Figure 1. ADS-946 Functional Block Diagram
FEATURES
• 14-bit resolution
• 8MHz guaranteed sampling rate
• No missing codes over full military temperature range
• Ideal for both time and frequency-domain applications
• Excellent THD (–75dB) and SNR (77dB)
• Edge-triggered; No pipeline delays
• Small, 24-pin, ceramic DDIP or SMT
• Requires only ±5V supplies
• Low-power, 2 Watts
• MIL-STD-883 screening optional
GENERAL DESCRIPTION
The low-cost ADS-946 is a 14-bit, 8MHz sampling A/D
converter. This device accurately samples full-scale input
signals up to Nyquist frequencies with no missing codes.
Excellent differential nonlinearity error (DNL), signal-to-noise
ratio (SNR), and total harmonic distortion (THD) make the
ADS-946 the ideal choice for both time-domain (CCD/FPA
imaging, scanners, process control) and frequency-domain
(radar, telecommunications, spectrum analysis) applications.
The functionally complete ADS-946 contains a fast-settling
sample-hold amplifier, a subranging (two-pass) A/D converter,
an internal reference, timing/control logic, and error-correction
circuitry. Digital input and output levels are TTL. The
ADS-946 only requires the rising edge of a start convert
pulse to operate.
Requiring only ±5V supplies, the ADS-946 typically dissipates
just 2 Watts. The device is offered with a bipolar input range
of ±2V. Models are available for use in either commercial
(0 to +70°C) or military (–55 to +125°C) operating
® ®
INNOV A TION and EX CELLENCE
temperature ranges. A proprietary, auto-calibrating, error-
correcting circuit allows the device to achieve specified
performance over the full military temperature range.
INPUT/OUTPUT CONNECTIONS
PIN FUNCTION PIN FUNCTION
1 BIT 1 (MSB) 24 ANALOG GROUND
2 BIT 2 23 OFFSET ADJUST
3 BIT 3 22 +5V ANALOG SUPPLY
4 BIT 4 21 ANALOG INPUT
5 BIT 5 20 –5V SUPPLY
6 BIT 6 19 ANALOG GROUND
7 BIT 7 18 START CONVERT
8 BIT 8 17 EOC
9 BIT 9 16 BIT 14 (LSB)
10 BIT 10 15 BIT 13
11 BIT 11 14 DIGITAL GROUND
12 BIT 12 13 +5V DIGITAL SUPPLY
ADS-946
14-Bit, 8MHz
Sampling A/D Converters
REF
DAC
RE
GI
ST
ER
RE
GI
ST
ER
OU
TP
UT
R
EG
IS
TE
R
16 BIT 14 (LSB)
15 BIT 13
12 BIT 12
11 BIT 11
10 BIT 10
9 BIT 9
8 BIT 8
7 BIT 7
6 BIT 6
5 BIT 5
4 BIT 4
3 BIT 3
2 BIT 2
1 BIT 1 (MSB)
TIMING AND
CONTROL LOGIC
OFFSET ADJUST 23
ANALOG INPUT 21
START CONVERT 18
EOC 17
+5V ANALOG SUPPLY 22
+5V DIGITAL SUPPLY 13
–5V SUPPLY 20
ANALOG GROUND 19, 24
DIGITAL GROUND 14
–
+
S/H
BUFFER
DI
GI
TA
L C
OR
RE
CT
IO
N
LO
GI
C
FLASH
ADC
1
FLASH
ADC
2
POWER AND GROUNDING
Σ
AMP
DATEL, Inc., 11 Cabot Boulevard, Mansfield, MA 02048 (U.S.A.) • Tel: (508)339-3000 Fax: (508)339-6356 • For immediate assistance: (800) 233-2765