®
®
ADS-929
14-Bit, 2MHz, Low-Power Sampling A/D Converters
PRODUCT OVERVIEW
The ADS-929 is a high-performance, 14-bit,
2MHz sampling A/D converter. This device samples
input signals up to Nyquist frequencies with no
missing codes. The ADS-929 features outstanding
dynamic performance including a THD of –79dB.
Housed in a small 24-pin DDIP or SMT (gull-
wing) package, the functionally complete ADS-929
contains a fast-settling sample-hold amplifier, a
subranging (two-pass) A/D converter, a precise
voltage reference, timing/control logic, and error-
correction circuitry. Digital input and output levels
are TTL.
Requiring ±15V (or ±12V) and +5V supplies,
the ADS-929 typically dissipates 1.7W (1.4W for
±12V). The unit is offered with a bipolar input
(–5V to +5V). Models are available for use in
either commercial (0 to +70°C), industrial (–40
to +100°C), or HI-REL (–55 to +125°C) operating
temperature ranges. Applications include radar,
sonar, spectrum analysis, and graphic/medical
imaging.
FEATURES
14-bit resolution
2MHz sampling rate
missing codes
No
Functionally complete
Small 24-pin DDIP or SMT package
power, 1.7 Watts
Low
Operates from ±15V or ±12V supplies
Edge-triggered; No pipeline delays
Bipolar ±5V input range (for unipolar 0 to +10V
input range see ADS-919 data sheet)
BLOCK DIAGRAM
PIN
1
2
3
4
5
6
7
8
9
10
11
12
INPUT/OUTPUT CONNECTIONS
FUNCTION
PIN FUNCTION
BIT 14 (LSB)
BIT 13
BIT 12
BIT 11
BIT 10
BIT 9
BIT 8
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
24
23
22
21
20
19
18
17
16
15
14
13
–12V/–15V SUPPLY
ANALOG GROUND
+12V/+15V SUPPLY
+10V REFERENCE OUT
ANALOG INPUT
ANALOG GROUND
BIT 1 (MSB)
BIT 2
START CONVERT
EOC
DIGITAL GROUND
+5V SUPPLY
DAC
18 BIT 1 (MSB)
17 BIT 2
+10V REF. OUT 21
S
2
FLASH
ADC
S/H
ANALOG INPUT 20
–
REGISTER
REGISTER
REF
DIGITAL CORRECTION LOGIC
12 BIT 3
11 BIT 4
10 BIT 5
9
8
7
6
5
4
3
2
1
BIT 6
BIT 7
BIT 8
BIT 9
BIT 10
BIT 11
BIT 12
BIT 13
BIT 14 (LSB)
S
1
BUFFER
+
START CONVERT 16
TIMING AND
CONTROL LOGIC
EOC 15
13
+5V SUPPLY
14
DIGITAL GROUND
22
+12V/+15V SUPPLY
19, 23
ANALOG GROUND
24
–12V/–15V SUPPLY
Figure 1. ADS-929 Functional Block Diagram
DATEL
•
11 Cabot Boulevard, Mansfield, MA 02048-1151 USA •
Tel: (508) 339-3000
•
www.datel.com
• e-mail: help@datel.com
10 Oct 2013 MDA_ADS-929.D01
Page 1 of 9
®
®
ADS-929
14-Bit, 2MHz, Low-Power Sampling A/D Converters
UNITS
Volts
Volts
Volts
Volts
Volts
°C
PHYSICAL/ENVIRONMENTAL
PARAMETERS
MIN.
TYP.
MAX.
