JP6511842B2 - Constant voltage DC power supply - Google Patents

Description

  According to the present invention, when the current value of the output current reaches a preset current limit value, a constant current voltage droop that drops the voltage value of the output voltage while maintaining the current value of the output current at the current limit value. The present invention relates to a constant voltage DC power supply device including an overcurrent protection circuit that performs an operation and configured to be able to select and set the current limit value among a plurality of different current limit values.

  As this kind of constant voltage DC power supply device, a constant voltage DC power supply device disclosed in Patent Document 1 below is known. The constant voltage DC power supply device includes a constant voltage control circuit, a limited current value command circuit, and a current limit signal generation circuit (so-called over current protection circuit), and functions as a battery charging circuit for charging a battery.

  The constant voltage control circuit of the constant voltage DC power supply device compares the battery voltage differentially with the first reference voltage inside the device, and charges the battery voltage to a predetermined second voltage (for example, 4.2 V). Generate a voltage control signal. Also, when the battery voltage gradually rises from a low voltage and reaches a third voltage (eg, about 4.0 V) slightly lower than the second voltage, a differential comparison output is generated and supplied to the limiting current value command circuit Do.

  The limited current value command circuit is configured of a logic circuit, and receives battery voltage in addition to the differential comparison output, and the first pre-charging current value (for example, 50 mA), the second according to those inputs. The first to fourth limit current command values for the pre-charge current value (for example, 150 mA), the first current value (for example, 700 mA), the second current value (for example, 300 mA), etc. Supply to the circuit.

  The current limit signal generation circuit compares the voltage drop (voltage drop at the current detection resistor for charging current detection) with the current limit value at that time, and when the voltage drop reaches the current limit command value, The constant voltage control signal is suppressed by generating the current limit signal and supplying it to the constant voltage control circuit. Thereby, the charging current is limited to a value corresponding to each limiting current command value.

  In this current limit signal generation circuit, a variable resistor whose resistance value is changed in accordance with the command value between the second reference voltage and the ground according to the first to fourth limit current command values from the limit current value command circuit (Fixed resistance) are connected in series. Thereby, a voltage corresponding to the limited current command value can be obtained from this resistance (fixed resistance). In the current limit signal generation circuit, the drop voltage and the voltage of the resistor (fixed resistance) (ie, the limit current command value) are compared by the comparator, and when the drop voltage exceeds the limit current command value at that time, The output is inverted to H level, the constant voltage control signal is suppressed, and current limitation is performed.

  Therefore, in this way, the constant voltage DC power supply with a current limit function capable of changing the current limit value (constant voltage DC power supply with an overcurrent protection circuit) limits the current at the desired current limit value. While charging the battery (constant current charging the battery with a desired current value) is possible.

JP-A-2004-159477 (pages 5-6, 1-4)

  However, the above-described constant voltage DC power supply device has the following problems to be solved. That is, in the current limit signal generation circuit of the constant voltage DC power supply device described above, the resistance value is set between the second reference voltage and the ground according to the first to fourth limit current command values from the limit current value command circuit. Therefore, the variable resistor to be changed and the resistor (fixed resistor) are connected in series, and the voltage generated on this resistor (fixed resistor) is compared with the voltage drop in the comparator. However, since there are variations in the reference voltage value, the resistance value of the variable resistor that is changed according to the command value, and the resistance value of the resistor (fixed resistor), the voltage generated in the resistor (fixed resistor) due to this variation There are also variations. Therefore, in this constant voltage DC power supply device, the current limit value corresponding to each limited current command value varies due to this variation, that is, it is difficult to accurately define the desired current limit value. There are some issues that should be done.

  The present invention has been made to solve such problems, and it is an object of the present invention to provide a constant voltage DC power supply device capable of accurately defining a current limit value selected as a constant current value at the time of constant current voltage droop operation. Main purpose.

