REV. 0
AD5332/AD5333/AD5342/AD5343
–16–
SUGGESTED DATABUS FORMATS
In most applications GAIN and BUF are hard-wired. However,
if more flexibility is required, they can be included in a databus.
This enables you to software program GAIN, giving the option
of doubling the resolution in the lower half of the DAC range.
In a bused system GAIN and BUF may be treated as data inputs
since they are written to the device during a write operation and
take effect when LDAC is taken low. This means that the refer-
ence buffers and the output amplifier gain of multiple DAC
devices can be controlled using common GAIN and BUF lines.
The AD5333 and AD5342 databuses must be at least 10, and
12 bits wide respectively, and are best suited to a 16-bit data-
bus system.
Examples of data formats for putting GAIN and BUF on a 16-
bit databus are shown in Figure 32. Note that any unused bits
above the actual DAC data may be used for BUF and GAIN.
DB0
DB1DB2
DB3
DB4
DB5
DB6
DB7
DB8DB9
GAIN
X
X
AD5342
X = UNUSED BIT
BUF
DB0
DB1DB2DB3
DB4
DB5
DB6
DB7
DB8DB9
GAIN
XX
AD5333
X
X BUF
DB10DB11
Figure 32. GAIN and BUF Data on a 16-Bit Bus
APPLICATIONS INFORMATION
Typical Application Circuits
The AD5332/AD5333/AD5342/AD5343 can be used with a
wide range of reference voltages, especially if the reference inputs
are configured to be unbuffered, in which case the devices offer
full, one-quadrant multiplying capability over a reference range
of 0.25 V to V
DD
. More typically, these devices may be used with a
fixed, precision reference voltage. Figure 33 shows a typical
setup for the devices when using an external reference connected to
the unbuffered reference inputs. If the reference inputs are unbuf-
fered, the reference input range is from 0.25 V to V
DD
, but if the
on-chip reference buffers are used, the reference range is reduced.
Suitable references for 5 V operation are the AD780 and REF192.
For 2.5 V operation, a suitable external reference would be the
AD589, a 1.23 V bandgap reference.
AD5332/AD5333/
AD5342/AD5343
V
OUT
*
0.1F
V
DD
= 2.5V TO 5.5V
V
DD
GND
AD780/REF192
WITH V
DD
= 5V
OR
AD589 WITH V
DD
= 2.5V
V
REF
*
GND
V
OUT
V
IN
EXT
REF
*ONLY ONE CHANNEL OF V
REF
AND V
OUT
SHOWN
10F
Figure 33. AD5332/AD5333/AD5342/AD5343 Using
External Reference
Driving V
DD
from the Reference Voltage
If an output range of zero to V
DD
is required when the reference
inputs are configured as unbuffered, the simplest solution is to
connect the reference inputs to V
DD
. As this supply may not be
very accurate, and may be noisy, the devices may be powered
from the reference voltage, for example using a 5 V reference
such as the ADM663 or ADM666, as shown in Figure 34.
AD5332/AD5333/
AD5342/AD5343
V
OUT
*
V
DD
GND
V
REF
*
GND
V
OUT(2)
V
IN
ADM663/ADM666
VSET SHDN
SENSE
6V TO 16V
*ONLY ONE CHANNEL OF V
REF
AND V
OUT
SHOWN
0.1F
10F
0.1F
Figure 34. Using an ADM663/ADM666 as Power and Refer-
ence to AD5332/AD5333/AD5342/AD5343
Bipolar Operation Using the AD5332/AD5333/AD5342/AD5343
The AD5332/AD5333/AD5342/AD5343 have been designed
for single supply operation, but bipolar operation is achievable
using the circuit shown in Figure 35. The circuit shown has been
configured to achieve an output voltage range of –5 V < V
O
<
+5 V. Rail-to-rail operation at the amplifier output is achievable
using an AD820 or OP295 as the output amplifier.
The output voltage for any input code can be calculated as
follows:
V
O
= [(1 + R4/R3) × (R2/(R1 + R2) × (2 × V
REF
× D/2
N
)] – R4 × V
REF
/R3
where:
D is the decimal equivalent of the code loaded to the DAC, N is
DAC resolution and V
REF
is the reference voltage input.
With:
V
REF
= 2.5 V
R1 = R3 = 10 kΩ
R2 = R4 = 20 kΩ and V
DD
= 5 V.
V
OUT
= (10 × D/2
N
) – 5
AD5332/AD5333/
AD5342/AD5343
GND
V
DD
= 5V
EXT
REF
V
OUT
*
AD780/REF192
WITH V
DD
= 5V
OR
AD589 WITH V
DD
= 2.5V
GND
V
IN
V
OUT
V
REF
*
V
DD
R3
10k⍀
R1
10k⍀
R2
20k⍀
R4
20k⍀
ⴞ5V
+5V
–5V
*ONLY ONE CHANNEL OF V
REF
AND V
OUT
SHOWN
0.1F
0.1F
10F
Figure 35. Bipolar Operation using the AD5332/AD5333/
AD5342/AD5343
