JP6832082B2 - DC / DC converter and its control circuit, inductor short circuit detection method, control method, electronic equipment - Google Patents

Description

The present invention relates to a DC / DC converter.

In various electronic devices, a DC / DC converter that converts a DC voltage of one voltage value into a DC voltage of another voltage value is used. FIG. 1 is a block diagram showing a basic configuration of the DC / DC converter 800. The DC / DC converter 800 in FIG. 1 is a buck converter, and lowers the input voltage V _IN of the input line 802 to generate a regulated output voltage V _OUT (REF) at the target voltage V _{OUT (REF).} , Supply to a load (not shown) connected to the output line 804. The DC / DC converter 800 includes an output circuit 810 and a control circuit 900. The output circuit 810 includes a switching transistor M1, a synchronous rectifier transistor M2, an inductor L1, and an output capacitor C1. The control circuit 900 feedback-controls the switching duty ratio of the switching transistor M1 and the synchronous rectifier transistor M2 so that _{the output voltage V OUT} approaches the target voltage V _{OUT (REF).}

The resistors R11 and R12 divide the output voltage V _OUT input to the feedback (FB) terminal to generate a feedback voltage V _FB. The error amplifier 902 of the control circuit 900 amplifies the error between the feedback voltage V _FB and the reference voltage V _REF , and generates an error signal V _ERR. The pulse modulator 904 generates _{a pulse signal S PWM} having a duty ratio corresponding to _{the error signal VERR.} The driver 906 switches the switching transistor M1 and the synchronous rectification transistor M2 in response to the pulse signal S _PWM , and generates a rectangular voltage V _{LX having an input voltage V IN} and a ground voltage V _{GND at the switching (LX) terminal.}

The DC / DC converter 800 generally includes an overcurrent protection (OCP) function, and the control circuit 900 includes an OCP circuit 910. _{The OCP circuit 910 monitors the currents I 1} and IM ₂ flowing through the switching transistor M1 and / or the synchronous rectifier transistor M2, and asserts the OCP signal when a predetermined threshold value is exceeded or when the state is maintained. When the OCP signal is asserted, the control circuit 900 stops switching between the switching transistor M1 and the synchronous rectifier transistor M2.

Therefore, in the DC / DC converter 800 of FIG. 1, power cannot be supplied to the load in the overcurrent state. When the load of the DC / DC converter 800 is the main processor of the electronic device equipped with the DC / DC converter 800, the electronic device itself becomes inoperable.

The present invention has been made in view of the above problems, and one of the exemplary objects of the embodiment is to provide a DC / DC converter capable of supplying electric power to a load even in an abnormal state.

One aspect of the present invention relates to a control circuit of a multiphase DC / DC converter having a plurality of channels. The control circuit is an error amplifier that amplifies the error between the feedback signal according to the output voltage of the DC / DC converter and its target value and generates an error signal, and a pulse that generates a pulse signal of multiple channels based on the error signal. A modulator, multiple drivers that support multiple channels and drive the corresponding switching transistors based on the corresponding pulse signals, a short-circuit detection circuit that detects short circuits in the inductors of each of the multiple channels, and short-circuit detection. It is provided with a protection circuit for stopping the operation of the channel.

According to this aspect, power can be continuously supplied to the load by continuing the operation other than the channel in which the short circuit is detected. For short channels, stopping switching and fixing one end of the inductor to high impedance can prevent the influence on other channels.

In the short-circuit detection circuit, the first overcurrent state in which the current of the switching transistor of the DC / DC converter exceeds the threshold value and the second overcurrent state in which the current of the rectifier element of the DC / DC converter exceeds the threshold value are continuous. If it occurs, it may be determined that the inductor is short-circuited.
When the inductor is short-circuited, the inductance becomes substantially zero. Therefore, the currents of the switching transistor and the rectifying element are both overcurrent. According to this aspect, the short circuit of the inductor can be detected by monitoring the two overcurrent states.

The short-circuit detection circuit may determine that the inductor is short-circuited when the first overcurrent state and the second overcurrent state occur continuously over a plurality of cycles. This makes it possible to prevent erroneous detection of a short circuit due to noise or the like.

