JP4534621B2 - Reference voltage generation circuit and power supply device using the same - Google Patents

Description

  The present invention relates to a reference voltage generation circuit that controls a generated reference voltage by controlling a pulse width of a pulse signal, and a power supply apparatus that controls an output voltage based on a reference voltage generated from the reference voltage generation circuit.

  Conventionally, various switching power supply devices that control output voltage by pulse width control of a pulse signal have been proposed (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3). In these conventional switching power supply devices, an alternating voltage is induced in the secondary winding by turning on and off a switching element (for example, a transistor) connected to the primary winding of the transformer included in the converter circuit by a pulse signal. The induced AC voltage is rectified and smoothed to generate a DC voltage (output voltage). Then, by controlling the pulse width of the pulse signal, specifically, the output voltage is controlled by duty control of the pulse signal.

  In addition, a switching power supply of a type in which the primary winding of the transformer included in the converter circuit is divided into a power supply winding and a control winding, and a control transistor connected to the control winding is oscillated by itself is proposed. ing. This type of switching power supply can be configured, for example, as shown in FIG.

  In FIG. 1, the switching power supply device includes a reference voltage generation circuit 10, a control circuit 15, and a converter circuit 20. The reference voltage generation circuit 10 outputs a reference voltage Vr corresponding to the duty ratio of the pulse signal Vs. The output characteristics of the reference voltage generation circuit 10 are such that, for example, the reference voltage Vr decreases as the duty ratio (on duty) increases. The control circuit 15 is composed of a comparison circuit such as an operational amplifier, and compares the detection voltage obtained by dividing the output voltage Vout of the converter circuit 20 by the resistors Rs and Rc with the reference voltage Vr, and compares the comparison voltage Vr. The resulting control voltage is output to the converter circuit 20.

  The converter circuit 20 includes a transformer T in which a primary winding is divided into a power supply winding and a control winding, and a control transistor connected to the control winding. A control voltage from the control circuit 15 is supplied to the control transistor. It is designed to be applied. Then, by a self-excited oscillation operation corresponding to the control voltage of the control transistor connected to the control winding of the primary winding, an alternating current flows through the power winding on the primary side of the transformer T, and accordingly An alternating voltage is induced in the secondary winding of the transformer T. The AC voltage induced in the secondary winding of the transformer T is rectified and smoothed to obtain a DC output voltage Vout.

  In such a switching power supply device, a voltage corresponding to the reference voltage Vr controlled by the duty ratio of the pulse signal Vs is output from the converter circuit 20, and as a result, the output voltage Vout of the switching power supply device It is controlled by the duty ratio of the signal Vs.

  The reference voltage generation circuit 10 in the switching power supply described above can be configured as shown in FIG. 2, for example.

  In this reference voltage generating circuit 10, a resistor R1 is connected between the base of the transistor Q1 serving as a switching element and an input terminal, and two diodes D1 and D2 are connected in series between the base and the ground line. A capacitor C1 is connected between both ends of the resistor R1. The emitter of the transistor Q1 is connected to the ground line, and resistors R2 and R3 are connected in series between the collector and the power supply line Vcc. A smoothing circuit (R5, C2) is connected to a connection point between the resistor R2 and the resistor R3, and an output of the smoothing circuit is connected to a buffer circuit composed of an operational amplifier OP1 and a resistor R7 via a resistor R6. Yes.

  When the pulse signal Vs as shown in FIG. 3A is applied to the input terminal of the reference voltage generating circuit 10 configured in this way, the transistor Q1 is turned on and off in synchronization with the pulse signal Vs, and the resistor As shown in FIG. 3B, a voltage Va that changes in synchronization with the pulse signal Vs is generated at the connection point between R3 and R2. Further, the collector-emitter voltage VCE of the transistor Q1 changes as shown in FIG. The voltage Va is smoothed by a smoothing circuit (R5, C1) to obtain a smoothed voltage Vb as shown in FIG. Then, the buffer circuit (OP1, R7) outputs a voltage based on the smoothed voltage Vb as the reference voltage Vr.

