AD5306 datasheet(21/24 Pages) AD

21 / 24 page

AD5306/AD5316/AD5326

Rev. F | Page 21 of 24

AD5306/AD5316/AD5326 AS A DIGITALLY

PROGRAMMABLE WINDOW DETECTOR

A digitally programmable upper/lower limit detector using two

of the DACs in the AD5306/AD5316/AD5326 is shown in

Figure 39. The upper and lower limits for the test are loaded to

DACs A and B, which, in turn, set the limits on the CMP04. If

the signal at the VIN input is not within the programmed

window, an LED indicates the fail condition. Similarly, DAC C

and DAC D can be used for window detection on a second

VIN signal.

VDD

GND

VIN

PASS/FAIL

1/2

CMP04

1/6 74HC05

FAIL

PASS

0.1

μF

SCL

SDA

SCL

DIN

VREF

1 ADDITIONAL PINS OMITTED FOR CLARITY

μF

1/2

AD5306/

AD5316/

AD53261

VREFA

VREFB

VOUTB

VOUTA

Figure 39. Window Detection

COARSE AND FINE ADJUSTMENT USING THE

AD5306/AD5316/AD5326

Two of the DACs in the AD5306/AD5316/AD5326 can be

paired together to form a coarse and fine adjustment function,

as shown in Figure 40. DAC A is used to provide the coarse

adjustment while DAC B provides the fine adjustment. Varying

the ratio of R1 and R2 changes the relative effect of the coarse

and fine adjustments. With the resistor values and external

reference shown, the output amplifier has unity gain for the

DAC A output; therefore, the output range is 0 V to 2.5 V − 1

LSB. For DAC B, the amplifier has a gain of 7.6 × 10−3, giving

DAC B a range of 19 mV. Similarly, DAC C and DAC D can be

paired together for coarse and fine adjustment.

The circuit in Figure 40 is shown with a 2.5 V reference, but

reference voltages up to VDD may be used. The op amps

indicated allow a rail-to-rail output swing.

μF

VREFA

VDD

GND

VOUTB

0.1

μF

VOUT

VIN

GND

EXT

REF

AD820/

OP295

51.2k

390

AD780/REF192

WITH VDD = 5V

VOUTA

390

51.2k

VOUT

VDD = 5V

1/2

AD5306/

AD5316/

AD5326

VREFB

Figure 40. Coarse/Fine Adjustment

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