JP3117685U - Optical disk device and electronic device - Google Patents

Abstract

An operating power supply of a standard voltage is supplied to a power supply target IC without causing an increase in circuit scale and without inserting a step-down element in a DC output path for a low voltage IC.
A power supply target IC that uses a DC output 5 for low-voltage IC sent from a voltage stabilization circuit 11 as an operating power is provided, and the standard voltage of the operating power supply of the power supply target IC 21 is that of the DC output 5 for low-voltage IC. In the configuration in which the voltage is lower than the lowest value of the voltage setting range, from the detection position 15 for detecting the voltage error detection target of the DC output 5 for the low voltage IC, the input terminal of the operating power supply of the power supply target IC 21 The value obtained by adding the standard voltage of the operating power supply of the power supply target IC 21 to the voltage drop amount in the current path to the IC power supply position 211 that is the position is set as the voltage within the voltage settable range at the detection position 15.
[Selection] Figure 1

Description

  The present invention relates to an optical disc apparatus and an electronic apparatus in which a standard voltage of an operating power supply of an IC to be supplied with power is lower than a minimum value of a settable range of an output voltage of a voltage stabilizing circuit that generates the operating power supply.

  An IC used for signal processing of a DVD player has a large current value of an operating power supply because many functions are integrated in one package. As a result, the voltage drop that occurs in the path that leads the operating power output from the voltage stabilization circuit to the IC sometimes becomes a value that cannot be ignored. For this reason, a technique for solving the problem in the case where the voltage drop in the DC output path cannot be ignored has been proposed (the first conventional technique).

  That is, this technique is applied to a configuration in which a plurality of loads to which a direct current output is supplied via printed wiring patterns having different path lengths are provided. Then, an average voltage generation circuit is provided, and a voltage detected at each power feeding position of the plurality of loads and a voltage at the output point of the DC output are led to the average voltage generation circuit. The average voltage generation circuit is configured to generate and output a voltage that is an average of the voltage having the highest voltage value and the lowest voltage among the plurality of derived voltages. In addition, the voltage error of the DC output is detected based on the average voltage generated by the average voltage generation circuit. Therefore, for a plurality of loads having different voltage drop amounts due to the route of the printed wiring pattern, the minimum voltage value can be set within the allowable range for the load having the largest voltage drop amount, and the voltage drop amount For the load with the smallest value, the maximum value of the voltage can be set within the allowable range (see, for example, Patent Document 1).

Further, as a technique related to a voltage drop in the DC output path, the following technique has been proposed (referred to as a second conventional technique). In other words, the voltage stabilization circuit cannot stabilize the voltage of the DC output to a voltage lower than the reference voltage when detecting the voltage error. Therefore, for example, when an IC having a reference voltage of 1.25V is used for the voltage stabilizing circuit, the variable range of the DC output voltage is higher than 1.25V. On the other hand, the standard voltage of the operating power supply of the IC tends to be low, and there is a case where an IC having the standard voltage of the operating power supply of 1.2V has to be used. In such a case, a step-down element such as a resistor or a diode is inserted in the supply path of the operating power supply to the IC, and the voltage of 1.25 V is lowered to 1.2 V by the voltage drop due to the step-down element.
JP 2001-145336 A

  However, when the second prior art is used, a step-down element to be inserted into the operating power supply path is required, which causes a problem of an increase in the number of elements, leading to undesirable results such as an increase in cost.

  Since the first conventional technique is a configuration that stabilizes the voltage of the DC output based on the average voltage of the highest voltage value and the lowest voltage value among the plurality of voltage values, the range of the average voltage Can only be stabilized to a voltage range higher than the reference voltage used for error detection. However, this means that the voltage having the lowest voltage value can be stabilized to a voltage lower than the reference voltage. At the same time, it also means that a voltage higher than the reference voltage needs to be generated and supplied to the average voltage generation circuit. In other words, in order to generate a voltage in a voltage range lower than the reference voltage using the first conventional technique, both the voltage generation circuit that generates a voltage higher than the reference voltage and the average voltage generation circuit are indispensable. As a result, the circuit scale increases.

  The present invention was devised to solve the above-described problems, and its purpose is not to increase the circuit scale and to insert a step-down element in the low-voltage IC DC output path. It is possible to supply operating power of a specified voltage to the power supply target IC, to facilitate optimization of the amount of voltage drop in the DC output path for the low voltage IC, and to the current flowing through different ICs. An object of the present invention is to provide an optical disc apparatus capable of suppressing voltage fluctuation of an operating power supply of a power supply target IC even when fluctuation occurs.

