EMC1822 datasheet(19/103 Pages) MICROCHIP

19 / 103 page

The ALERT/THERM2 pin is used as an interrupt signal or as an I2C Alert signal that allows an SMBus/I2C

slave to communicate an error condition to the master. One or more ALERT/THERM2 outputs can be

hard-wired together.

7.5.2

ALERT/THERM2 Pin in Therm Mode

When the ALERT/THERM2 pin is configured to operate in Therm mode, it becomes asserted if any of the

measured temperatures exceed the respective high limit. The ALERT/THERM2 pin remains asserted until

all temperatures drop below the corresponding high limit, minus the Therm Hysteresis value.

When the ALERT/THERM2 pin is asserted in Therm mode, the corresponding high limit Status bits are

set. Reading these bits do not clear them until the ALERT/THERM2 pin is deasserted. Once the ALERT/

THERM2 pin is deasserted, the Status bits are automatically cleared.

The MASK_ALL bit does not block the ALERT/THERM2 pin in this mode; however, the individual channel

masks prevent the respective channel from asserting the ALERT/THERM2 pin.

7.6

System Shutdown

The EMC1822/23/24/25/43 devices contain a hardware configured temperature limit circuit that controls

the SYS_SHDN pin. The threshold temperature is determined by the pull-up resistors on both the

SYS_SHDN and ALERT pins. Note, Standby and One-shot modes cannot be enabled in device

configurations including system shutdown functionality .

Table 7-2. Pull-Up Resistor Values

Pull-Up Resistor

Bit 2

Bit 1

Bit 0

4.7k

6.8k

10k

15k

20k

33k

The final temperature decode is the responsibility of the digital block. The overall decode is shown in

Table 7-3.

Table 7-3. Temperature Select Encoding

SYS_SHDN Pull Up Decode

ALERT Pull-Up Decode

Combine

d Decode

(HEX)

Threshold

Temperatur

00h

77°C

01h

78°C

02h

79°C

03h

80°C

Multi-Channel Low Voltage Temp Sens...

System Block Diagram

Datasheet

DS20006048A-page 19

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