V

HYST

+

V

PRE

V

NOM

Drift +

V

OUTMAX

V

OUT

Temp Range

REF3212-EP, REF3220-EP, REF3225-EP

REF3230-EP, REF3233-EP, REF3240-EP

www.ti.com

SBVS078B

– OCTOBER 2006 – REVISED AUGUST 2011

Shutdown

The REF32xx can be placed in a low-power mode by pulling the ENABLE/SHUTDOWN pin low. When in

shutdown mode the output of the REF32xx becomes a resistive load to ground. The value of the load depends

on the model, and ranges from approximately 100 k

Ω to 400 kΩ.

Characteristics section of this datasheet. To maintain the low quiescent current (100

μA typ), the ENABLE pin

was designed without an internal pull-up resistor. In applications where the shutdown feature will not be used,

connecting the ENABLE pin high (to the IN pin) will ensure enabled operation of the device.

Thermal Hysteresis

Thermal hysteresis for the REF32xx 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. It can be expressed as:

(1)

Where:

range of

–40°C to 125°C and returned to 25°C

Temperature Drift

The REF32xx is designed to exhibit minimal drift error, which is defined as the change in output voltage over

varying temperature. The drift is calculated using the box method, as described by the following equation:

(2)

The REF32xx features a typical drift coefficient of 4 ppm/

°C from 0°C to 125°C — the primary temperature range

for many applications. For the extended temperature range of

–55°C to 125°C, the REF32xx family drift

increases to a typical value of 10.5 ppm/

°C.

Noise Performance

Typical 0.1-Hz to 10-Hz voltage noise can be seen in the Typical Characteristic curve, 0.1-Hz to 10-Hz Voltage

Noise. The noise voltage of the REF32xx increases with output voltage and operating temperature. Additional

filtering can be used to improve output noise levels, although care should be taken to ensure the output

impedance does not degrade ac performance.

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 shown by the long-term stability Typical Characteristic curves. The

typical drift value for the REF32xx is 55 ppm from 0 to 1000 hours. This parameter is characterized by measuring

30 units at regular intervals for a period of 1000 hours.

Copyright

© 2006–2011, Texas Instruments Incorporated

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Product Folder Link(s): REF3212-EP, REF3220-EP, REF3225-EP REF3230-EP, REF3233-EP, REF3240-EP