Power supply circuit

Abstract

This invention provides a power supply circuit that can suppress chip heat generation while keeping the circuit size down. [Solution] A power supply circuit mounted on an IC chip that supplies a power supply voltage to the logic circuit within the IC chip, comprising: a linear regulator that generates a power supply voltage by stepping down a first voltage; a PWM signal generation circuit that generates a power supply voltage by being connected to an external circuit provided outside the IC chip and configuring a switching regulator, and generating a PWM signal based on the first voltage and supplying it to the external circuit; and a switching unit that selectively switches the power supply source to either the linear regulator or the switching regulator based on the temperature change of the IC chip or the current change in the supply line that supplies the power supply voltage to the logic circuit.

Description

Technical Field

[0001] The present disclosure relates to a power supply circuit, and particularly to a power supply circuit that supplies power to a logic circuit.

Background Art

[0002] In recent years, as a driver for driving a display device, a TCON (Timing Controller)-embedded driver IC incorporating a TCON has been used. In the TCON-embedded driver IC, the power for the source circuit and the logic circuit is generated by a regulator such as a switching regulator or an LDO (Low Drop Out).

[0003] As such a power circuit, a power circuit has been proposed that is composed of a load switch and can switch the operation mode by switching the on state of a transistor connected between an input pin and an output pin (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] [Summary] In the TCON-embedded driver IC, the scale of the logic circuit has become large, and the consumption current of the LV (Low Voltage) system has increased. Therefore, when power is supplied by an LDO, there is a problem that the consumption current becomes large and heat generation of the chip occurs due to the Ron resistance.

[0006] Although it is possible to take measures against heat generation by providing a switching regulator instead of an LDO, in that case, there is a problem that a large number of external components are required regardless of the magnitude of the consumption current.

[0007] A power supply circuit according to one aspect of the present disclosure is a power supply circuit mounted on an IC chip and supplying a power supply voltage to a logic circuit within the IC chip, comprising: a linear regulator that receives a first voltage and steps it down to generate the power supply voltage; a PWM signal generation circuit that is connected to an external circuit provided outside the IC chip to constitute a switching regulator and generates a PWM signal which is supplied to the external circuit to generate the power supply voltage; and a switching unit that selectively switches the output to the outside to either the power supply voltage generated by the linear regulator or the PWM signal based on a temperature change of the IC chip or a current change in the supply line that supplies the power supply voltage to the logic circuit. [Brief explanation of the drawing]

[0008] [Figure 1] This is a circuit diagram showing the configuration of a power supply circuit according to Embodiment 1 of the present disclosure. [Figure 2] This circuit diagram shows the internal configuration of the PWM generation circuit and the circuit portion consisting of external components that make up the switching regulator. [Figure 3] This table shows the correspondence between the signal level of the detection signal and the selected regulator. [Figure 4] This is a circuit diagram showing the configuration of a power supply circuit according to Embodiment 2 of this disclosure.

[0009] [Detailed explanation] Preferred embodiments of the present disclosure are described in detail below. In the following descriptions and accompanying drawings, substantially identical or equivalent parts are denoted by the same reference numerals. [Example 1]

[0010] Figure 1 is a circuit diagram showing the configuration of a power supply circuit 100 according to Embodiment 1 of the present disclosure. The power supply circuit 100 is a circuit that supplies power to a logic circuit provided in an integrated circuit (IC) 11, and consists of an internal circuit provided inside the integrated circuit 11 (hereinafter also referred to as "inside the IC") and an external component provided outside the integrated circuit 11 (hereinafter also referred to as "outside the IC").

[0011] Inside the integrated circuit 11 are a logic circuit 12, a PWM (Pulse Width Modulation) generation circuit 13, an LDO (Low Drop Out) regulator 14, a temperature sensing circuit 15, and a switching unit 16.

[0012] The logic circuit 12 is a circuit that operates by receiving power from a switching regulator or LDO regulator 14, which is composed of a PWM generation circuit 13 and external components.

[0013] The PWM generation circuit 13 is a circuit that constitutes a switching regulator together with an external component located outside the integrated circuit 11. The PWM generation circuit 13 generates a PWM (Pulse Width Modulation) signal and outputs it from its output terminal OT. The output terminal OT of the PWM generation circuit 13 is connected to terminal T1 on the integrated circuit 11 via switch SW1. When switch SW1 is ON, the PWM signal output from the output terminal OT of the PWM generation circuit 13 is output outside the IC via terminal T1. Terminal T1 is connected to an external component outside the IC, and the PWM signal is supplied to this external component.

