Circuit board

Abstract

To solve the problem in which: it has been difficult to replace an IC with another IC replaceable with the IC.SOLUTION: A circuit board has an IC 1 and an IC 2 exclusively mounted thereon, and has: an attachment part ZIC; an attachment part Pren1 on which a resistance Rren1 is mounted when the IC 1 is mounted; attachment parts Z1-Z5 on which a voltage conversion part 801 is mounted when the IC 2 is mounted; a conductor pattern between a pad Pen of the attachment part ZIC and a pad of the attachment part Pren1; a conductor pattern between the pad Pen of the attachment part ZIC and a pad of the attachment part Z4; and a conductor pattern electrically connecting the other pad of the attachment Pren1 and a pad of the attachment part Z1.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a circuit board on which different integrated circuits can be exclusively mounted.

Background Art

[0002] Some electrical appliances are provided with a plurality of control circuit boards. On the control circuit board, a plurality of electrical components such as an electrical component for performing logical operation, an electrical component for performing drive control, and an electrical component for generating a power supply voltage are mounted. Each electrical component constitutes an electrical component assembly that realizes a predetermined function together with surrounding electrical components. For example, the electrical component assembly is configured by an integrated circuit (IC) and surrounding electrical components such as a resistor, a capacitor, and an inductor connected to input and output terminals of the IC.

[0003] A circuit board is manufactured by procuring and mounting a large number of electrical components. However, for various reasons, it may become difficult to obtain electrical components. For example, in recent years, shortage of IC supply has become a problem. In order to avoid such a situation, alternative parts having the same function and the same or similar shape and specification are investigated in advance for each electrical component, and the alternative parts are procured when a problem of parts procurement occurs. Manufacturing of the circuit board is continued using the alternative parts.

[0004] In a control circuit board, a required voltage value may differ depending on an actuator to be connected. Therefore, a plurality of electrical component assemblies for voltage generation that generate different voltage values are mounted on the circuit board. In such a configuration, power supply voltages of a plurality of different voltage values are generated in the control circuit board. As an electrical component assembly for voltage generation, a DC-DC converter IC with low heat loss is widely used (Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] For example, the electrical specifications of DC-DC converter ICs almost always differ from one IC to another. Therefore, replacing one IC with another is unlikely to guarantee proper operation due to the differing electrical specifications. Similarly, replacing a motor driver IC with another IC is also unlikely to guarantee proper operation.

[0007] As described above, circuit boards designed to implement specific functions have electrical component parts mounted on them, consisting of an IC and peripheral components (electrical parts) that complement the IC's functions. Furthermore, the wiring (conductor patterns) on the circuit board are often specific to the IC. Therefore, when replacing an IC with another IC, peripheral components and wiring (conductor patterns) corresponding to the replacement IC are required. In other words, replacing an IC with another IC requires redesigning the circuit board, which presents a problem as it makes IC replacement difficult.

[0008] Therefore, the present invention aims to provide a circuit board that allows for easy replacement of an IC with another IC that can substitute for the said IC. [Means for solving the problem]

[0009] To solve the above problems, the present invention provides a circuit board on which a first set comprising at least a first integrated circuit and a first electrical component, or a second set comprising at least a second integrated circuit and a second electrical component, is exclusively mounted, comprising: an IC mounting portion on which the first integrated circuit or the second integrated circuit is mounted; a first mounting portion configured to allow mounting of the first electrical component and comprising at least a first pad and a second pad; a second mounting portion configured to allow mounting of the second electrical component and comprising at least a third pad and a fourth pad; and the IC mounting portion and the first mounting portion The mounting device has a first conductor pattern that electrically connects to a pad, a second conductor pattern that electrically connects the IC mounting portion and the third pad of the second mounting portion, and a third conductor pattern that electrically connects the second pad of the first mounting portion and the fourth pad of the second mounting portion, wherein when the first electrical component is not mounted, the first pad and the second pad of the first mounting portion are open so as not to conduct electricity with each other, and when the second electrical component is not mounted, the third pad and the fourth pad of the second mounting portion are open so as not to conduct electricity with each other.

