JP2017163240A - High-temperature protection circuit, operation method thereof, and audio signal output device - Google Patents

Abstract

Provided is a high-temperature protection circuit which can change a setting of a dynamic range compression (DRC) circuit when a temperature becomes a predetermined value or more and can suppress a temperature rise smoothly.
When a high temperature protection circuit detects that the temperature of a device has reached a predetermined temperature value, a temperature detection circuit 360 that outputs a high temperature warning signal OTW, and when a high temperature warning signal OTW is received, the audio signal dynamics A DRC circuit 114 that lowers a predetermined threshold level Gth for compressing the range and compresses the volume of the volume of the audio signal based on the lowered threshold level Gth.
[Selection] Figure 5

Description

  The present embodiment relates to a high-temperature protection circuit, an operation method thereof, and an audio signal output device.

  Standards for safety functions (for example, fail-safe functions, abnormality detection functions, safety stop functions, etc.) for all parts mounted on automobiles are being reviewed. In particular, many in-vehicle devices are electrically / electronically controlled, and not only high performance and high functionality but also safety are important needs. This is not an exception in, for example, in-car audio / video devices.

  An international standard ISO 26262 that systematically summarizes development methods and management methods for safe in-vehicle devices has been formulated (for example, see Non-Patent Document 1).

"ISO 26262-1: 2011", [online], 2011-11-15, International Organization for Standardization, [Search February 17, 2016], Internet <URL: https://www.iso.org/obp / ui / # iso: std: iso: 26262: -1: ed-1: v1: en>

  In general, audio data is rarely a single piece of data of the same size (level), so if data that exceeds the design output limit level continues, the device will generate heat and temperature May exceed the upper design limit.

  In the present embodiment, the state of the power MOS of the output stage is monitored, and when the temperature exceeds a predetermined value, the setting of the DRC circuit is changed to smoothly increase the temperature (the listener feels uncomfortable in the sense of hearing) The present invention provides a high-temperature protection circuit that can be suppressed (so that there is no problem), a method of operating the same, and an audio signal output device.

  According to one aspect of the present embodiment, a temperature detection circuit that outputs a high temperature warning signal when detecting that the temperature of the device has reached a predetermined temperature value, and a dynamic range of an audio signal when the high temperature warning signal is received. There is provided a high temperature protection circuit including a dynamic range compression circuit that lowers a predetermined threshold level for compressing the audio signal, and compresses the amplitude of the volume of the audio signal based on the lowered threshold level.

  According to another aspect of the present embodiment, a digital signal processor block to which PCM data is input, an oversampling and noise shaper block connected to the digital signal processor block, and the oversampling and noise shaper block A PWM signal generation block connected to the PWM signal generation block; and a driver output stage block connected to the PWM signal generation block. When the driver output stage block detects that the temperature of the device has reached a predetermined temperature value, A temperature detection circuit for outputting a warning signal, and when the digital signal processor block receives the high temperature warning signal, the digital signal processor block lowers a predetermined threshold level for compressing the dynamic range of the audio signal, Audio signal output apparatus including a dynamic range compression circuit for compressing the intensity width of the volume of the audio signal based on the value level is provided.

  According to another aspect of the present embodiment, there is provided a method for operating a high temperature protection circuit comprising a temperature detection circuit, a threshold control circuit, and a dynamic range compression circuit, wherein the temperature detection circuit has a predetermined temperature of the device. Detecting that the value has been reached, outputting a high temperature warning signal; and receiving the high temperature warning signal, the threshold control circuit reducing a predetermined threshold level for compressing the dynamic range of the audio signal; The dynamic range compression circuit compresses the volume of the audio signal based on the lowered predetermined threshold level.

  According to the present embodiment, the state of the power MOS of the output stage is monitored, and when the temperature exceeds a predetermined value, the setting of the DRC circuit is changed so that the temperature rises smoothly (for the listener to be audible) Thus, it is possible to provide a high-temperature protection circuit that can be suppressed (so that there is no sense of incongruity), an operation method thereof, and an audio signal output device.

