AD7880CR Analog Devices Inc, AD7880CR Datasheet - Page 12

• Manufacturer Part Number: AD7880CR
• Description: IC ADC 12BIT MONO LP 24-SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD7880CR

• Rohs Status: RoHS non-compliant
• Number Of Bits: 12
• Sampling Rate (per Second): 66k
• Data Interface: Parallel
• Number Of Converters: 1
• Power Dissipation (max): 50mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-SOIC (0.300", 7.50mm Width)

AD7880
as a function of time for such operation. The total conversion
time for each cycle is 11
for a single conversion) corresponding to 1.65 10
Hence:
Average Power
AD7880 DATA ACQUISITION LAYOUT
Figure 24 shows the AD7880 in a data acquisition circuit. The
corresponding printed circuit board (PCB) layout and
silkscreen are shown in Figures 25 to 27.
The only additional component required for a full data acquisi-
tion system is an antialiasing filter. There is a component grid
provided near the analog input on the PCB which may be used
for such a filter or any other input conditioning circuitry. To fa-
cilitate this option there is a shorting link (labeled LK1 on the
PCB) on the analog input track. With LK1 in place, the analog
input connects to the buffer amplifier driving the AD7880.
With LK1 removed, a wire link is needed to connect the analog
input to the PCB component grid.
INTERFACE CONNECTIONS
The data acquisition board contains a parallel connection port
labeled SKT4. This is a 26-contact IDC Connector and pro-
vides for direct microprocessor connection to the board. This
connector, the pinout of which is shown in Figure 23, contains
all data, control and status signals of the AD7880 (with the ex-
ception of the CONVST and the CLKIN inputs both of which
are provided via SKT2 and SKT3 respectively). It also contains
decoded R/W and STRB inputs which are necessary for inter-
facing to many microprocessors including the TMS320C25 and
the Motorola 68000 series. Link LK7 selects RD directly or al-
ternatively, the decoded version. Note that the AD7880 CS in-
put must be decoded prior to the AD7880 evaluation board.
SKT1, SKT2 and SKT3 are three sub-miniature connectors
(SMC) which provide input connections for the analog input,
the CONVST input and the CLKIN input. Three different in-
put ranges can be accepted by the AD7880 each of which is
configured by selecting shorting plug options A, B or C of LK4.
Position A corresponds to the 0 V to 5 V unipolar configuration
of Figure 5, position B corresponds to the bipolar 5 V configu-
ration of Figure 7 and position C allows for a 0 V to +10 V uni-
polar range as shown in Figure 6.
POWER SUPPLY CONNECTIONS
The PCB requires a single +5 V power supply (labeled V
Good decoupling allows this supply to drive the AD7880 V
which also drives the V
supply. In circumstances where bipolar 5 V or a unipolar 0 V
to 10 V input ranges are required, provision has been allowed
for the connection of separate op amp power supplies ( 15 V,
allow for the selection of user defined op amp power supplies or
the on-board single +5 V supply.
LINK OPTIONS
There are seven link options which must be set before using the
board. These are outlined below:
12 V, 5 V, etc.) to V+ and V–. LK2 and LK3 shorting links
= Power
= {20 mW
+ {2 mW
= 2.029 mW
REF
15 s (where 15 s is the time taken
input as well as the op amp power
CONVERTING
(9.9998)/(10)}
(1.65
+ Power
10
–4
)/(10)}
POWER-DOWN
–4
secs.
DD
DD
).
–12–
LK1
LK2, LK3 Allows for various op amp power supplies to be
LK4
LK5
LK6
LK7
COMPONENT LIST
IC1
IC2
IC3
C1, C3, C5
C2, C4, C6, C7
R1, R2
LK1, LK2, LK3
LK4, LK5, LK6
LK7
SKT1, SKT2, SKT3 Sub-Miniature Connectors
SKT4
NOTE
*See ANALOG INPUT BUFFERING section.
.
Figure 23. SKT4, IDC Connector Pinout
Connects the analog input to a buffer amplifier. The
Configures the various analog input ranges, 0 V to
Selects reference input to V
mally connected to V
could also be wired in.
Selects power-down or sleep mode. The shorting
plug is connected to V
Connects the AD7880 RD input directly to the RD
input. This shorting plug setting depends on the
microprocessor, e.g., the TMS320C25 requires a
decoded RD signal.
analog input may also be connected to a component
grid for signal conditioning.
used to drive the input buffer of the AD7880. Ex-
ternal supplies may be connected to V+ and V–.
Alternatively, the AD7880’s +5 V system supply
and AGND can be selected to drive a single supply
op amp.
input of SKT4 or to a decoded STRB and R/W
5 V, 0 V to 10 V or 5 V.
Op Amp*
AD7880 Analog-to-Digital Converter
74HC00 Quad NAND Gate
10 F Capacitors
0.1 F Capacitors
10 k Pull-up Resistors
Shorting Links
Vendor No: Sealectro 50-051-0000 (Socket)
Vendor No:
26-Contact (2 Row) IDC Connector
BUSY
DB10
GND
R/W
DB8
DB6
DB4
DB2
DB0
+
N/C
RD
CS
5V
11
13
15
17
19
23
25
21
1
3
5
7
9
10
12
14
16
18
20
22
24
26
DD
2
4
6
8
Sealectro 50-007-0000 (Plug)
DD
. An external reference
STRB
N/C
N/C
BUSY
N/C
DB11
DB9
DB7
DB5
DB3
DB1
+
GND
for normal operation.
5V
REF
of AD7880. Nor-
REV. 0