In order to achieve the above object, a constant voltage DC power supply device according to the present invention comprises a current detection circuit that outputs a current detection voltage of a voltage value proportional to a current value of output current, and a voltage detection circuit proportional to the voltage value of the current detection voltage. The current value of the output current is detected when it is detected that the current value of the output current has reached a preset current limit value based on the comparison result of the comparison target voltage value and the predetermined reference voltage value. An over current protection circuit for performing a constant current voltage drooping operation to drop the output voltage while maintaining the current limiting value at the current limiting value, and selecting the current limiting value from among a plurality of different current limiting values different from each other A constant voltage DC power supply device configured to be settable to a current limit value, wherein the current detection voltage is divided by a first resistance circuit and a second resistance circuit connected in series with each other to compare the comparison target voltage values Comprising a voltage dividing circuit for outputting an elephant voltage, the first resistor circuit includes a plurality of fixed resistors defined in different resistance values a number smaller than the number of the current limit value, the plurality of fixed resistors and many And a rotary code switch capable of changing the combination pattern of the on / off state of the switch element according to the rotational position of the rotor, and the switch element is connected to each of the plurality of fixed resistors. And a series circuit formed in parallel is connected in parallel , and the combined resistance value can be changed stepwise corresponding to the plurality of current limit values by rotating the rotor to change the combination pattern. A variable resistor for finely adjusting the comparison target voltage value is disposed in at least one of the first resistor circuit and the second resistor circuit.

Further, in the constant voltage DC power supply device according to the present invention, a current detection circuit that outputs a current detection voltage having a voltage value proportional to the current value of the output current, and a comparison target voltage value proportional to the voltage value of the current detection voltage When it is detected that the current value of the output current has reached a preset current limit value based on the comparison result between the current value and the predetermined reference voltage value, the current value of the output current is used as the current limit value. And setting the current limit value at a selected current limit value selected from among a plurality of different current limit values. A constant-voltage DC power supply device configured to be capable of dividing a reference voltage by a first resistance circuit and a second resistance circuit connected in series with each other and outputting a reference voltage of the predetermined reference voltage value circuit Wherein the first resistor circuit, the rotation of the rotor comprises a plurality of fixed resistors defined in different resistance values a number smaller than the number of the current limit value, the plurality of fixed resistors and the same number of switching elements And a rotary code switch capable of changing the combination pattern of the on / off state of the switch element according to the position, and a series circuit formed by connecting the switch element to each of the plurality of fixed resistors is connected in parallel And the combined resistance value can be changed stepwise corresponding to the plurality of current limit values by rotating the rotor to change the combination pattern , the first resistance circuit and the first resistance circuit At least one of the second resistor circuits is provided with a variable resistor for finely adjusting the predetermined reference voltage value.

  Further, in the constant voltage DC power supply device according to the present invention, the variable resistor is disposed in the second resistor circuit.

According to the constant voltage DC power supply device of the present invention, the variable resistor is disposed in at least one of the first resistor circuit and the second resistor circuit in the voltage dividing circuit, so that the reference voltage value and Even if the resistance value of each fixed resistor constituting the first resistor circuit of the circuit is slightly dispersed, operating the variable resistor allows the current limit value selected by the rotary code switch to be set to the specification of the power supply device. Fine adjustment can be made to substantially match the above current limit value. Thus, the user of the power supply device operates the rotary code switch without using equipment such as a measuring instrument, thereby actually selecting a desired one of the plurality of current limit values specified in the specification. The current limit value can be set to supply the load (such as a battery) with the current limit value as specified in the specification.

Further, according to the constant voltage DC power supply device of the present invention, the variable resistor is disposed in the second resistor circuit connected in series to the first resistor circuit in which the rotary code switch is disposed. By operating, all the current limit values can be finely adjusted at once, so the adjustment operation can be simplified, and the reduction in the number of steps of the adjustment process can be achieved.

FIG. 2 is a block diagram of a power supply device 1; 5 is a characteristic diagram of an output voltage V2 with respect to an output current I2 of the power supply device 1. FIG. It is a corresponding | compatible figure about each selection ch about the selection switch 45 of the power supply device 1, the current limiting value Ir, and the ON state of each switch element SW. Resistance value of fixed resistance connected by each selection ch about the selection switch 45 of the power supply device 1, current limit value Ir, and each on-state switch element SW among the fixed resistances 41 to 44 of the first resistance circuit 31 FIG. 7 is a corresponding view of a combined resistance value of the first resistance circuit 31. FIG. It is a block diagram of constant voltage DC power supply device 1A.