The schematic diagram which illustrates the relationship between the input gain and output gain of the audio | voice signal input into the high temperature protection circuit which concerns on embodiment. The schematic diagram which illustrates the relationship between the frequency of an input audio | voice signal, and an output gain. It is a schematic diagram which shows the example of an input audio | voice signal, Comprising: (a) The audio | voice signal example which has a random fluctuation | variation amplitude characteristic, (b) The audio | voice signal example which has an amplitude characteristic comparable as positive / negative. The schematic diagram which shows an example of the flow of the protection process of the audio | voice signal output device which concerns on embodiment. 1 is a schematic configuration diagram illustrating a schematic configuration of a high-temperature protection circuit according to an embodiment. The schematic diagram which shows the example of adjustment of the predetermined threshold level of the DRC circuit in the high temperature protection circuit which concerns on embodiment. The typical block block diagram which shows an example of the audio | voice signal output device to which the high temperature protection circuit which concerns on embodiment is applied. It is a typical block block diagram which shows the structural example of the digital signal processor in the audio | voice signal output device which concerns on embodiment, (a) The internal structural example of a DRC circuit part, (b) DRC connected to the audio | voice signal processing part An example of a circuit part. The typical block block diagram which shows another example of the audio | voice signal output device to which the high temperature protection circuit which concerns on embodiment is applied. The typical wave form diagram which shows the operation | movement (transition) example of a DRC circuit. The schematic diagram which illustrates the DRC input / output gain characteristic in the high temperature protection circuit which concerns on embodiment. The typical block diagram which shows the example which applied the some DRC circuit for every some band. The schematic diagram which illustrates each threshold value of the DRC circuit for every some band. It is a schematic timing chart which shows the operation example of the high temperature protection circuit which concerns on embodiment, (a) High temperature warning signal, (b) Output gain, (c) Chip temperature. The typical timing chart which shows the operation example (high temperature warning signal and threshold value of DRC) of the high temperature protection circuit according to the embodiment. The schematic diagram which shows the schematic structural example of the temperature detection circuit in the high temperature protection circuit which concerns on embodiment. The typical block diagram which shows the connection example of the temperature detection circuit and DSP in the high temperature protection circuit which concerns on embodiment. 6 is a flowchart chart illustrating an example of an operation method of the high-temperature protection circuit according to the embodiment.

  Next, embodiments will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiment described below exemplifies an apparatus and a method for embodying the technical idea, and in this embodiment, the material, shape, structure, arrangement, etc. of the component parts are described below. It is not something specific. This embodiment can be modified in various ways within the scope of the claims.

[Embodiment]
(High temperature protection circuit)
FIG. 1 schematically illustrates a relationship (input / output characteristics) between an input gain Gi and an output gain Go of an audio signal input to the high-temperature protection circuit according to the embodiment. In the high-temperature protection circuit according to the embodiment, for example, as shown in FIG. 1, the dynamic range compression (DRC) function is maintained so that the output gain Go = Gth at the input gain Gi = Gi1. Has been.

  FIG. 2 schematically illustrates the relationship between the frequency f of the input audio signal and the output gain Go. In the high temperature protection circuit according to the embodiment, by having the DRC function, the output gain Go can be controlled for each frequency band, for example, as shown in FIG. For example, in the example shown in FIG. 2, the output gain Go fluctuates so as to have a peak-shaped peak level within the range of the band ΔF1 from the frequency 0 to f1, but the band ΔF2 from the frequency f1 to f2 In this range, the fluctuation range of the output gain Go is narrower than the output gain Go in the range of the band ΔF1.

  FIG. 3A schematically shows an example of an audio signal having an amplitude characteristic with large fluctuations, and FIG. 3B schematically shows an example of an audio signal having an amplitude characteristic of the same degree. In general, the audio data is rarely data having a signal level that is approximately the same (single) as positive and negative as illustrated in FIG. 3B, and the irregular fluctuation amplitude as illustrated in FIG. Has characteristics. However, if audio data having a size greater than the design output limit level continues, a device such as a speaker may generate heat, and its temperature may exceed the design upper limit.

  Dynamic range compression (as a function of restricting output smoothly (so that the listener does not feel uncomfortable about the audibility) for such an audio signal whose signal magnitude (signal level) fluctuates irregularly DRC (Dynamic Range Compression).

  As illustrated in FIGS. 1 and 2, DRC is a function that prevents data exceeding the threshold Gth from being output by lowering the gain when data exceeding a predetermined threshold (threshold) Gth is input. That is, by compressing the dynamic range of the audio signal within a predetermined threshold level Gth (reducing the volume of the volume), excessive input to the power MOS and the like at the subsequent stage is suppressed.

