Datasheet

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
V =
HYST
· 10 (ppm)
6
(
(
|V V |
V
PRE POST
NOM
-
REF5020-Q1, REF5025-Q1, REF5030-Q1
REF5040-Q1, REF5045-Q1, REF5050-Q1
www.ti.com SBOS456G –SEPTEMBER 2008–REVISED OCTOBER 2013
THERMAL HYSTERESIS
Thermal hysteresis for the REF50xx is defined as the 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 expressed
as Equation 2:
where
• V
HYST
= thermal hysteresis (in units of ppm)
• V
NOM
= the specified output voltage
• V
PRE
= output voltage measured at +25°C pretemperature cycling
• V
POST
= output voltage measured after the device has been cycled from +25°C through the specified
temperature range of –40°C to +125°C and returned to +25°C (2)
TEMPERATURE MONITORING
The temperature output terminal (TEMP, pin 3) provides a temperature-dependent voltage output with
approximately 60-kΩ source impedance. As seen in Figure 8, the output voltage follows the nominal relationship:
V
TEMP PIN
= 509 mV + 2.64 × T(°C) (3)
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 79-
mV change in voltage at the TEMP pin.
The TEMP pin has high output impedance (see Figure 25). 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 29.
Figure 29. Buffering the TEMP Pin Output
POWER DISSIPATION
The REF50xx family is specified to deliver current loads of ± 10 mA 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 resistance (°C/W) (4)
The REF50xx junction temperature must not exceed the absolute maximum rating of 150°C.
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