The control circuit compares the first detection signal corresponding to the current of the switching transistor with a predetermined first threshold signal, and uses the first overcurrent detection comparator to generate the first overcurrent detection signal and the current of the rectifying element. A second overcurrent detection comparator that compares the corresponding second detection signal with a predetermined second threshold signal and generates a second overcurrent detection signal may be further provided. The short circuit detection circuit may detect an inductor short circuit based on the first overcurrent detection signal and the second overcurrent detection signal.
By using a comparator for overcurrent detection to detect short circuits in inductors, it is possible to suppress an increase in hardware.

The first detection signal may be generated based on the drain-source voltage of the switching transistor. The rectifying element is a synchronous rectifying transistor, and the second detection signal may be generated based on the drain-source voltage of the synchronous rectifying transistor. The circuit configuration can be simplified by utilizing the known on-resistance of the transistor.

The first detection signal is based on the voltage drop of the impedance element provided in series with the switching transistor or the voltage drop of the impedance element provided in series with the replica transistor connected in parallel with the switching transistor. It may be generated. The impedance element may be a resistor or a wiring made of aluminum or the like.

The phase difference may be changed when the number of operating channels decreases as a result of detecting an inductor short circuit in a certain channel. This makes it possible to improve the stability of the system.

The number of channels of the DC / DC converter is M, and if an inductor short circuit is detected in a certain channel during operation in N channel (N <M), one of the unused channels may be switched to the operating state. In other words, if there is a vacancy in the channel, the same number of channels can be maintained by using it as an alternative.

The control circuit may further include a notification unit that notifies the outside when an inductor short circuit is detected.

The control circuit may further include an open detection circuit that detects the opening of the inductor of each of the plurality of channels. The protection circuit may stop the operation of the channel where the open is detected.

The phase difference may be changed when the number of operating channels decreases as a result of detecting the openness of the inductor in a certain channel. This makes it possible to improve the stability of the system.

The number of channels of the DC / DC converter is M, and one of the unused channels may be switched to the operating state when the openness of the inductor is detected in a certain channel while operating in the N channel (N <M). As a result, the number of operating channels can be maintained.

The control circuit may be integrally integrated on one semiconductor substrate. "Integrated integration" includes cases where all the components of a circuit are formed on a semiconductor substrate or cases where the main components of a circuit are integrated integrally, and some of them are used for adjusting circuit constants. A resistor, a capacitor, or the like may be provided outside the semiconductor substrate.

Another aspect of the invention relates to a DC / DC converter. The DC / DC converter includes any of the above control circuits.

Another aspect of the invention relates to electronic devices. The electronic device may include the above-mentioned DC / DC converter.

Another aspect of the invention relates to a multiphase DC / DC converter having multiple M channels. This DC / DC converter can supply the power required by the load in N channels (N <M), and when an abnormality is detected in any of the channels, only that channel is stopped and the remaining channels are loaded. Continue to supply power to.

It should be noted that any combination of the above components or components and expressions of the present invention that are mutually replaced between methods, devices, systems, and the like are also effective as aspects of the present invention.

According to an aspect of the present invention, power can be supplied to the load even in an abnormal state.

It is a block diagram which shows the basic structure of a DC / DC converter. It is a circuit diagram of the DC / DC converter including the control circuit which concerns on embodiment. 3 (a) and 3 (b) are diagrams for explaining the first protection operation of the DC / DC converter of FIG. 4 (a) and 4 (b) are diagrams for explaining the second protection operation of the DC / DC converter of FIG. 5 (a) and 5 (b) are diagrams for explaining the third protection operation of the DC / DC converter of FIG. 6 (a) and 6 (b) are diagrams for explaining the first short-circuit detection method. It is a circuit diagram which shows the structure related to the overcurrent detection of a control circuit. It is a circuit diagram of the open detection circuit of an inductor. It is a figure which shows an example of the electronic device which includes the DC / DC converter which concerns on embodiment.

Hereinafter, the present invention will be described with reference to the drawings based on preferred embodiments. The same or equivalent components, members, and processes shown in the drawings shall be designated by the same reference numerals, and redundant description will be omitted as appropriate. Further, the embodiment is not limited to the invention but is an example, and all the features and combinations thereof described in the embodiment are not necessarily essential to the invention.