  FIG. 4 schematically shows an example of the protection processing flow of the audio signal output apparatus according to the embodiment. As illustrated in FIG. 4, the high-temperature protection circuit according to the embodiment includes various types of protection processes in which output short-circuit protection, high-temperature warning, high-temperature protection, power reduction protection, speaker DC voltage application protection, and overcurrent protection are one cycle. Execute.

  FIG. 5 schematically illustrates a schematic configuration of the high-temperature protection circuit according to the embodiment. The high temperature protection circuit according to the embodiment includes a digital signal processor (DSP) block 110 and a power stage 350. The power stage 350 includes a temperature detection circuit 360 that outputs a high temperature warning signal OTW when it detects that the temperature of the device has reached a predetermined temperature value. When the DSP block 110 receives the high temperature warning signal OTW, the audio stage 350 receives an audio signal. A DRC circuit 114 that lowers a predetermined threshold level Gth for compressing the dynamic range of the audio signal and compresses the intensity level of the volume of the audio signal based on the lowered threshold level Gth.

  When the high temperature warning signal OTW continues to be released (the high temperature warning signal OTW is not received), the DRC circuit 114 raises the predetermined threshold level Gth, and the level of the volume of the audio signal based on the raised threshold level Gth To restore.

  A command (Command) and a PWM signal are transmitted from the DSP block 110 to the power stage 350. An error signal ERROR is input from the power stage 350 to the DSP block, and a power stage flag is transmitted in a time division manner. When the temperature detection circuit 360 detects that the temperature of the device (chip) in the power stage 350 has reached a predetermined temperature value (for example, 125 ° C.), a high temperature warning signal OTW is output from the power stage 350 to the DSP block 110. .

  Further, when the temperature detection circuit 360 detects that the temperature of the device (chip) has reached a predetermined temperature value (for example, 150 ° C.), a high temperature error signal OTP is output from the power stage 350 to the DSP block 110, and the power stage 350 Some or all of the operations are stopped. Specifically, when the high-temperature error signal OTP is output, the output to the speaker or the like is muted through mute to prevent thermal runaway.

  When the DRC circuit 114 receives the high temperature warning signal OTW from the power stage 350, the DRC circuit 114 lowers the predetermined threshold level Gth for compressing the dynamic range of the audio signal, and compresses the intensity range of the volume. In addition, when the high temperature warning OTW continues to be released (when the high temperature warning OTW is not transmitted from the power stage 350), the DRC circuit 114 increases the predetermined threshold level Gth and restores the volume level of the sound volume.

  The DSP block 110 including the DRC circuit 114 and the power stage 350 including the temperature detection circuit 360 illustrated in FIG. 5 may be integrated as a single semiconductor device, or the DSP block 110 and the power stage. 350 may be configured as a single semiconductor device.

  Also, the DRC circuit 114 may be configured as a semiconductor device integrated with the DSP block 110 in a form installed outside the DSP block 110. Further, the temperature detection circuit 360 may be configured as a semiconductor device integrated with the power stage 350 in a form installed outside the power stage 350.

  FIG. 6 schematically shows an example of adjusting the predetermined threshold level Gth of the DRC circuit 114.

  As illustrated in FIG. 6, when the high temperature warning signal OTW is output from the power stage 350 while the normal state continues (time t1), the predetermined threshold level Gth of the DRC circuit 114 is set to a predetermined value ΔG. As long as the high temperature warning signal OTW is output (until time t3), the predetermined threshold level Gth of the DRC circuit 114 is decreased by a predetermined value ΔG every predetermined time (ΔT), and the volume of the volume is compressed. .

  Thereafter, if the high temperature warning signal OTW continues to be released for a predetermined time (ΔT ′) (that is, from time t3 to t4), the high temperature warning signal OTW continues to be released every predetermined time (ΔT) (from time t4). (Up to t6) The predetermined threshold level Gth of the DRC circuit 114 is increased by a predetermined value ΔG to restore the intensity range of the volume.

  As described above, according to the high-temperature protection circuit according to the embodiment, the state of the power stage 350 (such as the power MOS of the output stage) is monitored, and when the temperature becomes a certain level or higher, By changing the set value of the threshold level Gth, the temperature rise can be suppressed smoothly (so that the listener does not feel uncomfortable in hearing).

