CN116505893B - AB type earphone driver - Google Patents
AB type earphone driver Download PDFInfo
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- CN116505893B CN116505893B CN202310768522.5A CN202310768522A CN116505893B CN 116505893 B CN116505893 B CN 116505893B CN 202310768522 A CN202310768522 A CN 202310768522A CN 116505893 B CN116505893 B CN 116505893B
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Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/52—Circuit arrangements for protecting such amplifiers
- H03F1/523—Circuit arrangements for protecting such amplifiers for amplifiers using field-effect devices
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
- H02H9/025—Current limitation using field effect transistors
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/181—Low frequency amplifiers, e.g. audio preamplifiers
- H03F3/183—Low frequency amplifiers, e.g. audio preamplifiers with semiconductor devices only
- H03F3/187—Low frequency amplifiers, e.g. audio preamplifiers with semiconductor devices only in integrated circuits
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
- H04R3/007—Protection circuits for transducers
Abstract
The invention relates to the technical field of integrated circuits, and discloses an AB type earphone driver which is used for stably and effectively limiting the maximum current flowing through an output-stage PMOS tube or an NMOS tube of the AB type earphone driver to be below a preset value so as to prevent a chip from being damaged due to overcurrent. The class AB earpiece driver includes: the system comprises an AB type operational amplifier, an output stage PMOS tube short-circuit protection module and an output stage NMOS tube short-circuit protection module; the output end of the AB type operational amplifier is respectively connected with the output-stage PMOS tube short-circuit protection module and the output-stage NMOS tube short-circuit protection module; the output stage PMOS tube short-circuit protection module is used for: if the current is short-circuited and reversely grounded, current limiting is carried out on the first mirror current according to a preset first maximum current; the output stage NMOS tube short-circuit protection module is used for: and if the current is short-circuited to the external power supply, current limiting the second mirror current according to a preset second maximum current.
Description
Technical Field
The invention relates to the technical field of integrated circuits, in particular to an AB type earphone driver.
Background
At present, the class AB earphone driver is a high-performance earphone driving circuit widely adopted by USB to 3.5mm audio interface chips, computer sound card chips, mobile phone audio chips and the like, and the output of the class AB earphone driver is usually connected to a 3.5mm audio jack of equipment first and then connected with an earphone with a 3.5mm plug inserted by a user. When a user inserts wrong equipment or metal connectors into a 3.5mm jack, the output of the class AB earphone driver is possibly short-circuited to ground or to a power supply to cause overcurrent damage in the chip, so that a proper output short-circuit protection circuit is required to be added when designing the circuit of the class AB earphone driver.
At present, the circuit of a conventional class AB earphone driver is schematically shown in fig. 1, wherein a typical two-stage class AB operational amplifier 101 in a unity gain following mode is responsible for the audio signal driving function. The PMOS transistor MPo and the NMOS transistor MNo of the class AB operational amplifier 101 operate in a push-pull output state under the action of the PMOS transistor MPf and the NMOS transistor MNf, which are used as floating current sources, and the drains of the PMOS transistor MPo and the NMOS transistor MNo are connected to the output Vo of the entire class AB earphone driver, so that the PMOS transistor MPo and the NMOS transistor MNo combine to form an output stage of the entire class AB earphone driver. When the output Vo of the conventional class AB earphone driver is shorted to the ground, a large short-circuit current ishart flows from the chip power supply through the PMOS transistor MPo inside the chip and then flows to the ground, which is likely to cause the PMOS transistor MPo to be damaged, so the conventional class AB earphone driver generally further includes the conventional output stage PMOS transistor short-circuit protection module 102 and the output stage NMOS transistor short-circuit protection module 103, but when the conventional scheme performs the overcurrent protection function, the short-circuit protection loop may be unstable, and sometimes continuously oscillates with a large signal, so that the maximum current flowing through the NMOS transistor MNo cannot be effectively limited.
Disclosure of Invention
The invention provides an AB type earphone driver which is used for stably and effectively limiting the maximum current flowing through an output-stage PMOS tube or an NMOS tube of the AB type earphone driver to be below a preset value, thereby preventing a chip from being damaged due to overcurrent.
