LTC2996
applicaTions inForMaTion
where η denotes the actual ideality factor if an external
IntheTemperatureMonitorexamplediscussedearlierwith
thresholds at VTL = 0°C and VTH = 90°C and a desired
ACT
sensor is used and T1 and T2 are the desired threshold
temperatures in degrees Kelvin.
reference current of 10μA, the required values for R ,
TA
R
TB
and R can be calculated as :
TC
2. Choose R to obtain the desired VTL threshold for
TA
a desired current through the resistive divider
1.093V
10µA
R
=
=
=
= 109.3K
(I ):
REF
TA
TB
TC
VTL
R
=
TA
1.453V – 1.093V
10µA
I
REF
R
R
= 36K
3. Choose R to obtain the desired VTH threshold:
TB
VTH– VTL
1.8V – 1.453V
R
=
= 34.7K
TB
I
10µA
REF
4. Finally R is determined by:
TC
1.8V – VTH
R
=
TC
I
REF
3.3V
+
D
V
LTC2996
CC
V
CC
V
CC
400k
OT
+
–
1.2V
1.8V
V
REF
200k
400k
R
TC
V
CC
VTH
VTL
–
+
400k
OT/UT
PULSE
GENERATOR
UT
UVLO
R
R
TB
–
+
V
PTAT
T/V
TA
–
D
GND
2996 F06
Figure 6. Monitoring Internal Temperature
2996f
12
Linear [ Linear ]