  Further, according to the high temperature protection circuit according to the embodiment, since the set value of the predetermined threshold level Gth of the DRC circuit 114 can be changed, the value of the threshold level Gth can be set relatively large. , A decrease in sound pressure due to DRC processing can be suppressed.

  In addition, according to the high-temperature protection circuit according to the embodiment, since the device (chip) temperature can be controlled so as not to rise excessively, the reliability of the entire system is improved.

  In addition, according to the high temperature protection circuit according to the embodiment, since the threshold level Gth of the DRC circuit 114 is changed (adjusted) instead of changing the gain of the DRC circuit 114, there is no sense of incongruity in the output sound. The sound pressure of the output sound can be stably maintained.

(Audio signal output device)
FIG. 7 schematically illustrates a block configuration example of an audio signal output device to which the high-temperature protection circuit according to the embodiment is applied.

  The audio signal output device includes a logic block, an analog signal (sine wave signal) block, and an analog signal (PWM signal) block.

  The logic block includes a DSP 110 to which PCM data is input, an 8-times oversampling filter (OVS) 120 of a logic unit connected to the DSP 110, and an error control circuit 140 connected to the DSP 110. The high temperature warning signal OTW and the high temperature error signal OTP output from the temperature detection circuit 360 included in the output FETs 320A and 320B are supplied to the DSP 110 through the error control circuit 140. Further, an overcurrent protection signal OCP for preventing deterioration or breakage of a speaker or the like due to DC data is also supplied to the error control circuit 140. When the error control circuit 140 receives the high temperature warning signal OTW, the high temperature error signal OTP, the overcurrent protection signal OCP, etc., the error control circuit 140 sends the error signal ERROR to a CPU such as a sensor or a CPU of an engine control unit (ECU) as necessary. Output. In response to the error signal ERROR, the CPU such as the sensor or the CPU executes processing for protecting the system (stopping the function, reducing the function, etc.) as necessary.

  The analog signal (sine wave signal) block includes a MUTE circuit 220 connected to the 8 × OVS 120, an inverting amplifier 230 connected to the MUTE circuit 220, an output of the inverting amplifier 230, and an output of the BIAS flip 240. Side output feedback control (FBC) circuit 250A, N-side output feedback control (FBC) circuit 250B for inputting the output of MUTE circuit 220 and the output of BIAS flip 240, and pulse width modulation connected to P-side FBC circuit 250A (PWM) circuit 270A and PWM circuit 270B connected to N-side FBC circuit 250B. The MUTE circuit 220 is a circuit for preventing a pop sound generated when the power is turned on.

  The analog signal (PWM signal) block includes a timing control (TCP) circuit 310A connected to the PWM circuit 270A, a timing control (TCN) circuit 310B connected to the PWM circuit 270B, and an output FET 320A connected to the TCP circuit 310A. And an output FET 320B connected to the TCN circuit 310B. Outputs from the output FETs 320A and 320B are output from the output terminals P and N to an external load (such as the speaker 190), respectively.

(DRC circuit)
FIG. 8A schematically shows an internal configuration example of the DRC circuit unit in the DSP block 110.

  As illustrated in FIG. 8A, the DSP block 110 includes a CPU 111 that controls each unit, a threshold control circuit 112 that changes a threshold level Gth, and a DRC circuit 114 that compresses / restores a dynamic range. As described with reference to FIG. 6, the threshold control circuit 112 sets a predetermined threshold level Gth of the DRC circuit 114 when the high temperature warning signal OTW is output from the power stage 350 while the normal state continues. As long as the high temperature warning signal OTW is output, the predetermined threshold level Gth of the DRC circuit 114 is decreased by the predetermined value ΔG every predetermined time (ΔT).

  Thereafter, when the high temperature warning signal OTW continues to be released for a predetermined time (ΔT ′), the threshold control circuit 112 performs a predetermined threshold value of the DRC circuit 114 every predetermined time (ΔT) for which the high temperature warning signal OTW continues to be released. The level Gth is increased by a predetermined value ΔG.

  The DRC circuit 114 compresses or restores the dynamic range of the audio signal according to the threshold level Gth changed (adjusted) by the threshold control circuit 112.

