1°C Temperature Sensor with Hardware Thermal Shutdown
Datasheet
Filter Impulse Response
90
80
70
60
50
40
30
20
10
0
Disabled
Level1
Level2
0
2
4
6
8
10
12
14
Samples
Figure 5.5 Temperature Filter Impulse Response
5.10
Temperature Monitors
In general, thermal diode temperature measurements are based on the change in forward bias voltage
of a diode when operated at two different currents. This ΔVBE is proportional to absolute temperature
as shown in the following equation:
where:
k = Boltzmann’s constant
⎛
⎞
η kT
I HIGH
⎜
⎜
⎟
⎟
Δ V BE
=
ln
T = absolute temperature in Kelvin
q = electron charge
[1]
q
I LOW
⎝
⎠
η = diode ideality factor
Figure 5.6 shows a block diagram of the temperature measurement circuit. The negative terminal for
the remote temperature diode, DN, is internally biased with a forward diode voltage referenced to
ground.
SMSC EMC1422
Revision 1.24 (02-05-08)
DATA2S1HEET
SMSC [ SMSC CORPORATION ]
