REF3212,REF3220

REF3225,REF3230

REF3233,REF3240

SBVS058 −JUNE 2005

www.ti.com

9

The REF32xx also features a low quiescent current of

100

µA, with a maximum quiescent current over

temperature of just 135

µA. The quiescent current typically

changes less than 2

µA over the entire supply range, as

shown in Figure 3.

110

108

106

104

102

100

98

96

94

1.5

2.0

3.0

4.0

2.5

3.5

4.5

6.0

5.0

5.5

Power Supply (V)

Figure 3. Supply Current vs Supply Voltage

Supply voltages below the specified levels can cause the

REF32xx to momentarily draw currents greater than the

typical quiescent current. This momentary current draw

can be prevented by using a power supply with a fast rising

edge and low output impedance.

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 100k

Ω to

400k

Ω.

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:

V

V

PRE

* V

POST

V

NOM

Where:

pretemperature cycling.

has been cycled through the specified temperature

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:

Drift

+

V

V

OUT

Temp Range

The REF32xx features a typical drift coefficient of 4ppm/

°C

from 0

_C to +125_C—the primary temperature range for

many

applications.

For

the

extended

industrial

temperature range of –40

_C to +125_C, the REF32xx

family drift increases to a typical value of 10.5ppm/

°C.

NOISE PERFORMANCE

Typical 0.1Hz to 10Hz voltage noise can be seen in the

Typical Characteristic curve, 0.1 to 10Hz 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.

(1)

(2)