In the present specification, "a state in which the member A is connected to the member B" means that the member A and the member B are physically directly connected, or the member A and the member B are electrically connected. It also includes cases of being indirectly connected via other members that do not affect the state or interfere with the function.

Similarly, "a state in which the member C is provided between the member A and the member B" means that the member A and the member C, or the member B and the member C are directly connected, and also electrically. It also includes the case of being indirectly connected via another member that does not affect the connection state or interfere with the function.

Further, "the signal A (voltage, current) corresponds to the signal B (voltage, current)" means that the signal A has a correlation with the signal B, and specifically, (i) the signal A. Is signal B, (ii) signal A is proportional to signal B, (iii) signal A is obtained by level-shifting signal B, (iv) signal A is obtained by amplifying signal B. If (v) signal A is obtained by inverting signal B, it means (vi) or any combination thereof, and the like. Those skilled in the art will understand that the range of "according to" is determined according to the types and applications of signals A and B.

FIG. 2 is a circuit diagram of a DC / DC converter 100 including the control circuit 200 according to the embodiment. Similar to FIG. 1, the DC / DC converter 100 is a multi-channel, multi-phase buck converter _{, receives a DC input voltage V IN} at the input line 102, steps down the DC input voltage V IN, and lowers the voltage to a predetermined target voltage V _OUT. A stabilized output voltage V _{OUT is generated in (REF)} and supplied to a load (not shown) connected to the output line 104.

The DC / DC converter 100 is composed of M channels (M is an integer of 2 or more). The number of channels M is arbitrary, and may be determined according to the application of the DC / DC converter 100, such as 2 channels, 3 channels, 4 channels, 6 channels, 8 channels, 12 channels, and 16 channels.

The DC / DC converter 100 can supply the power required by the load in N channels (N <M). For example, in the case of M = 2, N = 1 channel is configured to cover the required power of the load, and in the case of M = 4, N = 3 channels (or 2 channels or 1 channel) can cover the required power of the load. Is configured. When an abnormality is detected in any of the channels, the DC / DC converter 100 stops only that channel and continues to supply power to the load in the remaining channels. This is a basic feature of the DC / DC converter 100.

Hereinafter, the configuration of the DC / DC converter 100 will be described. The DC / DC converter 100 includes an output circuit 110 and a control circuit 200. The output circuit 110 has a switching transistor M1, a synchronous rectifier transistor M2, and an inductor L1 for each channel, and has an output capacitor C1 and resistors R11 and R12 common to the M channels. In the present embodiment, the switching transistor M1, the synchronous rectifier transistor M2, and the resistors R11 and R12 are integrated in the control circuit 200, but an external discrete element and chip components may be used.

The control circuit 200 is a functional IC (Integrated Circuit) integrated on a single semiconductor substrate. The control circuit 200 is provided with an input (VIN) terminal, a switching (LX) terminal, and a grounded (GND) terminal for each channel, and is provided with a feedback (FB) terminal common to all channels. A voltage corresponding to the output voltage V _OUT is fed back to the FB terminal. The control circuit 200 drives the switching transistors M1 and the synchronous rectifier transistors M2 of the plurality of channels CH1 to CHM so that the feedback signal V _{FB corresponding to the output voltage V OUT} approaches the target value V _REF.

The control circuit 200 includes an error amplifier 202, a pulse modulator 204, drivers 206_1 to 206_M, a main logic 210, a short detection circuit 220, and an open detection circuit 230. The error amplifier 202 amplifies the error between the feedback signal V _FB and its target value V _{REF according to the output voltage V OUT} , and generates the error signal V _ERR.

Pulse modulator 204 generates a pulse signal _S PWM1 _{to S PWMm} having a duty ratio corresponding to the error signal _{V ERR} (or frequency). The configuration and modulation method of the pulse modulator 204 are not particularly limited, but for example, a pulse width modulator in the peak current mode can be used.