  Hereinafter, embodiments of a constant voltage DC power supply device will be described with reference to the drawings.

  The power supply device 1 shown in FIG. 1 includes, as an example, a pair of input terminals 2a and 2b (hereinafter, also referred to as "input terminal 2" when not particularly distinguished), input smoothing circuit 3, transformer 4, switching circuit 5, current detection circuit 6, a rectifying circuit 7, an output smoothing circuit 8, a pair of output terminals 9a and 9b (hereinafter, also referred to as "output terminal 9" unless otherwise specified), a control circuit 10, and a voltage dividing circuit 11 It is configured as a constant voltage DC power supply having an over current protection function.

  In the power supply device 1, the input smoothing circuit 3 is composed of a capacitor connected between the input terminals 2a and 2b as shown in FIG. 1 as an example, and an input voltage (input voltage between the input terminals 2a and 2b) DC voltage) The ripple component of V1 is reduced (the input voltage V1 is smoothed). The input smoothing circuit 3 can adopt various known configurations, such as a combination of a coil and a capacitor, instead of the configuration of only the capacitor. In addition, when the input voltage V1 is sufficiently stable, a configuration in which the input smoothing circuit 3 is omitted can be employed.

  Transformer 4 includes at least a primary winding 4a and a secondary winding 4b electrically isolated from primary winding 4a, as shown in FIG. 1 as an example. The switching circuit 5 has a switch element 5a (FET, transistor, etc.) and a drive circuit 5b, and the drive circuit 5b performs on / off control of the switch element 5a based on the drive pulse S1 output from the control circuit 10. The input voltage V1 output from the input smoothing circuit 3 is switched and intermittently applied to the primary winding 4a of the transformer 4. The transformer 4 induces an alternating voltage in the secondary winding 4b by applying the input voltage V1 intermittently to the primary winding 4a.

  In FIG. 1, the switching circuit 5 is configured as a 1 stone forward type circuit as an example, but a 1 stone flyback type circuit, a push-pull type circuit, a full bridge type circuit, etc. It can also be configured with circuits of various known methods. Further, although the power supply device 1 includes the insulating transformer 4 and is configured as an insulating DCDC converter, although not shown, for example, a non-insulating type using a choke coil in place of the transformer 4 It can also be configured as a DCDC converter.

  Current detection circuit 6 is disposed on the primary side (the side of primary winding 4a of transformer 4) of power supply device 1 as shown in FIG. 1 as an example, and detects input current I1 flowing through switching circuit 5. At the same time, the current detection voltage Vi of a voltage value Viv (a voltage value based on the potential of the ground G on the primary side of the power supply device 1) proportional to the current value of the input current I1 is output. In this case, the current value of the input current I1 flows to the secondary side (the side of the secondary winding 4b of the transformer 4) of the power supply device 1 and the current value of the output current I2 supplied to the load connected to the output terminal 9 Proportional to Therefore, since the voltage value Viv of the current detection voltage Vi is also proportional to the current value of the output current I2, detecting the voltage value Viv substantially detects the current value of the output current I2. .

  In the present example, the current detection circuit 6 is configured by a current detection resistor having a low resistance value (for example, a minute resistance value less than 1 Ω) as an example, but is not limited thereto. For example, the input current I1 flows A configuration (current transformer) having a magnetic core mounted on a path and a coil wound around the magnetic core, a magnetic core mounted in this manner, and a magnetoelectric conversion element (a Hall element or the like provided on the magnetic core) The current detection circuit 6 can also be configured with a current probe or the like that outputs a current detection voltage Vi having a voltage value Viv proportional to the current value of the input current I1. Alternatively, the current detection circuit 6 may be disposed on the secondary side of the power supply device 1 to directly detect the current value of the output current I2 and output the current detection voltage Vi.

  The rectifying circuit 7 rectifies an alternating voltage induced in the secondary winding 4b to convert it into a pulsating current and outputs it. The output smoothing circuit 8 smoothes the pulsating current output from the rectifier circuit 7 to convert it into an output voltage (DC voltage) V2 and outputs it from between the output terminals 9a and 9b.

