Datasheet

DNC
TEMP
V
OUT
V
IN
GND
DNC
NC
TRIM/NR
REF50xx
C1
1 Fm
+V
SUPPLY
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)
REF5020-EP, REF5025-EP
REF5040-EP, REF5050-EP
www.ti.com SBOS471A –APRIL 2010–REVISED JUNE 2010
The TEMP pin has high output impedance (see
Figure 22). 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 26.
Figure 25. 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:
Figure 26. Buffering the TEMP Pin Output
(1)
POWER DISSIPATION
The REF50xx features a maximum drift coefficient of
The REF50xx family is specified to deliver current
3 ppm/°C for the high-grade version, and 8 ppm/°C
loads of ±10 mA over the specified input voltage
for the standard-grade.
range. The temperature of the device increases
according to the equation:
T
J
= T
A
+ P
D
× q
JA
(2)
TEMPERATURE MONITORING
Where:
T
J
= Junction temperature (°C)
The temperature output terminal (TEMP, pin 3)
provides a temperature-dependent voltage output
T
A
= Ambient temperature (°C)
with approximately 60-kΩ source impedance. As
P
D
= Power dissipated (W)
seen in Figure 8, the output voltage follows the
q
JA
= Junction-to-ambient thermal resistance
nominal relationship:
(°C/W)
V
TEMP PIN
= 509 mV + 2.64 × T(°C)
The REF50xx junction temperature must not exceed
the absolute maximum rating of +150°C.
This pin indicates general chip temperature, accurate
to approximately ±15°C. Although it is not generally
suitable for accurate temperature measurements, it
NOISE PERFORMANCE
can be used to indicate temperature changes or for
Typical 0.1-Hz to 10-Hz voltage noise for each
temperature compensation of analog circuitry. A
member of the REF50xx family is specified in the
temperature change of 30°C corresponds to an
Electrical Characteristics: Per Device table. The noise
approximate 79 mV change in voltage at the TEMP
voltage increases with output voltage and operating
pin.
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.
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Product Folder Link(s): REF5020-EP REF5025-EP REF5040-EP REF5050-EP