Toshiba TA8266HQ, Руководство по описанию и применению

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TA8266HQ
2006-04-28
6
6. Prevention of speaker burning accident
(In Case of Rare Short Circuit of Speaker)
When the direct current resistance between OUT + and OUT − terminal becomes 1 Ω or less and output
current over 4 A flows, this IC makes a protection circuit operate and suppresses the current into a speaker.
This system makes the burning accident of the speaker prevent as below mechanism.
< The guess mechanism of a burning accident of the speaker >
Abnormal output offset voltage (voltage between OUT
+
and OUT
−
) over 4 V is made by the external
circuit failure.(Note 4)
↓
The speaker impedance becomes 1 Ω or less as it is in a rare short circuit condition.
↓
The current more than 4 A flows into the speaker and the speaker is burned.
Note 4: It is appeared by biased input DC voltage
(for example, large leakage of the input capacitor, short-circuit between copper patterns of PCB.)
Current into a speaker
Speaker impedance
Less than 4
Ω
Figure 9
About 1
Ω
4
Ω
Operating point of protector