AD5337/AD5338/AD5339
APPLICATIONS
TYPICAL APPLICATION CIRCUIT
The AD5337/AD5338/AD5339 can be used with a wide range of
reference voltages for full, one-quadrant multiplying capability
over a reference range of 0 V to VDD. More typically, these
devices are used with a fixed precision reference voltage.
Suitable references for 5 V operation are the AD780, the REF192,
and the ADR391 (2.5 V references). For 2.5 V operation, a
suitable external reference would be the AD589 or AD1580, a
1.23 V band gap reference. Figure 36 shows a typical setup for
the AD5337/AD5338/AD5339 when using an external reference.
Note that A0 can be high or low.
VDD = 2.5V TO 5.5V
0.1µF
10µF
VIN
VOUT
EXT
1µF
REF
AD780/REF192/ADR391
WITH VDD = 5V OR
AD589/AD1580 WITH
VDD = 2.5V
REFIN
AD5337/
AD5338/
AD5339
VOUTA
VOUTB
SCL
SDA
A0
GND
SERIAL
INTERFACE
Figure 36. AD5337/AD5338/AD5339 Using External Reference
If an output range of 0 V to VDD is required, the simplest
solution is to connect the reference input to VDD. Because this
supply may be inaccurate and noisy, the AD5337/AD5338/
AD5339 may be powered from a reference voltage, for example,
using a 5 V reference such as the REF195 which provides a
steady output supply voltage. With no load on the DACs, the
REF195 is required to supply 600 µA supply current to the DAC
and 112 µA to the reference input. When the DAC outputs are
loaded, the REF195 also needs to supply the current to the
loads; therefore, the total current required with a 10 kΩ load on
each output is
712 µA + 2(5 V/10 kΩ) = 1.7 mA
The load regulation of the REF195 is typically 2 ppm/mA,
which results in an error of 3.4 ppm (17 µV) for the 1.7 mA
current drawn from it. This corresponds to a 0.0009 LSB error
at 8 bits and a 0.014 LSB error at 12 bits.
BIPOLAR OPERATION
The AD5337/AD5338/AD5339 are designed for single-supply
operation, but a bipolar output range is also possible using the
circuit in Figure 37. This circuit gives an output voltage range of
±5 V. Rail-to-rail operation at the amplifier output is achievable
using an AD820 or an OP295 as the output amplifier.
6V TO 12V
R1 = 10kΩ
R2 = 10kΩ
+5V
10µF
0.1µF
+5V
AD820/
OP295
±5V
VDD
VOUTA
AD1585
VIN
VOUT
AD5339
–5V
REFIN
VOUTB
GND
1µF
A0
GND SCL SDA
2-WIRE
SERIAL
INTERFACE
Figure 37. Bipolar Operation with the AD5339
The output voltage for any input code can be calculated as
follows:
VOUT [(REFIN (D 2N )× (R1 + R2 ) R1) − REFIN × (R2 R1)]
where:
D is the decimal equivalent of the code loaded to the DAC.
N is the DAC resolution.
REFIN is the reference voltage input.
With REFIN = 5 V, R1 = R2 = 10 kΩ:
VOUT = (10 × D/2N) − 5
MULTIPLE DEVICES ON ONE BUS
Figure 38 shows two AD5339 devices on the same serial bus.
Each has a different slave address because the state of the A0 pin
is different. This allows each of four DACs to be written to or
read from independently.
VDD
PULL-UP
RESISTORS
A0
AD5339
SDA SCL
MICROCONTROLLER
SDA SCL
A0 AD5339
Rev. A | Page 20 of 24
Figure 38. Multiple AD5339 Devices on One Bus