  Another object of the present invention is to provide a power supply target IC that uses a DC output for a low-voltage IC as an operating power source, and to reduce the amount of voltage drop in the current path of the DC output for the low-voltage IC. By adding the voltage to a voltage within the settable range of the DC output voltage for the low voltage IC, the step-down element is inserted into the path of the DC output for the low voltage IC without increasing the circuit scale. It is an object of the present invention to provide an electronic device that can supply an operating power supply with a specified voltage to a power supply target IC.

  In addition to the above purpose, an electronic device that can easily optimize the voltage drop amount in the low-voltage IC DC output path by using a flexible flat cable in a part of the low-voltage IC DC output path. It is to provide.

  Further, in addition to the above-described purpose, the DC output path for the low voltage IC is formed by one core wire of the flexible flat cable, and the ground level path is formed by a plurality of core wires, thereby causing fluctuations in currents flowing through different ICs. Sometimes, an object is to provide an electronic apparatus capable of suppressing voltage fluctuations in the operating power supply of a power supply target IC.

  In order to solve the above-described problems, an optical disk device according to the present invention is provided on a first printed wiring board, provided on a second printed wiring board, a voltage stabilizing circuit for sending a DC output for a low-voltage IC, A power supply target IC that uses a DC output for a low-voltage IC sent from a voltage stabilization circuit as an operating power source, and the power supply target IC is an IC that processes a signal reproduced from an optical disk. The first printed wiring board is led to the second printed wiring board via a flexible flat cable that electrically connects the first printed wiring board and the second printed wiring board, and the power supply target IC This is applied to an optical disc apparatus in which the standard voltage of the operating power supply is lower than the lowest value of the voltage setting range of the DC output voltage for the low voltage IC. The position of the input terminal of the operation power supply of the power supply target IC is from the position on the path of the DC output for the low-voltage IC and the detection position for detecting the voltage error detection target of the DC output for the low-voltage IC. The value obtained by adding the standard voltage of the operating power supply of the power supply target IC to the amount of voltage drop in the current path of the DC output for low-voltage IC to the IC power supply position is used as the voltage within the settable voltage range at the detection position. The path of the DC output for the low-voltage IC in the cable is formed by one core wire of the flexible flat cable, and the ground level path in the flexible flat cable is formed by a plurality of core wires of the flexible flat cable.

  That is, a value obtained by adding the standard voltage of the operating power supply of the power supply target IC to the voltage drop amount in the current path of the DC output for the low-voltage IC (hereinafter referred to as an added voltage) is within the voltage setting range at the detection position. The voltage is Therefore, the voltage at the detection position can be set as the addition voltage. When the voltage at the detection position is set as the addition voltage, the voltage supplied to the power supply target IC is equal to the specified voltage of the operating power supply of the power supply target IC. Further, when the thickness of the core wire of the flexible flat cable is changed, the voltage drop amount in the path of the DC output for the low voltage IC changes along with the change. Further, when fluctuations occur in the currents flowing in different ICs, the fluctuations occur in the current flowing in the ground level. However, when the ground level path is formed by a plurality of core wires, the equivalent DC resistance component at the ground level is reduced. Accordingly, the potential fluctuation of the ground level of the second printed wiring board caused by the fluctuation of the current flowing to the ground level is suppressed to a minute value.

  An electronic device according to the present invention includes a voltage stabilization circuit that sends out a DC output for a low-voltage IC, and a power supply target IC that uses the DC output for the low-voltage IC sent from the voltage stabilization circuit as an operation power supply. This is applied to an electronic device in which the standard voltage of the operating power supply of the supply target IC is lower than the minimum voltage setting range of the DC output voltage for the low voltage IC. In the current path of the DC output for the low voltage IC from the detection position for detecting the voltage that is the detection target of the voltage error of the DC output for the low voltage IC to the IC power supply position that is the position of the input terminal of the operating power supply of the power supply target IC A value obtained by adding the standard voltage of the operating power supply of the power supply target IC to the voltage drop amount is set as a voltage within a settable range of the voltage at the detection position.

  That is, the value obtained by adding the standard voltage of the operating power supply of the power supply target IC to the voltage drop amount in the current path of the DC output for the low voltage IC (hereinafter referred to as the added voltage) is within the voltage setting range at the detection position. The voltage is Therefore, the voltage at the detection position can be set as the addition voltage. When the voltage at the detection position is set as the addition voltage, the voltage supplied to the power supply target IC is equal to the specified voltage of the operating power supply of the power supply target IC.

