Toshiba TA8266HQ, Руководство по описанию и применению

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TA8266HQ
2006-04-28
15
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Use an appropriate power supply fuse to ensure that a large current does not continuously flow in case of over
current and/or IC failure. The IC will fully break down when used under conditions that exceed its absolute
maximum ratings, when the wiring is routed improperly or when an abnormal pulse noise occurs from the wiring or
load, causing a large current to continuously flow and the breakdown can lead smoke or ignition. To minimize the
effects of the flow of a large current in case of breakdown, appropriate settings, such as fuse capacity, fusing time
and insertion circuit location, are required.
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If your design includes an inductive load such as a motor coil, incorporate a protection circuit into the design to
prevent device malfunction or breakdown caused by the current resulting from the inrush current at power ON or
the negative current resulting from the back electromotive force at power OFF. For details on how to connect a
protection circuit such as a current limiting resistor or back electromotive force adsorption diode, refer to individual
IC datasheets or the IC databook. IC breakdown may cause injury, smoke or ignition.
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Use a stable power supply with ICs with built-in protection functions. If the power supply is unstable, the protection
function may not operate, causing IC breakdown. IC breakdown may cause injury, smoke or ignition.
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Carefully select external components (such as inputs and negative feedback capacitors) and load components
(such as speakers), for example, power amp and regulator. If there is a large amount of leakage current such as
input or negative feedback condenser, the IC output DC voltage will increase. If this output voltage is connected to
a speaker with low input withstand voltage, overcurrent or IC failure can cause smoke or ignition. (The over
current can cause smoke or ignition from the IC itself.) In particular, please pay attention when using a Bridge Tied
Load (BTL) connection type IC that inputs output DC voltage to a speaker directly.
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Over current Protection Circuit
Over current protection circuits (referred to as current limiter circuits) do not necessarily protect ICs under all
circumstances. If the Over current protection circuits operate against the over current, clear the over current status
immediately. Depending on the method of use and usage conditions, such as exceeding absolute maximum
ratings can cause the over current protection circuit to not operate properly or IC breakdown before operation. In
addition, depending on the method of use and usage conditions, if over current continues to flow for a long time
after operation, the IC may generate heat resulting in breakdown.
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Thermal Shutdown Circuit
Thermal shutdown circuits do not necessarily protect ICs under all circumstances. If the Thermal shutdown circuits
operate against the over temperature, clear the heat generation status immediately. Depending on the method of
use and usage conditions, such as exceeding absolute maximum ratings can cause the thermal shutdown circuit
to not operate properly or IC breakdown before operation.
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Heat Radiation Design
When using an IC with large current flow such as power amp, regulator or driver, please design the device so that
heat is appropriately radiated, not to exceed the specified junction temperature (Tj) at any time and condition.
These ICs generate heat even during normal use. An inadequate IC heat radiation design can lead to decrease in
IC life, deterioration of IC characteristics or IC breakdown. In addition, please design the device taking into
considerate the effect of IC heat radiation with peripheral components.
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Installation to Heat Sink
Please install the power IC to the heat sink not to apply excessive mechanical stress to the IC. Excessive
mechanical stress can lead to package cracks, resulting in a reduction in reliability or breakdown of internal IC
chip. In addition, depending on the IC, the use of silicon rubber may be prohibited. Check whether the use of
silicon rubber is prohibited for the IC you intend to use, or not. For details of power IC heat radiation design and
heat sink installation, refer to individual technical datasheets or IC databooks.