EMC1072-A-ACZL-TR SMSC, EMC1072-A-ACZL-TR Datasheet - Page 18

• Manufacturer Part Number: EMC1072-A-ACZL-TR
• Description: Board Mount Temperature Sensors SMBus Temp Sensor Selectable Address
• Manufacturer: SMSC

Specifications of EMC1072-A-ACZL-TR

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

Revision 1.39 (10-11-10)
5.4
5.5
5.6
5.7
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 EMC1072 is designed for external diodes with an ideality factor of 1.008. Not all external diodes,
processor or discrete, will have this exact value. This variation of the ideality factor introduces error in
the temperature measurement which must be corrected for. This correction is typically done using
programmable offset registers. Since an ideality factor mismatch introduces an error that is a function
of temperature, this correction is only accurate within a small range of temperatures. To provide
maximum flexibility to the user, the EMC1072 provides a 6-bit register for each external diode where
the ideality factor of the diode used is programmed to eliminate errors across all temperatures.
The EMC1072 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 pin asserts (unless masked, see
"Consecutive
limit will not be checked). A diode fault is defined as one of the following: an open between DP and
DN, a short from V
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 EMC1072 contains multiple consecutive alert counters. One set of counters applies to the ALERT
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 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
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. The typical filter performance is shown in
and
Programmable External Diode Ideality Factor
Diode Faults
Consecutive Alerts
Digital Filter
Figure 5.4, "Temperature Filter Impulse
Section 6.11
6.10) will prevent the respective channel from asserting the ALERT pin.
Alerts") and the temperature data reads 00h in the MSB and LSB registers (note: the low
for more details on the consecutive alert function.
DD
to DP, or a short from V
DATASHEET
18
Response".
DD
to DN.
Figure 5.3, "Temperature Filter Step Response"
1°C Temperature Sensor with Selectable Address
SMSC EMC1072
Section 5.6,
Datasheet