1.5°C SMBus Temperature Sensor in Miniature SOT-23

Datasheet

Revision 1.6 (01-29-07)

10

SMSC EMC1001

DATASHEET

Figure 4.2 Detailed Block Diagram

Figure 4.2 shows a detailed block diagram of the temperature measurement circuit. The EMC1001

incorporates switched capacitor technology that integrates the temperature diode

ΔV

bias currents. The negative terminal, DN, for the temperature diode is internally biased with a forward

diode voltage referenced to ground.

The advantages of this architecture over Nyquist rate FLASH or SAR converters are superb linearity

and inherent noise immunity. The linearity can be directly attributed to the delta-sigma ADC single-bit

comparator while the noise immunity is achieved by the ~20ms integration time which translates to

50Hz input noise bandwidth.

4.2

Temperature Measurement Results and Data

The 10-bit temperature measurement results are stored in temperature value registers. Table 4.1

shows the two’s complement temperature data format with an LSB equivalent to 0.25

Note 4.1

Temperature measurement returns 1100 0000 00 for all temperatures

≤ -64.00°C

Note 4.2

Temperature measurement returns 0111 1111 11 for all temperatures

≥ +127.75

The eight most significant bits are stored in the Temperature Value High Byte register and the two least

significant bits stored in the Temperature Value Low Byte register as outlined in Table 4.2. The six LSB

positions of the Temperature Value Low Byte register always read zero. In Table 4.2, the upper case

Table 4.1 Temperature Data Format

TEMPERATURE

VALID RANGE

–40

TWO’S COMPLEMENT

-0.25

1111 1111 11 Note 4.1

0.0

0000 0000 00

+0.25

0000 0000 01

+0.50

0000 0000 10

+0.75

0000 0000 11

+1

0000 0001 00

+125

0111 1101 00 Note 4.2

Delta Vbe

Sample

&

Hold

I

bias

I

low

I

high

1-bit

delta-sigma

Modulator

Digital

Averaging

Filter

V

DD

Internal or

Remote Diode

Bias

Diode

10-bit Output