  In addition to the above configuration, the voltage stabilization circuit is provided on the first printed wiring board, the power supply target IC is provided on the second printed wiring board, and the first printed wiring board and the second printed wiring board are provided. Are electrically connected via a flexible flat cable, and the low-voltage IC direct current output is led from the first printed wiring board to the second printed wiring board via the flexible flat cable.

  That is, when the thickness of the core wire of the flexible flat cable is changed, the voltage drop amount in the path of the DC output for the low voltage IC changes with this change.

  In addition to the above configuration, the DC output path for the low voltage IC in the flexible flat cable is formed by one core wire of the flexible flat cable, and the ground level path in the flexible flat cable is formed by a plurality of core wires of the flexible flat cable. ing.

  That is, when the current flowing through different ICs varies, the current flowing to the ground level varies. However, when the ground level path is formed by a plurality of core wires, the equivalent DC resistance component at the ground level is reduced. Therefore, the potential fluctuation of the ground level of the second printed wiring board caused by the fluctuation of the current flowing to the ground level is suppressed to a minute value.

  According to the present invention, the value (added voltage) obtained by adding the standard voltage of the operating power supply of the power supply target IC to the voltage drop amount in the current path of the DC output for the low voltage IC is within the settable range of the voltage at the detection position. It is a voltage. Therefore, the voltage at the detection position can be set as the addition voltage. When the voltage at the detection position is set as the addition voltage, the voltage supplied to the power supply target IC is equal to the specified voltage of the operating power supply of the power supply target IC. Further, when the thickness of the core wire of the flexible flat cable is changed, the voltage drop amount in the path of the DC output for the low voltage IC changes along with the change. Further, when fluctuations occur in the currents flowing in different ICs, the fluctuations occur in the current flowing in the ground level. However, when the ground level path is formed by a plurality of core wires, the equivalent DC resistance component at the ground level is reduced. Accordingly, the potential fluctuation of the ground level of the second printed wiring board caused by the fluctuation of the current flowing to the ground level is suppressed to a minute value. Therefore, it is possible to supply an operating power supply with a specified voltage to the power supply target IC without causing an increase in circuit scale and without inserting a step-down element into the DC output path for the low voltage IC, and It is possible to easily optimize the amount of voltage drop in the DC output path for low-voltage ICs, and suppress fluctuations in the voltage of the operating power supply of the power supply target IC even when fluctuations occur in the current flowing in different ICs. be able to.

  Further, according to the present invention, the value (added voltage) obtained by adding the standard voltage of the operating power supply of the power supply target IC to the voltage drop amount in the current path of the DC output for the low voltage IC is within the settable range of the voltage at the detection position. The voltage is Therefore, the voltage at the detection position can be set as the addition voltage. When the voltage at the detection position is set as the addition voltage, the voltage supplied to the power supply target IC is equal to the standard voltage of the operating power supply of the power supply target IC. For this reason, it is possible to supply the operating power of the specified voltage to the power supply target IC without increasing the circuit scale and without inserting a step-down element in the path of the DC output for the low voltage IC.

  Further, when the thickness of the core wire of the flexible flat cable is changed, the voltage drop amount in the DC output path for the low voltage IC changes with the change, and thus the voltage drop amount in the DC output path for the low voltage IC. Can be easily optimized.

  Furthermore, when a current flowing in a different IC varies, a current flowing in the ground level varies. However, when the ground level path is formed by a plurality of core wires, the equivalent DC resistance component at the ground level is reduced. For this reason, the potential fluctuation of the ground level of the second printed wiring board caused by the fluctuation of the current flowing to the ground level is suppressed to a minute value. Therefore, even when fluctuations occur in currents flowing in different ICs, fluctuations in the voltage of the operating power supply of the power supply target IC can be suppressed.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an explanatory diagram showing an outline of a component arrangement of a substrate and a path of a DC output for a low voltage IC in an optical disk apparatus (specifically, a DVD player) which is an embodiment of an electronic apparatus according to the present invention. It is explanatory drawing which shows the electrical structure of embodiment, and the equivalent circuit of a power supply path | route.

  In the figure, on the first printed wiring board 1, a switching power supply circuit 12 that generates DC outputs 121 and 122 of plural kinds of voltages (other DC outputs are also generated), and a switching power supply circuit 12. And a voltage stabilizing circuit 11 for generating a DC output 5 for low-voltage IC using the DC output output from the IC as an operating power supply. The second printed wiring board 2 is provided with a power supply target IC 21 in which the standard voltage of the operating power supply is lower than the voltage of the low-voltage IC DC output 5. The second printed wiring board 2 is provided with a driver IC 22, SDRAM 23, flash memory 24, and DAC 25.

