EMC1182 datasheet(22/48 Pages) MICROCHIP

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

Datasheet

Revision 1.0 (07-11-13)

SMSC EMC1182

DATASHEET

APPLICATION NOTE: When monitoring a substrate transistor or CPU diode and beta compensation is enabled, the

Ideality Factor should not be adjusted. Beta Compensation automatically corrects for most

ideality errors.

5.7

Diode Faults

The EMC1182 detects an open on the DP and DN pins, and a short across the DP and DN pins. For

each temperature measurement made, the device checks for a diode fault on the external diode

channel(s). When a diode fault is detected, the ALERT / THERM2 pin asserts (unless masked, see

Section 5.8) and the temperature data reads 00h in the MSB and LSB registers (note: the low limit will

not be checked). A diode fault is defined as one of the following: an open between DP and DN, a short

from VDD to DP, or a short from VDD to DN.

If a short occurs across DP and DN or a short occurs from DP to GND, the low limit status bit is set

and the ALERT / THERM2 pin asserts (unless masked). This condition is indistinguishable from a

temperature measurement of 0.000°C (-64°C in extended range) resulting in temperature data of 00h

in the MSB and LSB registers.

If a short from DN to GND occurs (with a diode connected), temperature measurements will continue

as normal with no alerts.

5.8

Consecutive Alerts

The EMC1182 contains multiple consecutive alert counters. One set of counters applies to the ALERT

/ THERM2 pin and the second set of counters applies to the THERM pin. Each temperature

measurement channel has a separate consecutive alert counter for each of the ALERT / THERM2 and

THERM pins. All counters are user programmable and determine the number of consecutive

measurements that a temperature channel(s) must be out-of-limit or reporting a diode fault before the

corresponding pin is asserted.

See Section 6.11, "Consecutive ALERT Register 22h" for more details on the consecutive alert

function.

5.9

Digital Filter

To reduce the effect of noise and temperature spikes on the reported temperature, the External Diode

channel uses a programmable digital filter. This filter can be configured as Level 1, Level 2, or Disabled

(default) (see Section 6.14). The typical filter performance is shown in Figure 5.4 and Figure 5.5.

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