[0010] Furthermore, in order to solve the above problems, another circuit board of the present invention is, A circuit board on which a first set comprising at least a first integrated circuit and a first electrical component, or a second set comprising at least a second integrated circuit and a second electrical component, is exclusively mounted, comprising: an IC mounting portion on which the first integrated circuit or the second integrated circuit is mounted; a first mounting portion configured to allow mounting of the first electrical component and comprising at least a first pad and a second pad; a second mounting portion configured to allow mounting of the second electrical component and comprising at least a third pad and a fourth pad; the IC mounting portion; a first conductor pattern electrically connecting the first pad of the first mounting portion and the third pad of the second mounting portion; and a second conductor pattern electrically connecting the second pad of the first mounting portion and the fourth pad of the second mounting portion, wherein the first pad and the second pad of the first mounting portion are open so as not to conduct electricity to each other when the first electrical component is not mounted, and the third pad and the fourth pad of the second mounting portion are open so as not to conduct electricity to each other when the second electrical component is not mounted. [Effects of the Invention]

[0011] According to the present invention, an IC can be easily replaced with another IC that is interchangeable with it. [Brief explanation of the drawing]

[0012] [Figure 1] Schematic diagram of an image forming apparatus connected via a network. [Figure 2] System block diagram of an image forming apparatus [Figure 3] Functional block diagram for power control of an image forming apparatus [Figure 4] Circuit block diagram of a DC-DC converter with integrated circuit implementation. [Figure 5]Circuit block diagram of the voltage conversion section [Figure 6] Schematic diagram of the DC-DC converter circuit board. [Figure 7] Circuit block diagram of a high-side switch with integrated circuit implementation. [Figure 8] Timing chart showing signals at each terminal of an integrated circuit [Figure 9] Schematic diagram of the high-side switch circuit board. [Modes for carrying out the invention]

[0013] The following explanation will use a circuit board provided in an image forming apparatus 100 as an example, but the present invention is applicable to circuit boards used in information equipment such as PCs and servers, as well as electrical equipment in general such as air conditioners and refrigerators.

[0014] Figure 1 is a schematic diagram of an image forming apparatus 100 connected to multiple PCs via a network. The image forming apparatus 100 is connected to LAN 106 using LAN cable 107. Multiple image forming apparatuses can be connected to the same LAN 106 without any problems. PCs 103, 104, and 105 are connected to LAN 106 using LAN cables 108, 109, and 110, respectively. Although Figure 1 explains the connection using LAN cables, a connection using wireless LAN is also acceptable. When a print job is sent from PC 103, the print job is sent to the image forming apparatus 100. Also, if PC 104 wants to turn off the power to the image forming apparatus 100, a remote shutdown instruction is sent to the image forming apparatus 100 via LAN 106.

[0015] Figure 2 shows a system block diagram of the image forming apparatus 100. Power is supplied to each block of the image forming apparatus 100 from the power supply unit 200. The power control power supply unit 202 controls the power supply to the power supply unit 200 and the control unit 220 of the image forming apparatus 100. The power control power supply unit 202 is implemented in the control unit 201 and is a block that controls whether to supply power to each block according to user instructions such as power switches. Details are explained in Figure 3. The control unit 220 has a CPU 203 that executes a software program that controls the entire image forming apparatus 100. The CPU 203 is connected to ROM 204, RAM 205, and storage 206. Storage 206 is, for example, an HDD or SSD. ROM 204 stores the startup program and various setting values ​​of the image forming apparatus 100. RAM 205 is used for temporary data storage when the image forming apparatus 100 is controlled. Storage 206 is connected to the CPU 203 by Serial ATA (hereinafter referred to as SATA). Note that CPU 203 may be configured to connect to multiple storage devices. For example, it may be configured to use RAID0 (striping) or RAID1 (mirroring), but a detailed explanation will be omitted. CPU 203 writes or reads data to or from storage 206. Storage 206 stores temporary image data and some of the software necessary to operate the image forming apparatus 100.

