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    AMPLIFICATION STEP PROTECTIVE CIRCUIT
    1.
    发明专利
    AMPLIFICATION STEP PROTECTIVE CIRCUIT 失效

    公开(公告)号：JPH07273563A

    公开(公告)日：1995-10-20

    申请号：JP32798494

    申请日：1994-12-28

    Applicant: ST MICROELECTRONICS SRL

    Inventor： TAVAZZANI CLAUDIO ,  FASSINA ANDREA ,  STEFANI FABRIZIO

    IPC: H03F1/30 ,  H03F1/52

    Abstract: PURPOSE: To obtain the amplification state protecting circuit which is reduced in the total number of circuit elements, specially, sense circuits and therefore improved in the reliability of protection and decreased in the integration area of the circuit. CONSTITUTION: This circuit is provided with a circuit switching means G which is piloted by a logic OR gate F by a monostable M and generates a turn-on command signal with predetermined continuation duration in case of an abnormal operating conditions. After a sense circuit B which senses an abnormal state at a start or in the normal operation enables an AND gate H, a turn-off signal is sent through the OR gate. The signal of the AND gate arrives as a confirmation signal through an OR logic gate C from a window comparator A coupled with an amplification stage start member, a monostable flip-flop, and the output terminal of the AND gate H.

    ON-OFF CONTROL CIRCUIT AND AMPLIFICATION CIRCUIT FOR AUDIO AMPLIFIER AND ON-OFF METHOD OF AUDIO AMPLIFIER
    2.
    发明专利
    ON-OFF CONTROL CIRCUIT AND AMPLIFICATION CIRCUIT FOR AUDIO AMPLIFIER AND ON-OFF METHOD OF AUDIO AMPLIFIER 失效

    公开(公告)号：JPH0637560A

    公开(公告)日：1994-02-10

    申请号：JP12154793

    申请日：1993-05-24

    Applicant: ST MICROELECTRONICS SRL

    Inventor： NEBULONI DANIELA ,  FASSINA ANDREA

    IPC: H03F1/00 ,  H03F1/30 ,  H03G1/04 ,  H03G3/34

    Abstract: PURPOSE: To provide a circuit for controlling the on/off-switching of an audio amplifier with a method for preventing the steep fluctuation of output (V0 ) during switching, which is not suppressed, and preventing the production of noise (popping) that is not desirable in a loudspeaker. CONSTITUTION: The circuit for generating positive potential (V->V+) controlled by a negative input terminal against the positive input terminal of the audio amplifier 1 when the audio amplifier 1 is on/off-switched is provided. Particularly when on-switching, a potential difference is maintained while all the powers of the audio amplifier 1 are switched and it is removed for making output (V0 ) reach a standby state value at a slow and controlled mode. The potential difference in off-switching is gradually generated for gradually grounding the output of the audio amplifier 1 before the audio amplifier 1 itself is turned off.

    TURN-OFF CONTROL CIRCUIT
    4.
    发明专利
    TURN-OFF CONTROL CIRCUIT 失效

    公开(公告)号：JPH0637548A

    公开(公告)日：1994-02-10

    申请号：JP12003393

    申请日：1993-05-21

    Applicant: ST MICROELECTRONICS SRL

    Inventor： NEBULONI DANIELA ,  FASSINA ANDREA

    IPC: H03F1/00 ,  H03F1/30 ,  H03G3/34

    Abstract: PURPOSE: To provide a turn-off control circuit for removing noise produced when a sound amplifier is turned off. CONSTITUTION: A clock means constituted of a control means 13 connected to a power line 11, a filter 17 as a voltage source connected to the control means 13 and a transistor 10 where an emitter is connected to the output terminal of the sound amplifier 1, is grounded through a switch 15 and a base is connected to the control means is provided.

    METHOD AND DEVICE FOR MEASURING SWITCHING NOISE OF AUDIO AMPLIFIER
    5.
    发明专利
    METHOD AND DEVICE FOR MEASURING SWITCHING NOISE OF AUDIO AMPLIFIER 失效

    公开(公告)号：JPH08189945A

    公开(公告)日：1996-07-23

    申请号：JP15349095

    申请日：1995-06-20

    Applicant: ST MICROELECTRONICS SRL

    Inventor： FASSINA ANDREA ,  AVENIA GIOVANNI ,  PAGANI ELIA

    IPC: G01R29/26 ,  G01R31/00 ,  G01R31/28 ,  H03F3/181 ,  H03G3/10

    Abstract: PURPOSE: To obtain apparatus and method for measuring the switching noise of an audio amplifier with a sensitivity close to that of human ear and which can be constituted easily using a modern test facility and applicable to any type (bridge type or single end type) of amplifier. CONSTITUTION: An apparatus 10 for switching an audio amplifier 1 based on a control signal s1 and weighting the energy according to the frequency and the sensitivity of human ear comprises a control signal generator 12, an audio band filter 13 connected with the output terminal 3 of the audio amplifier 1, a meter 14 for measuring the power of filtered signal, and an integration element 15 for calculating the energy of filtered signal.

    PROTECTION DEVICE FOR AMPLIFIER OUTPUT NODE UNDER SPU CONDITION
    6.
    发明专利
    PROTECTION DEVICE FOR AMPLIFIER OUTPUT NODE UNDER SPU CONDITION 失效

    公开(公告)号：JPH06303047A

    公开(公告)日：1994-10-28

    申请号：JP5275094

    申请日：1994-02-24

    Applicant: ST MICROELECTRONICS SRL

    Inventor： BOTTI EDOARDO ,  FASSINA ANDREA ,  FERRARI PAOLO

    IPC: H03F1/52

    Abstract: PURPOSE: To protect a power transistor TR of an output stage functionally connected between an output node and a supply rail by short-circuiting the base-emitter junction of a TR under a reverse bias condition on the occurrence of an SPU condition. CONSTITUTION: This device comprises a TR QS which has the emitter connected to a base B1 of a power TR Q1 and has the collector connected to an output node Out and has the base B2 connected to a supply rail Vcc of an amplification circuit. While the device normally functions, the protection TR QS of the same type as the power TR Q1 to be protected is turned off because the potential on the base (node B2 ) is higher than that existing on emitter and collector nodes E and C. Actually, the base potential is practically equal to the supply voltage Vcc of the amplifier.

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