REF3230 datasheet(10/21 Pages) TI2

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HYST

PRE

POST

NOM

´ 10 (ppm)

(

Drift=

OUTMAX

OUTMIN

OUT

TempRange

´ 10 (ppm)

(

LOAD

0.47 F

+5V

GND_F

ContactandTraceResistance

GND_S

ENABLE

OUT_F

OUT_S

REF32xx

REF3212, REF3220

REF3225, REF3230

REF3233, REF3240

SBVS058C

– JUNE 2005 – REVISED AUGUST 2011

www.ti.com

THERMAL HYSTERESIS

LONG-TERM STABILITY

Thermal hysteresis for the REF32xx is defined as the

Long-term stability refers to the change of the output

change in output voltage after operating the device at

voltage of a reference over a period of months or

+25

°C, cycling the device through the specified

years. This effect lessens as time progresses, as is

temperature range, and returning to +25

°C. It can be

shown by the long-term stability Typical Characteristic

expressed as:

curves. The typical drift value for the REF32xx is

55ppm from 0 to 1000 hours. This parameter is

characterized by measuring 30 units at regular

intervals for a period of 1000 hours.

Where:

LOAD REGULATION

VHYST = thermal hysteresis (in units of ppm).

Load regulation is defined as the change in output

VNOM = the specified output voltage.

voltage as a result of changes in load current. The

VPRE = output voltage measured at +25°C

load regulation of the REF32xx is measured using

pretemperature cycling.

force and sense contacts, as shown in Figure 24.

VPOST = output voltage measured after the device

has

been

cycled

through

the

specified

temperature range of

–40°C to +125°C and

returned to +25

°C.

(1)

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

calculated using the box method, as described by

Equation 2:

(2)

The REF32xx features a typical drift coefficient of

4ppm/

°C

from

°C

+125

°C—the

primary

temperature range for many applications. For the

extended industrial temperature range of

–40°C to

Figure 24. Accurate Load Regulation of REF32xx

+125

°C, the REF32xx family drift increases to a

typical value of 10.5ppm/

°C.

The force and sense lines can be used to effectively

NOISE PERFORMANCE

eliminate the impact of contact and trace resistance,

resulting

accurate

voltage

the

load.

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

connecting the force and sense lines at the load, the

the Typical Characteristic curve, 0.1Hz to 10Hz

REF32xx compensates for the contact and trace

Voltage Noise. The noise voltage of the REF32xx

resistances because it measures and adjusts the

increases

with

output

voltage

and

operating

voltage actually delivered at the load.

temperature. Additional filtering can be used to

improve output noise levels, although care should be

The GND_S pin is connected to the internal ground of

taken to ensure the output impedance does not

the device through ESD protection diodes. Because

degrade AC performance.

of that connection, the maximum differential voltage

between the GND_S and GND_F pins must be kept

below

200mV

prevent

these

dioes

from

unintentionally turning on.

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