According to the reference voltage generating circuit 10 as described above, when the ON width of the pulse signal Vs is widened (when the on-duty becomes large), the low level width of the voltage Va is correspondingly widened. As a result, the smoothed voltage Vb The reference voltage Vr based on this decreases. The output characteristic theoretically indicates that the reference voltage Vr decreases linearly as the on-duty of the pulse signal Vs increases.
JP 7-20727 A JP-A-9-84341 JP 2003-304686 A

  By the way, the transistor Q1 as a switching element controlled to be turned on / off by the pulse signal Vs generally has a turn-on time tON, an accumulation time tstg, a falling time tr, and a collector saturation voltage VCE (sat). As a result, the voltage Va appearing at the connection point between the resistors R2 and R3 on the collector side of the transistor Q1 does not actually become a rectangular wave accurately synchronized with the pulse signal Vs, but is shown in FIGS. Thus, the waveform has a dull falling and rising edge. Further, the voltage Va (low level) when the transistor Q1 is turned on (conducting state) is equal to the collector saturation voltage VCE (sat) from the theoretical voltage value (Vcc × {R2 / (R2 + R3)}. For this reason, normally, the smoothed voltage Vb of the voltage Va becomes higher than the theoretical value, and accordingly, the reference voltage Vr also becomes higher than the theoretical value.

  The turn-on time tON, the accumulation time tstg, and the fall time tr are constant regardless of the width of the on-state and off-state of the transistor Q1. Therefore, in particular, the influence of the turn-on time tON of the transistor Q1 on the voltage Va is larger when the on-duty of the pulse signal Vs shown in FIG. 4 is smaller than when the on-duty of the pulse signal Vs shown in FIG. 5 is large. Become. That is, the difference between the smoothed voltage Vb of the voltage Va and the ideal value increases as the on-duty of the pulse signal Vs decreases.

  Thus, the smaller the on-duty of the pulse signal Vs, the larger the difference between the value of the smoothed voltage Vb and the ideal value is, as shown in FIG. 6, the reference voltage Vr based on the smoothed voltage Vb. The characteristic (see the solid line) has a larger difference from the ideal characteristic (see the broken line) as the on-duty of the pulse signal Vs decreases. When the on-duty of the pulse signal Vs is 100%, that is, when the transistor Q1 is conductive, there is no substantial effect on the voltage Va of the turn-on time tON, but the influence of the collector saturation voltage VCE (sat) on the voltage Va. Thus, when the on-duty of the pulse signal Vs is 100%, the actual value of the reference voltage Vr is slightly larger than the value on the ideal characteristic (the value at the right end of each characteristic line (solid line and broken line) in FIG. 6). ).

  Further, the actual characteristics of the reference voltage Vr can be obtained by adjusting each circuit constant of the reference voltage generating circuit 10 shown in FIG. 2 so that the on-duty of the pulse signal Vs is 80 as shown in FIG. 7, for example. %, It can be matched with ideal characteristics. However, even in this case, the difference between the actual value and the ideal value of the reference voltage Vr is large in the region where the on-duty of the pulse signal Vs is small.

  Further, when the actual characteristics of the reference voltage Vr are examined in detail, the characteristics tend not to be a straight line but to be a curve as shown in FIG. 8, due to the nonlinearity of the transistor Q1. For this reason, the difference between the output characteristic of the reference voltage Vr and the ideal characteristic is further increased.

  As described above, since the output characteristics from the reference voltage generation circuit 10 deviate greatly from the ideal characteristics particularly in the region where the on-duty of the pulse signal Vs is small, the output voltage of the power supply device controlled based on the reference voltage Vr. As shown in FIG. 9, the characteristic of Vout is greatly deviated from the ideal characteristic in the region where the on-duty of the pulse signal Vs is small, and its linearity is also lost (refer to the part surrounded by a chain line in FIG. 9).

  For this reason, in the conventional power supply apparatus, the duty control of the pulse signal Vs must be performed in consideration of the deviation from the ideal characteristics, and the control is complicated. Further, in order to avoid such complicated control, control is performed using a region that is relatively close to the ideal characteristic, so that the use efficiency of nonlinear elements such as the transistor Q1 and the transformer T is low.

  The present invention has been made to solve such a conventional problem, and provides a reference voltage generation circuit capable of obtaining output characteristics as close to ideal characteristics as possible and a power supply apparatus using the reference voltage generation circuit. .

