8.2 Long-Term Stability

One of the key parameters of the REF34xx references is long-term stability. Typical characteristic expressed

as: curves shows the typical drift value for the REF34xx is 25 ppm from 0 to 1000 hours. This parameter is

characterized by measuring 32 units at regular intervals for a period of 1000 hours. It is important to understand

that long-term stability is not ensured by design and that the output from the device may shift beyond the typical

25 ppm specification at any time. For systems that require highly stable output voltages over long periods of

time, the designer should consider burning in the devices prior to use to minimize the amount of output drift

exhibited by the reference over time.

Hours

0

100

200

300

400

500

600

700

800

900 1000

-40

-35

-30

-25

-20

-15

-10

-5

0

5

10

D022

8.3 Thermal Hysteresis

Thermal hysteresis is measured with the REF34xx soldered to a PCB, similar to a real-world application.

Thermal hysteresis for the device is defined as the change in output voltage after operating the device at 25°C,

cycling the device through the specified temperature range, and returning to 25°C. The PCB was baked at

150°C for 30 minutes before thermal hysteresis was measured. Hysteresis can be expressed by Equation 1:

6

PRE

POST

HYST

NOM

| V

V

|

V

10

ppm

V

§

·

u

¨

¸

©

¹

(1)

where

range of –40°C to +125°C and returns to 25°C.

Typical thermal hysteresis distribution is as shown in Figure 8-4 and Figure 8-5.

REF3425, REF3430, REF3433, REF3440, REF3450

SBAS804F – SEPTEMBER 2017 – REVISED JUNE 2021

www.ti.com

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