EMC1183 datasheet(20/48 Pages) MICROCHIP

20 / 48 page

Triple Channel 1°C Temperature Sensor with Beta Compensation and 1.8V SMBus Communications

Datasheet

Revision 1.0 (07-11-13)

SMSC EMC1183

DATASHEET

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.

5.4.1

THERM Pin Considerations

Because of the decode method used to determine the SMBus Address, it is important that the pull-up

resistance on THERM pin be within ±10% tolerance. Additionally, the pull-up resistor on the THERM

pin must be connected to the same 3.3V supply that drives the VDD pin.

For 15ms after power up, the THERM pin must not be pulled low or the SMBus Address will not be

decoded properly. If the system requirements do not permit these conditions, the THERM pin must be

isolated from the bus during this time. One method of isolating this pin is shown in Figure 5.2.

5.5

ALERT / THERM2 Output

The ALERT / THERM2 pin is an open drain output and requires a pull-up resistor to VDD and has two

modes of operation: interrupt mode and comparator mode. The mode of the ALERT / THERM2 output

is selected via the ALERT / COMPALERT/THERM bit in the Configuration Register (see Section 6.4).

5.5.1

ALERT / THERM2 Pin InterruptALERT Mode

When configured to operate in interrupt mode, the ALERT / THERM2 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, functioning as any standard ALERT in on the SMBus. The ALERT / THERM2 pin will remain

asserted as long as an out-of-limit condition remains. Once the out-of-limit condition has been

removed, the ALERT / THERM2 pin will remain asserted until the appropriate status bits are cleared.

The ALERT/ THERM2 pin can be masked by setting the MASK_ALL bit. Once the ALERT / THERM2

pin has been masked, it will be de-asserted and remain de-asserted until the MASK_ALL bit is cleared

by the user. Any interrupt conditions that occur while the ALERT / THERM2 pin is masked will update

the Status Register normally. There are also individual channel masks (see Section 6.11).

The ALERT / THERM2 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 / THERM2 outputs

can be hard-wired together.

Figure 5.2 Isolating THERM Pin

EMC1183

SMDATA

SMCLK

ALERT

VDD

DP1

DN1

THERM / ADDR

GND

+3.3V

Shared THERM

4.7K -

+2.5 - 5V

DP2

DN2

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