8.3 Feature Description

8.3.1 Temperature Monitoring

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

approximately 60kΩ source impedance. As illustrated in Figure 6-8, the output voltage follows the nominal

relationship:

REF50xxI, REF50xxAI: VTEMP PIN = 509mV + 2.64 × T(°C)

(1)

REF50xxEI: VTEMP PIN = 625mV + 2.64 × T(°C)

(2)

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

accurate temperature measurements, this pin can be used to indicate temperature changes or for temperature

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

in voltage at the TEMP pin.

The TEMP pin has high-output impedance (see Section 8.2). Loading this pin with a low-impedance circuit

induces a measurement error; however, this pin does not have any effect on VOUT accuracy.

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

drift op amp, such as the OPA333, OPA335, or OPA376, as shown in Figure 8-3.

DNC

TEMP

V

OUT

V

IN

GND

DNC

NC

TRIM/NR

REF50xx

V

TEMP

2.6mV/ C

°

OPA(1)

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

+V

Figure 8-3. Buffering the TEMP Pin Output

8.3.2 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 in Equation 3.

Drift

V

OUTMAX

V

OUTMIN

V

OUT

Tem p Range

106(ppm)

=

(

–

×

) ×

(3)

The REF50xx features a maximum drift coefficient of 2.5ppm/°C for the enhanced-grade version, 3ppm/°C for

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

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REF5010, REF5020, REF5025, REF5030, REF5040, REF5045, REF5050

SBOS410L – JUNE 2007 – REVISED OCTOBER 2024

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