The plurality of drivers 206 correspond to a plurality of channels. The driver 206_i of each channel drives the corresponding switching transistor M1 and the synchronous rectifier transistor M2 according to the corresponding _{pulse signal S PWMi.}

The main logic 210 is a logic circuit that controls the control circuit 200 in an integrated manner, and controls the activation sequence, the phase difference of a plurality of channels, and the like.

The short circuit detection circuit 220 detects a short circuit in the inductor L1 of each of the plurality of channels CH1 to CHM. The protection circuit 212 of the main logic 210 stops the operation of the channel in which the short circuit is detected.

Further, the open detection circuit 230 detects the opening of the inductor L1 of each of the plurality of channels CH1 to CHM. The protection circuit 212 stops the operation of the channel on which the open is detected.

When the short circuit or open of the inductor is detected, the notification unit 240 may notify the external circuit of the occurrence of an abnormality. Notification unit 240, via a pin 242 may be a serial interface circuit connected to the bus such as I ^{2 C.} Alternatively, the notification unit 240 may change the electrical state of the pin 242 depending on the presence or absence of an abnormality.

The above is the basic configuration of the DC / DC converter 100. Next, the operation will be described. 3A and 3B are diagrams for explaining the first protection operation of the DC / DC converter 100 of FIG. M = 2, and FIG. 3A shows the normal operation. Under normal conditions, the LX terminal of the first channel CH1 and the LX terminal of the second channel CH2 are switched with a phase difference of 180 degrees.

FIG. 3B shows an operation when the inductor L1 of the first channel CH1 is short-circuited. At this time, the protection circuit 212 turns off both the switching transistor M1 and the synchronous rectifier transistor M2 of the first channel CH1 to stop switching, and puts the LX terminal in a high impedance state. As a result, the DC / DC converter 100 continues to operate as a single-phase DC / DC converter in which only the second channel CH2 is active.

4 (a) and 4 (b) are diagrams for explaining the second protection operation of the DC / DC converter 100 of FIG. M = 2, and FIG. 3A shows normal operation in a light load state where the _{output current I OUT is small.} The main logic 210 controls to reduce the number of channels when the load is light. Specifically, the second channel CH2 is set as an unused channel, and the switching transistor M1 and the synchronous rectifier transistor M2 are turned off. The LX terminal of the second channel CH2 has a high impedance, and the LX terminal of the first channel CH1 performs a single-phase operation of switching.

FIG. 4B shows an operation when the inductor L1 of the first channel CH1 is short-circuited under a light load. At this time, the protection circuit 212 turns off both the switching transistor M1 and the synchronous rectifier transistor M2 of the first channel CH1 to stop switching, and puts the LX terminal in a high impedance state. Then, the second channel CH2, which was an unused channel, is switched to the used channel. As a result, the DC / DC converter 100 continues to operate as a single-phase DC / DC converter in which only the second channel CH2 is active.

5 (a) and 5 (b) are diagrams for explaining the third protection operation of the DC / DC converter 100 of FIG. M = 4, and FIG. 5 (a) shows the normal operation. Under normal conditions, the LX terminal of the first channel CH1 to the LX terminal of the fourth channel CH4 are switched with a phase difference of 90 degrees.

FIG. 5B shows an operation when the inductor L1 of the first channel CH1 is short-circuited. At this time, the protection circuit 212 turns off both the switching transistor M1 and the synchronous rectifier transistor M2 of the first channel CH1 to stop switching, and puts the LX terminal in a high impedance state. As a result, in the DC / DC converter 100, the three channels of the second channel CH2 to the fourth channel CH4 continue to operate actively. The main logic 210 changes the phase difference based on the changed number of active channels when the number of operating channels decreases. In this example, since the changed number of channels is N = 3, the phase difference is switched to 360 degrees / 3 = 120 degrees.

The above is the operation of the DC / DC converter 100.
According to the DC / DC converter 100, power can be continuously supplied to the load by continuing the operation other than the channel in which the short circuit is detected. For short channels, stopping switching and fixing one end of the inductor to high impedance can prevent the influence on other channels.

Further, as shown in FIGS. 4A and 4B, when there is a vacancy in the channel, the same number of channels can be maintained by using the vacant channel instead.

The same protection operation is executed even when the openness of the inductor is detected in any of the channels.

