18 BIT 13 OUT
3 ANALOG INPUT 19 BIT 12 OUT
4 SIGNAL GROUND 20 BIT 11
5 OFFSET ADJUST 21 BIT 10 OUT
6 GAIN ADJUST 22 BIT 9 OUT
7 OVERFLOW 23 BIT 8 OUT
8 COMP BIN 24 BIT 7 OUT
9 ENABLE 25 BIT 6 OUT
10 +5V SUPPLY 26 BIT 5 OUT
11 DIGITAL GROUND 27 BIT4 OUT
12 +15V SUPPLY 28 BIT 3 OUT
13 -15V SUPPLY 29 BIT 2 OUT
14 NO CONNECTION 30 BIT 1 OUT (MSB)
15 ANALOG GROUND 31 BIT 1 OUT (MSB)
16 EOC 32 START CONVERT
ADS-928
500kHz, 14-Bit 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-928.B02 Page 1 of 4
ABSOLUTE MAXIMUM RATINGS
PARAMETERS LIMITS UNITS
+15V Supply (Pin 12) 0 to +16 Volts
–15V Supply (Pin 13) 0 to –16 Volts
+5V Supply (Pin 10) 0 to +6 Volts
Digital Inputs (Pins 9, 32) –0.3 to +7.0 Volts
Analog Input (Pin 3) -7.5 to +12.5 Volts
Lead Temp. (10 seconds) 300 max. °C
FUNCTIONAL SPECIFICATIONS
(TA = +25°C, ±VCC = +15V, +VDD =+5V, 500kHz sampling rate, and a 5 minute
warmup unless otherwise specifi ed.)
ANALOG INPUTS MIN. TYP. MAX. UNITS
Input Voltage Range
— 0 to +10 — Volts
— ±5 — Volts
Input Impedence 4.9 5 — kΩ
Input Capacitance — 7 15 pF
DIGITAL INPUTS
Logic Levels
Logic "1" +2.0 — — Volts
Logic "0" — — +0.8 Volts
Logic Loading "1" — — +20 μA
Logic Loading "0" — — –20 μA
PERFORMANCE
Integral Non-Linearity @ fin = 10kHz
+25°C — ±1/2 ±2 LSB
0 to +70°C — ±1 ±2 LSB
–55 to +125°C — ±1 ±3 LSB
Differential Non-Linearity @ fin = 10kHz
+25°C — ±1/2 ±0.85 LSB
0 to +70°C — ±1/2 ±0.95 LSB
–55 to +125°C — ±3/4 ±2 LSB
Full Scale Absolute Accuracy
+25°C — ±0.08 ±0.3 %FSR
0 to +70°C — ±0.2 ±0.6 %FSR
–55 to +125°C — ±0.4 ±0.8 %FSR
Unipolar Zero Error
+25°C — ±0.1 ±0.15 %FSR
0 to +70°C — ±0.1 ±0.2 %FSR
–55 to +125°C — ±0.2 ±0.3 %FSR
Bipolar Zero Error
+25°C (Tech note 1) — ±0.1 ±0.15 %FSR
0 to +70°C — ±0.1 ±0.25 %FSR
–55 to +125°C — ±0.25 ±0.5 %FSR
Bipolar Offset Error
+25°C (Tech note 1) — ±0.05 ±0.1 %FSR
0 to +70°C — ±0.1 ±0.25 %FSR
–55 to +125°C — ±0.25 ±0.45 %FSR
Gain Error
+25°C (Tech note 1) — ±0.1 ±0.3 %FSR
0 to +70°C — ±0.15 ±0.45 %FSR
–55 to +125°C — ±0.25 ±0.75 %FSR
No Missing Codes
14 Bits 0 to +70°C
13 Bits –55 to +125°C
Resolution 14 Bits
Output Coding
Pin 8 High Staight binary/Offset binary/ 2's Comp.