[0014] Furthermore, the feedback terminal FB of the PWM generation circuit 13 is connected to terminal T2 provided on the integrated circuit 11. The PWM generation circuit 13 receives a feedback voltage from an external component outside the IC via terminal T2.

[0015] In this embodiment, a transistor 21, a diode 22, an inductor 23, and a capacitor 24 are connected to the integrated circuit 11 as external components.

[0016] The transistor 21 is composed of a P-channel MOSFET, and its source is connected to the voltage supply line of the power supply voltage VDD. The gate of the transistor 21 is connected to the terminal T1 of the integrated circuit 11.

[0017] The diode 22 is a rectifier diode provided between the transistor 21 and the supply line of the ground potential VSS. The anode of the diode 22 is connected to the supply line of the ground potential VSS, and the cathode is connected to the drain of the transistor 21.

[0018] One end of the inductor 23 is connected to the connection terminal connecting the drain of the transistor 21 and the cathode of the diode 22. The other end of the inductor 23 is connected to the terminal T2 of the integrated circuit 11.

[0019] One end of the capacitor 24 is connected to the other end of the inductor 23 and the terminal T2, and the other end is connected to the supply line of the ground potential VSS.

[0020] FIG. 2 is a circuit diagram showing a state in which the switch SW1 is turned on in the power supply circuit 100 shown in FIG. 1 and the PWM generation circuit 13 is connected to an external component via the terminal T1.

[0021] The PWM generation circuit 13 is composed of a control circuit 31, a transistor PM1, and a transistor NM1. The control circuit 31 generates a pulse signal PS composed of a continuous pulse of a predetermined width and supplies it to the gates of the transistors PM1 and NM1.

[0022] The transistor PM1 is composed of a P-channel MOSFET, and its source and back gate are connected to the voltage supply line of the power supply voltage. The transistor NM1 is composed of an N-channel MOSFET, and its source and back gate are connected to the voltage supply line of the reference voltage.

[0023] The drains of transistor PM1 and transistor NM1 are commonly connected, and they are connected to terminal T1 via switch SW1 (not shown in FIG. 2). Also, the gates of transistor PM1 and transistor NM1 are connected to each other and to control circuit 31.

[0024] Transistors PM1 and NM1 receive the supply of the pulse signal PS from control circuit 31 and alternately turn on and off. Thereby, a PWM signal is generated and output outside the IC via terminal T1.

[0025] The PWM signal output from terminal T1 is supplied to the gate of transistor 21, which is an external component. Transistor 21 switches between on and off states according to the change in the signal level of the PWM signal.

[0026] Diode 22 becomes non-conductive during the period when transistor 21 is on and becomes conductive during the period when transistor 21 is off.

[0027] When transistor 21 is on and diode 22 is non-conductive, the current flowing through transistor 21 flows into inductor 23, and energy is accumulated in inductor 23. On the other hand, when transistor 21 is off and diode 22 is conductive, the energy accumulated in inductor 23 is released.

[0028] By repeating such a switching operation, a power supply voltage V1 is generated at the other end of inductor 23 and supplied to logic circuit 12 via power supply line L1.

[0029] Referring to FIG. 1 again, LDO regulator 14 is a linear regulator that receives the reference voltage RV as an input voltage and generates the power supply voltage V2 based on this input voltage. The output terminal of LDO regulator 14 is configured to be connectable to terminal T2 provided in integrated circuit 11 via switch SW2.

[0030] The power supply voltage V2 generated by the LDO regulator 14 is output outside the IC via terminal T2 when the switch SW2 is ON. Terminal T2 is connected to one end of a capacitor 24, which is an external component located outside the IC, and is also connected to a power supply line L1 that supplies power supply voltage to the logic circuit 12. As a result, when the switch SW2 is ON, the power supply voltage V2 output from the LDO regulator 14 is supplied to the logic circuit 12 via the power supply line L1.

[0031] The temperature detection circuit 15 is a circuit that detects the temperature of the IC chip that makes up the integrated circuit 11 (hereinafter referred to as the chip temperature). Based on the temperature detection result, the temperature detection circuit 15 supplies a detection signal DS to the switching unit 16 indicating whether or not the IC chip is generating heat. For example, if the detected chip temperature is below a threshold temperature, the temperature detection circuit 15 supplies a detection signal DS of logic level 1 (i.e., H level) to the switching unit 16, indicating that the IC chip is not generating heat. Also, if the detected chip temperature is above a threshold temperature, the temperature detection circuit 15 supplies a detection signal DS of logic level 0 (i.e., L level) to the switching unit 16, indicating that the IC chip is generating heat.