The first aspect of the present invention provides a class AB earphone driver comprising: the system comprises an AB type operational amplifier, an output stage PMOS tube short-circuit protection module and an output stage NMOS tube short-circuit protection module; the output end of the AB type operational amplifier is respectively connected with the output-stage PMOS tube short-circuit protection module and the output-stage NMOS tube short-circuit protection module;
the output-stage PMOS tube short-circuit protection module is used for: receiving a target output voltage of the AB class operational amplifier, and generating a first mirror current according to the target output voltage; comparing the first mirror current with a preset first reference current, and judging whether the target output voltage is shorted to the ground or not; if the current is short-circuited and reversely grounded, current limiting is carried out on the first mirror current according to a preset first maximum current;
the output stage NMOS tube short-circuit protection module is used for: receiving a target output voltage of the AB class operational amplifier, and generating a second mirror current according to the target output voltage; comparing the second mirror current with a preset second reference current, and judging whether the target output voltage is short-circuited to an external power supply or not; and if the current is short-circuited to an external power supply, current limiting is carried out on the second mirror current according to a preset second maximum current.
With reference to the first aspect, in a first implementation manner of the first aspect of the present invention, the output stage PMOS transistor short-circuit protection module is further configured to:
if the first mirror current is not shorted to the ground, determining that the first mirror current is smaller than the first reference current, and outputting a first output voltage when the first mirror current is smaller than the first reference current;
and controlling the first NMOS tube according to the first output voltage so as not to start the first grid voltage of the first PMOS tube, so that the AB type earphone driver keeps a normal working state.
With reference to the first aspect, in a second implementation manner of the first aspect of the present invention, the output stage NMOS transistor short-circuit protection module is further configured to:
if the external power supply is not shorted, determining that the second mirror current is smaller than the second reference current, and outputting a second output voltage when the second mirror current is smaller than the second reference current;
and controlling the second PMOS tube to not start the second grid voltage of the second NMOS tube to enable the AB type earphone driver to keep a normal working state according to the second output voltage.
With reference to the first aspect, in a third implementation manner of the first aspect of the present invention, the output stage PMOS transistor short-circuit protection module further includes:
when the output-stage PMOS tube short-circuit protection module plays a role of overcurrent protection, the output-stage PMOS tube short-circuit protection module has a first high-impedance node;
and determining a first low-frequency pole according to the first high-impedance node so as to keep the short-circuit protection module of the PMOS transistor of the output stage stable.
With reference to the first aspect, in a fourth implementation manner of the first aspect of the present invention, the output stage NMOS transistor short-circuit protection module further includes:
when the output stage NMOS tube short-circuit protection module plays a role of overcurrent protection, the output stage NMOS tube short-circuit protection module is provided with a second high-impedance node;
and determining a second low-frequency pole according to the second high-impedance node so as to keep the output stage NMOS tube short-circuit protection module stable.
With reference to the first aspect, in a fifth implementation manner of the first aspect of the present invention, the output stage PMOS transistor short-circuit protection module is specifically configured to:
calculating a plurality of first current mirror ratios based on a preset first allocation strategy;
and controlling the first mirror current to be 1/M of the current flowing through the first PMOS tube according to the multiple first current mirror ratios.
With reference to the first aspect, in a sixth implementation manner of the first aspect of the present invention, the output stage NMOS transistor short-circuit protection module is specifically configured to:
calculating a plurality of second current mirror ratios based on a preset second allocation strategy;
and controlling the second mirror current to be 1/M of the current flowing through the second NMOS tube according to the second current mirror ratios.
In the technical scheme provided by the invention, the AB type earphone driver comprises: the system comprises an AB type operational amplifier, an output stage PMOS tube short-circuit protection module and an output stage NMOS tube short-circuit protection module; the output end of the AB type operational amplifier is respectively connected with the output-stage PMOS tube short-circuit protection module and the output-stage NMOS tube short-circuit protection module; the output stage PMOS tube short-circuit protection module is used for: if the current is short-circuited and reversely grounded, current limiting is carried out on the first mirror current according to a preset first maximum current; the output stage NMOS tube short-circuit protection module is used for: if the current is short-circuited to an external power supply, the second mirror current is limited according to the preset second maximum current, and when the output of the AB type earphone driver is short-circuited, the output short-circuit protection circuit of the AB type earphone driver provided by the invention can stably and effectively limit the maximum current flowing through the PMOS tube or the NMOS tube of the output stage of the AB type earphone driver to be below a preset value, so that the chip is prevented from being damaged due to overcurrent.
