tb2936hq TOSHIBA Semiconductor CORPORATION, tb2936hq Datasheet - Page 7

• Manufacturer Part Number: tb2936hq
• Description: 49 W ? 4-ch Btl Audio Power Ic
• Manufacturer: TOSHIBA Semiconductor CORPORATION

5. Prevention of speaker damage
Note 4: An abnormal DC offset voltage is incurred when the input bias to the power IC is lost due to a leakage
< Speaker damaging scenario >
When the DC resistance between the OUT+ and OUT− pins falls below 1 Ω, the output current exceeds 4 A.
At this time, the protection circuit is activated to limit the current draw into the speaker.
This feature prevents the speaker from being damaged, as follows:
A DC current of over 4 V is applied to the speaker due to an external circuit failure (Note 4).
(Abnormal DC output offset)
The speaker impedance becomes 1 Ω or less due to a layer short.
A current of over 4 A flows into the speaker, damaging the speaker.
current from a coupling capacitor at the input or a short-circuit between the IN and adjacent lines.
Less than 4 A
↓
↓
Current into the speaker
(in case of a layer short-circuit of the speaker)
About 1 Ω
Figure 8
7
The short-circuit protection is activated
4 Ω
Speaker Impedance
TB2936HQ
2009-02-04