Pin 8 Low Comp. binary/Comp. offset binary/C2C
OUTPUTS MIN. TYP. MAX. UNITS
Logic Level
Logic "1" +2.4 — — Volts
Logic "0" — — +0.4 Volts
Logic Loading "1" — — –4 mA
Logic Loading "0" — — +4 mA
Internal Reference Voltage, +25°C +9.98 +10.0 +10.02 Volts
Drift — ±30 — ppm/°C
External Current — — 2 mA
DYNAMIC PERFORMANCE
Total Harm. Distort. (–0.5dB)
dc to 100kHz — –90 – 83 dB
100kHz to 250kHz — –82 – 77 dB
SNR (wo/distortion, –0.5dB)
dc to 100kHz 78 83 — dB
100kHz to 250kHz 74 77 — dB
SNR (& distortion, –0.5dB)
dc to 100kHz 77 80 — dB
100kHz to 250kHz 72 76 — dB
Two-tone Intermodulation Distortion
(fin = 100kHz, 240kHz,
fs = 500khz, –0.5dB) — 80 — dB
Input Bandwith (–3dB)
Small Signal (–20dB input) 6 — — MHz
Large Signal (0.5dB input) 1.75 — — MHz
Feedthrough (25 kHz) — 90 — dB
Slew Rate — ±90 — V/μs
Aperture Delay Time — ±20 — ns
Aperture Uncertainty — 50 — ps rms
Overvoltage Recovery Time; 20% — — 500 ns
S/H Acq. Time
(to 0.003%FS (10V step) — 680 750 ns
Overvoltage Recovery, ±12V — 600 1000 ns
A/D Conversion Rate 500 — — kHz
POWER REQUIREMENTS
Power Supply Range
+15V Supply +14.5 +15.0 +15.5 Volts
–15V Supply –14.5 –15.0 –15.5 Volts
+5V Supply +4.75 +5.0 +5.0 Volts
Power Supply Current
+15V Supply — +78 +110 mA
–15V Supply — –65 –95 mA
+5V Supply
➀ — +68 +95 mA
Power Dissipation — 2.5 3.4 Watts
Power Supply Rejection — — ±0.02 %FSR%V
PHYSICAL/ENVIRONMENTAL
Operating Temp. Range, Case
ADS-928MC 0 — +70 °C
ADS-928MM –55 — +125 °C
Storage Temperature Range –65 — +150 °C
Package Type 32-pin, hermetic sealed, ceramic TDIP
Weight 0.42 ounces (12 grams)
➀ All power supplies should be on before applying a start convert pulse. All supplies
and the clock (start convert pulse) must be present during warm up period.
Table 1. Input Connections
INPUT RANGE INPUT PIN TIE TOGETHER
0 to -10V Pin 3 Pins 2 and 4
±5V Pin 3 Pins 1 and 2
ADS-928
500kHz, 14-Bit 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-928.B02 Page 2 of 4
TECHNICAL NOTES
1. Use external potentiometers to remove system errors or the small initial
errors to zero. Use a 20k trimming potentiometer for gain adjustment with
the wiper tied to pin 6 (ground pin 6 for operation without adjustments).
Use a 20k trimming potentiometer with the wiper tied to pin 5 for zero/
offset adjustment (connect pin 5 to pin 15, analog ground for operation
without adjustment).
2. Rated performance requires using good high-frequency circuit board
layout techniques. The analog and digital grounds are not connected
internally. Avoid ground-related problems by connecting the digital and
analog grounds to one point, the ground plane beneath the converter. Due
to the inductance and resistance of the power supply return paths, return
the analog and digital ground separately to the power supplies.
3. Bypass the analog and digital supplies and the +1OV reference (pin 1) to
ground with a 4.7μF, 25V tantalum electrolytic capacitor in parallel with
a 0.1 μF ceramic capacitor. Bypass the +10V reference (pin 1) to analog
ground (pin 15).
4. Obtain straight binary/offset binary output coding by tying COMP BIN (pin
8) to +5V or leaving it open. The device has an internal pull-up resistor
on this pin. To obtain complementary binary or complementary offset binary
output coding, tie the COMP BIN pin to ground. The COMP BIN signal is com-
patible to CMOS/TTL logic levels for those users desiring logic control of this
function.
5. To enable the three-state outputs, connect ENABLE (pin 9) to a logic ·"0"·
(low). To disable, connect ENABLE (pin 9) to a logic "1" (high).
6. The 200 ns minimum START CONVERT pulse width assures the hold mode
settling time requirements are met.
7. The specifi cations listed in Figure 2 (timing diagram) apply over the full
operating temperature range unless otherwise specifi ed.
Table 2. Zero and Gain Adjust
FSR ZERO ADJUST
+½ LSB
GAIN ADJUST
FS - ½ LSB
0 to -10V -305 μV -9.999085V
±5V +305V +4.999085V
CALIBRATION PROCEDURE
1. Connect the converter per Figure 3, and Table 1 for the appropriate full-
scale range (FSR). Apply a pulse of 200 nanoseconds minimum to the
START CONVERT input (pin 32) at a rate of 200kHz. This rate is chosen to
reduce fl icker if LED's are used on the outputs for calibration purposes.
2. Zero Adjustments Apply a precision voltage reference source between
the analog input (pin 3) and signal ground (pin 4). Adjust the output of the
reference source per Table 2.
For unipolar, adjust the zero trimming potentiometer so that the output
code fl ickers equally between 00 0000 0000 0000 and 00 0000 0000
0001 with the COMP BIN (pin 8) tied high (straight binary) or between 11
1111 1111 1111 and 11 1111 1111 1110 with the pin 8 tied low (comple-
mentary binary).
For bipolar operation, adjust the potentiometer such that the code fl ickers
equally between 10 0000 0000 0000 and 10 0000 0000 0001 with pin
8 tied high (offset binary) or between 01 1111 1111 1111 and 01 1111
1111 1110 with pin 8 tied low (complementary offset binary).
Two's complement coding requires use of the MSB (pin 31) with pin 8 tied
high, adjusting the potentiometer such that the code fl ickers between 00
0000 0000 0000 and 00 0000 0000 0001.
3. Full-Scale Adjustment
Set the output of the voltage reference used in step 2 to the value shown
in Table 2.