Drawings
Fig. 1 is a schematic circuit diagram of a conventional class AB earphone driver according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of an embodiment of a class AB earphone driver including an output short-circuit protection circuit according to an embodiment of the present invention.
Detailed Description
The embodiment of the invention provides an AB type earphone driver, which is used for stably and effectively limiting the maximum current flowing through an output-stage PMOS tube or an NMOS tube of the AB type earphone driver to be below a preset value, thereby preventing a chip from being damaged due to overcurrent. The terms "first," "second," "third," "fourth" and the like in the description and in the claims and in the above drawings, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments described herein may be implemented in other sequences than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed or inherent to such process, method, article, or apparatus.
For ease of understanding, a specific flow of an embodiment of the present invention is described below with reference to fig. 2, which is a schematic circuit diagram of an embodiment of a class AB earphone driver including an output short-circuit protection circuit:
the class AB earpiece driver includes: the system comprises an AB type operational amplifier, an output stage PMOS tube short-circuit protection module and an output stage NMOS tube short-circuit protection module; the output end of the AB type operational amplifier is respectively connected with the output-stage PMOS tube short-circuit protection module and the output-stage NMOS tube short-circuit protection module;
in this embodiment, the class AB operational amplifier includes an input end and an output end, the input end is configured to receive an input voltage Vi, the output end is respectively connected to the output stage PMOS transistor short-circuit protection module and the output stage NMOS transistor short-circuit protection module, and the output end is configured to output a target output voltage. The input end and the output end of the output-stage PMOS tube short-circuit protection module are connected with the two ends of the PMOS tube MPo, and the input end and the output end of the output-stage NMOS tube short-circuit protection module are connected with the two ends of the NMOS tube MNo.
The output-stage PMOS tube short-circuit protection module is used for: receiving a target output voltage of the AB class operational amplifier, and generating a first mirror current according to the target output voltage; comparing the first mirror current with a preset first reference current, and judging whether the target output voltage is shorted to the ground or not; if the current is short-circuited and reversely grounded, current limiting is carried out on the first mirror current according to a preset first maximum current;
the output stage NMOS tube short-circuit protection module is used for: receiving a target output voltage of the AB class operational amplifier, and generating a second mirror current according to the target output voltage; comparing the second mirror current with a preset second reference current, and judging whether the target output voltage is short-circuited to an external power supply or not; and if the current is short-circuited to an external power supply, current limiting is carried out on the second mirror current according to a preset second maximum current.
The circuit of an embodiment of a class AB earphone driver of the output short-circuit protection circuit proposed by the present invention is schematically shown in fig. 2, wherein what really takes over the driving function of the audio signal is a typical two-stage class AB operational amplifier 201 in unity gain following mode. PMOS transistor MPo (i.e., first PMOS transistor) and NMOS transistor MNo (i.e., second NMOS transistor) of class AB operational amplifier 201 operate in a push-pull output state under the action of PMOS transistor MPf and NMOS transistor MNf, which are used as floating current sources, and the drains of PMOS transistor MPo (i.e., first PMOS transistor) and NMOS transistor MNo (i.e., second NMOS transistor) are also connected to the output Vo of the entire class AB earphone driver, so that PMOS transistor MPo (i.e., first PMOS transistor) and NMOS transistor MNo (i.e., second NMOS transistor) combine to form the output stage of the entire class AB earphone driver. When the output Vo of the class AB earphone driver is shorted to the ground, a large short-circuit current ishart flows from the chip power source through the PMOS transistor MPo (i.e., the first PMOS transistor) in the chip and then flows to the ground, which is likely to cause damage to the PMOS transistor MPo (i.e., the first PMOS transistor), so the class AB earphone driver further includes the output stage PMOS transistor short-circuit protection module 202. When the output Vo of the class AB earphone driver is shorted to the external power source, a large short-circuit current ishart flows from the external power source to the NMOS transistor MNo (i.e., the second NMOS transistor) inside the chip, which is likely to cause damage to the NMOS transistor MNo (i.e., the second NMOS transistor), so the class AB earphone driver according to the present invention further includes the output stage NMOS transistor short-circuit protection module 203 according to the present invention.