The present invention extends to various devices and circuits grasped as the block diagram and circuit diagram of FIG. 2 or derived from the above description, and is not limited to a specific configuration. Hereinafter, more specific configuration examples and examples will be described not for narrowing the scope of the present invention but for helping the understanding of the essence of the invention and the circuit operation and clarifying them.

Subsequently, short circuit detection of the inductor will be described.
(First short detection method)
6 (a) and 6 (b) are diagrams for explaining the first short-circuit detection method. FIG. 6A is a waveform diagram in a normal state. FIG. 6B shows a waveform when the inductor is short-circuited. When the inductor L1 is short-circuited, the inductance becomes substantially zero, and the peak value of the _{current IL1'flowing in the short-circuit path increases.} Since this current _IL1'is supplied from the switching transistor M1 and the synchronous rectifier transistor M2, the respective currents _IM1 and _IM2 are in an overcurrent state.

Therefore, the short-circuit detecting circuit 220 includes a first overcurrent condition φ1 current _{I M1} of the switching transistor M1 exceeds a threshold _{I OCP1,} current _{I M2} of the synchronous rectification transistor M2 is rectifying element the threshold _{I OCP2} When the second overcurrent state φ2 that exceeds is continuously generated, it is determined that the inductor L1 is short-circuited.

More preferably, the short circuit detection circuit 220 may determine that the inductor is short-circuited when the first overcurrent state φ1 and the second overcurrent state φ2 are continuously generated over a plurality of cycles. The number of cycles is not particularly limited, but about 2 to 5 cycles is preferable. This makes it possible to prevent erroneous detection of a short circuit due to noise or the like.

FIG. 7 is a circuit diagram showing a configuration related to overcurrent detection of the control circuit 200. The first overcurrent detection comparator OCP_COMP1 the first detection signal CS ₁ is compared with a predetermined first threshold signal _{I OCP1,} the comparison result the first overcurrent detection indicating the corresponding to the current _{I M1} of the switching transistor M1 ( OCP) Generates _{signal S OCP1.} Second overcurrent detection comparator OCP_COMP2 compares the second detection signal CS ₂ corresponding to the current _{I M2} of the synchronous rectification transistor M2 and a predetermined second threshold signal _{I OCP2,} comparison second overcurrent detection indicating the (OCP) Generate _{signal S OCP2.} The 1OCP signal _{S OCP1} and the 2OCP signal _{S OCP2} is supplied to the OCP circuit 250. The OCP circuit 250 is provided for normal overcurrent protection, and the first OCP signal _SOCP1 is continuously asserted for several cycles, or the second OCP signal _SOCP2 is continuously asserted for several cycles. If this happens, the switching of all channels is stopped.

The short circuit detection circuit 220 detects a short circuit in the inductor L1 based on the _{first OCP signal SOC1} and the second OCP signal _SOC2. By using a comparator for overcurrent detection to detect short circuits in inductors, it is possible to suppress an increase in hardware.

The first detection signal CS ₁ may be generated based on the drain-source voltage V _{DS 1 of the switching transistor M1.} Similarly, the second detection signal CS ₂ may be generated based on the drain-source voltage V _{DS 2 of the synchronous rectifier transistor M2.} The circuit configuration can be simplified by utilizing the known on-resistance of the transistor.

Alternatively, the first detection signal CS ₁ and the second detection signal CS ₂ may be generated based on the voltage drop of the impedance element provided in series with the switching transistor M1 and the rectifying element M2. The impedance element may be a resistance element or a wiring made of aluminum or the like.

Alternatively, the first detection signal CS ₁ may be a signal obtained by connecting a replica transistor in parallel with the switching transistor M1 and _{converting the current IM1'flowing} through the replica transistor into a voltage. Similarly, the second detection signal CS ₂ may be a signal obtained by connecting a replica transistor in parallel with the synchronous rectifier transistor M2 and _{converting the current IM2'flowing} through the replica transistor into a voltage.

As described above, the method of detecting the current of the switching transistor M1 and the synchronous rectifying transistor M2 is not particularly limited.

