Over-current protection circuit and method for protecting switching power amplifier circuits
First Claim
1. A method for protecting circuits within an integrated circuit having an audio amplifier switching driver stage and coupled to an inductive load by power switching devices, the method comprising:
- receiving an over-current indication that indicates the output of the integrated circuit should be shut down due to an over-current condition;
responsive to receiving the over-current signal, first disabling a first one of the power switching devices that has a conduction direction corresponding to the over-current condition;
responsive to receiving the over-current signal, enabling a second one of the power switching devices that has a conduction direction opposite to the conduction direction of the first power switching device; and
subsequent to discharging energy from said inductive load, second disabling the second power switching device, whereby an output of the audio amplifier is not completely disabled until the energy stored in the inductive load is reduced through the second power switching device.
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Accused Products
Abstract
An over-current protection circuit protection circuit and method for protecting switching power amplifier circuits provides protection against latch-up and other failures due to energy returned from an inductive load when one or more transistors in the amplifier output are disabled in response to an over-current condition. Upon detection of an over-current condition, the transistor corresponding to the over-current conduction direction is disabled. At the same time, the transistor corresponding to the conduction direction opposite the over-current direction is enabled for a predetermined time period, or until the magnitude of the load current has dropped, so that energy stored in inductance of the load is reduced, preventing back-currents that would otherwise cause latch-up and consequent destruction of the output stage when the switching power output stage is disabled. After the predetermined time period has elapsed or the load current has dropped below a threshold, the entire output stage is disabled.
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Citations
25 Claims
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1. A method for protecting circuits within an integrated circuit having an audio amplifier switching driver stage and coupled to an inductive load by power switching devices, the method comprising:
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receiving an over-current indication that indicates the output of the integrated circuit should be shut down due to an over-current condition; responsive to receiving the over-current signal, first disabling a first one of the power switching devices that has a conduction direction corresponding to the over-current condition; responsive to receiving the over-current signal, enabling a second one of the power switching devices that has a conduction direction opposite to the conduction direction of the first power switching device; and subsequent to discharging energy from said inductive load, second disabling the second power switching device, whereby an output of the audio amplifier is not completely disabled until the energy stored in the inductive load is reduced through the second power switching device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An integrated circuit, comprising:
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an audio amplifier switching driver stage having an output connected to the output terminal and controlled by an audio signal; at least one output terminal for coupling the audio amplifier switching driver stage to an inductive load; and a control circuit responsive to an over-current indication for disabling an audio amplifier switching power stage, wherein the control circuit disables a first switching device of the switching power stage having a conduction direction corresponding to the over-current condition and enables a second switching device of the switching power stage having a conduction direction opposite to the conduction direction of the first switching device in response to the over-current indication to reduce energy stored in the inductive load, and wherein the control circuit disables the second switching device after discharging energy from the inductive load, whereby the switching power stage is not completely disabled until the energy stored in the inductive load is reduced. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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- 23. An integrated circuit including a protection circuit for protecting switching power amplifier circuits from latch-up and other failures due to energy returned from an inductive load when one or more transistors in an amplifier switching power output stage are disabled in response to an over-current condition, wherein the protection circuit detects an over-current condition and disables a transistor corresponding to the over-current conduction and enables another transistor corresponding to the conduction direction opposite the over-current direction so that energy stored in inductance of the load is reduced, preventing back-currents that would otherwise may cause latch-up and consequent destruction of the integrated circuit when the amplifier switching power output stage is disabled.
Specification