REF5045A datasheet(11/19 Pages) TI1

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Drift +

OUTMAX

* VOUTMIN

OUT

Temp Range

106(ppm)

DNC

TEMP

OUT

GND

DNC

TRIM/NR

REF50xx

TEMP

2.6mV/ C

OPA(1)

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

HYST

10 (ppm)

(

PRE

POST

NOM

REF5020-Q1, REF5025-Q1, REF5030-Q1

REF5040-Q1, REF5045-Q1, REF5050-Q1

www.ti.com

SBOS456F

– SEPTEMBER 2008 – REVISED SEPTEMBER 2011

TEMPERATURE DRIFT

To avoid errors caused by low-impedance loading,

buffer

the

TEMP

output

with

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

3 ppm/

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

temperature range, and returning to +25

°C. It can be

POWER DISSIPATION

expressed as Equation 2:

The REF50xx family is specified to deliver current

loads of

±10 mA over the specified input voltage

range. The temperature of the device increases

(2)

according to the equation:

Where:

TJ = TA + PD × θJA

(3)

VHYST = thermal hysteresis (in units of ppm).

Where:

VNOM = the specified output voltage.

TJ = Junction temperature (°C)

VPRE = output voltage measured at +25°C

TA = Ambient temperature (°C)

pretemperature cycling.

PD = Power dissipated (W)

VPOST = output voltage measured after the device

θJA = Junction-to-ambient thermal resistance

has

been

cycled

from

+25

°C

through

the

(

°C/W)

specified temperature range of

–40°C to +125°C

and returned to +25

°C.

The REF50xx junction temperature must not exceed

the absolute maximum rating of 150

°C.

TEMPERATURE MONITORING

NOISE PERFORMANCE

The temperature output terminal (TEMP, pin 3)

provides a temperature-dependent voltage output

Typical 0.1Hz to 10Hz voltage noise for each member

with approximately 60-k

Ω source impedance. As

of the REF50xx family is specified in the Electrical

seen in Figure 8, the output voltage follows the

Characteristics: Per Device table. The noise voltage

nominal relationship:

increases

with

output

voltage

and

operating

temperature. Additional filtering can be used to

VTEMP PIN = 509 mV + 2.64 × T(°C)

improve output noise levels, although care should be

This pin indicates general chip temperature, accurate

taken to ensure the output impedance does not

to approximately

±15°C. Although it is not generally

degrade performance.

suitable for accurate temperature measurements, it

For additional information about how to minimize

can be used to indicate temperature changes or for

noise and maximize performance in mixed-signal

temperature compensation of analog circuitry. A

applications such as data converters, refer to the

temperature change of 30

°C corresponds to an

series of Analog Applications Journal articles entitled,

approximate 79-mV change in voltage at the TEMP

How a Voltage Reference Affects ADC Performance.

pin.

This three-part series is available for download from

The TEMP pin has high output impedance (see

the TI website under three literature numbers:

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

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

circuit induces a measurement error; however, it does

and Part III, respectively.

not have any effect on VOUT accuracy.

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