(Second short detection method)
As shown in FIG. 6 (b), in short the state of the inductor, the switching transistor M1, the synchronous rectification transistor M2 respectively current _{I M1, I M2} becomes steeper. Therefore, if the _{states in which the slopes of the currents IM1} and _IM2 exceed the threshold value continue, it may be determined that the inductor is short-circuited.

(Open detection method)
FIG. 8 is a circuit diagram of an inductor open detection circuit. Although only the configuration for one channel is shown in FIG. 8, other channels can be configured in the same manner. The open detection circuit 230 includes resistors R ₂₁ , R ₂₂ and a capacitor C ₂₁ . The resistors R ₂₁ and R ₂₂ are connected in parallel with the inductor L1, and the capacitor C ₂₁ is connected in parallel with the resistor R _21. The node A, a voltage is generated in accordance with the current I _L1 of inductor L1, since the inductor L1, the voltage V _A of the node becomes an open A decrease can detect the open state by monitoring the voltage V _A. For example open detection circuit 230 includes a comparator 232 that compares the voltage _{V A} of the node A and the threshold value _{V OPEN,} when V _{A <V OPEN} occurs, it may be determined that the open of the inductor L1 abnormal. The comparator 232 can be integrated in the control circuit 200.

Alternatively, when the inductor is opened, the currents of both the switching transistor M1 and the synchronous rectifier transistor M2 become zero. Therefore, the open detection circuit 230 may determine that the inductor is in the open state when both the _{currents IM1} and _{IM2 are smaller than the threshold current set near zero.}

(Use)
The DC / DC converter 100 can be mounted on a battery-powered electronic device such as a tablet terminal, a smartphone, a notebook PC, or a digital camera. FIG. 9 is a diagram showing an example of an electronic device 700 including the DC / DC converter 100 according to the embodiment. The electronic device 700 includes a housing 702, a battery 704, a microprocessor 706, and a DC / DC converter 100. The DC / DC converter 100 receives the battery voltage V _BAT (= V _IN ) from the battery 704 at its input terminal, and supplies the _{output voltage V OUT} to the microprocessor 706 connected to the output terminal.

The present invention has been described above based on the embodiments. This embodiment is an example, and it will be understood by those skilled in the art that various modifications are possible for each of these components and combinations of each processing process, and that such modifications are also within the scope of the present invention. is there. Hereinafter, such a modification will be described.

The DC / DC converter 100 may be a diode rectifying type. Further, the present invention is not limited to the step-down converter, and the present invention can be applied to the step-up type or the step-down pressure type. The high-side transistor may be an N-channel MOSFET. Further, as the switching transistor M1 and the synchronous rectifying transistor M2, an IGBT or a bipolar transistor may be used instead of the MOSFET.

In the embodiment, when the openness of the inductor is detected in a certain channel, the switching of the channel is stopped, but the switching may be continued. This is because if the inductor is open, it does not affect other channels. However, when switching is stopped as described in the embodiment, there is an advantage that wasteful power consumption can be suppressed or switching noise can be reduced.

Although the present invention has been described using specific terms and phrases based on the embodiments, the embodiments merely indicate the principles and applications of the present invention, and the embodiments are defined in the claims. Many modifications and arrangement changes are permitted without departing from the ideas of the present invention.

100 ... DC / DC converter, 102 ... input line, 104 ... output line, 110 ... output circuit, M1 ... switching transistor, M2 ... synchronous rectifier transistor, L1 ... inductor, C1 ... output capacitor, 200 ... control circuit, 202 ... error Amplifier, 204 ... Pulse modulator, 206 ... Driver, 210 ... Main logic, 212 ... Protection circuit, 220 ... Short detection circuit, 230 ... Open detection circuit, 700 ... Electronic equipment, 702 ... Housing, 704 ... Battery, 706 ... Microprocessor.

