Drift +

V

OUTMAX

V

OUT

Temp Range

DNC

TEMP

V

OUT

V

IN

GND

DNC

NC

TRIM/NR

REF50xx

V

TEMP

2.6mV/ C

°

NOTE:(1)Lowdriftopamp,suchastheOPA333,OPA335,orOPA376.

+V

V

=

HYST

6

(

(

|V

V

|

V

PRE

POST

NOM

-

REF5010, REF5020

REF5025, REF5030

REF5040, REF5045, REF5050

www.ti.com

SBOS410E – JUNE 2007 – REVISED JUNE 2010

TEMPERATURE DRIFT

To avoid errors caused by low-impedance loading,

buffer

the

TEMP

pin

output

with

a

suitable

The REF50xx is designed for minimal drift error,

low-temperature drift op amp, such as the OPA333,

which is defined as the change in output voltage over

OPA335, or OPA376, as shown in Figure 32.

temperature. The drift is calculated using the box

method, as described by the following equation:

(1)

The REF50xx features a maximum drift coefficient of

3ppm/°C for the high-grade version, and 8ppm/°C for

the standard-grade.

space

THERMAL HYSTERESIS

Thermal hysteresis for the REF50xx is defined as the

Figure 32. Buffering the TEMP Pin Output

change in output voltage after operating the device at

+25°C, cycling the device through the specified

POWER DISSIPATION

temperature range, and returning to +25°C. It can be

expressed as Equation 2:

The REF50xx family is specified to deliver current

loads of ±10mA over the specified input voltage

range. The temperature of the device increases

according to the equation:

(2)

(3)

Where:

Where:

pretemperature cycling.

(°C/W)

has

been

cycled

from

+25°C

through

the

specified temperature range of –40°C to +125°C

The REF50xx junction temperature must not exceed

and returned to +25°C.

the absolute maximum rating of +150°C.

TEMPERATURE MONITORING

NOISE PERFORMANCE

The temperature output terminal (TEMP, pin 3)

Typical 0.1Hz to 10Hz voltage noise for each member

provides a temperature-dependent voltage output

of the REF50xx family is specified in the Electrical

with approximately 60k

Ω source impedance. As seen

Characteristics: Per Device table. The noise voltage

in Figure 8, the output voltage follows the nominal

increases

with

output

voltage

and

operating

relationship:

temperature. Additional filtering can be used to

improve output noise levels, although care should be

taken to ensure the output impedance does not

This pin indicates general chip temperature, accurate

degrade performance.

to approximately ±15°C. Although it is not generally

For additional information about how to minimize

suitable for accurate temperature measurements, it

noise and maximize performance in mixed-signal

can be used to indicate temperature changes or for

applications such as data converters, refer to the

temperature compensation of analog circuitry. A

series of Analog Applications Journal articles entitled,

temperature change of 30°C corresponds to an

How a Voltage Reference Affects ADC Performance.

approximate 79mV change in voltage at the TEMP

This three-part series is available for download from

pin.

the TI website under three literature numbers:

The TEMP pin has high output impedance (see

SLYT331, SLYT339, and SLYT355 for Part I, Part II,

Figure 28). Loading this pin with a low-impedance

and Part III, respectively.

circuit induces a measurement error; however, it does

Copyright © 2007–2010, Texas Instruments Incorporated

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