OUTPUT-STAGE CIRCUIT AND METHOD FOR OVER CURRENT PROTECTION THEREOF AND AUDIO AMPLIFY SYSTEM

• US 20140294205A1
• Filed: 07/29/2013
• Published: 10/02/2014
• Est. Priority Date: 03/29/2013
• Status: Active Grant

• Current Assignee: Anpec Electronics Corporation
• Original Assignee: Anpec Electronics Corporation
• Inventors: CHANG, MING-HUNG, WU, CHIA-PAUO
• Granted Patent: US 9,257,835 B2
• Time in Patent Office: Days
• US Class Current: 381/120
• CPC Class Codes: H02H 9/04 responsive to excess voltage lightning arrestors H01C7/12, H01C8/04, H01G9/18, H01T
• CPC Class Codes: H03F 1/52 Circuit arrangements for protecting such amplifiers monitoring arrangements G01R31/28; increasing reliability in communication systems, e.g. using redundancy H04B1/74
• CPC Class Codes: H03F 3/217 Class D power amplifiers; Switching amplifiers
• CPC Class Codes: H04R 2400/00 Loudspeakers
• CPC Class Codes: H04R 3/007 Protection circuits for transducers

Abstract

An output-stage circuit is disclosed. The output-stage circuit includes high-side output driver, first body selector, low-side output driver, second body selector and inductance. When output current is larger than current threshold value so as to make the low-side output driver generate overcurrent, the low-side output driver controlled by second control signal is disabled, and the high-side output driver controlled by first control signal is enabled so as to create first current channel. When output current is larger than current threshold value so as to make the high-side output driver generate overcurrent, the high-side output driver controlled by the first control signal is disabled, and the low-side output driver controlled by the second control signal is enabled so as to create second current channel to avoid current flowing through low-side output driver'"'"'s body, and thus reduce the output current and voltage spiking of the output voltage.

Claims

1. An output-stage circuit, comprising:

a high-side output driver, electrically connected to a system voltage and a first control signal;

a first body selector, electrically connected to the high-side output driver, and the first body selector receiving a first reference voltage and the system voltage;

a low-side output driver, electrically connected to a ground voltage and a second control signal, wherein the high-side output driver is directly connected to the low-side output driver and generating an output voltage;

a second body selector, electrically connected to the low-side output driver, and the second body selector receiving a second reference voltage and the ground voltage; and

an inductor, having an end electrically connected to the output voltage, and another end electrically connected to a third reference voltage, and there is an output current flowing through the inductor,

wherein, when the output current is larger than a current threshold value so that the low-side output driver generates an overcurrent, the low-side output driver controlled by the second control signal is disabled and the high-side output driver controlled by the first control signal is enabled so as to create a first current channel of low impedance, and then changes current of the output current and accordingly to reduce the spiking voltage of the output voltage after an overcurrent prevention started by the low-side output driver,

when the output current is larger than the current threshold value so that the high-side output driver generates an overcurrent, the high-side output driver controlled by the first control signal is disabled, and the low-side output driver controlled by the second control signal is enabled so as to create a second current channel, and then changes current of the output current and a current path and accordingly to reduce the output current and a voltage spiking of the output voltage after an overcurrent prevention started by the high-side output driver.

2. The output-stage circuit according to claim 1, wherein when the output current reduces until becoming a zero current, and the high-side output driver controlled by the first control signal is disabled to close the first current channel, wherein the first current channel has a better feature of low impedance in comparison to the first body selector.

3. The output-stage circuit according to claim 1, wherein when the output current reduces until becoming a zero current, and the low-side output driver controlled by the second control signal is disabled to close the second current channel, wherein the second current channel has a better feature of low impedance in comparison to the second body selector.

4. The output-stage circuit according to claim 1, further comprising:

a detector, detecting if an output current is larger than the current threshold value or the zero current, and accordingly transmitting a detecting result; and

a controller, electrically connected to the detector, and according to the detecting result received to respectively transmitting the first control signal and the second control signal to the high-side output driver and the low-side output driver corresponded so as to control a state of being disabled or being enabled.

5. The output-stage circuit according to claim 1, wherein the third reference voltage is the system voltage or the ground voltage.

