JP2009110217A - Semiconductor integrated circuit device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate a stable power supply voltage while improving reliability by performing the protecting operation of a series regulator circuit outside a main loop. <P>SOLUTION: An input current adjusting part 2 for performing control such as current restriction by various protecting operations is arranged in the pre-stage of a transistor 4 for regulation as the output element of a series regulator circuit. Thus, it is possible to simplify the circuit configurations of a main series regulator circuit, and to sharply improve the degree of freedom of phase characteristic adjustment, and to make a power source IC1 stably operate, and to perform precise protecting operation control. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for generating a stable arbitrary power supply voltage, and more particularly to a technique effective for stabilizing a power supply voltage using a series regulator circuit.

  A regulator that generates and outputs a stable voltage is widely used in a power supply unit of a semiconductor integrated circuit device or an electronic system using the semiconductor integrated circuit device. As this regulator, for example, a series regulator is known.

  The series regulator includes, for example, a regulation transistor, an error amplifier, a current limit / overheat protection circuit, and the like. The transistor is connected in series to the load, and the error amplifier compares the output voltage output from the transistor with the reference voltage, and outputs the comparison result to the current limit / overheat protection circuit.

  In the comparison result of the error amplifier, the current limit / overheat protection circuit outputs a control signal so that the output current of the transistor becomes small when the output voltage is larger than the reference voltage, and when the output voltage is smaller than the reference voltage, A control signal is output so that the output current of the transistor is increased.

  The current limit / overheat protection circuit performs a protection operation to stop the transistor when an overvoltage occurs or the load current increases.

In this type of regulator, for example, a MOS (Metal Oxide Semiconductor) transistor is arranged in the power supply line of the charge pump and the gate of the transistor is controlled to suppress noise in the power supply line (for example, , See Patent Document 1).
US Patent Application Publication No. 2002/6411531

  However, the present inventors have found that the power supply stabilization technology using the series regulator as described above has the following problems.

  That is, in the configuration of the series regulator described above, since the current limit / overheat protection circuit is in the main feedback loop, control for delaying the start of the protection function operation, precise control for the return of the protection operation, and load current It has become very difficult to perform overvoltage control when the voltage drops rapidly.

  In the control that delays the start of the protection function operation, for example, when the load current suddenly increases due to the operation of the logic circuit, the current limit / overheat protection circuit detects the increase in the load current and stops the transistor. There is a risk that the necessary power supply cannot be supplied.

  In addition, in the precise control of the return of the protective operation, when the load current decreases, the current limit / overheat protection circuit performs the automatic return control, so that there is some failure in the load side circuit. In this case, the supply of power and the automatic return are repeatedly performed, which may cause a problem with respect to safety.

  Furthermore, when the load current decreases rapidly, an overvoltage occurs, which may adversely affect the logic circuit to which power is supplied.

  An object of the present invention is to provide a technique capable of generating a stable power supply voltage while improving reliability by performing a protection operation of a series regulator circuit outside a main loop.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  A semiconductor integrated circuit device according to the present invention includes a series regulator circuit that regulates an input voltage and generates an arbitrary power supply voltage, and is provided in a preceding stage of the series regulator circuit, and outputs to the series regulator circuit based on a detection signal. And an input current adjustment control unit that adjusts the current of the input voltage.

  Moreover, the outline | summary of the other invention of this application is shown briefly.

  In the semiconductor integrated circuit device of the present invention, the input current adjustment control unit is based on a detection unit that outputs a detection signal when a protective operation of the series regulator circuit is necessary, and a detection signal output from the detection unit, The control unit is configured to output a control signal, and based on the control signal of the control unit, a current adjustment unit configured to limit or stop the current of the input voltage output to the series regulator circuit.

  In the semiconductor integrated circuit device of the present invention, the detection unit detects an overcurrent of the series regulator circuit, a short-circuit detection unit detects that the series regulator circuit is in a short-circuit state, and a series An overvoltage detection unit for detecting overvoltage of the regulator circuit and an overheat detection unit for detecting overheating in the semiconductor integrated circuit device are provided.

  Furthermore, in the semiconductor integrated circuit device of the present invention, when the short-circuit detection unit compares the voltage output from the series regulator circuit with the reference voltage, and the voltage output from the series regulator circuit becomes equal to or lower than the reference voltage. A comparison unit that outputs a detection signal upon determining a short-circuit state, and a low-pass filter that is connected to the output unit of the comparison unit and passes only a detection signal of a low-frequency, and the low-pass filter includes: If the detected signal is less than or equal to an arbitrary time, the detection signal is not output to the control unit.

