EMC1424 SMSC Corporation, EMC1424 Datasheet - Page 22

• Manufacturer Part Number: EMC1424
• Description: (EMC1423 / EMC1424) Temperature Sensor
• Manufacturer: SMSC Corporation

APPLICATION NOTE: When monitoring a substrate transistor or CPU diode and beta compensation is enabled, the
Revision 1.16 (03-15-07)
5.8
5.9
5.10
Diode Faults
Consecutive Alerts
Digital Filter
temperatures. To provide maximum flexibility to the user, the EMC1423 and EMC1424 provides a 6-
bit register for the External Diode 2 channel (and External Diode 3 channel for the EMC1424) where
the ideality factor of the diode can be programmed to eliminate errors across all temperatures.
The EMC1423 and EMC1424 detect 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 pin asserts (unless masked, see
Section
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 pin asserts (unless masked). This condition is indistinguishable from a temperature
measurement of 0.000degC (-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.
The EMC1423 and EMC1424 contain multiple consecutive alert counters. One set of counters applies
to the ALERT pin and the second set of counters applies to the SYS_SHDN pin. Each temperature
measurement channel has a separate consecutive alert counter for each of the ALERT and
SYS_SHDN 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
To reduce the effect of noise and temperature spikes on the reported temperature, the External Diode
1 channel uses a programmable digital filter. This filter can be configured as Level 1, Level 2, or
Disabled. The typical filter performance is shown in
Section 6.13
5.9) and the temperature data reads 00h in the MSB and LSB registers (note: the low limit will
Ideality Factor should not be adjusted. Beta Compensation automatically corrects for most
ideality errors.
for more details on the consecutive alert function.
DATASHEET
22
1°C Temperature Sensor with Hardware Thermal Shutdown
Figure 5.5
and
Figure
5.6.
SMSC EMC1423/EMC1424
Datasheet