  In the example shown in FIG. 8A, the threshold control circuit 112 and the DRC circuit 114 are individually configured. However, the threshold control circuit 112 and the DRC circuit 114 are integrated as a DRC circuit 114. Also good.

  FIG. 8B schematically shows an example of the DRC circuit 114 connected to the audio signal processing unit (digital signal processing unit) 113. The audio signal processing unit 113 includes a scaler circuit 1131 for inputting audio data, a volume circuit 1132 connected to the scaler circuit 1131, a balance circuit 1133 connected to the volume circuit 1132, and an equalizer circuit connected to the balance circuit 1133. The DRC circuit 114 is connected to the equalizer circuit 1134.

  FIG. 9 schematically shows another block configuration example of the audio signal output device to which the high-temperature protection circuit according to the embodiment is applied.

  The audio signal output apparatus illustrated in FIG. 9 is connected to a DSP block 110 to which PCM data is input, an oversampling and noise shaper block 410 connected to the DSP block 110, and an oversampling and noise shaper block 410. The PWM signal generation block 420 and a driver output stage block 430 that is connected to the PWM signal generation block 420 and includes a temperature detection circuit 360 (not shown in FIG. 9). The DSP block 110 includes a digital signal processing unit 113 such as an equalizer and a volume, a DRC circuit 114, and a post scheduler / high pass filter (HPF) processing unit 115.

  The high temperature warning signal OTW output from the temperature detection circuit 360 in the driver output stage block 430 is supplied to the DSP block 110 (DRC circuit 114). In response to the high temperature warning signal OTW, as long as the predetermined threshold level Gth of the DRC circuit 114 is lowered by a predetermined value ΔG and the high temperature warning signal OTW is output, the DRC circuit 114 The predetermined threshold level Gth is lowered by a predetermined value ΔG. Thereafter, if the high temperature warning signal OTW continues to be released for a predetermined time (ΔT ′), the predetermined threshold level Gth of the DRC circuit 114 is set to a predetermined value every predetermined time (ΔT) for which the high temperature warning signal OTW is released. Increased by the value ΔG.

  FIG. 10 is a waveform diagram schematically showing an example of operation (transition) of the DRC circuit 114. DRC is a function that prevents data greater than the threshold Gth from being output by lowering the gain when data greater than a predetermined threshold (threshold) Gth is input. The dynamic range of the audio signal is reduced to a predetermined threshold level Gth. , The excessive input to the power MOS etc. in the subsequent stage is suppressed.

  As illustrated in FIG. 10, the period ATIME is a detection time (time t <b> 1 to t <b> 2) when it is detected that data having a predetermined threshold value Gth or more is input. When data of a predetermined threshold Gth or more is input during the period ATIME (between times t1 and t2), the gain is lowered (compressed) over the period A_RATE (between times t2 and t3), and the output data level is reduced. The threshold level is adjusted to about AGC_TH.

  Thereafter, during the period R_TIME (between times t4 and t5), if data less than or equal to the predetermined threshold Gth continues to be input (if the output data level continues below the threshold level AGC_TH), during the period R_RATE (between times t5 and t5) (during t6), the gain is raised (restored) to adjust the output data level to about the threshold level AGC_TH.

FIG. 11 schematically illustrates DRC input / output gain _Go characteristics in the high-temperature protection circuit according to the embodiment.

  Expression (1) for obtaining the slope α of the DRC compression level in FIG. 11 is exemplified below.

  For the slope α, a value obtained by calculation is converted into 2's complement 8-bit Hex data.

α = (10 ^{(y / 20)} −10 ^{(x / 20)} ) / (10 ^{(TH / 20)} −10 ^{(x / 20)} ) × 128 (1)

Here, TH is the threshold value AGC_TH1, x is the input level, and y is the output level.

  For example, α when the threshold AGC_TH1 = −12 dB, x = 0 dB, and y = −6 dB is obtained by the following equations (2) to (3).

α = (10 ^(−6/20) −10 ^(0/20) ) / (10 ^(−12/20) −10 ^(0/20) ) × 128 (2)
α = 85.266 → 55 _H (3)

Here, the obtained 55 _H is set as a command.

(DRC circuit for multiple bands)
FIG. 12 schematically shows a configuration example in which the DRC circuit 114 is applied to each of a plurality of predetermined bands in the high-temperature protection circuit according to the embodiment.

