1°C Triple Temperature Sensor with Resistance Error Correction & Hotter of Two Zones

Datasheet

Revision 1.44 (04-14-08)

14

SMSC EMC1053

DATASHEET

3.5

Temperature Measurement Results and Data

Each temperature result for each zone is available in two byte wide data registers. As shown in

Section 4.1, the 11-bit format has the 8 most significant bits stored in the high byte register and the 3

least significant bits stored in the three MSB positions of the low byte register. The delta-sigma ADC

may be operated with more than 11 bits of resolution for improved averaging as described in

Section 4.5, but the temperature result is reported at 11-bit resolution.

The temperature results for the two remote zones are also stored in extended format with a range from

-64°C to +191°C. The data format is a 2’s complement number offset by 64°C as shown in Section 4.2.

The data for each of the remote zones in both legacy and extended format is stored in separate data

registers so that both data formats are always available. Table 3.2 shows the default and extended

range formats.

3.6

Resistance Error Correction (REC)

Resistance error correction is an automatic feature that eliminates the need to characterize and

compensate for series resistance in the external diode lines. The EMC1053 corrects for as much as

100 ohms of series resistance.

When using a temperature sensor that does not include resistance error correction, voltage developed

across the parasitic resistance in the external diode path produces an error in the reported

temperature. The error introduced by this resistance is approximately +0.7°C per ohm. Sources of

series resistance are PCB trace resistance, on die (i.e. on the processor) metal resistance, bulk

resistance in the base and emitter of the temperature transistor.

Table 3.2 EMC1053 Temperature Data Format

TEMPERATURE (°C)

RANGE -64°C TO 127°C

RANGE -64°C TO 191°C

BINARY

OFFSET BINARY

Diode Fault

100 0000 0000

100 0000 0000

<= -64

110 0000 0000

100 0000 0000

-63.875

110 0000 0001

100 0000 0001

-63

110 0000 1000

100 0000 1000

-1

111 1111 1000

101 1111 1000

0

000 0000 0000

110 0000 0000

0.125

000 0000 0001

110 0000 0001

1

000 0000 1000

110 0000 1000

64

010 0000 0000

000 0000 0000

65

010 0000 1000

000 0000 1000

127

011 1111 1000

001 1111 1000

127.875

011 1111 1111

001 1111 1111

128

011 1111 1111

010 0000 0000

191

011 1111 1111

011 1111 1000

>= 191.875

011 1111 1111

011 1111 1111