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On-Chip Temperature Transducer
Temperature Comparator Gives
Threshold Temperature Alarm
Power Reference Permits Airflow
Diagnostics
Precision 2.5V Power Reference
Permits Airflow Diagnostics
Transducer Output is Easily Scaled
for Increased Sensitivity
Low 2.5mA Quiescent Current
DESCRIPTION
The UC1730 family of integrated circuit devices are designed to be used in
a number of thermal monitoring applications. Each IC combines a tempera-
ture transducer, precision reference, and temperature comparator allowing
the device to respond with a logic output if temperatures exceed a user pro-
grammed level. The reference on these devices is capable of supplying in
excess of 250mA of output current
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by setting a level of power dissipation
the rise in die temperature will vary with airflow past the package, allowing
the IC to respond to airflow conditions
These devices come in an 8-Pin DIP, plastic or ceramic, a 5-Pin TO-220 or a
PLCC-20 version. In the 8-Pin version, a PTAT (proportional to absolute
temperature) output reports die temperature directly. This output is config-
ured such that its output level can be easily scaled up with two external gain
resistors. A second PTAT source is internally referenced to the temperature
comparator. The other input to this comparator can then be externally pro-
grammed to set a temperature threshold. When this temperature threshold
is exceeded an alarm delay output is activated. Following the activation of
the delay output, a separate open collector output is turned on. The delay
pin can be programmed with an external RC to provide a time separation
between activation of the delay pin and the alarm pin, permitting shutdown
diagnostics in applications where the open collector outputs of multiple parts
are wire OR鈥檈d together.
The 5-Pin version in the TO-220 package is well suited for monitoring
heatsink temperatures. Enhanced airflow sensitivities can be obtained with
this package by mounting the device to a small heatsink in the airstream.
This version of the device does not include the PTAT output or the open col-
lector alarm output.
BLOCK DIAGRAM
Pin numbers shown for 8-Pin DIP, ( ) number for 5-Pin TO-220.
10/94
1
2
3
4
5
