Special integrated amplifier for headphone amplifier LM4880-03

The automatic shutdown circuit in the picture is
implemented by a MOS field effect tube. When the earphones are plugged in, the contacts
are disconnected, the gate of the MOS tube is connected to high level, and the tube is turned
on. , ⑤ pin is grounded, LM4880 enters the amplification working
state. The port pulls out the earphone tMOS tube gate through the contact
and R, grounded, the MOS tube is cut off, ⑤ pin is connected to high level
, I. M4880 automatically shuts down.
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    LM4880 can also be applied to make an automatic switching
power amplifier circuit, as shown in Figure 5-42. LM4861 can output 0.5w power at Sv voltage. When
the earphone is inserted into the speaker sound port in the machine , pin ① is connected to the positive power supply through RV, and the speaker current is automatically turned off. When pulled out, the ① pin of LM 4861
is grounded through the contact and support, and enters the working state, while the I.M4880 is just turned off and works alternately.