  In the present embodiment, the control circuit 10 includes a reference voltage generation circuit 21, a comparison circuit 22, and a drive signal generation circuit 23, as shown in FIG. 1 as an example. The control circuit 10 performs a constant voltage control operation to control the duty ratio of the driving pulse S1 to be output such that the voltage value becomes a predetermined voltage value Vo based on the voltage value of the output voltage V2 being detected. And a set current limit value (selected from a plurality of current limit values as described later) based on a comparison target voltage value Vdv of the comparison target voltage Vd described later output from the voltage dividing circuit 11. When it is detected that the current value of the output current I2 reaches “Ilim” (also referred to as “selected current limit value”) because it is a current limit value, the constant current voltage droop type overcurrent protection function operates. A constant current control operation is performed to control the duty ratio of the drive pulse S1 to be output.

  Specifically, the reference voltage generation circuit 21 generates a reference voltage Vr having a constant voltage value (reference voltage value Vrv, a voltage value based on the potential of the ground G (in this example, a minus voltage value as an example)). Output. The comparison circuit 22 divides a reference voltage value Vdv (a voltage value as a comparison target voltage value proportional to the voltage value Viv) and a predetermined reference voltage value (an example in this example) obtained by dividing the reference voltage value Vrv. Although the voltage division ratio is 1 and is the reference voltage value Vrv itself, it may be a voltage value obtained by dividing the reference voltage value Vrv by less than 1), and the voltage value Vdv is referred to. When the voltage value (in this example, the reference voltage value Vrv as described above) is reached (that is, when the current value of the output current I2 reaches the selection current limit value Ilim), the detection signal S2 is output.

  The drive signal generation circuit 23 outputs a constant voltage control operation until the detection signal S2 is output from the comparison circuit 22 (until the current value of the output current I2 reaches the selected current limit value Ilim). The duty ratio of the drive pulse S1 is controlled such that the voltage value of the voltage V2 is maintained at a predetermined voltage value Vo.

  In addition, the drive signal generation circuit 23 executes the constant current control operation when the detection signal S2 is output from the comparison circuit 22 (when the current value of the output current I2 reaches the selection current limit value Ilim). Thus, the duty ratio of the drive pulse S1 is controlled such that the current value of the output current I2 is maintained at the selected current limit value Ilim. As a result, the voltage value of the output voltage V2 decreases. With this configuration, the control circuit 10 functions as an overcurrent protection circuit that exerts a constant current voltage droop type overcurrent protection function when the drive signal generation circuit 23 performs this constant current control operation.

  The voltage dividing circuit 11 includes a first resistor circuit 31 and a second resistor circuit 32 connected in series with each other. Further, in this example, the voltage dividing circuit 11 is disposed between the output side of the current detection voltage Vi in the current detection circuit 6 and the ground G to divide the voltage value Viv of the current detection voltage Vi into the voltage division ratio (first By dividing by the resistance value of the resistance circuit 31 / (the resistance value of the first resistance circuit 31 + the resistance value of the second resistance circuit 32), the comparison voltage Vd of the comparison voltage value Vdv is output.

  In this case, the first resistor circuit 31 includes a plurality of fixed resistors (four fixed resistors 41, 42, 43 and 44 as an example in this example) defined to have mutually different resistance values, and the plurality of fixed resistors (fixed And a selection switch 45 for connecting in series only the selected fixed resistor among the resistors 41, 42, 43, 44) to the second resistor circuit 32. The first resistor circuit 31 further includes a fixed resistor 46 connected in parallel to the entire series circuit of the plurality of fixed resistors and the selection switch 45.

  In this example, as an example, the selection switch 45 is also referred to as the switch element SW 1, SW 2, SW 3, SW 4 in the same number as the number (4) of fixed resistors 41, 42, 43 And a rotary code switch provided with The rotary code switch is, for example, S-1000A manufactured by Copal Corporation, according to the rotational position of the rotor (hereinafter, also referred to as a selection channel (abbreviated as "selection ch")) on / off of each switch element SW. It is a switch which can change the combination pattern of a state.

  In this selection switch 45, since there are four switch elements SW, there are 2 4 (16) combination patterns, and 16 selection ch0, ch1, ..., corresponding to each combination pattern. ch9, chA,..., chE, chF (hereinafter also referred to as selected ch when not particularly distinguished) are defined. Thus, the selection switch 45 can select the combination pattern of the on / off state of the switch element SW corresponding to the selected channel by rotating the rotor to the desired selected channel.