Adjust the gain trimming potentiometer so that the output code fl ickers
equally between 11 1111 1111 1110 and 11 1111 1111 1111 for pin 8
tied high (straight binary) or between 00 0000 0000 0000 and 00 0000
0000 0001 for pin 8 tied low (complementary binary).
Two's complement coding requires use of the MSB (pin 31) with the pin 8
tied high, adjusting the gain trimming potentiometer so that the output code
fl ickers equally between 01 1111 1111 1110 and 01 1111 1111 1111.
4. To confi rm proper operation of the device, vary the precision reference
voltage source to obtain the output coding listed in Table 3.
Figure 2. ADS-928 Timing Diagram
START
CONVERT
N
S/H
CONTROL
OUT
(INTERNAL)
ENABLED DATA N VALID
DATA N VALID
INVALID
BUSY
SAMPLE
HOLD MODE SETTLING
S/H ACQ. TIME
DATA N-1 VALID
OUTPUT
DATA
280ns min.
30ns min.
25ns min.
10ns min., 25ns max.
20ns min., 35ns max.
10ns max. DATA INHIBITED 10ns max.
700ns min.
A/D EOC
OUT EOC
NOTES: NOT DRAWN TO SCALE
Retriggering START CONVERT before EOC
goes low will not start a new conversion.
HOLD
ENABLE
ADS-928
500kHz, 14-Bit 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-928.B02 Page 3 of 4
Table 3. Output Coding for Unipolar Operation
STRAIGHT BIN. COMP. BINARY
UNIPOLAR
SCALE
INPUT RANGES, Vdc
0 to ·10V
OUTPUT CODING COMP. BINARY INPUT RANGE
±5Vdc
BIPOLAR
SCALE
MSB LSB MSB LSB MSB LSB
FS -1 LSB -9.999390 11 1111 1111 1111 00 0000 0000 0000 01 1111 1111 1111 -4.99939 +FS -1 LSB
7/8 FS -8.750000 11 1000 0000 0000 00 0111 1111 1111 01 1000 0000 0000 -3.75000 +3/4 FS
3/4 FS -7.500000 11 0000 0000 0000 00 1111 1111 1111 01 0000 0000 0000 -2.50000 +1/2 FS
1/2 FS -5.000000 10 0000 0000 0000 01 1111 1111 1111 00 0000 0000 0000 0.00000 0
1/4 FS -2.500000 01 0000 0000 0000 10 1111 1111 1111 10 0000 0000 0000 +2.50000 -1/2 FS
1/8 FS -1.250000 00 1000 0000 0000 11 0111 1111 1111 10 1000 0000 0000 +3.75000 -3/4 FS
1 LSB -0.000610 00 0000 0000 0001 11 1111 1111 1110 10 0000 0000 0001 +4.99939 -FS +1 LSB
0 0.000000 00 0000 0000 0000 11 1111 1111 1111 10 0000 0000 0000 +5.00000 -FS
OFF. BINARY COMP. OFF. BIN.
Figure 3. Typical ADS-928 Connection Diagram
ADS-928
GAIN ADJUST
ZERO/OFFSET ADJUST
+10V REF. OUT
ANALOG INPUT
BIPOLAR
START CONVERT
NO CONNECTION
SIGNAL GROUND
COMP BIN
GAIN
ADJUST
6
1
12 15 13
09 ENABLE
31 BIT 1 (MSB)
30 BIT 1 (MSB)
29 BIT 2
28 BIT 3
27 BIT 4
26 BIT 5
25 BIT 6
24 BIT 7
23 BIT 8
22 BIT 9
21 BIT 10
20 BIT 11
19 BIT 12
18 BIT 13
17 BIT 14 (LSB)
07 OVERFLOW
16 EOC
10 11
2
3
8
32
14
4
5
+15V
-15V
+5V DC
20K
+15V
+15V +5V-15V
-15V
20K
4.7F
0.1F
4.7F
+
++ +
0.1F
4.7F
0.1F
4.7F
0.1F
0 to -10V
MECHANICAL DIMENSIONS
INCHES (mm)
SEATING
PLANE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
PIN 1
INDEX
0.190 MAX.
(4.826)
0.235 MAX.
(5.969)
0.035/0.015
(0.889/0.381)
0.021/0.016
(0.534/0.406)
0.045/0.035
(1.143/0.889)
0.015/0.009
(0.381/0.228)
0.92/0.89
(23.37/22.60)
1.72/1.69
(43.69/42.92)
0.11/0.09
(2.80/2.28)
1.11/1.08
(28.20/27.43)
0.200/0.175
(5.08/4.44)
0.100 BSC
(2.54)
Figure 4. ADS-928 FFT Analysis
ORDERING INFORMATION
MODEL
NUMBER
OPERATING
TEMP. RANGE SEAL ACCESSORIES
ADS-928MC 0 to +70°C Hermetic ADS-EVAL1 Evaluation Board (without ADS-928)
ADS-928MM -55 to +125°C Hermetic
Receptacle for PC board mounting can be ordered
through AMP Inc., Part # 3-331272-8 (Component Lead
Socket), 32 required.
For availibility of MIL-STD-883B versions, contact DATEL.
ADS-928
500kHz, 14-Bit 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-928.B02 Page 4 of 4