Diodes ZXLD1371 - Manual (Page 35)

ZXLD1371
ZXLD1371
Document number: DS35436 Rev. 1 - 2
35 of 42
www.diodes.com
February 2012
© Diodes Incorporated
A Product Line of
Diodes Incorporated
Applications Information (cont.)
Figure 14. Thermal Feedback Network
The thermistor resistance, R
T
, at a temperature of T degrees Kelvin is given by
R
T
= R
R
e
B
1
T
-
1
TR
Where
R
R
is the thermistor resistance at the reference temperature, T
R
T
R
is the reference temperature, in Kelvin, normally 273 + 25 = 298K (25°C)
B is the “beta” value of the thermistor.
For example,
1) Temperature threshold T
threshold
= 273 + 70 = 343K (70˚C)
2) TH1 = 10k Ω at 25˚C and B = 3900 Æ R
T
= 1.8k Ω @ 70˚C
3) R
th
= R
T
at T
threshold
= 1.8k Ω
Over-Temperature Shutdown
The ZXLD1371 incorporates an over-temperature shutdown circuit to protect against damage caused by excessive die
temperature. A warning signal is generated on the STATUS output when die temperature exceeds 125°C nominal and the
output is disabled when die temperature exceeds 150°C nominal. Normal operation resumes when the device cools back
down to 125°C.