  In the semiconductor integrated circuit device of the present invention, the short-circuit detection unit maintains the signal state of the detection signal until a start signal is input from the outside when the detection signal is output via the low-pass filter. A maintenance unit is provided.

  Furthermore, in the semiconductor device of the present invention, the detection unit includes a start detection unit that detects that the series regulator circuit has started, and the control unit detects that the start detection unit outputs when the series regulator circuit starts. When a signal is output, a control signal is output to the current adjustment unit so as to limit the current of the input voltage output to the series regulator circuit for an arbitrary period.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  (1) Since the series regulator circuit can be simplified, a stable power supply voltage can be generated.

  (2) Further, since the protective operation of the series regulator circuit can be performed with high precision and precision, the reliability can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

  FIG. 1 is a block diagram showing a configuration example of a power supply IC according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing a circuit configuration example of an input current adjustment unit provided in the power supply IC of FIG. These are tables showing the output state of the logic unit provided in the input current adjusting unit of FIG. 2 and the operation state of each transistor.

  In the present embodiment, a power supply IC (Integrated Circuit) 1 is a power generation semiconductor integrated circuit device that generates and outputs a stable voltage and supplies it as a power supply voltage.

  As shown in FIG. 1, the power supply IC 1 includes an input current adjustment unit 2, an output adjustment unit 3, a regulation transistor 4, an overcurrent detection unit 5, a short circuit detection unit 6, an output overvoltage detection unit 7, a temperature detection unit 8, and a startup. It comprises a timer 9, UVLO (UnderVoltage LockOut) 10, a reference voltage generator 11, a negative AND circuit 12, an inverter 12 a, and a logic unit 13.

  In addition, the input current adjustment unit 2, overcurrent detection unit 5, short circuit detection unit 6, output overvoltage detection unit 7, temperature detection unit 8, startup timer 9, and logic unit 13 constitute a current adjustment control unit. Further, the output regulator 3 and the regulation transistor 4 constitute a series regulator circuit.

  The input current adjustment unit 2 serving as a current adjustment unit adjusts the current input to the regulation transistor 4 based on the control of the logic unit 13 serving as a control unit. The output adjustment unit 3 controls the output of the regulation transistor 4 to be constant.

  The output adjustment unit 3 includes resistors 3a and 3b, a capacitance element 3c, and an operational amplifier 3d. The resistors 3a and 3b are connected in series between the output terminal VOUT and the reference potential VSS.

  The positive (+) side input terminal of the operational amplifier 3d is connected so that a voltage divided by the resistors 3a and 3b is input. The output terminal VOUT is connected to one connection part of the capacitive element 3c, and the positive (+) side input terminal of the operational amplifier 3d is connected to the other connection part of the capacitive element 3c. Yes.

  Further, the negative (−) side input terminal of the operational amplifier 3d is connected so that the reference voltage VREF is input, and a control signal for controlling the output of the regulation transistor 4 is output from the output section of the operational amplifier 3d. Is output.

  The regulation transistor 4 outputs an arbitrary output voltage based on the control signal output from the output adjustment unit 3. The output portion of the input current adjustment unit 2 is connected to one connection portion of the regulation transistor 4, and the control signal output from the output adjustment unit 3 is input to the gate of the regulation transistor 4. So connected.

  An output terminal VOUT is connected to the other connection portion of the regulation transistor 4, and this output terminal VOUT becomes an output portion of the power supply IC 1.

  The overcurrent detection unit 5 detects that the current value of the power supply IC 1 has exceeded an arbitrary set value, and outputs it to the logic unit 13 as an overcurrent detection signal. The overcurrent detector 5 includes a transistor 5a having a mirror circuit configuration with the regulation transistor 4, an operational amplifier 5b that converts the drain current of the transistor 5a (similar to the drain current of the regulation transistor 4) into a drain voltage, and a resistor 5c transistor 5e, And an operational amplifier 5d.

  The output portion of the input current adjusting unit 2 is connected to one connection portion of the transistor 5a, and one connection portion of the transistor 5e is connected to the other connection portion of the transistor 5a.

  Further, the gate of the regulation transistor 4 is connected to the gate of the transistor 5a. One connection part of the resistor 5c and the positive (+) side input terminal of the operational amplifier 5d are connected to the other connection part of the transistor 5e. A reference potential VSS is connected to the other connection portion of the resistor 5c.