The output-stage PMOS tube short-circuit protection module is also used for:
if the first mirror current is not shorted to the ground, determining that the first mirror current is smaller than the first reference current, and outputting a first output voltage when the first mirror current is smaller than the first reference current;
and controlling the first NMOS tube according to the first output voltage so as not to start the first grid voltage of the first PMOS tube, so that the AB type earphone driver keeps a normal working state.
The short-circuit protection module 202 of the output stage PMOS tube provided by the invention is used for comparing the first mirror current flowing through the PMOS tube MPb with the preset first reference current Ib REFP By comparing, whether the output Vo of the class AB earphone driver provided by the invention is short-circuited to ground can be judged. If the output Vo of the AB type earphone driver is not shorted to the ground, the first mirror current flowing through the PMOS tube MPb is smaller than the preset first reference current Ib REFP The voltages VP output after comparison OCP (i.e., the first output voltage) approaches ground, when the gate receives the voltage VP OCP (i.e., first output voltage) controlled NMOS transistor MN OCP (i.e., the first NMOS transistor) will not turn on the gate Vgp (i.e., the first gate voltage) of the pull-up PMOS transistor MPo (i.e., the first PMOS transistor), so the class AB earphone driver of the present invention maintains its normal operating state. If the output Vo of the AB type earphone driver provided by the invention is short-circuited to the ground, the first mirror current flowing through the PMOS tube MPb is larger than the preset first reference current Ib REFP The voltages VP output after comparison OCP (i.e., the first output voltage) approaches the chip power supply when the gate is subjected to the voltage VP OCP (i.e., first output voltage) controlled NMOS transistor MN OCP (i.e., the first NMOS transistor) will turn on the gate VGp (i.e., the first gate voltage) of the pull-up PMOS transistor MPo (i.e., the first PMOS transistor) to limit the maximum current flowing through the PMOS transistor MPo (i.e., the first PMOS transistor) to M.Ib REFP (i.e., a preset first maximum current) to achieve the purpose of output short-circuit protection.
The output stage NMOS tube short-circuit protection module is also used for:
if the external power supply is not shorted, determining that the second mirror current is smaller than the second reference current, and outputting a second output voltage when the second mirror current is smaller than the second reference current;
and controlling the second PMOS tube to not start the second grid voltage of the second NMOS tube to enable the AB type earphone driver to keep a normal working state according to the second output voltage.
The output stage NMOS transistor short-circuit protection module 203 according to the present invention is configured to compare the second mirror current flowing through the NMOS transistor MNb with the preset second reference current Ib REFN By comparing, whether the output Vo of the class AB earphone driver provided by the invention is short-circuited to an external power supply or not can be judged. If the output Vo of the class AB earphone driver is not shorted to the external power source, the second one flows through the NMOS tube MNbThe mirror current is smaller than the preset second reference current Ib REFN The voltage VN output after comparison OCP (i.e., the second output voltage) approaches the chip power supply when the gate is subjected to voltage VN OCP (i.e., the second output voltage) controlled PMOS tube MP OCP (i.e., the second PMOS transistor) will not turn on the gate Vgn (i.e., the second gate voltage) of the pull-down NMOS transistor MNo (i.e., the second NMOS transistor), so the class AB earphone driver of the present invention maintains its normal operating state. If the output Vo of the class AB earphone driver is short-circuited to an external power supply, the second mirror current flowing through the NMOS tube MNb is larger than the preset second reference current Ib REFN The voltage VN output after comparison OCP (i.e., the second output voltage) approaches ground when the gate receives voltage VN OCP (i.e., the second output voltage) controlled PMOS tube MP OCP (i.e., the second PMOS transistor) will turn on the gate Vgn (i.e., the second gate voltage) of the pull-down NMOS transistor MNo (i.e., the second NMOS transistor) to limit the maximum current flowing through the NMOS transistor MNo (i.e., the second NMOS transistor) to M.Ib REFN (i.e., a preset second maximum current) to achieve the purpose of output short-circuit protection.
