AD5674 datasheet(29/32 Pages) AD

29 / 32 page

Data Sheet

AD5674/AD5674R/AD5679/AD5679R

Rev. B | Page 29 of 32

SOLDER HEAT REFLOW

As with all IC reference voltage circuits, the reference value

experiences a shift induced by the soldering process. Analog

Devices, Inc., performs a reliability test called precondition to

mimic the effect of soldering a device to a board. The output

voltage specification quoted previously includes the effect of

this reliability test.

Figure 64 shows the effect of solder heat reflow (SHR) as

measured through the reliability test (precondition).

Figure 64. SHR Reference Voltage Shift

LONG-TERM TEMPERATURE DRIFT

Figure 65 shows the change in VREF value after 1000 hours at 25°C

ambient temperature.

Figure 65. Reference Drift Through to 1000 Hours

THERMAL HYSTERESIS

Thermal hysteresis is the voltage difference induced on the

reference voltage by sweeping the temperature from ambient to

cold to hot, and then back to ambient.

Figure 66 shows thermal hysteresis data. Thermal hysteresis is

measured by sweeping the temperature from ambient to −40°C,

then to +125°C, and returning to ambient. The ∆VREF, shown in

blue in Figure 66, is then measured between the two ambient

measurements. The same temperature sweep and measurements

are immediately repeated and the results are shown in red in

Figure 66.

Figure 66. Thermal Hysteresis

100

150

200

250

300

350

400

VREF (V)

POSTSOLDER HEAT REFLOW

PRESOLDER HEAT REFLOW

120

–40

–30

–20

–10

100

110

ELAPSED TIME (Hours)

100

200

300

400

500

600

700

800

900

1000

–130 –110

–90

–70

–50

–30

–10

DISTORTION (ppm)

FIRST TEMPERATURE SWEEP

SUBSEQUENT TEMPERATURE SWEEPS

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