The reference voltage generation circuit according to the present invention is turned on by a pulse signal applied to the first resistance element , the second resistance element, and the control terminal between the first voltage line and the second voltage line. , and oFF operation, and a switching element for the blocking and tolerance of the first from said voltage line of the first resistive element and the current toward the second through said resistive element second voltage line A reference voltage generating circuit connected in series and outputting a reference voltage based on a smoothed voltage obtained by smoothing a voltage appearing between the first resistance element and the second resistance element, wherein the switching An adjustment resistor element that is connected in parallel to the element or the second resistor element and the switching element, and that causes the current from the first voltage line to flow to the second voltage line when the switching element is off. Is provided.

With such a configuration, when the switching element is turned on, the first resistance element, the second resistance element, and the switching element are connected in the case where the adjustment resistance element is connected in parallel to the second resistance element and the switching element. A current flows from the first voltage line to the second voltage line via the first voltage line, and a current flows from the first voltage line to the second voltage line via the first resistance element and the adjustment resistance element. Therefore, at the connection point between the first resistance element and the second resistance element, the voltage of the first voltage line, the resistance value of the first resistance element, the second resistance element, the adjustment resistance element, The first voltage value corresponding to the parallel combined resistance of the first appears. Further, in the case of the configuration in which the adjustment resistance element is connected in parallel to the switching element, when the switching element is turned on, a current is supplied to the adjustment resistance element via the first resistance element and the second resistance element. Flowing. At this time, the first voltage value appearing at the connection point between the first resistance element and the second resistance element is the voltage of the first voltage line, the resistance value of the first resistance element, and the second resistance value. A first voltage value corresponding to the resistance value of the element and the resistance value of the adjustment resistance element appears.
In addition, when the switching element is turned off, in the case of the configuration in which the adjustment resistor element is connected in parallel to the second resistor element and the switching element, the first resistor element and the adjustment resistor element are connected to the first resistor element. Current flows from the voltage line to the second voltage line. Therefore, the connection point between the first resistance element and the second resistance element depends on the voltage of the first voltage line, the resistance value of the first resistance element, and the resistance value of the adjustment resistance element. A second voltage value appears. In the case where the adjustment resistor element is connected in parallel to the switching element, when the switching element is turned off, the adjustment resistor element receives a current through the first resistor element and the second resistor element. Flowing. Therefore, the second voltage value appearing at the connection point between the first resistance element and the second resistance element is the voltage of the first voltage line, the resistance value of the first resistance element, and the second resistance value. A second voltage value appears according to the resistance value of the element and the resistance value of the adjustment resistance element. When the on / off operation of the switching element is controlled by controlling the pulse width of the pulse signal, the first voltage value and the second voltage value are repeated with a width corresponding to the pulse width in synchronization with the pulse signal. A voltage having a waveform appears between the first resistance element and the second resistance element.

  Therefore, the longer the OFF operation time of the switching element, the greater the influence of the adjustment resistance element on the voltage appearing between the first resistance element and the second resistance element. That is, the longer the OFF operation time of the switching element, the more effectively the voltage appearing between the first resistance element and the second resistance element can be adjusted by the adjustment resistance element.

  Further, in the reference voltage generation circuit according to the present invention, the first resistance element and the second resistance element are directly connected, a connection point between the first resistance element and the second resistance element, and the The adjustment resistance element may be connected to the second voltage line.

  With such a configuration, when the switching element is in the OFF state, a current flows from the first voltage line toward the second voltage line via the first resistance element and the adjustment resistance element. As a result, the voltage difference between the first voltage line and the second voltage line is divided by the first resistance element and the adjustment resistance element so that the divided voltage is the first resistance element and the second resistance. Appears at the connection point with the element.

  Furthermore, the reference voltage generation circuit according to the present invention may be configured such that the adjustment resistance element is connected between the terminals of the switching element.

  With such a configuration, when the switching element is in the OFF state, current flows from the first voltage line toward the second voltage line via the first resistance element, the second resistance element, and the adjustment resistance element. Flows. As a result, the voltage difference between the first voltage line and the second voltage line is divided by the first resistance element, the second resistance element, and the adjustment resistance element. Appears between the resistive element.

  In the reference voltage generation circuit according to the present invention, the adjustment resistor element may be a variable resistor element.

  With such a configuration, the resistance value of the adjustment resistance element can be arbitrarily set, so that the voltage appearing between the first resistance element and the second resistance element when the switch element is turned off is reduced. It can be adjusted arbitrarily.

