® ®
A SUBSIDIARY OF C&D TECHNOLOGIES
FEATURES
• 18-bit resolution
• 1MHz minimum sampling rate
• No missing codes over extended temperature range
• Very low power, 1.45 Watts
• Small, 32-pin, side-brazed, ceramic TDIP
• Edge-triggered
• Excellent performance, –95dB peak harmonics
• Ideal for both time and frequency-domain applications
• Low cost
ing temperature ranges. A proprietary, auto-calibrating, error-
correcting circuit enables the device to achieve specifi ed per-
formance over the full military temperature range.
ADS-953
18-Bit, 1MHz, Low-Distortion
Sampling A/D Converters
GENERAL DESCRIPTION
The ADS-953 is an 18-bit, 1MHz sampling A/D converter. This
device accurately samples full-scale input signals up to Nyquist
frequencies with no missing codes. This feature, combined with
excellent signal-to-noise ratio (SNR) and –95dB peak harmonic
distortion (THD), makes the ADS-953 the ideal choice for both
time-domain (medical imaging, scanners, process control) and
frequency-domain (radar, telecommunications, spectrum analy-
sis) applications.
Packaged in a 32-pin, side-brazed, metal-sealed, ceramic TDIP,
the functionally complete ADS-953 contains a fast-settling sam-
ple-hold amplifi er, a subranging (two-pass) A/D converter, an
internal reference, timing/control logic, and error-correction cir-
cuitry. Digital input and output levels are TTL, and the ADS-953
only requires the rising edge of the start convert pulse to
operate.
Requiring ±15V and ±5V supplies, the ADS-953 typically dis-
sipates 1.45 Watts. The device is offered with a bipolar (±5V)
analog input range. Models are available for use in either
commercial (0 to +70°C) or extended (–40 to +110°C) operat-
INPUT/OUTPUT CONNECTIONS
Figure 1. ADS-953 Functional Block Diagram
1 BIT 2 32 BIT 3
2 BIT 1 (MSB) 31 BIT 4
3 ANALOG GROUND 30 BIT 5
4 ANALOG INPUT 29 BIT 6
5 +5V REFERENCE OUT 28 BIT 7
6 GAIN ADJUST 27 BIT 8
7 COMPENSATION 26 BIT 9
8 –15V SUPPLY 25 BIT 10
9 +15V SUPPLY 24 BIT 11
10 +5V ANALOG SUPPLY 23 BIT 12
11 –5V ANALOG SUPPLY 22 BIT 13
12 ANALOG GROUND 21 BIT 14
13 DIGITAL GROUND 20 BIT 15
14 +5V DIGITAL SUPPLY 19 BIT 16
15 EOC 18 BIT 17
16 START CONVERT 17 BIT 18 (LSB)
PIN FUNCTION PIN FUNCTION
DATEL, Inc., Mansfi eld, MA 02048 (USA) • Tel: (508) 339-3000, (800) 233-2765 Fax: (508) 339-6356 • Email: sales@datel.com • Internet: www.datel.com
REF
DAC
2 BIT 1 (MSB)
1 BIT 2
32 BIT 3
31 BIT 4
30 BIT 5
29 BIT 6
28 BIT 7
27 BIT 8
26 BIT 9
25 BIT 10
24 BIT 11
23 BIT 12
22 BIT 13
21 BIT 14
20 BIT 15
19 BIT 16
18 BIT 17
17 BIT 18 (LSB)
TIMING AND
CONTROL LOGIC
ANALOG INPUT 4
START CONVERT 16
EOC 15
–
+
S/H
BUFFER
DI
GI
T
A
L
CORRE
CT
I
O
N L
OGI
C
FLASH
ADC
1
FLASH
ADC
2
Σ
AMP
GAIN
CIRCUIT
COMPENSATION 7
+5V REFERENCE OUT 5
10
+5V ANALOG
SUPPLY
11
–5V ANALOG
SUPPLY
3, 12
ANALOG
GROUND
14
+5V DIGITAL
SUPPLY
9
+15V
SUPPLY
8
–15V
SUPPLY
13
DIGITAL
GROUND
GAIN ADJUST 6