  In the power supply device 1, ten current limit values Ir0, Ir1, Ir2, Ir3, Ir4, Ir5, Ir6, Ir7, Ir8, Ir9 (as one example of a plurality of current limit values, as shown in FIGS. Ir0 <Ir1 <Ir2 <Ir3 <Ir4 <Ir5 <Ir7 <Ir8 <Ir9) Hereinafter, the current limit values Ir0 to Ir9 are also referred to as current limit value Ir), and any of these may be prepared. A configuration is adopted in which one current limit value Ir is selected as the actual current limit value Ilim (the selected current limit value is “selected current limit value”). For this reason, in the power supply device 1, as an example, only the ten selected ch0, ch1, ..., ch8, ch9 of the selected ch0 to chF are used, and these selected ch0, ch1, ... , Ch 8 and ch 9 correspond to the current limit values Ir 0, Ir 1,..., Ir 8 and Ir 9 in this order as shown in FIG.

  In this case, as shown in FIG. 3, the combination pattern of the on / off state of each switch element SW of the selection switch 45 changes corresponding to each selection ch0, ch1,..., Ch8, ch9. As a result of changing the combination of the fixed resistors 41 to 44 of the first resistor circuit 31 connected in series to the second resistor circuit 32, the voltage dividing ratio of the voltage dividing circuit 11 is changed stepwise. The switch element SW with 素 子 in FIG. 3 represents the on state, and the switch element SW without ○ represents the off state.

  For example, each resistance value R1, R2, R3, R4, R0 of fixed resistances 41, 42, 43, 44, 46 is 680 [.OMEGA.], 330 [.OMEGA.], 160 [.OMEGA.], 82 [.OMEGA.], 100 k [. When the fixed resistor 41 is connected to the switch element SW1, the fixed resistor 42 to the switch element SW2, the fixed resistor 43 to the switch element SW3, and the fixed resistor 44 to the switch element SW4, as shown in FIG. Resistance value of the entire first resistance circuit 31 at selection ch0, ch1, ch2, ch3, ch4, ch5, ch6, ch7, ch8, ch9 (switch element SW of on state of fixed resistances 41, 42, 43, 44 The combined resistance value of the fixed resistance connected via the fixed resistance 46 and the fixed resistance 46 always connected) is selected from 100 k [Ω] at the selected ch0 at the selected ch1 as shown in FIG. Stepwise change (decrease in this example) such as 75 [Ω], 329 [Ω] at selection ch2, ..., 82 [Ω] at selection ch8, 73 [Ω] at selection ch9 Can.

  Thereby, since the voltage division ratio of the voltage dividing circuit 11 in each selection ch0, ch1,..., Ch8, ch9 can be changed (decreased) stepwise, the selection ch of the selection switch 45 is selected ch0 The comparison target voltage value Vdv of the comparison target voltage Vd output from the voltage dividing circuit 11 is changed to the reference voltage value Vrv by changing toward the selection ch 9 side such as selection ch 1, selection ch 2,. Increasing the current value of the input current I1 (as a result, the current value of the output current I2) when reaching the voltage value) in a stepwise manner, that is, the current limit values Ir0, Ir1, Ir2 selected as the selection current limit value Ilim , Ir3, Ir4, Ir5, Ir6, Ir7, Ir8, and Ir9 are gradually increased in this order as described above (the current limit value Ir0 <Ir1 <I 2 <Ir3 <Ir4 <Ir5 <Ir6 <Ir7 <Ir8 <be as IR9) becomes possible.

  Further, each fixed resistor 41, 42, 43, 44, 46 can be configured by only a single resistor element whose resistance value is fixed, or a resistor formed by connecting a plurality of resistor elements in parallel or in series Since it can be configured by a network, it is possible to define any resistance value. Therefore, in the power supply device 1, the current limiting value Ir at each of the selected ch0, ch1,..., Ch8, ch9 can be obtained by appropriately setting the resistance value of each fixed resistor 41, 42, 43, 44, 46. Each selection ch0, ch1,..., Ch8, so as to conform to the specification (each of a plurality of current limit values that can be selected as the selection current limit value Ilim) of the selection current limit value Ilim of the power supply device 1 of this example. It is possible to set the voltage division ratio of the voltage divider circuit 11 at ch 9 to the voltage division ratio on the specifications.

