EMC1002-1-ACZT-TR SMSC, EMC1002-1-ACZT-TR Datasheet - Page 18

• 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

Chapter 5 Application Information
Revision 1.4 (12-18-07)
5.1
5.1.1
5.1.1.1
Maintaining Accuracy
GND PLANE
This chapter provides information on maintaining accuracy when using diodes as remote sensors with
SMSC Environmental Monitoring and Control devices. It is assumed that the users have some
familiarity with hardware design and transistor characteristics.
SMSC supplies a family Environmental Monitoring and Control (EMC) devices that are capable of
accurately measuring temperatures. Most devices include an internal temperature sensor along with
the ability to measure one or more external sensors. The characteristics of an appropriate diode for
use as the external sensor are listed in this chapter. Recommendations for the printed circuit board
layout are provided to help reduce error caused by electrical noise or trace resistance.
Physical Factors
Temperature measurement is performed by measuring the change in forward bias voltage of a diode
when different currents are forced through the junction. The circuit board itself can impact the ability
to accurately measure these small changes in voltage.
Layout
Apply the following guidelines when designing the printed circuit board:
1. Route the remote diode traces on the top layer.
2. Place a ground guard signal on both sides of the differential pair. This guard band should be
3. Place a ground plane on the layer immediately below the diode traces.
4. Keep the diode traces as short as possible.
5. Keep the diode traces parallel, and the length of the two traces identical within 0.3 inches.
6. Use a trace width of 0.01 inches with a 0.01 inch guard band on each side.
7. Keep the diode traces away from sources of high frequency noise such as power supply filtering
8. When the diode traces must cross high speed digital signals, make them cross at a 90 degree
9. Avoid joints of copper to solder that can introduce thermocouple effects.
These recommendations are illustrated in
connected to the ground plane at least every 0.25 inches.
or high speed digital signals.
angle.
.01 GAP MIN.
RECOMMEND VIA STICTCHING AT .25 INCH INTERVALS.
COPPER TRACE
.01 WIDE MIN.
Figure 5.1 Routing the Diode Traces
DP or DN
COPPER PLANE (TO SHIELD FROM NOISE)
DATASHEET
BOARD MATERIAL
.01 GAP MIN.
Figure 5.1 Routing the Diode Traces on page
18
1°C Dual SMBus Sensor with Resistance Error Correction
COPPER TRACE
.01 WIDE MIN.
DP or DN
.01 GAP MIN.
GND PLANE
SMSC EMC1002
18.
Datasheet