The reference voltage generating circuit according to the present invention, makes connection between said adjusting resistor element and the switching element in parallel, or switch circuit are disconnected the parallel connection of said the adjusting resistor element and the switching element It can be set as the structure which has.

  With such a configuration, the characteristics of the pulse width of the pulse signal of the voltage appearing between the first resistance element and the second resistance element are switched by switching the connection and non-connection of the adjustment resistance element with the switch circuit. The characteristics for can be switched. That is, the output characteristics of the reference voltage based on the voltage appearing between the first resistance element and the second resistance element can be switched.

  Furthermore, the reference voltage generation circuit according to the present invention can be configured such that the switching element is a transistor element based on the control terminal or an FET element whose gate is the control terminal.

  A power supply apparatus according to the present invention includes any of the reference voltage generation circuits described above and a converter circuit that generates a voltage output by a self-excited oscillation operation based on the reference voltage output from the reference voltage generation circuit. It becomes composition.

  With such a configuration, the output voltage based on the reference voltage based on the voltage appearing between the first resistance element and the second resistance element adjusted by the adjustment resistance element in the reference voltage generation circuit is a comparator circuit. Will occur.

  According to the reference voltage generation circuit of the present invention, the voltage appearing between the first resistance element and the second resistance element is effectively adjusted by the adjustment resistance element as the OFF operation time of the switching element is longer. Therefore, even if the voltage appearing between the first resistance element and the second resistance element based on the ON / OFF operation of the switching element does not have an accurate rectangular waveform, the switching element The longer the OFF operation time of the switching element, that is, the smoother the voltage appearing between the first resistance element and the second resistance element as the ON duty of the pulse signal for ON / OFF control of the switching element decreases. The control voltage can be effectively adjusted by the adjusting resistance element. Accordingly, the output characteristic of the reference voltage generated by the reference voltage generation circuit with respect to the pulse width of the pulse signal is ideally the voltage appearing between the first resistance element and the second resistance element. In the case of a rectangular waveform, adjustment can be made so as to approximate the output characteristics of an ideal reference voltage based on the smoothed voltage of the voltage.

  Hereinafter, a reference voltage generation circuit and a power supply apparatus according to embodiments of the present invention will be described with reference to the drawings.

  The power supply apparatus including the reference voltage generation circuit according to the first embodiment of the present invention is configured as shown in FIG. The power supply device can be used as a power supply for developing bias of a developing device such as an electrophotographic copying machine or printer.

10, this power supply device has the same basic configuration as the power supply device shown in FIG. 1, and includes a reference voltage generation circuit 100, a control circuit 15, and a converter circuit 20. Similar to the reference voltage generation circuit 10 shown in FIG. 2, the reference voltage generation circuit 100 includes a transistor Q1 (switching element), a capacitor C1, a resistor R1, diodes D1, D2, resistors R2, R3, and a smoothing circuit (R5, C2). , Resistor R6, and buffer circuit (peamplifier OP1, resistor R7), resistors R3 and R2, and transistor Q1 receiving pulse signal Vs at its base are connected in series between voltage line Vcc and ground line. Has been. Further, the reference voltage generating circuit 100 is different from the reference voltage generating circuit 10 shown in FIG. 2 in that the transistor Q1 is connected between the connection point of the resistor R3 and the resistor R2, one end of which is connected to the voltage line Vcc, and the ground line. An adjustment resistor R4 connected in parallel is provided. The adjustment resistor R4 has a sufficiently large resistance value as compared with the resistor R2.

  The reference voltage Vr output from the reference voltage generating circuit 100 having the above-described configuration is input to one input terminal (the inverting input terminal of the operational amplifier OP2) of the control circuit 15 configured by the operational amplifier OP2 or the like. A detection voltage obtained by dividing the voltage difference between the output voltage of the converter circuit 20, the voltage line, and Vcc by the resistors Rs and Rc is input to the other input terminal of the control circuit 15 (the non-inverting input terminal of the operational amplifier OP2). The control circuit 15 compares the detection voltage with the reference voltage Vr, and outputs a control voltage as a comparison result to the converter circuit 20. A capacitor C4 is connected between the input terminal (the non-inverting input terminal of the operational amplifier OP2) to which the detection voltage of the control circuit 15 is fed back and the ground line.