[0016] The CPU 203 is connected to the image processing unit 207, and the image processing unit 207 is connected to the reader 230 and the printer 240. The control of the image forming apparatus 100 may be executed directly by the CPU 203, or may be executed via the image processing unit 207. The image processing unit 207 performs image processing such as color space conversion on the data received from the reader 230 to convert it into print data, and outputs the converted data to the printer 240. The reader 230 includes an ADF (Auto Document Feeder) and a scanner unit, reads an image of a document placed on a document table or the ADF, generates image data, and transmits the data to the image processing unit 207. The data processing of the image data may be performed by a CPU (not shown) incorporated in the reader 230, or may be performed by the image processing unit 207. The printer 240 prints the image data received from the image processing unit 207 on a sheet. A LAN controller (hereinafter described as LANC) is connected to the LAN 106 (network) using a LAN cable 107, and is used for input control of print jobs and the like from a PC or the like. The operation unit 250 is an IF that receives instructions from a user, and receives instructions such as copying, scanning, printing, or shifting to a power saving mode. The operation unit 250 is configured with an LCD panel, a touch panel, and the like.

[0017] Figure 3 shows a functional block diagram related to the power control of the image forming apparatus 100. The first power supply unit 301 and the second power supply unit 302 of the image forming apparatus 100 are supplied with power 330 input from 300. The first power supply unit 301 supplies power as power supply 331 to the power control unit 202 and each power supply block, and the power control unit 202 controls the OFF / ON of each power supply block. At this time, the first power supply unit 301 converts the voltage to match that of the power control unit 202 and supplies power. The power supply units used in the following explanation do not each represent a single power supply, but rather convert the voltage to match the supply destination and output according to the instructions of the power control unit. Details of the output voltage and power sequence of each power supply will be omitted. The power control unit 202 outputs power control signals (340~344) so ​​that each block can be individually turned OFF / ON. Power is supplied to each block from the power supply blocks (310~314) by the first power supply unit 301. When each power supply is turned OFF, not only are the individual power supply blocks (340-344) turned OFF, but the specifications for each block are also maintained by signals (350-354) that control the charge depletion circuits (320-324). At this time, the charge depletion circuits are shown only as transistors in a simplified diagram, but resistors are used to adjust the current value to maintain the specifications for each block. Also, to reduce power consumption, for blocks with a large power load, such as the printer 240 and reader 230, power is supplied only when needed from a separate second power supply unit 302 as power supply 332, controlled by the power control unit 202. The second power supply unit 302 supplies power to each block from the power supply blocks (315, 316). When each power supply is turned OFF, not only are the individual power supply blocks (345, 346) turned OFF, but the specifications for each block are also maintained by signals (355, 356) that control the charge depletion circuits (325, 326). As shown in Figure 3, power supply circuits are widely used in electronic devices. Its purpose is to generate power according to the specifications of the electronic device being used, and to switch the power on and off. Although each power block is described independently, they can be shared with other power blocks.

[0018] (First Embodiment) As the circuit board of the first embodiment, in the following, a circuit board of a DC-DC converter is described that can exclusively mount integrated circuits that have the same number of terminal pins, the same terminal pin arrangement, and the same functions, but differ in the threshold value to be compared with the input voltage of the enable terminal.

[0019] FIG. 4(A) is a circuit block diagram of the DC-DC converter when IC1 is mounted as the integrated circuit. FIG. 4(B) is a circuit block diagram of the DC-DC converter when IC2 is mounted as the integrated circuit. As shown in Table 1, IC1 and IC2 have different input thresholds for the EN terminal. The other terminals are arranged to be common including the peripheral board patterns.

[0020] [Table 1]

[0021] As shown in FIG. 4(A) and FIG. 4(B), the integrated circuit (IC) mounted on the DC-DC converter has an input terminal (VIN terminal), an output terminal (SW terminal), a GND terminal, and a feedback terminal (FB). It is important that these terminals also have a common arrangement and common electrical specifications. The VIN terminal and SW terminal, through which a large current flows, require conductor patterns that are thicker than the conductor patterns for other terminals. Furthermore, a capacitor is required near the VIN terminal and the SW terminal to reduce switching noise. In addition, since the feedback terminal compares a reference voltage with an input voltage and switches the SW terminal on / off based on the result, it is necessary to use a wiring (conductor pattern) that is not affected by noise in order to ensure output accuracy. Therefore, in order to make the thickness of the conductor patterns and the arrangement of peripheral components (electrical components) common, these terminals share a common arrangement and common electrical specifications.

