DNC

TEMP

V

OUT

V

IN

GND

DNC

NC

TRIM/NR

REF50xx

V

TEMP

2.6mV/ C

°

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

+V

6

OUTMAX

OUTMIN

OUT

V

V

Drift

10 (ppm)

V

Temp Range

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REF5020-EP, REF5025-EP, REF5040-EP, REF5050-EP

www.ti.com

SBOS471B – APRIL 2010 – REVISED JUNE 2015

Feature Description (continued)

7.3.2 Low Temperature Drift

The REF50xx is designed for minimal drift error, which is defined as the change in output voltage over

temperature. The drift is calculated using the box method, as described by Equation 1:

(1)

The REF50xx features a maximum drift coefficient of 3 ppm/°C for the high-grade version, and 8 ppm/°C for the

standard-grade.

7.3.3 Temperature Monitoring

The temperature output terminal (TEMP, pin 3) provides a temperature-dependent voltage output with

approximately 60-k

Ω source impedance. As seen in Figure 8, the output voltage follows the nominal relationship:

(2)

This pin indicates general chip temperature, accurate to approximately ±15°C. Although it is not generally

suitable for accurate temperature measurements, it can be used to indicate temperature changes or for

temperature compensation of analog circuitry. A temperature change of 30°C corresponds to an approximate 79

mV change in voltage at the TEMP pin.

The TEMP pin has high output impedance (see Functional Block Diagram). Loading this pin with a low-

avoid errors caused by low-impedance loading, buffer the TEMP pin output with a suitable low-temperature drift

operational amplifiers, such as the OPA333, OPA335, or OPA376, as shown in Figure 23.

Figure 23. Buffering the TEMP Pin Output

7.3.4 Noise Performance

Typical 0.1-Hz to 10-Hz voltage noise for each member of the REF50xx family is specified in the Electrical

Characteristics: Per Device table. The noise voltage increases with output voltage and operating temperature.

Additional filtering can be used to improve output noise levels, although take care to ensure the output

impedance does not degrade performance.

For additional information about how to minimize noise and maximize performance in mixed-signal applications

such as data converters, refer to the series of Analog Applications Journal articles entitled, How a Voltage

Reference Affects ADC Performance. This three-part series is available for download from the TI website under

three literature numbers: SLYT331, SLYT339, and SLYT355, respectively.

Copyright © 2010–2015, Texas Instruments Incorporated

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