UNITS
Operating Temp. Range, Case
ADS-929MC, GC, MC-C, GC-C
0
—
+70
°C
ADS-929ME, GE, ME-C, GE-C
–40
—
+100
°C
ADS-929MM, GM, MM-C, GM-C
–55
—
+125
°C
ADS-929MM-QL, 883, MM-QL-C, -C/883
–55
—
+125
°C
ADS-929GM-QL, G/883, GM-QL-C, G-C/883 –55
—
+125
°C
Thermal Impedance
—
6
—
°C/Watt
θjc
—
24
—
°C/Watt
θca
Storage Temperature Range
–65
—
+150
°C
24-pin, metal-sealed, ceramic DDIP or SMT
Package Type
Weight
0.42 ounces (12 grams)
ABSOLUTE MAXIMUM RATINGS
PARAMETERS
LIMITS
+12V/+15V Supply (Pin 22)
0 to +16
–12V/–15V Supply (Pin 24)
0 to –16
+5V Supply (Pin 13)
0 to +6
Digital Input (Pin 16)
–0.3 to +V
DD
+0.3
±15
Analog Input (Pin 20)
Lead Temperature (10 seconds)
+300
FUNCTIONAL SPECIFICATIONS
(TA = +25°C, ±VCC = ±15V (or ±12V), +VDD = +5V, 2MHz sampling rate, and a minimum 1 minute warmup
➀
unless otherwise specified.)
ANALOG INPUT
Input Voltage Range
➁
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 (f
in
= 10kHz)
Differential Nonlinearity (f
in
= 10kHz)
Full Scale Absolute Accuracy
Bipolar Zero Error (Tech Note 2)
Bipolar Offset Error (Tech Note 2)
Gain Error (Tech Note 2)
No Missing Codes (f
in
= 10kHz)
DYNAMIC PERFORMANCE
Peak Harmonics (–0.5dB)
dc to 500kHz
500kHz to 1MHz
Total Harmonic Distortion (–0.5dB)
dc to 500kHz
500kHz to 1MHz
Signal-to-Noise Ratio (w/o distortion, –0.5dB)
dc to 500kHz
500kHz to 1MHz
Signal-to-Noise Ratio (& distortion, –0.5dB)
➃
dc to 500kHz
500kHz to 1MHz
Two-tone Intermodulation Distortion (f
in
= 200kHz,
500kHz, f
s
= 2MHz, –0.5dB)
Noise
Input Bandwidth (–3dB)
Small Signal (–20dB input)
Large Signal (–0.5dB input)
Feedthrough Rejection (f
in
= 1MHz)
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
DATEL
•
MIN.
—
—
—
+25°C
TYP.
±5
1
7
MAX.
—
—
15
MIN.
—
—
—
0 TO +70°C
TYP.
±5
1
7
MAX.
—
—
15
–55 TO +125°C
MIN.
TYP.
MAX.
—
±5
—
—
1
—
—
7
15
UNITS
Volts
kΩ
pF
+2.0
—
—
—
20
—
—
—
—
200
—
+0.8
+20
–20
—
+2.0
—
—
—
20
—
—
—
—
200
—
+0.8
+20
–20
—
+2.0
—
—
—
20
—
—
—
—
200
—
+0.8
+20
–20
—
Volts
Volts
μA
μA
ns
—
—
—
—
—
—
—
14
14
±0.5
±0.5
±0.05
±0.05
±0.05
±0.1
—
—
—
+0.95
±0.15
±0.15
±0.15
±0.3
—
—
—
—
—
—
—
—
14
14
±0.75
±0.5
±0.15
±0.1
±0.15
±0.3
—
—
—
±0.95
±0.4
±0.25
±0.4
±0.5
—
—
—
—
—
—
—
—
14
14
±1
±0.5
±0.3
±0.4
±0.4
±0.5
—
—
—
±0.99
±1.0
±0.75
±1.0
±1.5
—
Bits
LSB
LSB
%FSR
%FSR
%FSR
%FSR
Bits
—
—
—
—
76
75
72
70
—
—
—
—
—
—
—
—
150
—
2
–80
–80
–79
–79
78
77
75
75
–83
300
9
8
82
±200
±20
5
190
400
—
–75
–74
–74
–74
—
—
—
—
—
—
—
—
—
—
—
—
230
500
—
—
—
—
—
76
75
72
70
—
—
—
—
—
—
—
—
150
—
2
–80
–80
–79
–79
78
77
75
75
–82
450
9
8
82
±200
±20
5
190
400
—
–75
–74
–74
–74
—
—
—
—
—
—
—
—
—
—
—
—
230
500
—
•
—
—
—
—
75
72
71
65
—
—
—
—
—
—
—
—
150
—
2
–79
–74
–77
–72
77
76
74
73
–80
600
9
8
82
±200
±20
5
190
400
—
–74
–65
–72
–65
—
—
—
—
—
—
—
—
—
—
—
—
230
500
—
dB
dB
dB
dB
dB
dB
dB
dB
dB
μVrms
MHz
MHz
dB
V/μs
ns
ps rms
ns
ns
MHz
11 Cabot Boulevard, Mansfield, MA 02048-1151 USA •
Tel: (508) 339-3000
www.datel.com
• e-mail: help@datel.com
10 Oct 2013 MDA_ADS-929.D01
Page 2 of 9
®
®
ADS-929
14-Bit, 2MHz, Low-Power Sampling A/D Converters
MIN.
