VHYSTppm =  VPRE−VPOST

VPRE ×106

(3)

where-

• VHYST = thermal hysteresis (in units of ppm)

• VPRE = output voltage measured at 25°C pre-temperature cycling

• VPOST = output voltage measured after the device has cycled from 25°C through the specified temperature

range of 0°C to75°C and returns to 25°C.

Thermal Hysteresis (ppm)

0

0.5

1

1.5

2

2.5

3

0

10

20

30

40

50

Figure 8-4. Thermal Hysteresis (Cycle 1)

Distribution (0°C to 70°C)

Thermal Hysteresis (ppm)

0

0.2

0.4

0.6

0.8

1

0

20

40

60

80

Figure 8-5. Thermal Hysteresis (Cycle 2)

Distribution (0°C to 70°C)

8.4 Noise Performance

8.4.1 1/f Noise

1/f noise, also known as flicker noise, is dominant mostly in the lower frequency bands. Flicker noise affects the

device output voltage which can affect the ENOB of the signal chain. REF80 data sheet specifies flicker noise for

0.1Hz to 10Hz frequency band where 1/f noise has maximum power. Flicker noise is measured by filtering the

output from 0.1Hz to 10Hz. Since the 1/f noise is an extremely low value, the frequency of interest needs to be

amplified and band-pass filtered as shown in Figure 8-6. 1/f noise must be tested in a Faraday cage enclosure

to block environmental noise. Refer to application note Techniques for Noise Measurements in Precision Series

References for more detail on noise measurement for precision series references.

www.ti.com

REF80

SNAS856A – SEPTEMBER 2024 – REVISED MARCH 2025

Copyright © 2025 Texas Instruments Incorporated

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