REF5010 Datasheet, PDF (10/20 Pages) Texas Instruments – Low-Noise, Very Low Drift, Precision VOLTAGE REFERENCE

REF5010, REF5020
REF5025, REF5030
REF5040, REF5045, REF5050
SBOS410C – JUNE 2007 – REVISED DECEMBER 2008.................................................................................................................................................. www.ti.com
+V_SUPPLY
REF50xx
DNC DNC
V_IN
TEMP
NC
V_OUT
GND TRIM/NR
C1
1mF
The TEMP pin has high output impedance (see
Figure 21). Loading this pin with a low-impedance
circuit induces a measurement error; however, it does
not have any effect on V_OUT 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 25.
+V
Figure 24. Noise Reduction Using the TRIM/NR
Pin
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 the following equation:
ǒ Ǔ Drift +
V_OUTMAX * V_OUTMIN
V_OUT Temp Range
10⁶(ppm)
(1)
The REF50xx features a maximum drift coefficient of
3ppm/°C for the high-grade version, and 8ppm/°C for
the standard-grade.
TEMPERATURE MONITORING
The temperature output terminal (TEMP, pin 3)
provides a temperature-dependent voltage output
with approximately 60kΩ source impedance. As seen
in Figure 8, the output voltage follows the nominal
relationship:
V_{TEMP PIN} = 509mV + 2.64 × T(°C)
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 79mV change in voltage at the TEMP
pin.
V_TEMP
2.6mV/°C
OPA⁽¹⁾
REF50xx
DNC
DNC
V_IN
TEMP
NC
V_OUT
GND TRIM/NR
NOTE: (1) Low drift op amp, such as the OPA333, OPA335, or OPA376.
Figure 25. Buffering the TEMP Pin Output
POWER DISSIPATION
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:
T_J = T_A + P_D × θ_JA
Where:
T_J = Junction temperature (°C)
T_A = Ambient temperature (°C)
P_D = Power dissipated (W)
θ_JA = Junction-to-ambient thermal
(°C/W)
resistance
The REF50xx junction temperature must not exceed
the absolute maximum rating of +150°C.
NOISE PERFORMANCE
Typical 0.1Hz to 10Hz 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 care should be
taken to ensure the output impedance does not
degrade performance.
10
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