AD7243 Analog Devices, AD7243 Datasheet - Page 8

• Manufacturer Part Number: AD7243
• Description: LC2MOS 12-Bit Serial DACPORT
• Manufacturer: Analog Devices

APPLYING THE AD7243
Power Supply Decoupling
To achieve optimum performance when using the AD7243, the
V
0.1 µF capacitors. In noisy environments it is recommended
that 10 µF capacitors be connected in parallel with the 0.1 µF
capacitors.
The internal scaling resistors provided on the AD7243 allow
several output voltage ranges. The part can produce unipolar
output ranges of 0 V to +5 V or 0 V to +10 V and a bipolar out-
put range of ± 5 V. Connections for the various ranges are out-
lined below.
Unipolar (0 V to +10 V) Configuration
The first of the configurations provides an output voltage range
of 0 V to +10 V. This is achieved by connecting the output off-
set resistor R
is selected by connecting BIN/COMP (Pin 4) to DGND. In this
configuration, the AD7243 can be operated using either single
or dual supplies. Note that the V
for this range in order to maintain sufficient amplifier head-
room. Dual supplies may be used to improve settling time and
give increased current sink capability for the amplifier. Figure 9
shows the connection diagram for unipolar operation of the
AD7243. Table I shows the digital code vs. analog output for
this configuration.
Input Data Word
XXXX 1111 1111 1111 +2 REFIN × (4095/4096)
XXXX 1000 0000 0001 +2 REFIN × (2049/4096)
XXXX 1000 0000 0000 +2 REFIN × (2048/4096) = +REFIN
XXXX 0111 1111 1111 +2 REFIN × (2047/4096)
XXXX 0000 0000 0001 +2 REFIN × (1/4096)
XXXX 0000 0000 0000 0 V
X = Don’t Care.
Note: 1 LSB = 2 REFIN/4096.
AD7243
DD
REFOUT
and V
REFIN
Table I. Unipolar Code Table (0 V to +10 V Range)
MSB
SS
*ADDITIONAL PINS OMITTED FOR CLARITY
OFS
lines should each be decoupled to DGND using
(Pin 13) to AGND. Natural Binary data format
COMP
BIN/
LSB
Analog Output, V
DGND
AD7243*
DAC
DD
V
DD
V
supply must be ≥+14.25 V
DD
AGND
2R
2R
0V OR V
V
SS
OUT
V
R
0V TO + 10V
OUT
OFS
SS
Unipolar (0 V to +5 V) Configuration
The 0 V to +5 V output voltage range is achieved by connecting
R
either single or dual supplies. The table for output voltage vs.
digital code is as in Table I, with 2REFIN replaced by REFIN.
Note, for this range, 1 LSB = REFIN • (2
Bipolar ( 5 V) Configuration
The bipolar configuration for the AD7243, which gives an out-
put range of –5 V to +5 V, is achieved by connecting R
REFIN. The AD7243 must be operated from dual supplies to
achieve this output voltage range. Either offset binary or two’s
complement data format may be selected. Figure 10 shows the
connection diagram for bipolar operation. An AD586 provides
the reference voltage for the DAC but this could be provided by
the on-chip reference by connecting REFOUT to REFIN.
Bipolar Operation (Two’s Complement Data Format)
The AD7243 is configured for two’s complement data format
by connecting BIN/COMP (Pin 4) high. The analog output vs.
digital code is shown in Table II.
Input Data Word
XXXX 0111 1111 1111
XXXX 0000 0000 0001
XXXX 0000 0000 0000
XXXX 1111 1111 1111
XXXX 1000 0000 0001
XXXX 1000 0000 0000
X = Don’t Care.
Note: 1 LSB = REFIN/2048.
Bipolar Operation (Offset Binary Data Format)
The AD7243 is configured for Offset Binary data format by
connecting BIN/COMP (Pin 4) low. The analog output vs. digi-
tal code may be obtained by inverting the MSB in Table II.
OFS
GND
AD586
to V
Table II. Two’s Complement Bipolar Code Table
+V
MSB
OUT
IN
V
OUT
. Once again, the AD7243 can be operated using
REFIN
BIN/ COMP
*ADDITIONAL PINS OMITTED FOR CLARITY
LSB
+REFIN × (2047/2048)
+REFIN × (1/2048)
0 V
–REFIN × (1/2048)
–REFIN × (2047/2048)
–REFIN × (2048/2048) = –REFIN
Analog Output, V
V
DD
R
OFS
DAC
DGND
V
V
DD
DD
–12
2R
AD7243*
) = (REFIN/4096).
OUT
AGND
2R
V
SS
V
OFS
SS
V
–5V TO + 5V
to
OUT