Figure 1. ADS-947 Functional Block Diagram
FEATURES
• 14-bit resolution
• 10MHz minimum sampling rate
• No missing codes over full military temperature range
• Ideal for both time and frequency-domain applications
• Excellent THD (–81dB) and SNR (76dB)
• Edge-triggered
• Small, 24-pin, ceramic DDIP or SMT
• Requires only +5V and –5.2V supplies
• Low-power, 2 Watts
• Low cost
GENERAL DESCRIPTION
The low-cost ADS-947 is a 14-bit, 10MHz 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-947 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-947 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-947
only requires the rising edge of a start convert pulse to
operate.
Requiring only +5V and –5.2V supplies, the ADS-947 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
®®
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
PRELIMINARY PRODUCT DATA
REF
DAC
REGISTER
REGISTER
OUTPUT REGI
STER
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
DATA VALID 17
+5V ANALOG SUPPLY 22
+5V DIGITAL SUPPLY 13
–5.2V SUPPLY 20
ANALOG GROUND 19, 24
DIGITAL GROUND 14
–
+
S/H
BUFFER
DI
GI
TAL CORRECTI
ON LOGI
C
FLASH
ADC
1
FLASH
ADC
2
POWER AND GROUNDING
C83
AMP
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 –5.2V SUPPLY
6 BIT 6 19 ANALOG GROUND
7 BIT 7 18 START CONVERT
8 BIT 8 17 DATA VALID
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-947
14-Bit, 10MHz
Sampling A/D Converters
DATEL, Inc., Mansfield, MA 02048 (USA) • Tel: (508) 339-3000, (800) 233-2765 Fax: (508) 339-6356 • Email: sales@datel.com • Internet: www.datel.com