  The output portion of the operational amplifier 5b is connected to the gate of the transistor 5e, and the connection portion between the transistor 5a and the transistor 5e is connected to the negative (−) side input terminal of the operational amplifier 5b. The other connection portion of the regulation transistor 4 is connected to the positive (+) side input terminal of the operational amplifier 5b.

  Thus, the converted drain voltage is input to the positive (+) side input terminal of the operational amplifier 5d, and the reference voltage VREF is input to the negative (−) side input terminal of the operational amplifier 5d. ing. The operational amplifier 5d outputs an overcurrent detection signal to the logic unit 13 when the drain voltage becomes higher than the reference voltage VREF.

  The short circuit detection unit 6 detects a short circuit of the output terminal VOUT of the power supply IC 1 and outputs it to the logic unit 13 as a short circuit detection signal. The short-circuit detection unit 6 includes an operational amplifier 6a, a low-pass filter 6b, a negative OR circuit 6c, a flip-flop 6d, and an inverter 6e serving as a comparison unit.

  The output terminal VOUT is connected to the positive (+) side input terminal of the operational amplifier 6a serving as a comparison unit, and the reference voltage VREF is connected to the negative (−) side input terminal of the operational amplifier 6a. Has been.

  The input part of the low-pass filter 6b is connected to the output part of the operational amplifier 6a, and one input part of the negative OR circuit 6c constituting the state maintaining part is connected to the output part of the low-pass filter 6b. Yes.

  The other input section of the NOR circuit 6c is connected to the output section of the NOR circuit 12, and the output section of the NOR circuit 6c is a set of flip-flops 6d constituting a state maintaining section. Terminal S is connected.

  One input portion of the NAND circuit 12 is connected so that a start signal CE is input from an externally connected microcomputer or the like, and an inverter is connected to the other input portion of the NAND circuit 12. The output unit 12a is connected. The output section of the UVLO 10 is connected to the input section of the inverter 12a.

  Further, the negation of the set terminal input is input to the reset terminal R of the flip-flop 6d through the inverter 6e. The low-pass filter 6b cuts a signal that transitions in a short time. Therefore, even if the operational amplifier 6a detects a momentary short-circuit state, it is not output to the negative OR circuit 6c at the subsequent stage, and a logic circuit such as a semiconductor integrated circuit device connected to the power supply IC1 operates to temporarily Even if a large current or the like flows in the circuit, it is possible to prevent an erroneous determination that the short circuit state is determined.

  The output overvoltage detection unit 7 detects that the voltage output from the output terminal VOUT of the power supply IC1 has exceeded an arbitrary voltage value, and outputs the detected voltage to the logic unit 13 as an overvoltage detection signal. The output overvoltage detection unit 7 is composed of an operational amplifier or the like, and is connected so that the reference voltage VREF is input to the positive (+) side input terminal, and the voltage of the output terminal VOUT is connected to the negative (−) side input terminal. Are divided so that the divided voltage is divided by the resistors R1 and R2.

  The temperature detection unit 8 detects the temperature inside the power supply IC 1, and outputs an overheat detection signal to the logic unit 13 when the temperature exceeds an arbitrary temperature. The start-up timer 9 serving as a start-up detection unit is a timer that counts up after starting up the power supply IC 1 and notifies the logic unit 13 that an arbitrary time has elapsed.

  The UVLO 10 outputs a stop signal for stopping the operation when the input voltage VIN becomes equal to or lower than an arbitrary voltage. The logic unit 13 controls all of the power supply IC 1 and outputs a control signal to the input current adjusting unit 2 so as to control the current supplied to the regulation transistor 4 to be optimum.

  Next, the circuit configuration of the input current adjusting unit 2 will be described with reference to FIG.

  The input current adjustment unit 2 includes transistors 14 to 20 and constant current sources 21 and 22. Transistors 14, 15, 16, and 17 are P-channel MOS (Metal Oxide Semiconductor) transistors, and transistors 18 to 20 are N-channel MOS transistors.

  An input terminal VIN to which a power source is connected is connected to one connection portion of the transistors 14, 15, and 17, respectively. One input portion of the regulation transistor 4 is connected to the other connection portion of the input current adjusting transistor 14. The other connection part of the transistor 14 serves as an output part of the input current adjusting part 2.

  The gate of the transistor 14 is connected to the gate of the transistor 15, the other connection portion of the transistor 17, and one connection portion of the transistor 18. One connection part of the transistors 19 and 20 is connected to the other connection part of the transistors 16 and 17, respectively.

  Further, the reference potential VSS is connected to the other connection portion of the transistor 19 via the constant current source 21. The other connection portion of the transistor 20 is connected to the reference potential VSS via the constant current source 22, and the other connection portion of the transistor 18 is connected to the reference potential VSS.

