AD974AR Analog Devices Inc, AD974AR Datasheet - Page 5

• 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

Pin No.
1
2–5, 25–28
6
7
8
12
13
14
15
16
17
18, 19
20
21
22, 23
24
REV. A
9
10
11
Mnemonic
AGND1
BIP
CAP
REF
AGND2
V
PWRD
DATACLK
WR1, WR2
CS
BUSY
V
VxA, VxB
R/C
EXT/INT
DGND
SYNC
DATA
A1, A0
DIG
ANA
Description
Analog Ground. Used as the ground reference point for the REF pin.
Analog Input. Refer to Table I for input range configuration.
Bipolar Offset. Connect VxA inputs to provide Bipolar input range.
Reference Buffer Output. Connect a 2.2 F tantalum capacitor between CAP and Analog
Ground.
Reference Input/Output. The internal +2.5 V reference is available at this pin. Alternatively an
external reference can be used to override the internal reference. In either case, connect a 2.2 F
tantalum capacitor between REF and Analog Ground.
Analog Ground.
Read/Convert Input. Used to control the conversion and read modes. With CS LOW, a falling
edge on R/C holds the analog input signal internally and starts a conversion; a rising edge enables
the transmission of the conversion result.
Digital Power Supply. Nominally +5 V.
Power-Down Input. When set to a logic HIGH, power consumption is reduced and conversions
are inhibited. The conversion result from the previous conversion is stored in the onboard shift
register.
Digital select input for choosing the internal or an external data clock. With EXT/INT tied LOW,
after initiating a conversion, 16 DATACLK pulses transmit the previous conversion result as
shown in Figure 3. With EXT/INT set to a Logic HIGH, output data is synchronized to an
external clock signal connected to the DATACLK input. Data is output as indicated in Figure 4
through Figure 9.
Digital Ground.
Digital output frame synchronization for use with an external data clock (EXT/INT = Logic
HIGH). When a read sequence is initiated, a pulse one DATACLK period wide is output
synchronous to the external data clock.
Serial data clock input or output, dependent upon the logic state of the EXT/INT pin. When
using the internal data clock (EXT/INT = Logic LOW), a conversion start sequence will initiate
transmission of 16 DATACLK periods. Output data is synchronous to this clock and is valid on
both its rising and falling edges (Figure 3). When using an external data clock (EXT/INT = Logic
HIGH), the CS and R/C signals control how conversion data is accessed.
The serial data output is synchronized to DATACLK. Conversion results are stored in an on-
chip register. The AD974 provides the conversion result, MSB first, from its internal shift regis-
ter. When using the internal data clock (EXT/INT = Logic LOW), DATA is valid on both the
rising and falling edges of DATACLK. Using an external data clock (EXT/INT = Logic HIGH)
allows previous conversion data to be accessed during a conversion (Figures 5, 7 and 9) or the
conversion result can be accessed after the completion of a conversion (Figures 4, 6 and 8).
Multiplexer Write Inputs. These inputs are internally ORed to generate the mux latch inputs.
The latch is transparent when WR1 and WR2 are tied low.
Chip Select Input. With R/C LOW, a falling edge on CS will initiate a conversion. With R/C
HIGH, a falling edge on CS will enable the serial data output sequence.
Busy Output. Goes LOW when a conversion is started, and remains LOW until the conversion is
completed and the data is latched into the on-chip shift register.
Address multiplexer inputs latched with the WR1, WR2 inputs.
Analog Power Supply. Nominally +5 V.
PIN FUNCTION DESCRIPTIONS
A1
0
0
1
1
–5–
A0
0
1
0
1
Data Available from Channel
AIN 1
AIN 2
AIN 3
AIN 4
AD974