[0032] The switching unit 16 switches switches SW1 and SW2 on and off based on the detection signal DS. In this embodiment, the switching unit 16 switches either SW1 or SW2 on and the other off complementaryly based on the detection signal DS. As a result, either the PWM signal output from the PWM generation circuit 13 or the power supply voltage V2 output from the LDO regulator is output outside the integrated circuit 11 (i.e., outside the IC). In other words, either the switching regulator consisting of the PWM generation circuit 13 or the LDO regulator 14 is selected as the power supply circuit that supplies power to the logic circuit 12.

[0033] Figure 3 shows the correspondence between the signal level of the detection signal DS and the regulator that is selected by switching according to the detection signal DS and used as a power supply circuit.

[0034] When the detection signal DS is at a high level, the switching unit 16 turns switch SW1 off and switch SW2 on. As a result, the power supply voltage V2 generated by the LDO regulator 14 is supplied to the power supply line L1 via terminal T2. In other words, when the detection signal DS is at a high level, the LDO regulator 14 is selected as the power supply circuit that supplies power to the logic circuit 12.

[0035] On the other hand, when the detection signal DS is at a low level, the switching unit 16 turns switch SW1 on and switch SW2 off. As a result, the PWM signal output from the PWM generation circuit 13 is supplied to the gate of transistor 21 via terminal T1. This forms a switching regulator with the PWM generation circuit 13, transistor 21, diode 22, inductor 23, and capacitor 24, and the power supply voltage V1 generated by the switching regulator is supplied to the logic circuit 12 via the power supply line L1. In other words, when the detection signal DS is at a low level, the switching regulator consisting of the PWM generation circuit 13 is selected as the power supply circuit that supplies power to the logic circuit 12.

[0036] As described above, the power supply circuit 100 of this embodiment includes a temperature detection circuit 15 for detecting the temperature of the IC chip, and a switching unit 16 for switching the switches SW1 and SW2 on and off. The switching unit 16 switches the switches based on the detection result of the temperature detection circuit 15, depending on whether the temperature of the IC chip is above a threshold.

[0037] When the IC chip temperature is below a threshold, i.e., when no heat is observed from the IC chip, the switching unit 16 turns switch SW1 off and switch SW2 on so that the power supply voltage V2 generated by the LDO regulator 14 is output outside the IC. As a result, the power supply voltage V2 is sent to the power supply line L1 and supplied to the logic circuit 12. In this state, the only external component that needs to be located outside the IC is the capacitor 24, and the other external components (transistor 21, diode 22, and inductor 23) are unnecessary. Therefore, the circuit size outside the IC of the power supply circuit 100 can be reduced.

[0038] On the other hand, if the temperature of the IC chip exceeds a threshold, i.e., if heat generation of the IC chip is detected, the switching unit 16 turns on switch SW1 and off switch SW2 so that the PWM signal generated by the PWM generation circuit 13 is output outside the IC. As a result, the PWM signal is supplied to the gate of transistor 21 located outside the IC. The switching regulator consisting of the PWM generation circuit 13, transistor 21, diode 22, inductor 23, and capacitor 24 generates a power supply voltage V1, which is supplied to the logic circuit 12 via the power supply line L1. By supplying power to the logic circuit 12 using a switching regulator in this way, it is possible to suppress the increase in current consumption and the heat generation of the chip caused by on-resistance (Ron) that may occur when using a linear regulator such as an LDO regulator 14. [Example 2]

[0039] Next, Embodiment 2 of this disclosure will be described. The power supply circuit of Embodiment 2 differs from the power supply circuit 100 of Embodiment 1 in that it switches the circuit based on the current value of the power supply line of the logic circuit, rather than the temperature of the IC chip.

[0040] Figure 4 is a circuit diagram showing the configuration of a power supply circuit 100A according to Embodiment 2 of this disclosure. The power supply circuit 100A includes a resistor 25 and a current sensing circuit 26 provided outside the IC.

[0041] Resistor 25 is inserted into the power supply line L1. One end of resistor 25 is connected to terminal T3, and the other end is connected to one end of capacitor 24.

[0042] The current sensing circuit 26 is connected in parallel with the resistor 25. One end of the current sensing circuit 26 is connected to one end of the resistor 25, and the other end of the current sensing circuit 26 is connected to the other end of the resistor 25. The current sensing circuit 26 is also connected to terminal T4.