The converter circuit 20 includes a transformer T having a primary side winding N2 and a secondary side winding N2 which are divided into a power supply winding N11 and a control winding N12. The other end is connected to the circuit power source Vc and the collector of the transistor Q2. The emitter of the transistor Q2 is connected to the ground line, and its base is connected to one end of the control winding N12. The other end of the control winding N12, a control voltage from the control circuit 15, the resistor R8, to the input via the charging and discharging circuit configured by a capacitor C 3 and resistor R9. A diode D3 and a capacitor C5 are connected to the secondary winding N2 of the transformer T. The self-excited oscillation operation of the transistor Q1 due to charging and discharging operation of the reference voltage the charging and discharging circuit corresponding to the control voltage based on the Vr (resistor R8, a capacitor C 3 and resistor R9), alternating current power source winding N11 of the primary side A current flows and an AC voltage corresponding to the current is induced in the secondary winding N2. The AC voltage induced in the secondary winding N2 of the transformer T is rectified by the diode D3 and smoothed by the capacitor C5. A DC voltage obtained by smoothing with the capacitor C5 is obtained as the output voltage Vout.

  A stabilized power supply circuit REG is connected to the circuit power supply Vc, and the output voltage of the stabilized power supply circuit REG is supplied to the voltage line Vcc.

In the power supply device having such a configuration, the pulse signal Vs is supplied to the base of the transistor Q1 of the reference voltage generation circuit 100, and the transistor Q1 performs an on / off operation according to the pulse signal Vs. When the transistor Q1 is turned on, a current flows from the voltage line Vcc through the resistors R3 and R2 and the transistor Q1 to the ground line, and a slight current flows through the adjustment resistor R4. As a result, the voltage Va is applied to the connection point between the resistors R3 and R2.
Va = Vcc × (R4 // R2) / {(R4 // R2) + R3} (where Vce (on) = 0V)
R4 // R2: A parallel combined resistance value of resistors R4 and R2 appears.

On the other hand, when the transistor Q1 is turned off, a current flows from the power supply line Vcc to the ground line via the resistors R3 and R4. As a result, the voltage Va ′ is applied to the connection point between the resistors R3 and R2.
Va ′ = Vcc × R4 / (R4 + R3) (where R4 is sufficiently larger than R2)
Appears.

  Therefore, when the transistor Q1 is repeatedly turned on and off according to the pulse signal Vs, the connection point between the resistors R3 and R2 is synchronized with the pulse signal Vs as shown by the broken line in FIG. A pulse voltage that repeats the voltage Va (low level) and the voltage Va ′ (high level) is generated. In FIG. 11, a solid line indicates a voltage waveform appearing at a connection point between the resistor R3 and the resistor R2 in a state where the adjustment resistor R4 is not connected (see FIG. 2). In the voltage waveform in the reference voltage generating circuit 100 shown by the broken line in FIG. 11, the voltage level Va ′ when the transistor Q1 is turned off is ΔV compared to the corresponding voltage level Vcc in the voltage waveform shown by the solid line. Only a low voltage value is obtained. In the voltage waveform indicated by the broken line in FIG. 11, the voltage level Va when the transistor Q1 is turned on is substantially the same as the corresponding voltage level in the voltage waveform indicated by the solid line.

  Since the voltage waveform appearing at the connection point between the resistor R3 and the resistor R2 is shown by a broken line in FIG. 11, the influence of the voltage level decrease amount ΔV on the reference voltage Vr based on the smoothed voltage of the voltage is The smaller the on-duty of the pulse signal Vs, the larger it becomes. Therefore, as described above (see FIG. 6), the difference between the characteristic of the reference voltage Vr and the ideal characteristic becomes larger as the on-duty of the pulse signal Vs becomes smaller, depending on the turn-on time tON, the accumulation time tstg, and the fall time tr of the transistor Q1. Is suppressed. That is, as shown in FIG. 12, the difference between the characteristic of the reference voltage Vr (characteristic before correction: solid line) and the ideal characteristic (dashed line) when the adjustment resistor R4 is not provided is small in the on-duty of the pulse signal Vs. Even if it becomes larger, the adjustment resistor R4 reduces the reference voltage Vr (characteristic after correction: one-dot chain line) as the on-duty of the pulse signal Vs becomes smaller. The output characteristic of the reference voltage Vr after the correction by the method approaches the ideal characteristic.

