Datasheet

V =
HYST
· 10 (ppm)
6
(
(
|V V |
V
PRE POST
NOM
-
DNC
TEMP
V
OUT
V
IN
GND
DNC
NC
TRIM/NR
REF50xx
V
TEMP
2.6mV/ C°
OPA
(1)
NOTE:(1)Lowdriftopamp,suchastheOPA333,OPA335,orOPA376.
+V
Drift +
ǒ
V
OUTMAX
* V
OUTMIN
V
OUT
Temp Range
Ǔ
10
6
(ppm)
REF5010, REF5020
REF5025, REF5030
REF5040, REF5045, REF5050
www.ti.com SBOS410F –JUNE 2007–REVISED DECEMBER 2013
TEMPERATURE DRIFT To avoid errors caused by low-impedance loading,
buffer the TEMP pin output with a suitable low-
The REF50xx is designed for minimal drift error,
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)
T
J
= T
A
+ P
D
× θ
JA
(3)
Where:
Where:
V
HYST
= thermal hysteresis (in units of ppm).
T
J
= Junction temperature (°C)
V
NOM
= the specified output voltage.
T
A
= Ambient temperature (°C)
V
PRE
= output voltage measured at +25° C
P
D
= Power dissipated (W)
pretemperature cycling.
θ
JA
= Junction-to-ambient thermal resistance
V
POST
= output voltage measured after the device
(°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 60kΩ 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
V
TEMP PIN
= 509mV + 2.64 × T(°C)
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
not have any effect on V
OUT
accuracy.
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