  The second resistor circuit 32 is configured to have a variable resistor 47. In this example, as an example, as shown in FIG. 1, the second resistor circuit 32 is configured of one variable resistor 47, and one end side of the variable resistor 47 is supplied with the current detection voltage Vi. Is not connected to the end of the fixed resistor 41, 42, 43, 44 of the first resistor circuit 31 that is not connected to the switch element SW, and to the ground G of the fixed resistor 46. The end of the side is connected.

  With this configuration, the reference voltage value Vrv and the resistance values R1, R2, R3, R4, and R0 of the fixed resistors 41, 42, 43, 44, and 46 constituting the first resistance circuit 31 slightly vary among the power supply devices 1. Even in the adjustment process at the time of manufacture of the power supply device 1, the voltage dividing ratio of the voltage dividing circuit 11 in any one selected ch0, ch1,..., Ch8, ch9 is the second resistance By operating the variable resistor 47 of the circuit 32 to finely adjust the resistance value of the second resistor circuit 32, it is possible to match the voltage division ratio on the specification of this arbitrary one selected channel (also this result) The voltage division ratio of the voltage divider circuit 11 in the other selected channel is also substantially matched to the voltage division ratio on each specification).

  Thereby, in the power supply device 1, by changing the resistance value of the variable resistor 47 of the second resistor circuit 32, the current limit value Ir at each of the selected ch0, ch1,. It is possible to finely adjust and match the specifications (the respective current limit values that can be selected as the current limit value Ilim) of the selected current limit value Ilim of the power supply device 1 of this example almost exactly. . Although not shown, a fixed resistor may be connected in series to the variable resistor 47 in order to adjust the variable range and the degree of change of the resistance value of the entire second resistor circuit 32 when operating the variable resistor 47, A configuration in which a fixed resistor is connected in parallel to the variable resistor 47 can also be adopted.

  Subsequently, the operation of the power supply device 1 will be described by taking an example where the power supply device 1 charges a battery (hereinafter, also referred to as a battery 51) as the load 51.

  The power supply device 1 is, for example, controlled in constant voltage control operation with a dummy load connected between the output terminals 9a and 9b, for example, in the adjustment process at the time of manufacture, and the voltage value of the output voltage V2 is The voltage value is adjusted to be a predetermined voltage value Vo.

  Further, in another adjustment process at the time of manufacture, the power supply device 1 operates the selection switch 45 to set the selected channel of the rotor to one of selected ch0, ch1,..., Ch8, ch9, The current limit value Ir for the set selected channel becomes a current value conforming to the specifications of the power supply 1 (in other words, the voltage dividing ratio of the voltage dividing circuit 11 on this selected channel conforms to the specifications of the power supply 1 Fine adjustment by operating the variable resistor 47 of the second resistor circuit 32 so as to obtain the above voltage division ratio. As a result, current limit values Ir for all other selected channels are also defined to current values substantially matching the specifications of the power supply device 1.

  When constant-current charging the battery 51 using the power supply device 1, the user first determines the specifications of the power supply device 1 (current limit values Ir0 to Ir9 for each selection ch0 to ch9 for the selection switch 45). Check and operate selection switch 45 so that the selection ch of the rotor of selection switch 45 matches the desired charging current value for constant current charging of battery 51 of each of selection ch0 to ch9. The selected channel corresponding to the value Ir is set (in other words, the selected current limit value Ilim during the constant current control operation of the power supply 1 is set to the current limit value Ir). Next, the power supply device 1 is operated in constant current control. Thereby, the user can perform constant current charging of the battery 51 with the selected current limit value Ilim specified in the specification of the power supply device 1.