  The voltage stabilizing circuit 11 includes a regulator IC (4-terminal regulator) 13 and voltage dividing resistors R18 and R19. The regulator IC 13 includes a step-down circuit 131, an error amplifier 132, and a reference voltage source 14. The error amplifier 132 detects a difference between the voltage divided by the voltage dividing resistors R18 and R19 and the voltage supplied from the reference voltage source 14, and outputs the detection result to the step-down circuit 131 as an error signal. The step-down circuit 131 controls the voltage of the DC output 5 for the low voltage IC so that the error amount indicated by the error signal becomes zero.

  The power supply target IC 21 is an IC that processes a signal reproduced from the optical disc 41. For this reason, the output from the optical pickup 42 is guided. Further, a drive control signal is output to a driver IC 22 for driving a motor (not shown) of the mechanism unit 43 that moves the optical pickup 42 in the radial direction.

  Further, a flash memory 24 for storing various setting data and the like is connected to the power supply target IC 21 and when a compressed video / audio signal obtained by performing predetermined processing on the output of the optical pickup 42 is expanded. SDRAM 23 serving as a work area is connected. The power supply target IC 21 is connected to a DAC (D / A conversion IC) 25 that converts the decompressed digital video signal and digital audio signal into an analog video signal and an analog audio signal.

  The first printed wiring board 1 is provided with a connector 18, and the second printed wiring board 2 is provided with a connector 28. The connector 18 and the connector 28 are connected to each other via the flexible flat cable 3.

  Hereinafter, the path of the low-voltage IC DC output 5 will be described. The position 15 of the low-voltage IC DC output 5 on the first printed wiring board 1 in the path 17 is a voltage error detection target of the low-voltage IC DC output 5. This is a detection position for detecting a voltage. That is, the resistor R18 is connected to the path 17 of the DC output 5 for the low voltage IC.

  Further, as shown in FIG. 1, the DC output 5 for low voltage IC output from the voltage stabilizing circuit 11 is given a printed wiring pattern 17 (the same code as that of the path 17) in the first printed wiring board 1. Is led to the connector 18 and then led to the connector 28 via one core wire 37 of the flexible flat cable 3. The low-voltage IC direct current output 5 led to the connector 28 is led to the power supply terminal (IC feeding position) 211 of the power supply target IC 21 via the printed wiring pattern 27 in the second printed wiring board 2. .

  The DC outputs 121 and 122 output from the switching power supply circuit 12 are guided to the second printed wiring board 2 via the connector 18, the flexible flat cable 3, and the connector 28 (this path is shown in FIG. 1). (The illustration is omitted). The ground level in the first printed wiring board 1 is guided to the second printed wiring board 2 via the connector 18, the five core wires of the flexible flat cable 3, and the connector 28 (this route). Is omitted in FIG. 1).

  The resistance R11 in FIG. 2 is equivalent to the printed wiring pattern 17 (printed wiring pattern corresponding to the range 51 in the path of the DC output 5 for the low-voltage IC) from the detection position 15 to the connector 18 in the voltage stabilizing circuit 11. DC resistance component is shown. A resistor R31 indicates an equivalent DC resistance component of the core wire 37 (a route corresponding to the range 53 of the routes of the DC output 5 for the low-voltage IC) in the flexible flat cable 3. The resistor R21 is a printed wiring pattern 27 from the connector 28 to the IC power supply position 211 in the path of the DC output 5 for the low voltage IC (the printed wiring pattern corresponding to the range 52 in the path of the DC output 5 for the low voltage IC). ) Equivalent DC resistance component.

  Resistors R12 and R13 indicate equivalent DC resistance components of the printed wiring pattern forming the path of the DC outputs 121 and 122 in the first printed wiring board 1, and the resistors R32 and R33 are flexible flat cables. Of the three core wires, the equivalent DC resistance components of the core wires serving as the paths of the DC outputs 121 and 122 are shown. The resistors R35 to R39 are equivalent to each of the five core wires connecting the ground level in the first printed wiring board 1 and the ground level in the second printed wiring board 2 among the core wires of the flexible flat cable 3. The direct current resistance component is shown. Therefore, the values of the resistors R31 to 33 and R35 to R39 are equal to each other.

