EMC1002-1-ACZT-TR SMSC, EMC1002-1-ACZT-TR Datasheet - Page 10

• Manufacturer Part Number: EMC1002-1-ACZT-TR
• Description: Board Mount Temperature Sensors Dual Zone SMBus Temp Snsr
• Manufacturer: SMSC

Specifications of EMC1002-1-ACZT-TR

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

Revision 1.4 (12-18-07)
4.2
4.3
4.4
Resistance Error Correction
Ideality Factor Configuration
Temperature Measurement Results and Data
Figure 4.2
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.
The EMC1002 includes active resistance error correction implemented in the analog front end of the
chip. Without this automatic feature, voltage developed across the parasitic resistance in the remote
diode path causes the temperature to read higher than the true zone temperature. The error introduced
by parasitic resistance is approximately +0.7°C per ohm. Sources of parasitic resistance include bulk
resistance in the remote temperature transistor junctions along with resistance in the printed circuit
board traces and package leads.
Resistance error correction in the EMC1002 eliminates the need to characterize and compensate for
parasitic resistance in the remote diode path.
Temperature sensors like the EMC1002 are typically designed for remote diodes with an ideality factor
of 1.008. When the diode does not have this exact factor, an error is introduced in the temperature
measurement. Programmable offset registers are sometimes used to compensate for this error, but
this correction is only perfect at one temperature since the error introduced by ideality factor mismatch
is a function of temperature. The higher the temperature measured, the greater the error introduced.
The EMC1002 provides a 6-bit ideality factor register for the remote diode. The ideality factor of the
remote diode is programmed in a register to eliminate errors across all temperatures. See section
"Ideality Factor Register," on page 16
The 11-bit temperature measurement results are stored in temperature value registers. The EMC1002
has two temperature ranges and the default range is from 0 to 127°C. This range uses binary number
format, and the most significant bit is not used. The extended range is from –64°C to +191°C and is
binary offset by 64°C.
0.125°C. The format is selected as described in
Remote Diode
Internal or
V
DD
shows a detailed block diagram of the temperature measurement circuit. The EMC1002
I
high
I
Table 4.1
low
Figure 4.2 Detailed Block Diagram
Diode
Bias
I
bias
shows the two temperature data formats with an LSB equivalent to
DATASHEET
Delta Vbe
Sample
Hold
for details on programming this register.
&
10
4.10, "Configuration Register," on page
1°C Dual SMBus Sensor with Resistance Error Correction
Modulator
Sigma
Delta-
1-bit
Averaging
Digital
Filter
11-bit Output
BE
SMSC EMC1002
from different
14.
Datasheet
4.16,