[0022] IC1 or IC2, in addition to the above, has a capacitor terminal for bootstrap (VBST terminal), a capacitor terminal for power supply that drives the internal logic section (VREG terminal), an EN terminal for output control, and a PG terminal for the power good function. The power good function is a function that notifies when a specified voltage has been output. It may also have terminals for detecting abnormalities in the output voltage and terminals for controlling the switching frequency. The circuit board with the function of a DC-DC converter shown in Figures 4(A) and 4(B) has an 8-pin integrated circuit (IC1 or IC2) with GND as the bottom electrode mounted on it.

[0023] Here, the EN terminal is also used for control purposes, such as adjusting the timing when creating a power sequence. Therefore, it is necessary to input multiple power supply voltages to multiple controlled devices, but when multiple types of DC-DC converters are mounted on a common board pattern, each IC must adhere to the specifications of its respective EN terminal.

[0024] By exclusively mounting two DC-DC converter ICs (IC1 or IC2) on a common circuit board, which have the exact same number of pins, pin configuration, and terminal functions but differ slightly in pin characteristics, it becomes possible to flexibly respond to changes in procurement conditions.

[0025] As shown in Figures 4(A) and 4(B), the DC-DC converter receives power supply voltage at the VIN terminal. In this circuit diagram, a 12V power supply is input. Noise reduction capacitors (Cin1 and Cin2) are placed on the input power supply. Capacitor Cvbst and noise reduction resistor Rvbst are connected to the VBST terminal. Inductor L and output smoothing capacitors Cout1-3 are connected to the SW terminal, outputting a 5V output voltage. Note that the output voltage is not limited to 5V; it can be appropriately determined according to the electronic components used, such as 3.3V or 1.8V. The constant of inductor L should be selected according to the DC-DC converter being implemented, and in order to realize it on a common board, it is necessary to select one of approximately the same size that allows for a shared pattern. The GND terminal and the GND of the bottom electrode are directly connected to GND. The output voltage is supplied to the FB terminal. The connection method is such that a reference voltage is specified to control the OFF / ON of the SW terminal, so resistors Rfb1 and Rfb2 are connected to divide the voltage according to the DC-DC converter. The resistors Rfb1 and Rfb2 should be designed to match the desired output voltage. A capacitor Cvreg is connected to the VREG terminal.

[0026] The PG terminal is an open drain output terminal. By connecting it to the 5V power supply voltage via resistor Rpu, it notifies other control units, separate from IC1 and IC2, of a power good signal. Note that resistor Rpu is a pull-up resistor.

[0027] Here, we assume that CPU203 (Figure 3) inputs a 1.8V enable signal (EN_Sig) to the EN terminal. The enable signal (EN_Sig) is an example of an electrical signal. When IC1 is installed as shown in Figure 4(A), a pull-up resistor Ren1 is connected to the EN terminal. In Figure 4(A), IC1 receives a 1.8V enable signal (EN_Sig) to the EN terminal via the pull-up resistor Ren1. As shown in Table 1 above, when a 1.8V enable signal (EN_Sig) is input to the EN terminal of IC1, the input voltage is greater than or equal to VIHmin, so an output voltage of 5V is output from the SW terminal of IC1.

[0028] On the other hand, when IC2 is mounted as shown in Figure 4(B), an electrical component called a voltage conversion unit 801 is connected to the EN terminal. In Figure 4(B), the voltage conversion unit 801 converts the 1.8V enable signal voltage to, for example, 3.3V and inputs it to the EN terminal of IC2. As shown in Table 1, since the input voltage to the EN terminal of IC2 does not exceed VIHmin, a 5V output voltage cannot be output from the SW terminal of IC2. Therefore, the DC-DC converter shown in Figure 4(B) has a voltage conversion unit 801 that adjusts the voltage value of the enable signal from CPU203 (Figure 3) to a value greater than or equal to VIHmin in order to enable a predetermined function based on the enable signal from CPU203 (Figure 3).