6. The output-stage circuit according to claim 1, wherein the high-side output driver comprises a first P-type transistor, and the low-side output driver comprises a first N-type transistor, wherein the first P-type transistor has a gate receiving the first control signal and accordingly determining to be open or closed, a source connected to the system voltage, a drain connected to output node, a body connected to the first body selector, and a embedded drain (P+) to body (N-Well) diode called as first body diode, wherein the first N-type transistor has a second body diode having a gate receiving the second control signal and accordingly to determine whether to be open or closed, a source connected to the ground voltage, a drain connected to the same output node of the first P-type transistor, a body connected to the second body selector, and a embedded body (P-sub or P-well) to drain (N+) diode called as second body diode, wherein when a current value of the output current is larger than the current threshold value so that there is an overcurrent at the first N-type transistor, and the first N-type transistor controlled by the second control signal is disabled, and the first P-type transistor controlled by the first control signal is enabled so as to create the first current channel so as to reduce the current value of the output current and the spiking voltage of the output voltage, wherein the first current channel is the channel between a drain and a source of the first P-type transistor.

7. The output-stage circuit according to claim 6, wherein when the current value of the output current is larger than the current threshold value so that there is the overcurrent at the first P-type transistor, a first P-type transistor controlled by the first control signal is disabled, and the first N-type transistor controlled by the second control signal is enabled to create the second current channel so as to reduce the current value of the output current and the spiking voltage of the output voltage, wherein the second current channel is the channel between a drain and a source of the first N-type transistor.

8. The output-stage circuit according to claim 6, wherein the high-side output driver further comprises a second P-type transistor, and the low-side output driver further comprises a second N-type transistor, wherein the second P-type transistor has a third body diode having a source connected to a drain of the first P-type transistor, and having a gate receiving a third control signal so as to determine to be open or closed, and the second N-type transistor has a fourth body diode having a drain connected to a drain of the second P-type transistor and outputs an output voltage, and having a gate receiving a fourth control signal so as to determine to be open or closed, and having a source connected to a drain of the first N-type transistor.

13. An audio amplify system, comprising:

a pre-stage amplifier, receiving and amplifying an input signal;

an output-stage circuit according to claim 1, electrically connected to the pre-stage amplifier; and

a load, electrically connected to the output-stage circuit,

wherein the audio amplify system utilizes the over-current protection method according to claim 9 to reduce the output current and a voltage spiking of the output voltage.

9. An over-current protection method of an output-stage circuit, and the output-stage circuit comprising a high-side output driver, a first body selector, a low-side output driver, a second body selector, and an inductor, wherein the high-side output driver is electrically connected to a system voltage and a first control signal, and the first body selector is electrically connected to a high-side output driver, and receiving a first reference voltage and a system voltage, the low-side output driver is electrically connected to a ground voltage and a second control signal, and a high-side output driver is directly connected to the low-side output driver to generate an output voltage, and the second body selector is electrically connected to the low-side output driver and receives a second reference voltage and a ground voltage;

an end of an inductor is electrically connected to the output voltage, and another end is electrically connected to a third reference voltage, and there is an output current flowing through the inductor, and the over-current protection method comprising steps as follows;

detecting a current value of an output current;

determining whether there is an overcurrent at the high-side output driver or the low-side output driver;

when the current value of the output current is larger than a current threshold value so that there is an overcurrent at the low-side output driver, the low-side output driver is disabled and the high-side output driver is enabled to create a first current channel so as to reduce the current value of the output current and a spiking voltage of the output voltage, and

when the current value of the output current is larger than the current threshold value so that there is an overcurrent at the high-side output driver, the high-side output driver is disabled and the low-side output driver is enabled to create a second current channel so as to reduce the current value of the output current and a spiking voltage of the output voltage.

10. The over-current protection method according to claim 9, further comprising:

when an output current reduces until becoming a zero current, the high-side output driver controlled by the first control signal is disabled to close the first current channel, wherein the first current channel has a better feature of low impedance in comparison to the first body selector.

11. The over-current protection method according to claim 9, further comprising:

when an output current reduces until becoming a zero current, the low-side output driver controlled by the second control signal is disabled to close the second current channel, wherein the second current channel has a better feature of low impedance in comparison to the second body selector.

12. The output-stage circuit according to claim 9, wherein the output-stage circuit further comprising:

a detector, detecting if the output current is larger than the current threshold value or the zero current, and accordingly transmitting a detecting result; and

a controller, electrically connected to the detector, and according to the detecting result received to respectively transmitting the first control signal and the second control signal to the high-side output driver and the low-side output driver corresponded so as to control a state of being disabled or being enabled.