The output stage PMOS tube short-circuit protection module further comprises:
when the output-stage PMOS tube short-circuit protection module plays a role of overcurrent protection, the output-stage PMOS tube short-circuit protection module has a first high-impedance node;
and determining a first low-frequency pole according to the first high-impedance node so as to keep the short-circuit protection module of the PMOS transistor of the output stage stable.
The short-circuit protection module 202 of the PMOS transistor of the invention has the function of overcurrent protection due to the NMOS transistor MN with feedback control function OCP (i.e., the first NMOS tube) is operated in a source-follower state with low output impedance, so the whole short-circuit protection loop has 1 first high impedance node at the drain of the PMOS tube MPb only, and thus has 1 first low frequency pole, so the whole short-circuit protection loop is alwaysStable, thus can stably and effectively limit the maximum current flowing through the output stage PMOS tube MPo (i.e. the first PMOS tube) of the class AB earphone driver to the preset value M.Ib REFP (i.e., a preset first maximum current) or less, thereby preventing the chip from being damaged by overcurrent.
The output stage NMOS tube short-circuit protection module further comprises:
when the output stage NMOS tube short-circuit protection module plays a role of overcurrent protection, the output stage NMOS tube short-circuit protection module is provided with a second high-impedance node;
and determining a second low-frequency pole according to the second high-impedance node so as to keep the output stage NMOS tube short-circuit protection module stable.
The output stage NMOS transistor short-circuit protection module 203 of the present invention is due to the PMOS transistor MP with feedback control function when the overcurrent protection function is provided OCP (i.e., the second PMOS tube) is operated in the source-follower state of low output impedance, so that the whole short-circuit protection loop has 1 second high impedance node only at the drain of NMOS tube MNb, and thus has 1 second low frequency pole, so that the whole short-circuit protection loop is always stable, and thus the maximum current flowing through the output stage NMOS tube MNo (i.e., the second NMOS tube) of the class AB earphone driver can be stably and effectively limited to the preset value M.Ib REFN (i.e., the second maximum current) or less, thereby preventing the chip from being damaged by overcurrent.
The output-stage PMOS tube short-circuit protection module is specifically used for:
calculating a plurality of first current mirror ratios based on a preset first allocation strategy;
and controlling the first mirror current to be 1/M of the current flowing through the first PMOS tube according to the multiple first current mirror ratios.
In the output stage PMOS transistor short-circuit protection module 202 of the present embodiment, the preset first allocation policy includes the following steps: the unit gain following buffer formed by the operational amplifier AMP2 and the PMOS tube MPc senses the target output voltage of the following class AB earphone driver output Vo in real time and buffers the target output voltage to the drain electrode of the PMOS tube MPm, so that the drain voltages of the PMOS tube MPm and the PMOS tube MPo (namely, the first PMOS tube) are approximately equal. Because the gate of the PMOS transistor MPm and the gate of the PMOS transistor MPo (i.e., the first PMOS transistor) are both connected to the signal Vgp, in this embodiment, the source of the PMOS transistor MPm and the source of the PMOS transistor MPo (i.e., the first PMOS transistor) are both connected to the chip power supply, the current flowing through the PMOS transistor MPm is a relatively precise mirror image of the current flowing through the PMOS transistor MPo (i.e., the first PMOS transistor), and by adjusting the ratio of the two PMOS transistors W/L, the proportional relationship between the mirror current flowing through the PMOS transistor MPm and the current flowing through the PMOS transistor MPo (i.e., the first PMOS transistor) can be controlled. The mirror current flowing through the PMOS tube MPm also flows through the PMOS tube MPc and the NMOS tube MNx, and then is mirrored again to flow through the NMOS tube MNy, and the proportional relation between the mirror current flowing through the NMOS tube MNy and the current flowing through the NMOS tube MNx can be controlled by adjusting the proportional values of the two NMOS tubes W/L of MNx and MNy. The mirror current flowing through the NMOS tube MNy flows into the PMOS tube MPa, and then is mirrored by the PMOS tube MPb for the 3 rd time, and the proportional relation between the first mirror current flowing through the PMOS tube MPb and the current flowing through the PMOS tube MPa can be controlled by adjusting the proportional values of the two PMOS tubes W/L of the MPa and the MPb. Therefore, by reasonably distributing and designing the current mirror ratio between the PMOS transistor MPm and the PMOS transistor MPo (i.e., the first PMOS transistor), the first current mirror ratio between the NMOS transistor MNx and the NMOS transistor MNy, and the current mirror ratio between the PMOS transistor MPa and the PMOS transistor MPb, the first mirror current flowing through the PMOS transistor MPb can be controlled to be 1/M of the current flowing through the PMOS transistor MPo (i.e., the first PMOS transistor).
