CN2519532Y

CN2519532Y - Digital audio frequency power amplifier output overcurrent protective circuit

Info

Publication number: CN2519532Y
Application number: CN 02221385
Authority: CN
Inventors: 李斌; 周全才; 周莹
Original assignee: TIANAO INDUSTRY CO LTD CHENGDU
Current assignee: TIANAO INDUSTRY CO LTD CHENGDU
Priority date: 2002-01-23
Filing date: 2002-01-23
Publication date: 2002-10-30
Anticipated expiration: 2012-01-23

Abstract

The utility model provides a main output loop, an auxiliary output loop, and an H bridge circuit comprising of four MOSFET tubes. The main output loop comprises two symmetrical output filters; the auxiliary output loop comprises two symmetrical output filters, two difference detectors, and an or gate circuit; the output ends of the four MOSFET tubes are respectively connected with an input end of corresponding filter; a difference detector is respectively connected between every main output filter and an auxiliary output filter; the output ends of the two difference detecting circuits are both connected with the input end of the or gate circuit; by using the constructed auxiliary protection circuit, the utility model carries on difference comparison with the original main output circuit; the utility model can confirm over-current protection point via setting difference adjustment; by using the mode such as photo-electricity, the utility model can filter common mode voltage and take out difference signals excellently while being isolated; according to the size of the difference signals, the utility model sets an appropriate trigging level, produces a control signal, and makes the digital power amplifier in mute state, thereby reaching the purpose of protecting digital power amplifier.

Description

Digital audio frequency power amplifier output overcurrent protective circuit

Technical field:

The utility model relates to a kind of digital audio frequency power amplifier output overcurrent protective circuit.

Background technology:

At present; digital audio frequency power amplifier is in the stage in the ascendant; most output overcurrent protective circuit all uses conventional methods; promptly in main output loop, seal in the sampling resistor of a very little value; by detecting the voltage of sampling resistor, know promptly whether the output current of major loop is in over-current state.But the method is bigger to the technical indicator influence of digital power amplifier, and work is not very reliable.

Summary of the invention:

The purpose of this utility model is a kind of technical indicator that neither influences digital power amplifier of design, can make the digital audio frequency power amplifier output overcurrent protective circuit of digital power amplifier reliably working again.

The utility model digital audio frequency power amplifier output overcurrent protective circuit; it is characterized in that this protective circuit is by main output loop; auxiliary output circuit and four H bridge circuits that the MOSFET pipe constitutes; main output loop comprises the output filter of two symmetries; auxiliary output loop is made of the output filter of two symmetries and two difference detectors and an OR circuit; the corresponding set of number switch of the input of four MOSFET pipes code signal; its output links to each other with the input of a corresponding filter respectively; insert a difference testing circuit respectively between each main output filter and an auxiliary output filter, the output of two difference testing circuits all links to each other with the OR circuit input.This digital audio-frequency power amplifier output overcurrent protective circuit is utilized the auxiliary protection circuit of setting up, and carries out difference relatively with former main output circuit, by setting the difference adjustment, can determine over-current protection point.Because this circuit can be used for the way of output of H bridge, therefore a higher common-mode voltage is arranged in output loading.Can utilize modes such as photoelectricity; realize isolating on the one hand; leach common-mode voltage; simultaneously, can fine taking-up difference signal, according to the size of difference signal; set a suitable upset level; produce a control signal, make digital power amplifier be in mute state, thereby reach the purpose of protection digital power amplifier.

For reason given above, the difference testing circuit in the auxiliary protection circuit can be a photoelectric isolating device in the utility model.

The utility model circuit is simple, and result of use is good.No matter in which way its introducing not only can not make the technical indicator of primary circuit worsen, and can guarantee digital power amplifier output incorrect link, all can not cause the damage of power tube.

Description of drawings:

Fig. 1 the utility model circuit block diagram

Fig. 2 the utility model circuit diagram

Embodiment:

As seen from Figure 1, the utility model is by main output loop, auxiliary output loop and four H bridge circuits that the MOSFET pipe constitutes, main output loop comprises the main output filter of two symmetries, auxiliary output loop is by the auxiliary output filter of two symmetries, two difference detectors and an OR circuit constitute, the corresponding set of number switch of the input of four MOSFET pipes code signal end, its output links to each other with the input of a corresponding filter respectively, insert a difference testing circuit respectively between each main output filter and an auxiliary output filter, the output of two difference testing circuits all links to each other with the OR circuit input.As seen from Figure 2, this current foldback circuit master output circuit is made of two main output filters and load resistance RL., L1, C1, R1 and L2, C2, R2 constitute two main output filters of symmetry fully respectively, and L3, C3, R3, Q5 and L4, C4, R4, Q6 constitute two auxiliary output filters of symmetry fully respectively.Q1, Q2, Q3, Q4 are four MOSFET field effect transistor, link to each other with each output filter input respectively.Q5, Q6 are the photoelectricity isolated tube, and the output signal of two pipes is fed to OR circuit respectively.After in the digital power amplifier output circuit, introducing this protective circuit, can reliably play overcurrent protection.Circuit working just often, i.e. not short circuit of RL, or A point, the B any point of ordering is not when linking to each other with ground, VAA ' is approximately 0V; And connect when unusual when A, B two ends, (2 direct short-circuits of A, B, or any point of 2 of A, B links to each other with ground), the difference detector can detect the abnormal current that can cause damaging power MOSFET tube.

Claims

1; a kind of digital audio frequency power amplifier output overcurrent protective circuit; it is characterized in that this protective circuit is by main output loop; auxiliary output circuit and four H bridge circuits that the MOSFET pipe constitutes; main output loop comprises the output filter of two symmetries; auxiliary output loop is made of the output filter of two symmetries and two difference detectors and an OR circuit; the corresponding set of number switch of the input of four MOSFET pipes code signal end; its output links to each other with the input of a corresponding filter respectively; insert a difference testing circuit respectively between each main output filter and an auxiliary output filter, the output of two difference testing circuits all links to each other with the OR circuit input.

2, digital audio frequency power amplifier output overcurrent protective circuit as claimed in claim 1 is characterized in that this difference testing circuit is a photoelectric isolating device.