  The high-temperature protection circuit in FIG. 12 includes filters 116a, 116b, and 116c provided for each of a plurality of bands, a plurality of DRC circuits 114a, 114b, and 114c connected to the filters 116a, 116b, and 116c, and a plurality of DRC circuits, respectively. 114a, 114b and 114c, respectively. The filters 116a, 116b, and 116c divide the input audio signal into a plurality of bands (three bands in the example of FIG. 12). Each of the plurality of DRC circuits 114a, 114b, and 114c performs DRC processing on the corresponding band. The adder 18 adds (recombines) the outputs of the plurality of DRC circuits 114a, 114b, and 114c and outputs the result. With this configuration, DRC can be applied with a higher sound pressure. For example, such DRC circuits 114a, 114b, and 114c for each of a plurality of bands are used for the purpose of protecting a speaker and preventing clipping of a large audio signal.

  Non-clip output is possible for each of the three bands of the DRC circuits 114a, 114b, and 114c. It is also possible to set the slope α of the compression level of the DRC circuits 114a, 114b, 114c.

  Further, as illustrated in FIG. 13, threshold values Gth1, Gth2, and Gth3 of the DRC circuits 114a, 114b, and 114c for each of a plurality of bands can be set.

(Operation example of high-temperature protection circuit)
Figure 14 is a timing chart schematically showing an example of the operation of the high-temperature protection circuit according to the embodiment, FIG. 14 (a), the high temperature warning signal OTW, FIG. 14 (b) output gain G _o, 14 (C) shows the chip temperature TEMP.

Hot when warning signal OTW is outputted between times t1 to t2, the output gain G _o is lowered at an inclination OTAR, also lowered the chip temperature TEMP. The chip temperature TEMP decreases by ΔT every predetermined period (in this case, times t1 to t11).

When hot warning signal OTW is not output until the time t2 to t3, the output gain G _o is raised at an inclination OTRR, also increases the chip temperature TEMP.

When hot warning signal OTW between times t3~t4 is output again, output gain G _o is lowered again, the chip temperature TEMP is also lowered again.

  FIG. 15 is a schematic timing chart showing an operation example (high temperature warning signal OTW and threshold Gth of the DRC circuit 114) of the high temperature protection circuit according to the embodiment.

  As illustrated in FIG. 15, when the normal state continues, the high temperature warning signal OTW is output at time t1 and continues to be output until time t3. At time t2 to t3, a predetermined threshold level Gth of the DRC circuit 114 is output. Is reduced by a predetermined value ΔG (at the inclination of time t2 to t3). When the high-temperature warning signal OTW is canceled at time t3 and continues to be canceled as it is, the threshold level Gth is increased by a predetermined value ΔG (at the inclination of time t4 to t5) from time t4 to t5. Since the threshold level Gth is restored to the original level at time t5, the threshold level Gth is maintained at the original level even after the high temperature warning signal OTW is continuously released after time t5.

  High temperature warning signal OTW output detection time at times t1 to t2, high temperature warning signal OTW release detection time at times t3 to t4, slopes at times t2 to t3, and slopes at times t4 to t5 can be set from the outside by command input or the like It is.

  FIG. 16 schematically shows a schematic configuration example of the temperature detection circuit 360 in the high-temperature protection circuit according to the embodiment. As shown in FIG. 16, the temperature detection circuit 360 uses a series circuit of diodes D1 and D2 through which a constant current from the current source I is conducted and a diode comparator C1 to which a predetermined reference voltage Eo is input, to thereby obtain a reference voltage Vref. Can be generated.

  FIG. 17 schematically shows a connection example between the temperature detection circuit 360 and the DSP block 110 in the high-temperature protection circuit according to the embodiment. Comparing is performed using the temperature characteristic of the reference voltage Vref which is the output of the diode comparator C1. The detected temperature can be set by the reference voltage Eo.

(Operation method of high-temperature protection circuit)
FIG. 18 schematically illustrates an operation method of the high-temperature protection circuit according to the embodiment.

  In step S101, audio signal processing is started.

  In step S102, the DRC circuit 114 of the DSP block 110 refers to the flag from the power stage 350.