  As a supplementary explanation, the voltage of the reference voltage source 14 in the voltage stabilizing circuit 11 is 1.25V. Accordingly, the settable range of the voltage of the DC output 5 for the low voltage IC output from the voltage stabilizing circuit 11 (voltage at the detection position 15) is a voltage range higher than 1.25 V, and the voltage at the detection position 15 is It cannot be stabilized below 1.25V. On the other hand, the standard voltage of the operating power supply of the power supply target IC 21 is 1.2V.

Next, the voltage drop amount in the path of the DC output 5 for the low voltage IC will be described. A voltage drop amount due to the resistor R11 is V11, a voltage drop amount due to the resistor R31 is V31, and a voltage drop amount due to the resistor R21 is V21. Further, when the voltage at the IC power supply position 211 is V211 and the voltage at the detection position 15 of the DC output 5 for the low voltage IC is V15,
V211 = V15- (V11 + V31 + V21)
As shown. That is,
V15 = V211 + (V11 + V31 + V21)
It becomes. On the other hand, the voltage V211 at the IC power supply position 211 is the voltage of the operating power supplied to the power supply target IC21. Therefore, the voltage drop amount (V11 + V31 + V21) in the current path 17, 37, 27 of the DC output 5 for the low voltage IC from the detection position 15 to the IC power supply position 211 has a standard voltage (1.2V) of the operating power supply of the power supply target IC21. Is greater than 1.25V, which is the minimum value of the settable range of the DC output 5 for the low voltage IC, that is,
1.25V <1.2V + (V11 + V31 + V21) (assumed to be the first formula)
This means that it is possible to supply the operating voltage of 1.2 V, which is the standard voltage, to the power supply target IC 21.

  From the above, in this embodiment, the thickness of the conductor of the core wire of the flexible flat cable 3 is set so that the condition represented by the first formula is satisfied. That is, as for the thickness of the core wire of the flexible flat cable 3, three types of 18 μm, 35 μm, and 50 μm are available. For this reason, for example, when the first formula is not satisfied when the flexible flat cable 3 having a core wire thickness of 50 μm is used, the flexible flat cable 3 is changed to a flexible flat cable 3 having a core wire thickness of 35 μm. The first expression is satisfied by increasing the voltage drop amount V31 of the core wire 37 in the flat cable 3.

  After that, the voltage of the DC output 5 for the low voltage IC output from the voltage stabilization circuit 11 (the voltage at the detection position 15) is set so that the voltage at the IC power supply position 211 is 1.2V (for voltage division). This is done by adjusting the values of the resistors R18 and R19). When the voltage at the detection position 15 is 1.25 V and the voltage at the IC power supply position 211 is 1.2 V, the negative input of the error amplifier 132 can be directly connected to the detection position 15. The pressure resistors R18 and R19 can be omitted.

  In order to satisfy the first formula, the width and path length of the printed wiring patterns 17 and 27 that become the current path of the DC output 5 for the low-voltage IC are changed in addition to the method of changing the thickness of the core wire of the flexible flat cable 3. (This method is a time-consuming method compared to the method of changing the thickness of the core wire of the flexible flat cable 3).

  The operation of the embodiment having the above configuration will be described.

  As described above, the power supply target IC 21 is added to the voltage V15 at the detection position 15 (the sum of the voltage drop V11 in the printed wiring pattern 17, the voltage drop V31 in the core wire 37, and the voltage drop V21 in the printed wiring pattern 27). (The value obtained by adding the standard voltages of the operating power sources) is set so that the voltage at the IC power supply position 211 is 1.2V.

  That is, although the voltage V15 at the detection position 15 is set to a voltage range higher than 1.25 V, which is the voltage of the reference voltage source 14, the power supply target IC 21 has a voltage V15 higher than that of the reference voltage source 14. An operating power supply of 1.2 V, which is a low voltage, is supplied. In other words, the operating power supply having a voltage satisfying the standard is supplied to the power supply target IC 21. For this reason, the power supply target IC 21 can stably perform a predetermined operation.

  The ground level of the first printed wiring board 1 and the ground level of the second printed wiring board 2 are connected to each other by five core wires of the flexible flat cable 3. That is, the ground level of the first printed wiring board 1 and the ground level of the second printed wiring board 2 are connected to each other by a 1/5 direct current resistance component of the core wire 37.

