ADS-951

ADS-951
18-Bit, 1MHz, Low-Power Sampling A/D Converters
FEATURES
PRODUCT OVERVIEW
„ 18-bit resolution
The ADS-951 is an 18-bit, 1MHz sampling A/D
converter. This device provides low noise performance and dynamic specifications up to 100 kHz
with no missing codes. This, 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, SMT or side-brazed,
metal-sealed, ceramic package, the functionally complete ADS-951 contains a fast-settling
„ 1MHz minimum sampling rate
„ No missing codes over full HI-REL temperature
range
„ Very low power, 390mW
„ Small, 32-pin, SMT or side-brazed, ceramic
package
„ Edge-triggered, no pipeline delays
„ Excellent performance
„ Ideal for both time and frequency-domain
applications
„ Low cost
sample-hold amplifier, an A/D converter, an internal
reference, and timing/control logic. Digital input
and output levels are TTL, and the ADS-951 only
requires the rising edge of the start convert pulse
to operate.
The ADS-951 typically dissipates 390mW. The
device is offered with a bipolar (±5V) analog input
range. Models are available for use in commercial
(0 to +70°C), extended (–40 to +110°C), or HI-REL
(–55 to +125°C) operating temperature ranges.
Contact DATEL for converters with input ranges
of ±10V (ADS-951-1) or 0 to +10V (ADS-951-2).
BLOCK DIAGRAM
OFFSET ADJUST 5
BUFFER
ANALOG INPUT 3
–
S/H
+
GAIN ADJUST 6
GAIN
CIRCUIT
OUTPUT REGISTER
A/D
REF
+4.22V REFERENCE OUT 1
START CONVERT 27
25
BIT 1 (MSB)
24
BIT 2
23
BIT 3
22
BIT 4
21
BIT 5
20
BIT 6
19
BIT 7
18
BIT 8
17
BIT 9
16
BIT 10
15
BIT 11
14
BIT 12
13
BIT 13
12
BIT 14
11
BIT 15
10
BIT 16
9
BIT 17
8
BIT 18 (LSB)
TIMING AND
CONTROL LOGIC
EOC 26
30
32
2, 4, 31
29
7, 28
+5VA ANALOG
SUPPLY
–5VA ANALOG
SUPPLY
ANALOG
GROUND
+5VD DIGITAL
SUPPLY
DIGITAL
GROUND
Figure 1. ADS-951 Functional Block Diagram
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA
• Tel: (508) 339-3000
•
www.datel.com
•
e-mail: [email protected]
10 Sep 2015
MDA_ADS-951.E01 Page 1 of 7
ADS-951
18-Bit, 1MHz, Low-Power Sampling A/D Converters
ABSOLUTE MAXIMUM RATINGS
PARAMETERS
LIMITS
+5VA Supply (Pin 30)
0 to +6
+5VD Supply (Pin 29)
0 to +6
–5VA Supply (Pin 32)
0 to –6
Digital Input (Pin 27)
–0.3 to +5VD +0.3
Analog Input (Pin 3)
±7
Lead Temperature (10 seconds)
+300
PHYSICAL/ENVIRONMENTAL
PARAMETERS
MIN.
TYP.
MAX.
UNITS
Operating Temp. Range, Case
ADS-951MC, MC-C, GC, GC-C
0
—
+70
°C
ADS-951ME, ME-C, GE, GE-C
–40
—
+110
°C
ADS-951MM, MM-C, GM, GM-C
–55
—
+125
°C
Thermal Impedance
θjc
—
14.9
—
°C/Watt
θca
—
22.6
—
°C/Watt
Storage Temperature Range
–65
—
+150
°C
Package Type
32-pin, side-brazed, metal-sealed, ceramic TDIP
Weight
0.46 ounces (13 grams)
UNITS
Volts
Volts
Volts
Volts
Volts
°C
FUNCTIONAL SPECIFICATIONS
(TA = +25°C, +5VA = +5V, –5VA = –5V, +5VD = +5V, 1MHz sampling rate, and a minimum 1 minute warmup ➀ unless otherwise specified.)