  When the high temperature error signal OTP is output from the power stage 350 in step S103, a part or all of the operation of the power stage 350 is stopped in step S104. Specifically, when the high-temperature error signal OTP is output, the output to the speaker or the like is muted through mute to prevent thermal runaway.

  In step S105, when the high-temperature warning signal OTW is output from the power stage 350, the threshold control circuit 112 lowers a predetermined threshold level Gth for compressing the dynamic range of the audio signal (step S106), and the DRC circuit 114 The volume of the volume is compressed (step S109). The process of the DRC circuit 114 is executed until a predetermined time (ΔT) elapses (steps S111 → S109).

  When a predetermined time (ΔT) has elapsed (step S110), the process returns to step S102 again, and the flag from the power stage 350 is referred to.

  Thereafter, when the high temperature warning signal OTW from the power stage 350 is not output (cancel) for a predetermined time (ΔT ′) (step S105 → S107), the threshold control circuit 112 determines the predetermined threshold level Gth of the DRC circuit 114. Is increased by a predetermined value ΔG (step S108), and the DRC circuit 114 restores the volume level of the volume (step S109). The process of the DRC circuit 114 is executed until a predetermined time (ΔT) elapses (steps S111 → S109).

  When a predetermined time (ΔT) has elapsed (step S110), the process returns to step S102 again, and the same processing as described above is repeated (steps S102 to S110).

  As described above, according to the present embodiment, the state of the power MOS in the output stage is monitored, and when the temperature exceeds a predetermined value, the setting of the DRC circuit is changed to smoothly increase the temperature. It is possible to provide a high-temperature protection circuit that can be suppressed (so that the listener does not feel uncomfortable), a method for operating the same, a semiconductor device, and an audio signal output device.

[Other embodiments]
While the embodiments have been described as described above, the discussion and drawings that form part of this disclosure are illustrative and should not be construed as limiting. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the embodiment, the high-temperature protection circuit and the audio signal output device can be applied not only to an in-vehicle electronic device but also to an electronic device used for various purposes.

  As described above, various embodiments that are not described herein are included.

  The high-temperature protection circuit and the operation method thereof, and the audio signal output device according to the present embodiment are, for example, a TV, a radio, a radio cassette player, a car audio, a home theater system, an audio component, a mobile phone, a smart phone, an electronic musical instrument, etc. Widely applicable to all output devices.

110: Digital signal processor (DSP) block 111: CPU
112 ... Threshold control circuit 113 ... Audio signal processor (digital signal processor)
1331 ... Scaler circuit 1132 ... Volume circuit 1133 ... Balance circuit 1134 ... Equalizer circuits 114, 114a, 114b, 114c ... Dynamic range compression (DRC) circuit 115 ... Post scheduler / high pass filter (HPF) processing sections 116a, 116b, 116c ... Filter 120 ... 8 times oversampling filter (OVS)
140 ... Error control circuit 220 ... MUTE circuit 230 ... Inverting amplifier 240 ... BIAS flip 250A ... P-side output feedback control (FBC) circuit 250B ... N-side output feedback control (FBC) circuit 270A, 270B ... Pulse width modulation (PWM) circuit 310A ... Timing control (TCP) circuit 310B ... Timing control (TCN) circuit 320A, 320B ... Output FET
350 ... Power stage 360 ... Temperature detection circuit 410 ... Oversampling and noise shaper block 420 ... PWM signal generation block 430 ... Driver output stage block ATIME, A_RATE, R_TIME, R_RATE ... Period C1 ... Diode comparator Eo ... Reference voltage ERROR ... Error Signals Gth, Gth1, Gth2, Gth3, AGC_TH ... Threshold levels Gi, Gi1 ... Input gain Go ... Output gain OCP ... Overcurrent protection signal OTP ... High temperature error signal OTW ... High temperature warning signal t1, t2, t3, t4, t5, t11 ... time TEMP ... chip temperature α ... slope ΔT, ΔT '... predetermined time ΔG ... predetermined value

Claims (20)