  Further, by adjusting each circuit constant of the reference voltage generating circuit 100, for example, as shown in FIG. 13, when the on-duty of the pulse signal Vs is 80%, the reference voltage Vr that matches the ideal characteristic is set. Even when the output characteristic is obtained, by providing the adjustment resistor R4, the output characteristic (dashed line) of the reference voltage Vr can be brought close to the ideal characteristic (broken line).

  Further, when the output characteristics of the reference voltage Vr without the adjustment resistor R4 are viewed in detail, the characteristics (correction) are not curved as shown in FIG. Previous characteristic: solid line). By providing the adjustment resistor R4 as in the reference voltage generation circuit 100 described above, the amount of decrease in the reference voltage Vr increases as the on-duty of the pulse signal Vs decreases, so the output characteristics of the reference voltage Vr (after correction) (Characteristic: one-dot chain line) can be approximated to a straight line and can be approximated to an ideal characteristic (dashed line).

  As described above, by providing the adjustment resistor R4, the characteristic of the reference voltage Vr output from the reference voltage generation circuit 100 with respect to the duty of the pulse signal Vs approaches the ideal characteristic. The output voltage Vout generated by the circuit 20 also approaches the output voltage Vout generated based on the ideal characteristic reference voltage Vr. An example of the actual measurement result of the output voltage Vout is shown in FIG. In FIG. 15, the difference ΔV between the output voltage Vout generated based on the reference voltage Vr obtained when the adjustment resistor R4 is not provided and the output voltage Vout (ideal) generated based on the reference voltage Vr of ideal characteristics. The output voltage Vout generated based on the reference voltage Vr obtained based on the characteristic with respect to the on-duty (circle) and the reference voltage Vr obtained when the adjustment resistor R4 is provided, and the output voltage Vout generated based on the reference voltage Vr having the ideal characteristic The characteristic (x mark) with respect to the on-duty of the difference ΔV from (ideal) is shown.

  According to the result of the actual measurement, when the adjustment resistor R4 is not provided, the output voltage Vout has a large difference from the output voltage Vout (ideal) according to the ideal characteristics in a region where the on-duty of the pulse signal Vs is small. Become. On the other hand, when the adjustment resistor R4 is provided, the difference between the output voltage Vout and the output voltage Vout (ideal) according to the ideal characteristics is small over substantially the entire on-duty of the pulse signal Vs.

  Next, a reference voltage generation circuit according to a second embodiment of the present invention will be described. The reference voltage generating circuit according to the second embodiment has a structure in which an adjustment resistor R41 is connected between the collector and emitter of the transistor Q1, as shown in FIG.

  In the reference voltage generating circuit having such a structure, when the transistor Q1 is turned on, the current from the voltage line Vcc flows to the ground line via the resistors R3 and R2 and the transistor Q1. As a result, a voltage obtained by dividing the voltage difference between the voltage line Vcc and the ground line by the resistors R3 and R2 appears at the connection point between the resistors R3 and R2. On the other hand, when the transistor Q1 is turned off, the current from the voltage line Vcc flows to the ground line via the resistors R3 and R2 and the adjusting resistor R41. As a result, a voltage obtained by dividing the voltage difference between the power supply line Vcc and the ground line by the series combined resistance of the resistor R3, the resistor R2, and the adjusting resistor R41 appears at the connection point between the resistor R3 and the resistor R2.

  Also in this case, as in the case of the first embodiment described above, when the transistor Q1 is turned off, the voltage appearing at the connection point between the resistors R3 and R2 is the voltage (Vcc) in the case of ideal characteristics. ) (See the characteristic in FIG. 11). Therefore, since the reference voltage Vr generated by the reference voltage generation circuit is reduced as the on-duty of the pulse signal Vs is reduced, the output characteristic of the reference voltage Vr approaches the ideal characteristic (FIGS. 12 and 12). 13, see FIG.

  The reference voltage generation circuit according to the third embodiment of the present invention is configured as shown in FIG. In this reference voltage generating circuit, an FET element (FET) is provided instead of the transistor Q1 as the switching element shown in FIG. The pulse signal Vs is applied to the gate of the FET element via the resistor R10, the TLL circuit and the resistor R1. Thus, since the pulse signal Vs is applied to the gate of the FET element through the TLL circuit, the FET element can be driven even if the voltage level of the pulse signal Vs is low. It becomes like this.