ANALOG INPUT
Input Voltage Range d
Input Resistance
Input Capacitance
DIGITAL INPUT
Logic Levels
Logic "1"
Logic "0"
Logic Loading "1"
Logic Loading "0"
Start Convert Positive Pulse Width ➂
STATIC PERFORMANCE
Resolution
Integral Nonlinearity (fin = 10kHz)
Differential Nonlinearity (fin = 10kHz)
Full Scale Absolute Accuracy
Bipolar Zero Error (Tech Note 2)
Gain Error (Tech Note 2)
No Missing Codes (fin = 10kHz)
DYNAMIC PERFORMANCE
Peak Harmonics (–0.5dB)
dc to 100kHz
Total Harmonic Distortion (–0.5dB)
dc to 100kHz
Signal-to-Noise Ratio (w/o distortion, –0.5dB)
dc to 100kHz
Signal-to-Noise Ratio f (& distortion, –0.5dB)
dc to 100kHz
DC Noise
Two-Tone Intermodulation Distortion
(fin = 100kHz, 240kHz, fs = 1MHz, –0.5dB)
Input Bandwidth (–3dB)
Slew Rate
Aperture Delay Time
Aperture Uncertainty
S/H Acquisition Time ( to ±0.003%FSR, 10V step)
Overvoltage Recovery Time ➄
A/D Conversion Rate
ANALOG OUTPUT
Internal Reference
Voltage
External Current
MIN.
—
—
—
0 TO +70°C
TYP.
±5
500
7
MAX.
—
—
15
MIN.
—
—
—
–40 TO +110°C
TYP.
±5
500
7
MAX.
—
—
15
MIN.
—
—
—
–55 TO +125°C
TYP.
±5
500
7
MAX.
—
—
15
UNITS
Volts
Ω
pF
+2.0
—
—
—
20
—
—
—
—
500
—
+0.8
+20
–20
—
+2.0
—
—
—
20
—
—
—
—
500
—
+0.8
+20
–20
—
+2.0
—
—
—
20
—
—
—
—
500
—
+0.8
+20
–20
—
Volts
Volts
μA
μA
ns
—
—
–0.95
—
—
—
18
18
±1.25
±0.3
±0.05
±0.01
±0.1
—
—
—
+0.95
±0.15
±0.025
±0.2
—
—
—
–0.95
—
—
—
18
18
±1.25
±0.3
±0.1
±0.04
±0.15
—
—
—
+0.95
±0.25
±0.056
±0.25
—
—
—
–0.95
—
—
—
18
18
±1.25
±0.3
±0.2
±0.05
±0.2
—
—
—
+0.95
±0.47
±0.70
±0.30
—
Bits
LSB
LSB
%FSR
%FSR
%
Bits
—
–110
–99
—
–100
–99
—
–100
–95
dB
—
–98
–95
—
–98
–95
—
–98
–94
dB
92
94
—
92
94
—
91
93
—
dB
90
—
91
90
—
—
90
—
91
90
—
—
—
—
89
90
—
—
dB
μVrms
—
6.2
—
—
—
—
—
1
–96
—
110
12
3.5
260
750
—
—
—
—
—
—
—
—
—
—
6.2
—
—
—
—
—
1
–96
—
110
12
3.5
260
750
—
—
—
—
—
—
—
—
—
—
6.2
—
—
—
—
—
1
–96
—
110
12
3.5
260
750
—
—
—
—
—
—
—
—
—
dB
V/μs
ns
ps rms
ns
ns
MHz
+4.195
—
+4.220
—
+4.245
0.1
+4.192
—
—
—
+4.248
0.1
+4.191
—
—
—
+4.250
0.1
Volts
mA
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA
• Tel: (508) 339-3000
•
www.datel.com
•
e-mail: [email protected]
10 Sep 2015
MDA_ADS-951.E01 Page 2 of 7
ADS-951
18-Bit, 1MHz, Low-Power Sampling A/D Converters
DIGITAL OUTPUTS
Logic Levels
Logic "1"
Logic "0"
Logic Loading "1"
Logic Loading "0"
Output Coding
POWER REQUIREMENTS
Power Supply Ranges
+5VA, +5VD Supplies
–5VA Supply
Power Supply Currents
+5VD
+5VA Supply
–5VA Supply
Power Dissipation
Power Supply Rejection
MIN.
0 TO +70°C
TYP.
MAX.
MIN.
+2.4
—
—
—
—
—
—
—
—
+0.4
–4
+4
+2.4
—
—
—
+4.75
–4.75
+5.0
–5.0
+5.25
–5.25
+4.75
–4.75
+5.0
–5.0
—
—
—
—
—
+3.8
+71
–3.5
390
±0.005
+5
+80
–6.5
420
±0.02
—
—
—
—
—
+3.8
+71
–3.5
390
±0.005
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.
