TMPR4956C datasheet(32/286 Pages) TOSHIBA

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Handling Precautions

3.3.12

Electromagnetic Interference

Radio and TV reception problems have increased in recent years as a result of increased electromagnetic

interference radiated from electrical and electronic equipment. To use radio waves effectively and to maintain

the quality of radio communications, each country has defined limitations for the amount of electromagnetic

interference which can be generated by designated devices.

The types of electromagnetic interference include noise propagated through power supply and telephone lines,

and noise from direct electromagnetic waves radiated from equipment. Different measurement methods and

corrective actions are used for each type.

Difficulties in countering electromagnetic interference derive from the fact that there is no means for calculating

at the design stage the strength of the electromagnetic waves produced from each component in a piece of

equipment. As a result, it is after the prototype equipment has been completed that measurements are taken using

dedicated instruments to determine for the first time the strength of the electromagnetic interference. Yet it is

possible during system design to incorporate measures for the prevention of electromagnetic interference which

can facilitate corrective action after design completion. One effective method, for example, is to design the

product with several shielding options, and then select the optimum shielding method based on the results of the

measurements subsequently taken.

3.3.13

Peripheral Circuits

In many cases semiconductor devices are used with peripheral circuits and components. The input and output

signal voltages and currents in these circuits must be designed to match the specifications of the device, taking

into consideration the factors below.

(1) Input voltages and currents that are not appropriate with respect to the input pins may cause malfunction.

Some devices contain pull-up or pull-down resistors, depending on specifications. Design your system

taking into account the required voltage and current.

(2) The output pins on a device have a predetermined external circuit drive capability. If a drive capability

exceeding this value is required, either insert a compensating circuit or take that fact into account when

selecting components for use in external circuits

3.3.14

Safety Standards

Each country and region has established safety standards which must be observed. These safety standards

sometimes include requirements for quality certification systems and insulation design standards. The safety

standards of the respective countries and regions must be taken fully into account to ensure compliant device

selection and design.

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