The output stage NMOS tube short-circuit protection module is specifically used for:
calculating a plurality of second current mirror ratios based on a preset second allocation strategy;
and controlling the second mirror current to be 1/M of the current flowing through the second NMOS tube according to the second current mirror ratios.
In the output stage NMOS short-circuit protection module 203 of the present embodiment, the preset second allocation policy includes the following steps: the unity gain follower buffer composed of the operational amplifier AMP1 and the NMOS transistor MNc senses and buffers the voltage of the follower class AB headphone driver output Vo (i.e., the target output voltage) at the drain of the NMOS transistor MNm in real time, so that the drain voltages of the NMOS transistor MNm and the NMOS transistor MNo (i.e., the second NMOS transistor) are approximately equal. Because the gate of the NMOS transistor MNm and the gate of the NMOS transistor MNo (i.e., the second NMOS transistor) are both connected to the signal Vgn, and the source of the NMOS transistor MNm and the source of the NMOS transistor MNo (i.e., the second NMOS transistor) are both connected to ground, the current flowing through the NMOS transistor MNm is a relatively precise mirror image of the current flowing through the NMOS transistor MNo (i.e., the second NMOS transistor), and by adjusting the ratio of the two NMOS transistors W/L, the proportional relationship between the mirror current flowing through the NMOS transistor MNm and the current flowing through the NMOS transistor MNo (i.e., the second NMOS transistor) can be controlled. The mirror current flowing through the NMOS transistor MNm also flows through the NMOS transistor MNc and the PMOS transistor MPx, and then is mirrored again to flow through the PMOS transistor MPy, and the proportional relationship between the mirror current flowing through the PMOS transistor MPy and the current flowing through the PMOS transistor MPx can be controlled by adjusting the proportional values of the two PMOS transistors W/L of MPx and MPy. The mirror current flowing through the PMOS transistor MPy flows into the NMOS transistor MNa again, and then is mirrored by the NMOS transistor MNb for the 3 rd time, and the proportional relationship between the second mirror current flowing through the NMOS transistor MNb and the current flowing through the NMOS transistor MNa can be controlled by adjusting the proportional values of the two NMOS transistors W/L of MNa and MNb. Therefore, by reasonably distributing and designing the current mirror ratio between the NMOS transistor MNm and the NMOS transistor MNo (i.e., the second NMOS transistor), the second current mirror ratio between the PMOS transistor MPx and the PMOS transistor MPy and the current mirror ratio between the NMOS transistor MNa and the NMOS transistor MNb in this embodiment can control the second mirror current flowing through the NMOS transistor MNb to be 1/M of the current flowing through the NMOS transistor MNo (i.e., the second NMOS transistor).
In an embodiment of the present invention, the class AB earphone driver includes: the system comprises an AB type operational amplifier, an output stage PMOS tube short-circuit protection module and an output stage NMOS tube short-circuit protection module; the output end of the AB type operational amplifier is respectively connected with the output-stage PMOS tube short-circuit protection module and the output-stage NMOS tube short-circuit protection module; the output stage PMOS tube short-circuit protection module is used for: if the current is short-circuited and reversely grounded, current limiting is carried out on the first mirror current according to a preset first maximum current; the output stage NMOS tube short-circuit protection module is used for: if the current is short-circuited to an external power supply, the second mirror current is limited according to the preset second maximum current, and when the output of the AB type earphone driver is short-circuited, the output short-circuit protection circuit of the AB type earphone driver provided by the invention can stably and effectively limit the maximum current flowing through the PMOS tube or the NMOS tube of the output stage of the AB type earphone driver to be below a preset value, so that the chip is prevented from being damaged due to overcurrent.