Claims (17)

A control circuit for a multi-phase DC / DC converter with multiple channels.
An error amplifier that amplifies the error between the feedback signal corresponding to the output voltage of the DC / DC converter and its target value and generates an error signal, and
A pulse modulator that generates a multi-channel pulse signal based on the error signal, and
Multiple drivers that support multiple channels and drive the corresponding switching transistors based on the corresponding pulse signals,
A short-circuit detection circuit that detects short circuits in the inductors of multiple channels,
A protection circuit that stops the operation of the channel where a short circuit is detected, and
With
The short-circuit detection circuit has a first overcurrent state in which the current of the switching transistor of the DC / DC converter exceeds the threshold value and a second overcurrent state in which the current of the rectifier element of the DC / DC converter exceeds the threshold value. Doo is to occur continuously, features and to that control circuit determining that short circuit the inductor. A control circuit for a multi-phase DC / DC converter with multiple channels.
An error amplifier that amplifies the error between the feedback signal corresponding to the output voltage of the DC / DC converter and its target value and generates an error signal, and
A pulse modulator that generates a multi-channel pulse signal based on the error signal, and
Multiple drivers that support multiple channels and drive the corresponding switching transistors based on the corresponding pulse signals,
A short-circuit detection circuit that detects short circuits in the inductors of multiple channels,
A protection circuit that stops the operation of the channel where a short circuit is detected, and
With
The short-circuit detection circuit has a first overcurrent state in which the current of the switching transistor of the DC / DC converter exceeds the threshold value and a second overcurrent state in which the current of the rectifier element of the DC / DC converter exceeds the threshold value. A control circuit characterized in that when the continuation with and is continuously generated over a plurality of cycles, it is determined that the inductor is short-circuited. A first overcurrent detection comparator that compares a first detection signal corresponding to the current of the switching transistor with a predetermined first threshold signal and generates a first overcurrent detection signal.
A second overcurrent detection comparator that compares a second detection signal corresponding to the current of the rectifying element with a predetermined second threshold signal and generates a second overcurrent detection signal.
With more
The control circuit according to claim 1 or 2 , wherein the short circuit detection circuit detects a short circuit of the inductor based on the first overcurrent detection signal and the second overcurrent detection signal. The control circuit according to claim 3 , wherein the first detection signal is generated based on the voltage between the drain and source of the switching transistor. The rectifying element is a synchronous rectifying transistor and
The control circuit according to claim 3 or 4 , wherein the second detection signal is generated based on the voltage between the drain sources of the synchronous rectifier transistor. The first detection signal is a voltage drop of an impedance element provided in series with the switching transistor, or a voltage drop of an impedance element provided in series with a replica transistor connected in parallel with the switching transistor. The control circuit according to claim 3 , wherein the control circuit is generated based on the above. The control circuit according to any one of claims 1 to 6 , wherein when the number of operating channels decreases as a result of detecting a short circuit of the inductor in a certain channel, the phase difference is changed. The number of channels of the DC / DC converter is M.
The invention according to any one of claims 1 to 7 , wherein when a short circuit of the inductor is detected in a certain channel during operation on the N channel (N <M), one of the unused channels is switched to the operating state. Control circuit. The control circuit according to any one of claims 1 to 8 , further comprising a notification unit that notifies the outside when a short circuit of the inductor is detected. The control circuit according to any one of claims 1 to 9 , further comprising an open detection circuit for detecting the opening of the inductors of the plurality of channels. The control circuit according to claim 10 , wherein the protection circuit stops the operation of the channel in which the open is detected. The control circuit according to claim 11 , wherein the phase difference is changed when the number of operating channels is reduced as a result of detecting the opening of the inductor in a certain channel. The number of channels of the DC / DC converter is M.
The control circuit according to claim 10 or 11 , wherein when the openness of the inductor is detected in a certain channel during operation in the N channel (N <M), one of the unused channels is switched to the operating state. .. The control circuit according to any one of claims 1 to 13 , wherein the control circuit is integrally integrated on one semiconductor substrate. A DC / DC converter comprising the control circuit according to any one of claims 1 to 14. An electronic device comprising the DC / DC converter according to claim 15. This is a method for detecting a short circuit in the inductor of a DC / DC converter.
The step of detecting the first overcurrent state in which the current of the switching transistor of the DC / DC converter exceeds the threshold value, and
A step of detecting a second overcurrent state in which the current of the rectifying element of the DC / DC converter exceeds the threshold value, and
When the first overcurrent state and the second overcurrent state occur continuously, the step of determining that the inductor is short-circuited and
A method characterized by providing.

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