7.3.2 Thermal Hysteresis

Thermal hysteresis for the REF30 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, and can be expressed as

shown in Equation 1:

PRE

POST

6

HYST

NOM

abs V

V

V

=

• 10 (ppm)

V

æ

ö

-

ç

÷

ç

÷

è

ø

(1)

where

• VHYST = Calculated hysteresis

• VPRE = Output voltage measured at 25°C pretemperature cycling

• VPOST = Output voltage measured when device has been operated at 25°C, cycled through specified range of

–40°C to +125°C, and returned to operation at 25°C.

7.3.3 Temperature Drift

The REF30 exhibits minimal drift error, defined as the change in output voltage over varying temperature. Using

the box method of drift measurement, the REF30 features a typical drift coefficient of 20ppm from 0°C to 70°C,

the primary temperature range of use for many applications. For industrial temperature ranges of –40°C to

+125°C, the REF30 family drift increases to a typical value of 50ppm.

7.3.4 Noise Performance

The REF30 generates noise less than 50μVPP between frequencies of 0.1Hz to 10Hz, and can be seen in

Figure 6-27 The noise voltage of the REF30 increases with output voltage and operating temperature. Additional

filtering can be used to improve output noise levels; however, make sure the output impedance does not

degrade AC performance.

7.3.5 Long-Term Stability

Long-term stability refers to the change of the output voltage of a reference over a period of months or years.

This effect lessens as time progresses as is apparent by the long-term stability curves. The typical drift value for

the REF30 is 24ppm from 0 hours to 1000 hours, and 15ppm from 1000 hours to 2000 hours. This parameter is

characterized by measuring 30 units at regular intervals for a period of 2000 hours.

7.3.6 Load Regulation

Load regulation is defined as the change in output voltage as a result of changes in load current. Use a 4 wire

measurement (kelvin measurement) methodology for accurate load regulation measurement as shown in Figure

7-2. The force and sense lines tied to the contact area of the output pin reduce the impact of contact and trace

resistance, resulting in accurate measurement of the load regulation contributed solely by the REF30xx.

Output Pin

Meter

V

OUT

+

Sense Line

Force Line

Load

I

L

Contact and

Trace Resistance

Copyright © 2016, Texas Instruments Incorporated

Figure 7-2. Accurate Load Regulation of REF30

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REF30, REF30E

SBVS032J – MARCH 2002 – REVISED JULY 2025

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