[0043] The current detection circuit 26 is a circuit that detects the current flowing through the power supply line L1. Based on the current detection result, the current detection circuit 26 outputs a detection signal DS2 indicating whether the current is large or large. The detection signal DS2 is supplied to the switching unit 16 via terminal T4. For example, if the detected current is less than a threshold value, the current detection circuit 26 supplies a detection signal DS2 of logic level 1 (i.e., H level) to the switching unit 16A, indicating that the current is small. Also, if the detected current is greater than or equal to a threshold value, the current detection circuit 26 supplies a detection signal DS2 of logic level 0 (i.e., L level) to the switching unit 16A, indicating that the current is large.

[0044] The switching unit 16A switches switches SW1 and SW2 on and off based on the detection signal DS2. Similar to the switching unit 16 in Embodiment 1, the switching unit 16A switches the switches complementaryly so that one is on and the other is off. As a result, either the PWM signal output from the PWM generation circuit 13 or the power supply voltage V2 output from the LDO regulator is output outside the integrated circuit 11 (i.e., outside the IC). In other words, either the switching regulator consisting of the PWM generation circuit 13 or the LDO regulator 14 is selected as the power supply circuit that supplies power to the logic circuit 12.

[0045] When the detection signal DS2 is at a high level, the switching unit 16 turns switch SW1 off and switch SW2 on. As a result, the power supply voltage V2 generated by the LDO regulator 14 is supplied to the power supply line L1 via terminal T2.

[0046] When the detection signal DS2 is at a low level, the switching unit 16 turns switch SW1 on and switch SW2 off. As a result, the PWM signal output from the PWM generation circuit 13 is supplied to the gate of transistor 21 via terminal T1. Consequently, the power supply voltage V1 generated by the switching regulator consisting of the PWM generation circuit 13, transistor 21, diode 22, inductor 23, and capacitor 24 is supplied to the logic circuit 12 via the power supply line L1.

[0047] As described above, the power supply circuit 100A of this embodiment includes a current detection circuit 26 that detects the current flowing through the power supply line L1. The switching unit 16A switches the switch based on the detection result of the current detection circuit 26, depending on whether the current value is above a threshold.

[0048] When the current flowing through the power supply line L1 is below a threshold, the switching unit 16A turns off switch SW1 and on switch SW2 so that the power supply voltage V2 generated by the LDO regulator 14 is output outside the IC. As a result, the power supply voltage V2 is sent to the power supply line L1 and supplied to the logic circuit 12. In this state, no external components other than the capacitor 24 are required, so the circuit size outside the IC of the power supply circuit 100 can be reduced.

[0049] On the other hand, if the current flowing through the power supply line L1 is above a threshold, the switching unit 16A turns on switch SW1 and off switch SW2 so that the PWM signal generated by the PWM generation circuit 13 is output outside the IC. As a result, the PWM signal is supplied to the gate of transistor 21 located outside the IC. The switching regulator consisting of the PWM generation circuit 13, transistor 21, diode 22, inductor 23, and capacitor 24 generates the power supply voltage V1, which is supplied to the logic circuit 12 via the power supply line L1. By supplying power to the logic circuit 12 using a switching regulator in this way, it is possible to suppress the increase in current consumption and the heat generation of the chip caused by on-resistance (Ron) that may occur when using a linear regulator such as an LDO regulator 14.

[0050] This disclosure is not limited to the embodiments shown above. For example, although the above embodiments describe the case in which an LDO regulator 14 is used, other linear regulators other than LDOs may be used instead of the LDO regulator 14.

[0051] Furthermore, when the switch SW1 is OFF and SW2 is ON, and the state changes to an ON state and SW2 is OFF, that is, when the state changes from one where the power supply voltage V2 generated by the LDO regulator 14 is output outside the IC to one where the PWM signal generated by the PWM generation circuit 13 is output outside the IC, the switch state may be configured so that it does not return to its original state, regardless of the heat generated by the IC chip or the amount of current flowing through the power supply line L1. For example, this function can be realized by supplying a reset signal to the switching unit 16 from an external source, and setting the initial state to one where the switch SW1 is OFF and SW2 is ON, that is, when the LDO regulator 14 is selected as the power supply circuit, and allowing the switch SW1 and SW2 to be switched ON and OFF only once.

[0052] (Note) This specification discloses the following configuration:

[0053] (Composition 1) A power supply circuit mounted on an IC chip and supplying a power supply voltage to a logic circuit within the IC chip, comprising: a linear regulator that receives a first voltage and steps it down to generate the power supply voltage; a PWM signal generation circuit that is connected to an external circuit provided outside the IC chip to constitute a switching regulator and generates a PWM signal which is supplied to the external circuit to generate the power supply voltage; and a switching unit that selectively switches the output to the outside to either the power supply voltage generated by the linear regulator or the PWM signal based on a temperature change of the IC chip or a current change in the supply line that supplies the power supply voltage to the logic circuit.