[0029] Figure 5 is a circuit block diagram of the voltage conversion unit 801. When the 1.8V enable signal (EN_Sig) becomes High (1.8V), the NPN transistor 901 turns ON, and the gate terminal of the P-channel FET 902, which was pulled up by resistor 903, changes to Low. As a result, when the P-channel FET 902 turns ON, a voltage of VIHmin or higher is input to the EN terminal of IC2, and the function of IC2 to generate 5V from 12V is activated. Resistors 904 and 905 are used to adjust the voltage to a range that can be input to the EN terminal of IC2. Note that this circuit block diagram is merely one example of a circuit configuration for realizing the voltage conversion unit 801, and the voltage conversion unit 801 is not limited to the above configuration.

[0030] Figure 6 is a schematic diagram of the main part of a circuit board on which the electrical components constituting IC1 and resistor Ren1, and IC2 and voltage conversion unit 801 can be exclusively mounted. The circuit board shown in Figure 6 will be described as a double-sided board.

[0031] Figure 6(A) is a schematic diagram of the main components of the mounting surface (first surface) of the circuit board. The mounting surface (first surface) of the circuit board has a mounting section ZIC on which the integrated circuit (IC1 or IC2) is exclusively mounted, and a mounting section ZL on which the common electrical component, the inductor L, is mounted. The mounting surface also has an input section to which a 12V power supply voltage is input, and an output section to which a 5V output voltage is output.

[0032] Multiple terminals of an integrated circuit mounted on the mounting section ZIC are connected to pads, which are conductive parts formed on the mounting surface. The pads for the terminals of the integrated circuit have a pad Pvin, which is a conductive part to which the VIN terminal is connected, and a pad Pen, which is a conductive part to which the EN terminal is connected.

[0033] Figure 6(B) is a schematic diagram of the main components of the solder side (second side) of the circuit board. The solder side (second side) of the circuit board has an input section to which the enable signal (EN_Sig) is input, and a mounting section Pren1 on which the resistor Ren1 is mounted. The solder side (second side) of the circuit board further has a mounting section Z1 on which the NPN transistor 901 is mounted, a mounting section Z2 on which the P-channel FET 902 is mounted, and mounting sections Z3, Z4, and Z5 on which the resistors 903, 904, and 905 are mounted.

[0034] Furthermore, the circuit board has multiple vias formed to electrically connect the mounting side and the solder side. Pad Pen for the EN terminal is electrically connected to via Via1 via a conductor pattern. On the solder side, via Via1 is electrically connected via conductor patterns extending in three directions to one of the pads to which resistor Ren1 is connected, one of the pads to which resistor 904 is connected, and one of the pads to which resistor 905 is connected.

[0035] As shown in Figure 6(B), the solder side is electrically connected to the other pad to which resistor 904 is connected, and to one of the three pads of the P-channel FET 902 via a conductor pattern. The other two of the three pads of the P-channel FET 902 and the two pads to which resistor 903 is connected are each electrically connected via conductor patterns. In addition, one of the two pads to which resistor 903 is connected is electrically connected to via Via2 via a conductor pattern, and is electrically connected to the VIN terminal on the mounting side.

[0036] One of the three pads of the NPN transistor 901 is electrically connected to one of the three pads of the P-channel FET 902. The input of the enable signal (EN_Sig) is electrically connected via a conductor pattern to one of the other two pads of the NPN transistor 901 and to the other pad to which resistor Ren1 is connected. Therefore, the conductor pattern that conducts with the input of the enable signal (EN_Sig) has one end connected to the pad of the NPN transistor 901 and the other end connected to the pad of resistor Ren1.

[0037] In the solder side of the circuit board shown in Figure 6(B), when IC1 is mounted on the circuit board, resistor Ren1 is mounted, while NPN transistor 901, P-channel FET 902, resistors 903, 904, and 905 are not. On the other hand, when IC2 is mounted on the circuit board, NPN transistor 901, P-channel FET 902, resistors 903, 904, and 905 are mounted, but resistor Ren1 is not.