–40 TO +110°C
TYP.
–55 TO +125°C
TYP.
MAX.
UNITS
+2.4
—
—
—
—
—
—
—
—
+0.4
–4
+4
Volts
Volts
mA
mA
+5.25
–5.25
+4.75
–4.75
+5.0
–5.0
+5.25
–5.25
Volts
Volts
+5
+80
–6.5
420
±0.02
—
—
—
—
—
+3.8
+71
–3.5
390
±0.005
+5
+80
–6.5
420
±0.02
mA
mA
mA
mW
%FSR/%V
—
—
—
+0.4
—
–4
—
+4
Complementary Offset Binary
➃ Effective bits is equal to:
(SNR + Distortion) – 1.76 +
20 log
Full Scale Amplitude
Actual Input Amplitude
6.02
➄ This is the time required before the A/D output data is valid once the analog input
is back within the specified range.
PIN
INPUT/OUTPUT CONNECTIONS
FUNCTION
PIN FUNCTION
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
+4.22V REF OUT
ANALOG GROUND
ANALOG INPUT
ANALOG GROUND
OFFSET ADJUST
GAIN ADJUST
DIGITAL GROUND
BIT 18 (LSB)
BIT 17
BIT 16
BIT 15
BIT 14
BIT 13
BIT 12
BIT 11
BIT 10
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA
MIN.
MAX.
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
–5VA ANALOG SUPPLY
ANALOG GROUND
+5VA ANALOG SUPPLY
+5VD DIGITAL SUPPLY
DIGITAL GROUND
START CONVERT
EOC
BIT 1 (MSB)
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
BIT 8
BIT 9
• Tel: (508) 339-3000
•
www.datel.com
•
e-mail: [email protected]
10 Sep 2015
MDA_ADS-951.E01 Page 3 of 7
ADS-951
18-Bit, 1MHz, Low-Power Sampling A/D Converters
TECHNICAL NOTES
THERMAL REQUIREMENTS
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 (2, 4, 7, 28, and 31) directly to
a large analog ground plane beneath the package.
Bypass all power supplies to ground with 10μF tantalum capacitors in parallel with 0.1μF ceramic capacitors. Locate the bypass capacitors as close
to the unit as possible. The +4.22V REFERENCE OUTPUT (pin 1) should not
be bypassed externally. If needed to drive external circuitry, pin 1 should be
buffered close to the unit.
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. Connect pins 5 and 6 to ground if not using offset and gain adjust
circuits.
All DATEL sampling A/D converters are fully characterized and tested over
operating temperature (case) ranges of 0 to +70°C, –40 to +110°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. Electricallyinsulating, 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.
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.
Gain Adjust Procedure
CALIBRATION PROCEDURE
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. If Gain and Offset adjustment
pins are not used they should be left floating.
1. Apply –4.999943V to the ANALOG INPUT (pin 3).
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.
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).
Zero/Offset Adjust Procedure
1. Apply a train of pulses to the START CONVERT input (pin 27) so that the
converter is continuously converting.
2. For bipolar zero/offset adjust, apply –19μV to the ANALOG INPUT (pin 3).
3. Adjust the offset potentiometer until the output code flickers equally between 01 1111 1111 1111 1111 and 10 0000 0000 0000 0000.