  Further, the reference voltage generating circuit according to the fourth embodiment of the present invention is configured as shown in FIG. In this reference voltage generating circuit, an FET element (FET) is provided instead of the transistor Q1 as the switching element shown in FIG. As in the example shown in FIG. 17, the pulse signal Vs is applied to the gate of the FET element via the resistor R10 and the TLL circuit.

  In the reference voltage generation circuit according to each of the embodiments described above, the resistance value of the adjustment resistor R4 (R41) is set according to the output characteristics of the reference voltage Vr to be obtained. Even if circuit constants in various reference voltage generating circuits are slightly different, a reference voltage generating device in which the output characteristics of the reference voltage Vr become uniform by appropriately setting the resistance value of the adjusting resistor R4 (R41). Can be realized.

  From the viewpoint of adjusting the resistance value and from the viewpoint that the output characteristics of the reference voltage Vr can be made variable, the adjustment resistor R4 (R41) is preferably a variable resistor.

  Further, from the viewpoint of switching (variable) the output characteristics of the reference voltage Vr, the reference voltage generating circuit is shown in FIG. 19 (fifth embodiment of the present invention) and FIG. 20 (sixth embodiment of the present invention). ).

  In the reference voltage generating circuit shown in FIG. 19, an adjustment resistor R4 and a transistor Q3 as a switch circuit are connected in series between a connection point between the resistor R3 and the resistor R2 and the ground line. A voltage obtained by dividing the control voltage Vcont by the resistors R11 and R12 is applied to the base of the transistor Q3, and the transistor Q3 is turned on and off by the control voltage cont.

  When the transistor Q3 is turned on, the adjustment resistor R4 is connected between the connection point between the resistor R3 and the resistor R2 and the ground line. In this case, the configuration of the reference voltage generation circuit is substantially the same as the configuration of the reference voltage generation circuit shown in FIG. Therefore, the output characteristics of the reference voltage Vr are the same as the output characteristics in the reference voltage generation circuit shown in FIG. On the other hand, when the transistor Q3 is turned off, the adjustment resistor R4 is disconnected from the connection point between the resistor R3 and the resistor R2. In this case, the configuration of the reference voltage generation circuit is substantially the same as that of the reference voltage generation circuit shown in FIG. Therefore, the output characteristic of the reference voltage Vr is the same as the output characteristic in the reference voltage generation circuit when the adjustment resistor R4 is not provided.

  That is, in the reference voltage generating circuit shown in FIG. 19, the output characteristic of the reference voltage Vr can be switched by turning on and off the transistor Q3 by the control voltage Vcont.

  In the reference voltage generating circuit shown in FIG. 20, an adjustment resistor R41 and a transistor Q3 are connected in series between the collector and emitter of the transistor Q1. A voltage obtained by dividing the control voltage Vcont by the resistors R11 and R12 is applied to the base of the transistor Q3, and the transistor Q3 is turned on and off by the control voltage Vcont.

  When the transistor Q3 is turned on, the adjustment resistor R41 is connected between the collector and emitter of the transistor Q1. In this case, the configuration of the reference voltage generation circuit is substantially the same as the configuration of the reference voltage generation circuit shown in FIG. Therefore, the output characteristics of the reference voltage Vr are the same as the output characteristics in the reference voltage generation circuit shown in FIG. On the other hand, when the transistor Q3 is turned off, the adjustment resistor R4 is disconnected between the collector and the emitter of the transistor Q1, and the output characteristic of the reference voltage Vr is the reference when the adjustment resistor R4 is not provided. The output characteristics in the voltage generation circuit are the same. That is, even in the reference voltage generating circuit shown in FIG. 20, the output characteristics of the reference voltage Vr can be switched by turning on and off the transistor Q3 by the control voltage Vcont.

  As described above, the reference voltage generation circuit according to the present invention has an effect that an output characteristic closer to the ideal characteristic can be obtained, and the reference voltage generation that controls the generated reference voltage by controlling the pulse width of the pulse signal. In addition to being useful as a circuit, it is useful as a reference voltage generation circuit to be applied to a power supply apparatus that controls an output voltage based on a reference voltage.

