ta8275h TOSHIBA Semiconductor CORPORATION, ta8275h Datasheet - Page 6

• Manufacturer Part Number: ta8275h
• Description: Max Power 41 W Btl X 4 Ch Audio Power Ic
• Manufacturer: TOSHIBA Semiconductor CORPORATION

5.3
5.4
Note 1: it is appeared by biased input DC voltage
Prevention of speaker burning accident
becomes 1 ohm or less and output current over 4A flows, this IC makes a protection circuit operate
and suppresses the current into a speaker.
circuit failure.(Note1)
Application
25pin voltage that is smoothed out with LPF.
of LPF is changed according to an input signal.
(for example, Vth is set up to 4V if 25pin is pulled up to 5V line.)
When the direct current resistance between OUT+ and OUT- terminal
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 4V is made by the external
The speaker impedance becomes 1 ohm or less as it is in a rare short circuit condition.
The current more than 4A flows into the speaker and the speaker is burned.
When output terminals short-circuit to Vcc or GND, the voltage of 25pin is fixed to “L”.
And when shorting OUT+ to OUT-, “L” and “H” are switched according to an input signal.
Therefore, it is possible to judge how the power IC condition is if a micro-controller detects the
It is recommend that the threshold voltage(Vth) is set up as higher as possible because output level
(for example, large leakage of the input capacitor, short-circuit between copper patterns of PCB.)
Less than 4 W
Output voltage of L.P.F.
Current into a speaker
5 V
¯
¯
Operating point of protector
Figure 10
Figure 9
About 1 W
6
(In Case of Rare Short Circuit of Speaker)
Operating point of protector
4 W
Speaker impedance
Output power
2002-02-13
TA8275H