1 +5V ANALOG SUPPLY 32 START CONVERT
2 –5.2V DIGITAL SUPPLY 31 BIT 1 (MSB)
3 ANALOG INPUT 30 BIT 1 (MSB)
4 ANALOG GROUND 29 BIT 2
5 OFFSET ADJUST 28 BIT 3
6 ANALOG GROUND 27 BIT 4
7 GAIN ADJUST 26 BIT 5
8 COMP. BITS 25 BIT 6
9 OUTPUT ENABLE 24 BIT 7
10 +5V DIGITAL SUPPLY 23 BIT 8
11 ANALOG GROUND 22 BIT 9
12 +15V SUPPLY 21 BIT 10
13 –15V SUPPLY 20 BIT 11
14 –5.2V ANALOG SUPPLY 19 BIT 12
15 DIGITAL GROUND 18 BIT 13
16 EOC 17 BIT 14 (LSB)
FEATURES
• 14-bit resolution
• 5MHz minimum sampling rate
• No missing codes over full military temperature range
• Edge-triggered, no pipeline delay
• Low power, 2.95 Watts
• Small, 32-pin, ceramic TDIP package
• SMT package available
• Excellent dynamic performance
• MIL-STD-883 screening or DESC SMD available
® ® ADS-944
14-Bit, 5MHz
Sampling A/D Converters
DATEL, Inc., 11 Cabot Boulevard, Mansfield, MA 02048-1151 (U.S.A.) • Tel: (508) 339-3000 Fax: (508) 339-6356 • For immediate assistance: (800) 233-2765
GENERAL DESCRIPTION
The low-cost ADS-944 is a high-performance, 14-bit, 5MHz
sampling A/D converter. This device accurately samples full-
scale input signals up to Nyquist frequencies with no missing
codes. The dynamic performance of the ADS-944 has been
optimized to achieve a THD of –77dB and a SNR of 76dB.
Packaged in a small, 32-pin TDIP, the functionally complete
ADS-944 contains a fast-settling sample-hold amplifier, a
subranging (two-pass) A/D converter, an internal reference,
timing and control logic, three-state outputs, and error-
correction circuitry. Digital input and output levels are TTL.
Requiring ±15V, +5V and –5.2V supplies, the ADS-944
typically dissipates 2.95 Watts. The unit is offered with a
bipolar input range of ±1.25V. Models are available for use in
either commercial (0 to +70°C) or military (–55 to +125°C)
operating temperature ranges. Typical applications include
radar signal analysis, medical/graphic imaging, and
FFT spectrum analysis.
INPUT/OUTPUT CONNECTIONS
PIN FUNCTION PIN FUNCTION
Figure 1. ADS-944 Functional Block Diagram
REF
DAC
3-S
TA
TE
O
UT
PU
T
RE
GI
ST
ER
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)
TIMING AND
CONTROL LOGIC
ANALOG INPUT 3
START CONVERT 32
EOC 16
–
+
S/H
BUFFER
DI
GI
TA
L C
OR
RE
CT
IO
N
LO
GI
C
FLASH
ADC
1
FLASH
ADC
2
Σ
AMP
GAIN
CIRCUITGAIN ADJUST 7
OFFSET
CIRCUITOFFSET ADJUST 5
1
+5V
ANALOG
SUPPLY
2
–5.2V
DIGITAL
SUPPLY
4, 6, 11
ANALOG
GROUND
10
+5V
DIGITAL
SUPPLY
12
+15V
SUPPLY
14
–5.2V
ANALOG
SUPPLY
15
DIGITAL
GROUND
8
COMP.
BITS
9 OUTPUT ENABLE