It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, which are not repeated herein.
The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied essentially or in part or all of the technical solution or in part in the form of a software product stored in a storage medium, including instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a read-only memory (ROM), a random access memory (random acceS memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (3)
1.A class AB earphone driver, the class AB earphone driver comprising: the system comprises an AB type operational amplifier, an output stage PMOS tube short-circuit protection module and an output stage NMOS tube short-circuit protection module; the output end of the AB type operational amplifier is respectively connected with the output-stage PMOS tube short-circuit protection module and the output-stage NMOS tube short-circuit protection module;
the output-stage PMOS tube short-circuit protection module is used for: receiving a target output voltage of the AB class operational amplifier, and generating a first mirror current according to the target output voltage; comparing the first mirror current with a preset first reference current, and judging whether the target output voltage is shorted to the ground or not; if the current is short-circuited and reversely grounded, current limiting is carried out on the first mirror current according to a preset first maximum current; the output-stage PMOS tube short-circuit protection module is specifically used for: calculating a plurality of first current mirror ratios based on a preset first allocation strategy; according to the multiple first current mirror ratios, controlling the first mirror current to be 1/M of the current flowing through the first PMOS tube, wherein the preset first reference current is Ib REFP The preset first maximum current is a preset value M.Ib REFP The method comprises the steps of carrying out a first treatment on the surface of the The output stage PMOS tube short-circuit protection module further comprises: when the output-stage PMOS tube short-circuit protection module plays a role of overcurrent protection, the output-stage PMOS tube short-circuit protection module has a first high-impedance node; determining a first low-frequency pole according to the first high-impedance node so as to keep the short-circuit protection module of the output-stage PMOS tube stable;
the output stage NMOS tube short-circuit protection module is used for: receiving a target output voltage of the AB class operational amplifier, and generating a second mirror current according to the target output voltage; comparing the second mirror current with a preset second reference current, and judging whether the target output voltage is short-circuited to an external power supply or not; if the current is short-circuited to an external power supply, current limiting is carried out on the second mirror current according to a preset second maximum current; by a means ofThe output stage NMOS tube short-circuit protection module is specifically used for: calculating a plurality of second current mirror ratios based on a preset second allocation strategy; controlling the second mirror current to be 1/M of the current flowing through the second NMOS tube according to the plurality of second current mirror ratios, wherein the preset second reference current is Ib REFN The preset second maximum current is a preset value M.Ib REFN The method comprises the steps of carrying out a first treatment on the surface of the The output stage NMOS tube short-circuit protection module further comprises: when the output stage NMOS tube short-circuit protection module plays a role of overcurrent protection, the output stage NMOS tube short-circuit protection module is provided with a second high-impedance node; and determining a second low-frequency pole according to the second high-impedance node so as to keep the output stage NMOS tube short-circuit protection module stable.
2. The class AB earphone driver of claim 1, wherein the output stage PMOS transistor short-circuit protection module is further configured to:
if the first mirror current is not shorted to the ground, determining that the first mirror current is smaller than the first reference current, and outputting a first output voltage when the first mirror current is smaller than the first reference current;
and controlling the first NMOS tube according to the first output voltage so as not to start the first grid voltage of the first PMOS tube, so that the AB type earphone driver keeps a normal working state.
3. The class AB earphone driver of claim 1, wherein the output stage NMOS transistor short-circuit protection module is further configured to:
if the external power supply is not shorted, determining that the second mirror current is smaller than the second reference current, and outputting a second output voltage when the second mirror current is smaller than the second reference current;
and controlling the second PMOS tube to not start the second grid voltage of the second NMOS tube to enable the AB type earphone driver to keep a normal working state according to the second output voltage.
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| CN202310768522.5A CN116505893B (en) | 2023-06-28 | 2023-06-28 | AB type earphone driver |
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| CN202310768522.5A CN116505893B (en) | 2023-06-28 | 2023-06-28 | AB type earphone driver |
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| CN116505893B true CN116505893B (en) | 2023-09-26 |
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| CN116505893A (en) | 2023-07-28 |
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