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PCB DESIGN METHODOLOGY FOR ENHANCING TEMPERATURE SENSOR APPLICATION & TESTING

IP.com Disclosure Number: IPCOM000240367D
Publication Date: 2015-Jan-27
Document File: 4 page(s) / 144K

Publishing Venue

The IP.com Prior Art Database

Abstract

This document describes a methodology that, when applied to PCB designs, can result in a faster response time for a temperature sensor (TS) present inside a SOC or general purpose MCU. The design methodology can decrease the thermal resistance in the path of ambient temperature reaching the temperature sensor, thereby increasing the performance of the temperature sensor.

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PCB Design Methodology For Enhancing Temperature Sensor Application & Testing

Background

Some microcontroller systems are used in applications with a temperature sensor (TS) that is central to the functionality of the system, e.g., in a glucometer, optical line transceiver, or board temperature monitoring application.  Some applications require high accuracy (< +/-0.5oC), e.g., optical line transceiver applications.  The TS included in the microcontroller can have a diode architecture and can, in operation, depend on the amount of temperature transferred from the ambient air to the ground pin for its accuracy and response.  

In some of these systems, printed circuit board (PCB) design can be done with generic microcontroller methodology.  For example, the device package can be chosen without a ground/thermal plane, the design can lack a provision for using the ground plane as a thermal conduit, and a solder mask can be used that will increase the thermal resistance of ambient air to the board.  In such PCB’s the TS response time will be lower since the GND pins from device are the best means of transferring the heat to the device.  Figure 1 illustrates an example of a conventional PCB design for a temperature sensor application.

Figure 1: Conventional PCB

keywords

Microcontroller, system-on-a-chip (SOC), temperature sensor, printed circuit board (PCB), response time, glucometer, optical line transceiver, integrated circuit ground pad, thermal conduction, solder mask, integrated circuit conduit via. 

Summary

This document describes a methodology that, when applied to PCB designs, can result in a faster response time for a temperature sensor (TS) present inside a SOC or general purpose MCU.  The design methodology can decrease the thermal resistance in the path of ambient temperature reaching the temperature sensor, thereby increasing the performance of the temperature sensor.  The elements of the design methodology can include:

• Multiple vias from the IC ground pad connected to the ground plane of the PCB;

• Where space is available in the PCB, via patches are kept purposefully to act as conduit for the ambient heat to the ground plane;

• Solder mask is removed purposefully wherever (GND net) heat is planned to conduct;

• Conduit vias can be filled with solder to enhance thermal conductivity;

• IC package can have a large ground (thermal) pad; and

• Combined reduction in the thermal resistance results from the vias, solder mask, and ground plane heat conduction will give faster response for the ambient temperature measurement.

Description

Figure 2 illustrates an example PCB designed according to a design methodology to increase the response time for a temperatur...