It is a block diagram which shows the basic structural example of a switching power supply device. FIG. 2 is a circuit diagram showing a configuration of a reference voltage generation circuit in the switching power supply device shown in FIG. 1. 3 is a timing chart showing signal waveforms at various parts in the reference voltage generation circuit shown in FIG. 2. FIG. 3 is a waveform diagram showing a voltage waveform (No. 1) appearing at a connection point between a resistor R3 and a resistor R2 in the reference voltage generating circuit shown in FIG. FIG. 3 is a waveform diagram showing a voltage waveform (No. 2) appearing at a connection point between a resistor R3 and a resistor R2 in the reference voltage generating circuit shown in FIG. FIG. 3 is a characteristic diagram showing an output characteristic (No. 1) of a reference voltage Vr in the reference voltage generating circuit shown in FIG. 2. FIG. 3 is a characteristic diagram showing an output characteristic (No. 2) of a reference voltage Vr in the reference voltage generating circuit shown in FIG. 2. FIG. 3 is a characteristic diagram showing an output characteristic (No. 3) of a reference voltage Vr in the reference voltage generating circuit shown in FIG. 2. It is a characteristic view which shows the output voltage characteristic of the power supply device shown in FIG. It is a circuit diagram which shows the structure of the power supply device containing the reference voltage generator which concerns on 1st embodiment of this invention. FIG. 11 is a waveform diagram showing a voltage waveform appearing at a connection point between a resistor R3 and a resistor R2 in the reference voltage generating circuit shown in FIG. FIG. 11 is a characteristic diagram illustrating an output characteristic (No. 1) of a reference voltage Vr in the reference voltage generation circuit illustrated in FIG. 10. FIG. 11 is a characteristic diagram illustrating an output characteristic (No. 2) of a reference voltage Vr in the reference voltage generation circuit illustrated in FIG. 10. FIG. 11 is a characteristic diagram illustrating an output characteristic (No. 3) of a reference voltage Vr in the reference voltage generation circuit illustrated in FIG. 10. It is a figure which shows the actual value of the output characteristic of the power supply device shown in FIG. It is a circuit diagram which shows the structure of the reference voltage generation circuit which concerns on 2nd embodiment of this invention. It is a circuit diagram which shows the structure of the reference voltage generation circuit which concerns on 3rd embodiment of this invention. It is a circuit diagram which shows the structure of the reference voltage generation circuit which concerns on 4th embodiment of this invention. It is a circuit diagram which shows the structure of the reference voltage generation circuit which concerns on 5th embodiment of this invention. It is a circuit diagram which shows the structure of the reference voltage generation circuit which concerns on the 6th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Reference voltage generation circuit 15 Control circuit 20 Converter circuit 100 Reference voltage generation circuit

Claims (8)

Between the first voltage line and the second voltage line , the first resistance element , the second resistance element, and a pulse signal applied to the control terminal are turned on and off to A switching element that allows and cuts off current from the voltage line to the second voltage line via the first resistance element and the second resistance element is connected in series, and the first resistance A reference voltage generation circuit for outputting a reference voltage based on a smoothed voltage obtained by smoothing a voltage appearing between an element and the second resistance element,
For adjusting the switching element or the second resistance element and the switching element connected in parallel, and when the switching element is off, the current from the first voltage line flows through the second voltage line A reference voltage generation circuit comprising a resistance element . The first resistance element and the second resistance element are directly connected, and the adjustment voltage is connected between a connection point between the first resistance element and the second resistance element and the second voltage line. The reference voltage generating circuit according to claim 1, wherein a resistance element is connected. The reference voltage generating circuit according to claim 1, wherein the adjustment resistance element is connected between terminals of the switching element. The reference voltage generation circuit according to claim 1, wherein the adjustment resistance element is a variable resistance element. Makes connection between the switching element and the adjusting resistor elements in parallel, or according to any one of claims 1 to 4 having a switch circuit that disconnects the parallel connection of said the adjusting resistor element and the switching element Reference voltage generation circuit. 6. The reference voltage generation circuit according to claim 1, wherein the switching element is a transistor element based on the control terminal. 6. The reference voltage generation circuit according to claim 1, wherein the switching element is an FET element having the control terminal as a gate. A reference voltage generation circuit according to any one of claims 1 to 7,
And a converter circuit that generates a voltage output by a self-excited oscillation operation based on the reference voltage output from the reference voltage generation circuit.

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