  As described above, in the power supply device 1, the variable resistor 47 is disposed in the second resistor circuit 32 of the voltage dividing circuit 11. Therefore, according to the power supply device 1, the reference voltage value Vrv or the resistance value of the fixed resistors 41, 42, 43, 44, 46 constituting the first resistance circuit 31 of the voltage dividing circuit 11 is slightly Even if variation occurs, operating the variable resistor 47 fine-tunes the current limit value Ir at each selection channel of the selection switch 45 so as to substantially match the current limit value on the specifications of the power supply device 1 can do. Thus, the user of the power supply device 1 operates the selection switch 45 without using equipment such as a measuring instrument to select one of the plurality of current limit values Ir specified in the specification. By setting the actual selected current limit value Ilim, the current limit value Ir as specified in the specification can be supplied to the battery 51 as a load (the battery 51 is charged with a constant current).

  Although the power supply device 1 described above adopts a configuration in which the voltage value Viv of the current detection voltage Vi is divided by the voltage dividing circuit 11, the constant voltage DC power supply device 1A shown in FIG. ), Instead of the voltage value Viv of the current detection voltage Vi, the reference voltage Vr generated by the reference voltage generation circuit 21 is divided by the voltage dividing circuit 11 to obtain a reference voltage of a predetermined reference voltage value Vrfv. It is also possible to adopt a configuration of outputting to the control circuit 10 as Vrf. In addition, about the same structure as the power supply device 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  In this power supply device 1A, the fixed resistors 41, 42, 43, 44, and 46 constituting the first resistance circuit 31 are configured such that the voltage division ratio at each of the selected ch0 to ch9 gradually increases toward the selected ch9 side. By defining resistance values, current limit values Ir0, Ir1, Ir2, Ir3, Ir4, Ir5, Ir6, Ir7 at the respective selected ch0, ch1,. , Ir 8 and Ir 9 can be increased in this order in stages.

  Even in the power supply device 1A, a slight variation occurs in the reference voltage value Vrv and the resistance value of the fixed resistors 41, 42, 43, 44, and 46 constituting the first resistance circuit 31 of the voltage dividing circuit 11 at the time of manufacture. Even if the variable resistance 47 of the second resistance circuit 32 is operated, the current limit value Ir at each selection channel of the selection switch 45 is finely adjusted to a state substantially matching the current limit value on the specifications of the power supply 1. It can be adjusted. Thus, the user of the power supply device 1A operates the selection switch 45 without using equipment such as a measuring instrument to select one of the plurality of current limit values Ir specified in the specification. By setting the actual selected current limit value Ilim, the current limit value Ir as specified in the specification can be supplied to the battery 51 as a load (the battery 51 is charged with a constant current).

  Further, in the above-described power supply devices 1 and 1A, a rotary code switch in which all the switch elements SW may be turned off (in the case of selection ch0) is used as the selection switch 45 in the first resistance circuit 31. In the state, since the fine adjustment using the variable resistor 47 of the second resistor circuit 32 can not be performed, the fixed resistor 46 is disposed to avoid this, for example, a selection ch other than the selection ch0 of the rotary code switch Can be employed, and in this configuration, the fixed resistor 46 can be omitted.

  Further, in the above power supply devices 1 and 1A, by adopting a configuration in which the rotary code switch is used as the selection switch 45 in the first resistance circuit 31, the voltage division ratio of the voltage division circuit 11 is stepped to a larger value. It is possible to adopt a configuration in which a switch is used as the selection switch 45 such that only one of the switch elements SW in FIG. it can.

  Further, in the above-described power supply devices 1 and 1A, the variable resistor 47 is disposed in the second resistor circuit 32 connected in series to the first resistor circuit 31 in which the selection switch 45 is disposed, and the variable resistor 47 is operated. In this configuration, a configuration in which all current limit values Ir can be finely adjusted collectively (that is, a configuration in which the adjustment operation can be simplified to achieve reduction in the number of steps in the adjustment process) is adopted. Alternatively, the second resistor circuit 32 may be configured as a fixed resistor, and each fixed resistor 41, 42, 43, 44 of the first resistor circuit 31 may be configured to have a variable resistor 47. In this configuration, although it takes time for the adjustment operation to correspond to the increase in the number of adjustment locations, it becomes possible to finely adjust each current limit value Ir individually. Furthermore, although not shown, each of the fixed resistors 41, 42, 43 and 44 of the first resistor circuit 31 and the second resistor circuit 32 may be configured to have variable resistors. Further, instead of the above configuration in which the first resistance circuit 31 is disposed on the ground G side, a configuration in which the second resistance circuit 32 is disposed on the ground G side can also be adopted.