+9.95
—
—
ANALOG OUTPUT
Internal Reference
Voltage
Drift
External Current
DIGITAL OUTPUTS
Logic Levels
Logic "1"
Logic "0"
Logic Loading "1"
Logic Loading "0"
Delay, Falling Edge of EOC to Output Data Valid
Output Coding
POWER REQUIREMENTS , ±15V
Power Supply Ranges
+15V Supply
–15V Supply
+5V Supply
Power Supply Currents
+15V Supply
–15V Supply
+5V Supply
Power Dissipation
Power Supply Rejection
POWER REQUIREMENTS, ±12V
Power Supply Ranges
+12V Supply
–12V Supply
+5V Supply
Power Supply Currents
+12V Supply
–12V Supply
+5V Supply
Power Dissipation ±12V
Power Dissipation ±15V
Power Supply Rejection
Footnotes:
+25°C
TYP.
+10.0
±5
—
MAX.
+10.05
—
1.5
MIN.
+9.95
—
—
0 TO +70°C
TYP.
+10.0
±5
—
MAX.
+10.05
—
1.5
MIN.
+9.95
—
—
–55 TO +125°C
TYP.
MAX.
+10.0
±5
—
+10.05
—
1.5
UNITS
Volts
ppm/°C
mA
+2.4
—
—
—
—
—
—
—
—
—
—
+0.4
–4
+4
35
+2.4
—
—
—
—
—
—
—
+0.4
—
–4
—
+4
—
35
Offset Binary
+2.4
—
—
—
—
—
—
—
—
—
—
+0.4
–4
+4
35
Volts
Volts
mA
mA
ns
+14.5
–14.5
+4.75
—
—
—
—
—
+15.0
–15.0
+5.0
+45
–43
+89
1.7
—
+15.5
–15.5
+5.25
+65
–50
+98
1.99
±0.02
+14.5
–14.5
+4.75
—
—
—
—
—
+15.0
–15.0
+5.0
+45
–43
+89
1.7
—
+15.5
–15.5
+5.25
+65
–50
+98
1.99
±0.02
+14.5
–14.5
+4.75
—
—
—
—
—
+15.0
–15.0
+5.0
+45
–43
+89
1.7
—
+15.5
–15.5
+5.25
+65
–50
+98
1.99
±0.02
Volts
Volts
Volts
mA
mA
mA
Watts
%FSR/%V
+11.5
–11.5
+4.75
—
—
—
—
—
—
+12.0
–12.0
+5.0
+45
–43
+80
1.4
1.7
—
+12.5
–12.5
+5.25
+61
–50
+98
1.6
2.0
±0.02
+11.5
–11.5
+4.75
—
—
—
—
—
—
+12.0
–12.0
+5.0
+45
–43
+80
1.4
1.7
—
+12.5
–12.5
+5.25
+61
–50
+98
1.6
2.0
±0.02
+11.5
–11.5
+4.75
—
—
—
—
—
—
+12.0
–12.0
+5.0
+45
–43
+80
1.4
1.7
—
+12.5
–12.5
+5.25
+61
–50
+98
1.6
2.0
±0.02
Volts
Volts
Volts
mA
mA
mA
Watts
Watts
%FSR/%V
➃
Effective bits is equal to:
(SNR + Distortion) – 1.76 +
20 log
6.02
➄
This is the time required before the A/D output data is valid after the analog input
is back within the specified range.