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA
INPUT VOLTAGE
RANGE
ZERO ADJUST
(–½ LSB)
GAIN ADJUST
(–FS +1½ LSB)
±5V
–19μV
–4.999943
Table 1. Input Connections
BIPOLAR
SCALE
+FS –1 LSB
+3/4 FS
+1/2 FS
0
–1/2 FS
–3/4 FS
–FS +1 LSB
–FS
COMPLEMENTARY OFFSET BINARY
OUTPUT CODING
INPUT RANGE
±5V
MSB
LSB
+4.999962
00 0000 0000 0000 0000
+3.750000
00 0111 1111 1111 1111
+2.500000
00 1111 1111 1111 1111
+0.000000
01 1111 1111 1111 1111
–2.500000
10 1111 1111 1111 1111
–3.750000
11 0111 1111 1111 1111
–4.999962
11 1111 1111 1111 1110
–5.000000
11 1111 1111 1111 1111
Table 2. Output Coding
• Tel: (508) 339-3000
•
www.datel.com
•
e-mail: [email protected]
10 Sep 2015
MDA_ADS-951.E01 Page 4 of 7
ADS-951
18-Bit, 1MHz, Low-Power Sampling A/D Converters
10k
+5VA
ANALOG
–5VA
ANALOG
+5VA ANALOG
10k
6
26
5
GAIN
OFFSET
ADJUST ADJUST
–5VA ANALOG
EOC
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
29
+5VD DIGITAL
10μF
0.1μF
28 DIGITAL
GROUND
7
ADS-951
30
+5VA ANALOG
+
10μF
0.1μF
31 ANALOG
GROUND
0.1μF
32
2
4
1 +4.22V
REF. OUT
+
–5VA ANALOG
10μF
START CONVERT
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)
27
ANALOG INPUT
3
Figure 2. Typical ADS-951 Connection Diagram
N
START
CONVERT
N+1
500ns typ.
5ns typ.
INTERNAL S/H
Acquisition Time
740ns typ.
260ns typ.
Hold
65ns typ.
EOC
Conversion Time
730ns typ.
20ns typ.
OUTPUT
DATA
Invalid Data
20ns
N+1
Data N Valid
Data N-1 Valid
980ns typ.
Scale is approximately 50ns per division.
Figure 3. ADS-951 Timing Diagram
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA
• Tel: (508) 339-3000
•
www.datel.com
•
e-mail: [email protected]
10 Sep 2015
MDA_ADS-951.E01 Page 5 of 7
ADS-951
18-Bit, 1MHz, Low-Power Sampling A/D Converters
MECHANICAL DIMENSIONS – TDIP PACKAGE – INCHES (mm)
81/(6627+(5:,6(63(&,),('
',0(16,216$1'72/(5$1&(6
3/$&( >PP@
3/$&( >PP@
$1*/(6 7+,5'$1*/(352-(&7,21
/($'0$7(5,$/.29$5$//2<
/($'),1,6+X0,1*2/'29(5
X1201,&.(/
3,1,1',&$725
6($7,1*3/$1(
3,7&+
7<3
7<3
(463$&(6#>@
(48$/6>@
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 USA
• Tel: (508) 339-3000
•
www.datel.com
•
e-mail: [email protected]
10 Sep 2015
MDA_ADS-951.E01 Page 6 of 7
ADS-951
18-Bit, 1MHz, Low-Power Sampling A/D Converters
MECHANICAL DIMENSIONS – SURFACE MOUNT PACKAGE – INCHES (mm)
7+,5'$1*/(352-(&7,21
81/(6627+(5:,6(63(&,),('
',0(16,216$1'72/(5$1&(6
3/$&( >PP@
3/$&( >PP@
$1*/(6 /($'0$7(5,$/.29$5$//2<
/($'),1,6+X0,1*2/'29(5
X1201,&.(/
3,1,1',&$725
6($7,1*3/$1(
7<3
7<3
(463$&(6#>@
(48$/6>@
ORDERING INFORMATION
MODEL
NUMBER
OPERATING
TEMP. RANGE
32-PIN
PACKAGE
ROHS
ACCESSORIES
ADS-951MC
0 to +70°C
TDIP
No
ADS-951ME
–40 to +110°C
TDIP
No
ADS-951MM
–55 to +125°C
TDIP
No
ADS-951MC-C
0 to +70°C
TDIP
Yes
ADS-951ME-C
–40 to +110°C
TDIP
Yes
ADS-951MM-C
–55 to +125°C
TDIP
Yes
ADS-951GC
0 to +70°C
SMT
No
ADS-B951 – Evaluation Board (without ADS-951)
ADS-951GE
–40 to +110°C
SMT
No
ADS-951GM
–55 to +125°C
SMT
No
ADS-951GC-C
0 to +70°C
SMT
Yes
ADS-951GE-C
–40 to +110°C
SMT
Yes
ADS-951GM-C
–55 to +125°C
SMT
Yes
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.
DATEL is a registered trademark of DATEL, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 USA
DATEL, Inc. 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.
ITAR and ISO 9001/14001 REGISTERED
© 2015 DATEL, Inc.
www.datel.com • e-mail: [email protected]
10 Sep 2015
MDA_ADS-951.E01 Page 7 of 7