  The output terminal G1 of the logic unit 13 is connected to the gate of the transistor 16, and the output terminal G2 of the logic unit 13 is connected to the gate of the transistor 17. The output terminal G3 of the logic unit 13 is connected to the gate of the transistor 18, and the output terminal G4 of the logic unit 13 is connected to the gate of the transistor 19. The output terminal G5 of the logic unit 13 is connected to the gate of the transistor 20.

  Next, the operation of the input current adjustment unit 2 in the present embodiment will be described with reference to FIG. 1, FIG. 2, and FIG.

  FIG. 3 is a table showing the output states of the output terminals G1 to G5 of the logic unit 13 and the operating states of the transistors 14 to 20 in each mode.

  First, the startup time of the power supply IC 1 will be described.

  First, when a start signal CE is input from an externally connected microcomputer or the like, the start-up timer 9 operates and outputs a start signal to the logic unit 13 for an arbitrary period (for example, about 3 ms or less). While the start signal is being input, the logic unit 13 outputs Lo signals from the output terminals G1, G3, and G5, respectively, as shown in 'Startup / CE input' in FIG. 3, and the output terminals G2 and G4. To output Hi signals respectively.

  Thereby, the transistors 16 and 19 are turned on, and current limitation is applied to the transistors 14 and 15 constituting the mirror circuit. Therefore, even if there is a heavy capacitive load when the power supply IC 1 is activated, the inrush current can be reduced.

  Thereafter, when the logic unit 13 inverts the start signal of the start-up timer 9, normal operation is performed. In this normal operation, as shown in “normal operation” in FIG. 3, the logic unit 13 outputs Hi signals from the output terminals G1 to G3, and outputs Lo signals from the output terminals G4 and G5, respectively. .

  Therefore, the transistors 14, 15, and 18 are turned on, the transistors 16, 17, 19, and 20 are turned off, respectively, and the transistor 14 becomes completely conductive and becomes in a low resistance state. Supplied.

  When the short circuit detection unit 6 detects a short circuit of the power supply IC 1, the logic unit 13 outputs a Hi signal from the output terminal G 1 as shown in “Short circuit protection” in FIG. The Lo signal is output from G5.

  As a result, the transistors 14 to 16 and 18 to 20 other than the transistor 17 are turned off, and the regulation of the input current adjusting unit 2 is stopped.

  As described above, the short-circuit detection unit 6 is provided with the low-pass filter 6b, and is configured to suppress the short-circuit protection operation when the output voltage is lowered due to a transient large current flow.

  Generally, in a regulator circuit such as a power supply IC, since the current limit and the short circuit protection are the same foldback type, the capability of the output circuit is remarkably limited even with a transient voltage drop. In the configuration of the present embodiment, since the current limit and the short-circuit protection are operated separately, the transient characteristics are improved.

  Further, when the short circuit protection is activated, the short circuit detection signal is continuously output from the flip-flop 6d of the short circuit detection unit 6 unless the activation signal CE is input from an externally connected microcomputer or the like. Thereby, the automatic return | restoration at the time of short circuit protection can be prevented.

  Next, when the output overvoltage detection unit 7 detects an overvoltage and the overvoltage detection signal output from the output overvoltage detection 7 is input to the logic unit 13, the logic unit 13 performs “output overvoltage protection” in FIG. 3. As shown in Fig. 5, the Hi signal is output from the output terminal G1 and the Lo signal is output from the other output terminals G2 to G5, respectively, as in the case of short circuit protection. Thereby, also in this case, the regulation of the input current adjusting unit 2 is stopped.

  Since the output main loop of the series regulator circuit composed of the transistor 4 and the output adjustment unit 3 is extremely slow with respect to the load fluctuation, a phenomenon in which the output voltage jumps occurs when the output current rapidly decreases.

  For this reason, a device such as a semiconductor integrated circuit device connected to the output as a load may be destroyed. However, as described in the present embodiment, the output overvoltage detection unit 7 is disconnected from the main loop, so that the output voltage rise can be detected at high speed.

  Further, when the overcurrent detection unit 5 detects an overcurrent, an overcurrent detection signal is input to the logic unit 13. In response to this overcurrent detection signal, the logic unit 13 outputs a Hi signal from each of the output terminals G2 and G5, and outputs from the output terminals G1, G3, and G4, as shown in “Output overcurrent protection” in FIG. Respectively output Lo signals. Thereby, the transistors 16 and 19 are turned on, and the transistor 14 (15) is in a current limiting state.