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 warmup periods.
The device must be continuously converting during this time. There is a slight
degradation in performance when using ±12V supplies.
➁
See Ordering Information for 0 to +10V input range. Contact DATEL for availability
of other input voltage ranges.
➂
A 2MHz clock with a 200ns wide start convert pulse is used for all production
testing. See Timing Diagram for more details.
TECHNICAL NOTES
1. Obtaining fully specified performance from the ADS-929 requires care-
ful attention to pc-card layout and power supply decoupling. The device's
analog and digital ground systems are connected to each other internally.
For optimal performance, tie all ground pins (14, 19 and 23) directly to a
large
analog
ground plane beneath the package.
Bypass all power supplies and the REFERENCE OUTPUT (pin 21) 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. If the user-
installed offset and gain adjusting circuit shown in Figure 2 is used, also
locate it as close to the ADS-929 as possible.
2. The ADS-929 achieves its specified accuracies without the need for exter-
nal calibration. If required, the device's small initial offset and gain errors
DATEL
•
can be reduced to zero using the input circuit of Figure 2. When using this
circuit, or any similar offset and gain-calibration hardware, make adjust-
ments following warmup. To avoid interaction, always adjust offset before
gain.
3. When operating the ADS-929 from ±12V supplies, do not drive external
circuitry with the REFERENCE OUTPUT. The reference's accuracy and drift
specifications may not be met, and loading the circuit may cause accuracy
errors within the converter.
4. Applying a start convert pulse while a conversion is in progress (EOC =
logic "1") initiates a new and inaccurate conversion cycle. Data from the
interrupted and subsequent conversions will be invalid.
Tel: (508) 339-3000
•
www.datel.com
• e-mail: help@datel.com
11 Cabot Boulevard, Mansfield, MA 02048-1151 USA •
10 Oct 2013 MDA_ADS-929.D01
Page 3 of 9
®
®
ADS-929
14-Bit, 2MHz, Low-Power Sampling A/D Converters
Gain adjusting is accomplished when all bits are 1's and the LSB just
changes from a 1 to a 0. This transition ideally occurs when the analog
input is at +full scale minus 1½ LSB's (+4.999085V).
Zero/Offset Adjust Procedure
1. Apply a train of pulses to the START CONVERT input (pin 16) so the con-
verter is continuously converting. If using LED's on the outputs, a 200kHz
conversion rate will reduce flicker.
2. Apply +305μV to the ANALOG INPUT (pin 20).
3. Adjust the offset potentiometer until the output bits are a 1 and all 0's and
the LSB flickers between 0 and 1.
Gain Adjust Procedure
1. 1. Apply +4.999085V to the ANALOG INPUT (pin 20).
2. Adjust the gain potentiometer until the output bits are all 1's and the LSB
flickers between 1 and 0.
CALIBRATION PROCEDURE (Refer to Figures 2 and 3)
Any offset and/or gain calibration procedures should not be implemented
until devices are fully warmed up. To avoid interaction, offset must be
adjusted before gain. The ranges of adjustment for the circuit of Figure 2
are guaranteed to compensate for the ADS-929's initial accuracy errors
and may not be able to compensate for additional system errors.
All fixed resistors in Figure 2 should be metal-film types, and multiturn
potentiometers should have TCR’s of 100ppm/°C or less to minimize drift
with temperature.
