Datasheet

TMP708
www.ti.com SBOS585A –DECEMBER 2011– REVISED FEBRUARY 2012
APPLICATION INFORMATION
SET-POINT RESISTOR (R
SET
)
The temperature threshold is set by connecting R
SET
from the SET pin to GND. The value of R
SET
can be
determined using either Figure 2 or from Equation 1:
R
SET
(kΩ) = 0.0012T
2
– 0.9308T + 96.147
Where T = temperature threshold in degree Celsius. (1)
THERMAL CONSIDERATIONS
The TMP708 quiescent current is typically 40 μA. The device dissipates negligible power when the output drives
a high-impedance load. Thus, the die temperature is the same as the package temperature. In order to maintain
accurate temperature monitoring, a good thermal contact should be provided between the TMP708 package and
the device being monitored. The rise in die temperature as a result of self-heating is given by the following
equation:
ΔT
J
= P
DISS
× θ
JA
Where:
P
DISS
= power dissipated by the device.
θ
JA
= package thermal resistance. Typical thermal resistance for SOT-23 package is 217.9°C/W. (2)
To limit the effects of self-heating, keep the output current at a minimum level.
POWER-SUPPLY FILTERING
Any significant noise on the VCC pin may result in a trip-point error. This noise can be minimized by low-pass
filtering the device supply (V
CC
) using a 150-Ω resistor and a 0.1-μF capacitor.
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