  Subsequently, when the temperature detection unit 8 detects an abnormal overheat of the power supply IC 1 and outputs an overheat detection signal to the logic unit 13, the logic unit 13 performs short circuit protection as shown in “overheating protection” in FIG. 3. Similarly to the time, the Hi signal is output from the output terminal G1, and the Lo signal is output from the other output terminals G2 to G5. Thereby, also in this case, the regulation of the input current adjusting unit 2 is stopped.

  Thus, according to the present embodiment, the protection operation such as current limitation is performed by the input current adjusting unit 2 provided in the previous stage of the regulation transistor 4, so that it is not necessary to limit the current in the output main loop. it can.

  In addition, since the current limitation in the output main loop is not required, the series regulator circuit constituting the output main loop can be simplified, the degree of freedom of phase characteristic adjustment is increased, and stable operation can be performed. .

  Furthermore, since no current limitation is required in the output main loop, various detection and protection operations such as overcurrent, overvoltage, short circuit, and overheating can be performed with high precision and precision. Reliability can be improved.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  The present invention is suitable for a semiconductor integrated circuit device such as a power supply IC using a series regulator circuit.

It is a block diagram which shows the structural example of the power supply IC by one embodiment of this invention. FIG. 2 is an explanatory diagram illustrating a circuit configuration example of an input current adjusting unit provided in the power supply IC of FIG. 1. 3 is a table showing an output state of a logic unit provided in the input current adjustment unit of FIG. 2 and an operation state of each transistor.

Explanation of symbols

1 Power supply IC
2 Input current adjustment unit 3 Output adjustment unit 3a, 3b Resistor 3c Capacitance element 3d Operational amplifier 4 Regulation transistor 5 Overcurrent detection unit 5a Transistor 5b Operational amplifier 5c Resistance 5d Operational amplifier 5e Transistor 6 Short-circuit detection unit 6a Operational amplifier 6b Low-pass filter 6c Negation OR circuit 6d Flip-flop 6e Inverter 7 Output overvoltage detector 8 Temperature detector 9 Start-up timer 10 UVLO
DESCRIPTION OF SYMBOLS 11 Reference voltage generation part 12 NAND circuit 12a Inverter 13 Logic part 14-20 Transistor 21, 22 Constant current source

Claims (6)

A series regulator circuit that regulates the input voltage and generates an arbitrary power supply voltage;
A semiconductor integrated circuit device comprising: an input current adjustment control unit provided in a preceding stage of the series regulator circuit and configured to adjust a current of an input voltage output to the series regulator circuit based on a detection signal. The semiconductor integrated circuit device according to claim 1.
The input current adjustment control unit
A detection unit that outputs a detection signal when a protective operation of the series regulator circuit is required;
A control unit that outputs a control signal based on the detection signal output from the detection unit;
A semiconductor integrated circuit device comprising: a current adjusting unit for limiting or stopping current of an input voltage output to the series regulator circuit based on a control signal of the control unit. The semiconductor integrated circuit device according to claim 2.
The detector is
An overcurrent detector for detecting an overcurrent of the series regulator circuit;
A short-circuit detector for detecting that the series regulator circuit is in a short-circuit state;
An overvoltage detector for detecting an overvoltage of the series regulator circuit;
A semiconductor integrated circuit device comprising: an overheat detecting unit for detecting overheating in the semiconductor integrated circuit device. The semiconductor integrated circuit device according to claim 3.
The short circuit detector is
A comparison unit that compares a voltage output from the series regulator circuit with a reference voltage, and outputs a detection signal by determining a short circuit state when the voltage output from the series regulator circuit is equal to or lower than the reference voltage; ,
A low-pass filter that is connected to the output unit of the comparison unit and passes only a low-frequency detection signal;
The low-pass filter is
The semiconductor integrated circuit device, wherein the detection signal is not output to the control unit if the detection signal detected by the comparison unit is an arbitrary time or less. The semiconductor integrated circuit device according to claim 4.
The short circuit detector is
A semiconductor integrated circuit device comprising: a state maintaining unit that maintains a signal state of the detection signal until an activation signal is input from the outside when the detection signal is output through the low-pass filter. The semiconductor integrated circuit device according to claim 2 or 3,
The detector is
A start detection unit that detects that the series regulator circuit has started,
The controller is
When the start detection unit outputs a detection signal output when the series regulator circuit is started, the current adjustment unit is configured to limit the input voltage output to the series regulator circuit for an arbitrary period. A semiconductor integrated circuit device that outputs a control signal.

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