  Therefore, for example, even when the current flowing through the driver IC 22 fluctuates (for example, fluctuates in the range of 50 mA to 200 mA), the ground level of the first printed wiring board 1 and the ground of the second printed wiring board 2 The voltage difference from the level is suppressed within a negligible range (the current of the operating power supply of the power supply target IC 21 is about 700 mA, and the fluctuation range of the current of the driver IC 22 is the operation of the power supply target IC 21. It is about 1/5 of the current of the power supply). Therefore, even when the current flowing through the driver IC 22 fluctuates, the voltage of the operating power supplied to the power supply target IC 21 (the voltage at the ground level in the second printed wiring board 2 and the voltage at the IC feeding position 211 is Variation in the difference voltage is suppressed to a sufficiently small value. Therefore, the power supply target IC 21 can perform a stable operation even when the current flowing through the driver IC 22 fluctuates.

  The present invention is not limited to the above-described embodiment, and has been described for the case where it is applied to an optical disk device. However, the standard voltage of the operating power supply of the power supply target IC is the DC output for the low voltage IC output from the voltage stabilization circuit. In the case where the voltage is lower than the lowest value in the settable range, the present invention can be similarly applied to other devices.

  Moreover, although the number of core wires of the flexible flat cable 3 that connects the ground level of the first printed wiring board 1 and the ground level of the second printed wiring board 2 has been described as five, It can be the number (for example, 4 or 6).

It is explanatory drawing which shows the outline of the components arrangement | positioning of the board | substrate of the optical disk apparatus (specifically DVD player) which is one Embodiment of the electronic device which concerns on this invention, and the path | route of DC output for low voltage | pressure ICs. It is explanatory drawing which shows the electrical structure of embodiment, and the equivalent circuit of a power supply path | route.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st printed wiring board 2 2nd printed wiring board 3 Flexible flat cable 5 DC output 11 for low voltage IC Voltage stabilizing circuit 15 Detection position 37 Core wire 211 IC feeding position

Claims (4)

A voltage stabilizing circuit that is provided on the first printed wiring board and sends out a DC output for a low-voltage IC;
A power supply target IC provided on the second printed wiring board and using a DC output for a low voltage IC sent from a voltage stabilization circuit as an operation power supply;
The power supply target IC is an IC that processes a signal reproduced from the optical disc,
The DC output for the low voltage IC is guided from the first printed wiring board to the second printed wiring board through a flexible flat cable that electrically connects the first printed wiring board and the second printed wiring board. ,
In the optical disc apparatus in which the standard voltage of the operating power supply of the power supply target IC is lower than the minimum value of the settable range of the voltage of the DC output for the low voltage IC,
The IC power supply that is the position of the input terminal of the operating power supply target IC of the power supply target IC from the position on the DC output path for the low-voltage IC that detects the voltage that is the voltage error detection target of the low-voltage IC DC output The value obtained by adding the standard voltage of the operating power supply of the power supply target IC to the voltage drop amount in the current path of the DC output for the low voltage IC to the position is set as the voltage within the settable range of the voltage at the detection position,
The low-voltage IC direct current output path in the flexible flat cable is formed by one core wire of the flexible flat cable, and the ground level path in the flexible flat cable is formed by a plurality of core wires of the flexible flat cable. Optical disk device. A voltage stabilizing circuit for sending out a DC output for a low voltage IC;
A power supply target IC using a DC output for a low voltage IC sent from a voltage stabilization circuit as an operation power supply,
In the electronic device in which the standard voltage of the operating power supply of the power supply target IC is a voltage lower than the lowest value of the settable range of the voltage of the DC output for the low voltage IC,
The IC power supply that is the position of the input terminal of the operating power supply target IC of the power supply target IC from the position on the DC output path for the low-voltage IC that detects the voltage that is the voltage error detection target of the low-voltage IC DC output The value obtained by adding the standard voltage of the operating power supply of the power supply target IC to the voltage drop amount in the current path of the DC output for the low voltage IC to the position is set as the voltage within the settable range of the voltage at the detection position. Electronic device to play. The voltage stabilization circuit is provided on the first printed wiring board,
The power supply target IC is provided on the second printed wiring board,
The first printed wiring board and the second printed wiring board are electrically connected via a flexible flat cable,
3. The electronic device according to claim 2, wherein the DC output for the low-voltage IC is led from the first printed wiring board to the second printed wiring board through the flexible flat cable.   The low-voltage IC direct current output path in the flexible flat cable is formed by one core wire of the flexible flat cable, and the ground level path in the flexible flat cable is formed by a plurality of core wires of the flexible flat cable. The electronic device according to claim 3.

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