AD5313 datasheet(16/20 Pages) AD

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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

DB1

DB2

DB3

DB4

DB5

DB6

DB7

DB8

DB9

GAIN

AD5342

X = UNUSED BIT

BUF

DB0

DB1

DB2

DB3

DB4

DB5

DB6

DB7

DB8

DB9

GAIN

AD5333

BUF

DB10

DB11

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 VDD. 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 VDD, 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

VOUT*

0.1 F

VDD = 2.5V TO 5.5V

VDD

GND

AD780/REF192

WITH VDD = 5V

AD589 WITH VDD = 2.5V

VREF*

GND

VOUT

VIN

EXT

REF

*ONLY ONE CHANNEL OF VREF AND VOUT SHOWN

10 F

Figure 33. AD5332/AD5333/AD5342/AD5343 Using

External Reference

Driving VDD from the Reference Voltage

If an output range of zero to VDD is required when the reference

inputs are configured as unbuffered, the simplest solution is to

connect the reference inputs to VDD. 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

VOUT*

VDD

GND

VREF*

GND

VOUT(2)

VIN

ADM663/ADM666

VSET

SHDN

SENSE

6V TO 16V

*ONLY ONE CHANNEL OF VREF AND VOUT SHOWN

0.1 F

10 F

0.1 F

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 < VO <

+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:

VO = [(1 + R4/R3)

× (R2/(R1 + R2) × (2 × VREF × 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 VREF is the reference voltage input.

With:

VREF = 2.5 V

R1 = R3 = 10 k

Ω

R2 = R4 = 20 k

Ω and VDD = 5 V.

VOUT = (10

× D/2N) – 5

AD5332/AD5333/

AD5342/AD5343

GND

VDD = 5V

EXT

REF

VOUT*

AD780/REF192

WITH VDD = 5V

AD589 WITH VDD = 2.5V

GND

VIN

VOUT

VREF*

VDD

10k

20k

+5V

–5V

*ONLY ONE CHANNEL OF VREF AND VOUT SHOWN

0.1 F

10 F

Figure 35. Bipolar Operation using the AD5332/AD5333/

AD5342/AD5343

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