[0054] (Configuration 2) The power supply circuit according to configuration 1, which has a temperature detection circuit for detecting the temperature of the IC chip, and the switching unit switches the output to the outside based on the detection result of the temperature detection circuit.

[0055] (Composition 3) The power supply circuit according to configuration 2, wherein the switching unit switches so that when the temperature of the IC chip is below a predetermined level, the power supply voltage generated by the linear regulator becomes the output to the outside, and when the temperature of the IC chip is above a predetermined level, the PWM signal becomes the output to the outside.

[0056] (Composition 4) The power supply circuit according to any one of configurations 1 to 3, wherein the external circuit includes a current detection circuit that detects the current flowing through the supply line, and the switching unit switches the output to the external based on the detection result of the current detection circuit.

[0057] (Composition 5) The power supply circuit according to configuration 4, wherein the switching unit switches so that when the current flowing through the supply line is less than a predetermined value, the power supply voltage generated by the linear regulator becomes the output to the outside, and when the current flowing through the supply line is greater than or equal to a predetermined value, the PWM signal becomes the output to the outside.

[0058] (Composition 6) The linear regulator is an LDO (Low Drop Out) regulator, as described in any one of configurations 1 to 5 of the power supply circuit.

[0059] (Composition 7) The power supply circuit according to any one of configurations 1 to 6, wherein the IC chip has a first terminal, a second terminal and a third terminal, the first terminal is connected to the output terminal of the PWM signal generation circuit via a first switch and to one end of the supply line via the external circuit, the second terminal is connected to the output terminal of the linear regulator via a second switch and to one end of the supply line, and the third terminal is provided at a position that connects the other end of the supply line and the logic circuit, and the switching unit switches the switches so that one of the first switch and the second switch is on and the other is off. [Explanation of symbols]

[0060] 100 Power supply circuit 11 Integrated Circuits 12 Logic Circuits 13 PWM generation circuit 14 LDO Regulator 15. Temperature detection circuit 16 Switching section 21 transistors 22 diodes 23 Inductors 24 Capacitors 25 Resistors 26 Current detection circuit 31 Control circuits

Claims

1. A power supply circuit mounted on an IC chip that supplies power supply voltage to the logic circuit within the IC chip, A linear regulator that receives a first voltage and steps it down to generate the power supply voltage, A PWM signal generation circuit, which generates a PWM signal and supplies it to the external circuit, thereby generating the power supply voltage, is configured as a switching regulator by being connected to an external circuit provided outside the IC chip. A switching unit that selectively switches the output to the outside to either the power supply voltage generated by the linear regulator or the PWM signal, based on the temperature change of the IC chip or the current change in the supply line that supplies the power supply voltage to the logic circuit. A power supply circuit having

2. The IC chip has a temperature detection circuit for detecting the temperature of the IC chip, The power supply circuit according to claim 1, wherein the switching unit switches the output to the outside based on the detection result of the temperature detection circuit.

3. The power supply circuit according to claim 2, wherein the switching unit switches so that when the temperature of the IC chip is below a predetermined value, the power supply voltage generated by the linear regulator becomes the output to the outside, and when the temperature of the IC chip is above a predetermined value, the PWM signal becomes the output to the outside.

4. The external circuit includes a current detection circuit that detects the current flowing through the supply line. The power supply circuit according to claim 1, wherein the switching unit switches the output to the outside based on the detection result of the current detection circuit.

5. The power supply circuit according to claim 4, wherein the switching unit switches so that when the current flowing through the supply line is less than a predetermined value, the power supply voltage generated by the linear regulator becomes the output to the outside, and when the current flowing through the supply line is greater than or equal to a predetermined value, the PWM signal becomes the output to the outside.

6. The power supply circuit according to claim 1, wherein the linear regulator is an LDO (Low Drop Out) regulator.

7. The IC chip has a first terminal, a second terminal and a third terminal, The first terminal is connected to the output terminal of the PWM signal generation circuit via the first switch, and is also connected to one end of the supply line via the external circuit. The second terminal is connected to the output terminal of the linear regulator via the second switch, and is also connected to one end of the supply line. The third terminal is provided at a position that connects the other end of the supply line to the logic circuit. The power supply circuit according to claim 1, wherein the switching unit switches the switches such that one of the first switch and the second switch is on and the other is off.

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