A temperature detection circuit that outputs a high-temperature warning signal upon detecting that the temperature of the device has reached a predetermined temperature value; and
A dynamic range compression circuit that lowers a predetermined threshold level for compressing the dynamic range of the audio signal when receiving the high-temperature warning signal, and compresses the volume of the volume of the audio signal based on the lowered threshold level; A high temperature protection circuit comprising:   When the dynamic range compression circuit stops receiving the high-temperature warning signal, the dynamic range compression circuit raises a predetermined threshold level, and restores the intensity range of the audio signal based on the raised threshold level. The high-temperature protection circuit according to claim 1.   2. The high temperature protection according to claim 1, wherein the dynamic range compression circuit lowers the predetermined threshold level by a predetermined value every predetermined time while the state of receiving the high temperature warning signal continues. circuit.   3. The high temperature protection according to claim 2, wherein the dynamic range compression circuit raises the predetermined threshold level by a predetermined value every predetermined time while the high temperature warning signal is not received. circuit. The high temperature protection circuit includes a digital signal processor block and a power stage,
The high temperature protection circuit according to claim 1, wherein the dynamic range compression circuit is disposed in the digital signal processor block, and the temperature detection circuit is disposed in the power stage.   The high-temperature protection circuit according to claim 1, wherein the dynamic range compression circuit is arranged for each of a plurality of predetermined bands.   The high-temperature protection circuit according to claim 1, wherein the DC detection circuit and the error control circuit are each configured as a single semiconductor device.   The high-temperature protection circuit according to any one of claims 1 to 6, wherein the temperature detection circuit and the dynamic range compression circuit are configured as a semiconductor device integrated together. A digital signal processor block to which PCM data is input;
An oversampling and noise shaper block connected to the digital signal processor block;
A PWM signal generation block connected to the oversampling and noise shaper block;
A driver output stage block connected to the PWM signal generation block,
The driver output stage block includes a temperature detection circuit that outputs a high-temperature warning signal when detecting that the temperature of the device has reached a predetermined temperature value,
When the digital signal processor block receives the high-temperature warning signal, the digital signal processor block lowers a predetermined threshold level for compressing the dynamic range of the audio signal, and adjusts the volume of the volume of the audio signal based on the lowered threshold level. An audio signal output device comprising a dynamic range compression circuit for compression.   When the dynamic range compression circuit stops receiving the high-temperature warning signal, the dynamic range compression circuit raises a predetermined threshold level, and restores the intensity range of the audio signal based on the raised threshold level. The audio signal output device according to claim 9.   10. The audio signal according to claim 9, wherein the dynamic range compression circuit lowers the predetermined threshold level by a predetermined value every predetermined time while the state of receiving the high temperature warning signal continues. Output device.   11. The audio signal according to claim 10, wherein the dynamic range compression circuit raises the predetermined threshold level by a predetermined value every predetermined time while the high temperature warning signal is not received. Output device. The high temperature protection circuit includes a digital signal processor block and a power stage,
10. The audio signal output device according to claim 9, wherein the dynamic range compression circuit is disposed in the digital signal processor block, and the temperature detection circuit is disposed in the power stage.   The audio signal output device according to claim 9, wherein the dynamic range compression circuit is arranged for each of a plurality of predetermined bands.   15. The audio signal output device according to claim 9, wherein the DC detection circuit and the error control circuit are each configured as a single semiconductor device.   15. The audio signal output device according to any one of 9 to 14, wherein the temperature detection circuit and the dynamic range compression circuit are configured as a semiconductor device integrated together. A method of operating a high temperature protection circuit comprising a temperature detection circuit, a threshold control circuit, and a dynamic range compression circuit,
Outputting a high-temperature warning signal when the temperature detection circuit detects that the temperature of the device has reached a predetermined temperature value; and
Receiving the high temperature warning signal, the threshold control circuit lowering a predetermined threshold level for compressing the dynamic range of the audio signal;
The dynamic range compression circuit compresses the amplitude range of the audio signal based on the lowered predetermined threshold level. The method of operating a high-temperature protection circuit, When the high temperature warning signal is no longer received, the threshold control circuit raises a predetermined threshold level; and
The high-temperature protection circuit according to claim 17, further comprising: restoring the dynamic range of the audio signal based on the raised predetermined threshold level. How it works.   18. The high temperature protection circuit according to claim 17, wherein the threshold control circuit lowers the predetermined threshold level by a predetermined value every predetermined time while the state of receiving the high temperature warning signal continues. How it works.   19. The high temperature protection circuit according to claim 18, wherein the threshold control circuit raises the predetermined threshold level by a predetermined value every predetermined time while the state of not receiving the high temperature warning signal continues. How it works.

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