A/D converters are calibrated by positioning their digital outputs exactly
on the transition point between two adjacent digital output codes. This can
be accomplished by connecting LED's to the digital outputs and adjusting
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-929, offset adjusting is normally accomplished at the point
where the MSB is a 1 and all other output bits are 0's and the LSB just
changes from a 0 to a 1. This digital output transition ideally occurs when
the applied analog input is +½LSB (+305μV).
+15V
ZERO/
OFFSET
ADJUST
20k
200k
2k
Table 1. Zero and Gain Adjust
INPUT VOLTAGE
RANGE
±5V
ZERO ADJUST
+½ LSB
+305μV
GAIN ADJUST
+FS –1½ LSB
+4.999085V
–15V
SIGNAL
INPUT
GAIN
ADJUST
1.98k
50
+15V
Table 2. Output Coding
OUTPUT CODING
To Pin 20
of ADS-929
MSB
LSB
INPUT RANGE
±5V
+4.99939
+3.75000
+2.50000
0.00000
–2.50000
–3.75000
–4.99939
–5.00000
BIPOLAR SCALE
+FS –1 LSB
+3/4 FS
+1/2FS
0
–1/2FS
–3/4FS
–FS +1 LSB
–FS
11 1111 1111 1111
–15V
11 1000 0000 0000
11 0000 0000 0000
10 0000 0000 0000
01 0000 0000 0000
00 1000 0000 0000
00 0000 0000 0001
00 0000 0000 0000
Figure 2. ADS-929 Calibration Circuit
Coding is offset binary; 1LSB = 610μV.
18 BIT 1 (MSB)
+5V
4.7μF
+
13
0.1μF
14
DIGITAL
GROUND
17 BIT 2
12 BIT 3
11 BIT 4
10 BIT 5
9 BIT 6
8 BIT 7
7 BIT 8
6 BIT 9
5 BIT 10
4 BIT 11
3 BIT 12
2 BIT 13
1 BIT 14 (LSB)
15 EOC
START 16
CONVERT
–12V/–15V
4.7μF
4.7μF
+12V/+15V
+
+
0.1μF
0.1μF
24
ADS-929
ANALOG
19, 23 GROUND
22
ANALOG
20 INPUT
+
21 +10V REF. OUT
–5V to +5V
0.1μF
4.7μF
Figure 3. Typical ADS-929 Connection Diagram
DATEL
•
11 Cabot Boulevard, Mansfield, MA 02048-1151 USA •
Tel: (508) 339-3000
•
www.datel.com
• e-mail: help@datel.com
10 Oct 2013 MDA_ADS-929.D01
Page 4 of 9
®
®
ADS-929
14-Bit, 2MHz, Low-Power Sampling A/D Converters
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.
THERMAL REQUIREMENTS
All DATEL sampling A/D converters are fully characterized and speci-
fied 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 specifica-
tion tables.
These devices do not normally require heat sinks; however, standard
precautionary design and layout procedures should be used to ensure
N
START
CONVERT
200ns
typ.
10ns typ.
INTERNAL S/H
Hold
310ns typ.
N+1
Acquisition Time
190ns
±40ns
70ns ±10ns
30ns typ.
EOC
Conversion Time
360ns ±20ns
35ns max.
75ns max.
OUTPUT
DATA
Data (N – 1) Valid
Data N Valid
425ns min.
Invalid
Data
Notes: 1. f
s
= 2MHz.
2. The ADS-929 is an edge-triggered device. All internal operations
are triggered by the rising edge of the start convert pulse, which
may be as narrow as 20nsec. All production testing is performed
at a 2MHz sampling rate with 200nsec wide start pulses. For
lower sampling rates, wider start pulses may be used, however, a
minimum pulse width low of 20nsec must be maintained.
Figure 4. ADS-929 Timing Diagram
DATEL
•
11 Cabot Boulevard, Mansfield, MA 02048-1151 USA •
Tel: (508) 339-3000
•
www.datel.com
• e-mail: help@datel.com
10 Oct 2013 MDA_ADS-929.D01
Page 5 of 9
实时操作系统RTOS
