AD974AR Analog Devices Inc, AD974AR Datasheet - Page 10

• Manufacturer Part Number: AD974AR
• Description: A/D Converter (A-D) IC
• Manufacturer: Analog Devices Inc
• Type: Data Acquisition System (DAS)r

Specifications of AD974AR

• Package/case: 28-SOIC
• Features: 4?Ch., 200kSPS Data Acquisition System
• Interface Type: Serial
• Number Of Bits: 16
• Number Of Channels: 4
• Mounting Type: Surface Mount
• Rohs Status: RoHS non-compliant
• Resolution (bits): 16 b
• Sampling Rate (per Second): 200k
• Data Interface: Serial
• Voltage Supply Source: Analog and Digital
• Voltage - Supply: 5V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With: EVAL-AD974CB - BOARD EVAL FOR AD974
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

AD974
EXTERNAL DISCONTINUOUS CLOCK DATA READ
DURING CONVERSION WITH SYNC OUTPUT
GENERATED
Figure 7 illustrates the method by which data from conversion
“n-1” can be read during conversion “n” while using a discon-
tinuous external clock, with the generation of a SYNC output.
What permits the generation of a SYNC output is a transition of
DATACLK while either CS is High or while both CS and R/C
are low. In Figure 7 a conversion is initiated by taking R/C low
with CS tied low. While this condition exists a transition of
DATACLK, clock pulse #0, will enable the generation of a
SYNC pulse. Less then 83 ns after R/C is taken low the BUSY
output will go low to indicate that the conversion process has
Figure 7. Conversion and Read Timing for Reading Previous Conversion Results During a Conversion
Using External Discontinuous Data Clock (EXT/ INT Set to Logic High, CS Set to Logic Low)
DATACLK
BUSY
SYNC
DATA
EXT
R/C
t
15
t
2
0
t
t
t
13
1
17
t
15
1
t
12
t
12
2
t
14
BIT 15
(MSB)
t
18
–10–
3
BIT 14
t
20
begun. Figure 7 shows R/C then going high and after a delay of
greater than 15 ns (t
request the SYNC output. The SYNC output will appear ap-
proximately 40 ns after this rising edge and will be valid on the
falling edge of clock pulse #1 and the rising edge of clock pulse
#2. The MSB will be valid approximately 40 ns after the rising
edge of clock pulse #2 and can be latched off either the falling
edge of clock pulse #2 or the rising edge of clock pulse #3. The
LSB will be valid on the falling edge of clock pulse #17 and the
rising edge of clock pulse #18.
Data should be clocked out during the first half of BUSY to
avoid degrading conversion performance. This requires use of a
10 MHz DATACLK or greater, with data being read out as
soon as the conversion process begins.
4
17
(LSB)
BIT 0
18
t
18
15
) clock pulse #1 can be taken high to
t
22
REV. A