  In the above example, the power supply devices 1 and 1A adopting the switching method are described, but although not shown, the voltage dividing circuit described above is applied to a constant voltage DC power supply device adopting a series method. The arrangement of 11 can also be applied to configure multiple current limit values accurately.

  Further, in the above power supply devices 1 and 1A, since the current detection voltage Vi is a negative voltage with respect to the potential of the ground G of the control circuit 10, all of the voltage value Vdv, the reference voltage value Vrv and the reference voltage value Vrfv are negative. Although not shown, the current detection voltage Vi is a positive voltage with respect to the potential of the ground G of the control circuit 10, and the voltage value Vdv, the reference voltage value Vrv, and the reference voltage value are matched. It is also possible to adopt a configuration in which any of Vrfv has a positive voltage.

1, 1A power supply device 6 current detection circuit 10 control circuit 11 voltage dividing circuit 21 reference voltage generation circuit 31 first resistance circuit 32 second resistance circuit 41 to 44 fixed resistance 45 selection switch 47 variable resistance I2 output current Vd comparison voltage Vdv Comparison target voltage value Vi Current detection voltage Viv Current detection voltage voltage value Vrf Reference voltage Vrfv Reference voltage value Vrv Reference voltage value

Claims (3)

A current detection circuit that outputs a current detection voltage having a voltage value proportional to the current value of the output current;
It was detected that the current value of the output current reached a preset current limit value based on the comparison result of the comparison target voltage value proportional to the voltage value of the current detection voltage and a predetermined reference voltage value. And an overcurrent protection circuit for performing constant current voltage drooping operation to drop the output voltage while maintaining the current value of the output current at the current limit value, and a plurality of current limit values different from one another A constant voltage DC power supply device configured to be settable to a selected current limit value selected from among current limit values,
The voltage dividing circuit is configured to divide the current detection voltage by a first resistor circuit and a second resistor circuit connected in series with each other and output a comparison target voltage of the comparison target voltage value.
The first resistance circuit includes a plurality of fixed resistors whose number is less than the number of the current limit values and which is defined to have different resistance values, and the same number of switch elements as the plurality of fixed resistors, Accordingly, a rotary code switch capable of changing the combination pattern of the on / off state of the switch element is provided, and a series circuit formed by connecting the switch element to each of the plurality of fixed resistors is connected in parallel And by changing the combination pattern by rotating the rotor, the combined resistance value can be changed stepwise corresponding to the plurality of current limit values,
A constant voltage DC power supply device, wherein at least one of the first resistor circuit and the second resistor circuit is provided with a variable resistor for finely adjusting the comparison target voltage value. A current detection circuit that outputs a current detection voltage having a voltage value proportional to the current value of the output current;
It was detected that the current value of the output current reached a preset current limit value based on the comparison result of the comparison target voltage value proportional to the voltage value of the current detection voltage and a predetermined reference voltage value. And an overcurrent protection circuit for performing constant current voltage drooping operation to drop the output voltage while maintaining the current value of the output current at the current limit value, and a plurality of current limit values different from one another A constant voltage DC power supply device configured to be settable to a selected current limit value selected from among current limit values,
A voltage dividing circuit that divides a reference voltage by a first resistor circuit and a second resistor circuit connected in series with each other and outputs a reference voltage of the predetermined reference voltage value,
The first resistance circuit includes a plurality of fixed resistors whose number is less than the number of the current limit values and which is defined to have different resistance values, and the same number of switch elements as the plurality of fixed resistors, Accordingly, a rotary code switch capable of changing the combination pattern of the on / off state of the switch element is provided, and a series circuit formed by connecting the switch element to each of the plurality of fixed resistors is connected in parallel And by changing the combination pattern by rotating the rotor, the combined resistance value can be changed stepwise corresponding to the plurality of current limit values,
A constant voltage DC power supply device, wherein at least one of the first resistor circuit and the second resistor circuit is provided with a variable resistor for finely adjusting the predetermined reference voltage value.   The constant voltage DC power supply device according to claim 1, wherein the variable resistor is disposed in the second resistor circuit.

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