EMC1403-4-AIZL-TR SMSC, EMC1403-4-AIZL-TR Datasheet - Page 20

• Manufacturer Part Number: EMC1403-4-AIZL-TR
• Description: Board Mount Temperature Sensors Triple Temp Sensor Autobeta Comp
• Manufacturer: SMSC

Specifications of EMC1403-4-AIZL-TR

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Revision 1.37 (01-06-10)
5.2
5.3
5.3.1
5.3.2
5.4
The THERM output is asserted independently of the ALERT output and cannot be masked. Whenever
any of the measured temperatures exceed the user programmed THERM Limit values for the
programmed number of consecutive measurements, the THERM output is asserted. Once it has been
asserted, it will remain asserted until all measured temperatures drop below the THERM Limit minus
the THERM Hysteresis (also programmable).
When the THERM pin is asserted, the Therm status bits will likewise be set. Reading these bits will
not clear them until the THERM pin is deasserted. Once the THERM pin is deasserted, the THERM
status bits will be automatically cleared.
The ALERT pin is an open drain output and requires a pull-up resistor to V
operation: interrupt mode and comparator Mode. The mode of the ALERT output is selected via the
ALERT / COMP bit in the Configuration Register (see
ALERT Pin Interrupt Mode
When configured to operate in interrupt mode, the ALERT pin asserts low when an out of limit
measurement (> high limit or < low limit) is detected on any diode or when a diode fault is detected.
The ALERT pin will remain asserted as long as an out-of-limit condition remains. Once the out-of-limit
condition has been removed, the ALERT pin will remain asserted until the appropriate status bits are
cleared.
The ALERT pin can be masked by setting the MASK bit. Once the ALERT pin has been masked, it
will be de-asserted and remain de-asserted until the MASK bit is cleared by the user. Any interrupt
conditions that occur while the ALERT pin is masked will update the Status Register normally.
The ALERT pin is used as an interrupt signal or as an Smbus Alert signal that allows an SMBus slave
to communicate an error condition to the master. One or more ALERT outputs can be hard-wired
together.
ALERT Pin Comparator Mode
When the ALERT pin is configured to operate in comparator mode it will be asserted if any of the
measured temperatures exceeds the respective high limit. The ALERT pin will remain asserted until
all temperatures drop below the corresponding high limit minus the THERM Hysteresis value.
When the ALERT pin is asserted in comparator mode, the corresponding high limit status bits will be
set. Reading these bits will not clear them until the ALERT pin is deasserted. Once the ALERT pin is
deasserted, the status bits will be automatically cleared.
The MASK bit will not block the ALERT pin in this mode, however the individual channel masks (see
Section
The EMC1403 and EMC1404 are configured to monitor the temperature of basic diodes (e.g. 2N3904),
or CPU thermal diodes. It automatically detects the type of external diode (CPU diode or diode
connected transistor) and determines the optimal setting to reduce temperature errors introduced by
beta variation for the External Diode 1 channel only. Compensating for this error is also known as
implementing the transistor or BJT model for temperature measurement.
For discrete transistors configured with the collector and base shorted together, the beta is generally
sufficiently high such that the percent change in beta variation is very small. For example, a 10%
variation in beta for two forced emitter currents with a transistor whose ideal beta is 50 would contribute
approximately 0.25°C error at 100°C. However for substrate transistors where the base-emitter junction
is used for temperature measurement and the collector is tied to the substrate, the proportional beta
variation will cause large error. For example, a 10% variation in beta for two forced emitter currents
with a transistor whose ideal beta is 0.5 would contribute approximately 8.25°C error at 100°C.
The External Diode 2 and External Diode 3 channels do not support Beta Compensation.
THERM Output
ALERT Output
Beta Compensation
6.11) will prevent the respective channel from asserting the ALERT pin.
DATASHEET
20
Section
1°C Temperature Sensor with Beta Compensation
6.4).
DD
SMSC EMC1403 / EMC1404
and has two modes of
Datasheet