[0038] If resistor Ren1 is not installed, the mounting portion Pren1 on the solder side is left open so that the conductor patterns electrically connected to each pad do not conduct electricity. Similarly, if resistor 904 is not installed, the mounting portion Z4 on the solder side is left open so that the conductor patterns electrically connected to each pad do not conduct electricity. Other electrical components are also left open if they are not installed.

[0039] Thus, the circuit board described in this embodiment allows for the switching and mounting of electrical components according to the characteristics of the DC-DC converter, making it easy to replace IC1 with a replaceable IC2 (or IC2 with a replaceable IC1). Furthermore, since the circuit board of this embodiment has a configuration in which electrical components are exclusively mounted on a solder side different from the mounting side on which integrated circuits are mounted, it is possible to achieve space savings for the circuit board.

[0040] (Second Embodiment) As a circuit board of the second embodiment, the following describes a circuit board for an input-side switch (hereinafter referred to as a high-side switch) that can exclusively mount integrated circuits having the same number of terminal pins, terminal pin arrangement, and function, but different output characteristics for the overcurrent terminal. The high-side switch is provided in a USB interface, for example, to control the power supply to an optional device connected to the USB. Optional devices include, for example, expansion memory and card readers.

[0041] Figure 7(A) is a circuit block diagram of the high-side switch when IC4 is implemented as the integrated circuit. Figure 7(B) is a circuit block diagram of the high-side switch when IC5 is implemented as the integrated circuit. The integrated circuit IC4 (or IC5) implemented in the high-side switch has three main terminals: an input terminal (VIN), an output terminal (VOUT), and a GND terminal. It is important that the positions of these terminals are the same. This is because the VIN and VOUT terminals, which carry a large amount of current, require thicker patterns than other control terminals.

[0042] The integrated circuit IC4 (or IC5) further includes a resistor terminal for current limiting (ILIM terminal), an EN terminal for output control, and an overcurrent terminal (OC terminal) that notifies of an error when the current limiter is engaged. In this explanation, a 6-pin IC4 (or IC5) is used as the integrated circuit implemented in the high-side switch.

[0043] A 5V power supply is input to the VIN terminal. Furthermore, the VIN terminal is electrically connected to a noise reduction capacitor (Cin4). The output capacitor Cout4 is electrically connected to the VOUT terminal. The 5V voltage output from the VOUT terminal (hereinafter referred to as 5V_B for clarity) is supplied to the IC of the optional device connected to the USB interface. Note that the high-side switch in this embodiment is just an example; the input and output voltages may be 3.3V or 1.8V, and should be designed appropriately according to the electrical component to which the voltage output from the VOUT terminal is supplied.

[0044] The GND terminal is directly connected to GND. The EN terminal receives a power control signal if power timing control is required. Alternatively, if you want to output a free-running output voltage in accordance with the input power supply, a pull-up (PU) resistor connected to the power supply voltage is also acceptable. The ILIM terminal is connected to GND via the RILIM resistor. The current limiting resistor value differs for each high-side switch, so select the resistor that matches the desired current value.

[0045] The integrated circuit implemented in the high-side switch has an overcurrent protection function. The open current signal (OC_sig2) from the OC terminal indicates a high level if the current flowing through the ILIM terminal is below the threshold, and a low level if the current flowing through the ILIM terminal is above the threshold. The open current signal (OC_sig2) is an example of an electrical signal. Note that if IC4 is implemented, a short resistor 1301 will be implemented.

[0046] The open current signal (OC_sig2) is input to, for example, the CPU 203 (Figure 3), which functions as a signal processing unit. When the open current signal (OC_sig2) changes from a high level (first state) to a low level (second state), the CPU 203 (Figure 3) stops supplying power to the optional device connected downstream of the high-side switch. This reduces the impact on other devices by stopping the power supply to the optional device, even if the IC of the optional device shorts out and an overcurrent flows.

[0047] Here, since the OC terminal of IC4 is an open-drain output, it is electrically connected to the power supply voltage V_rec supplied to the subsequent optional device via resistor Rpu2, and outputs an open current signal (OC_sig2). On the other hand, there is also an integrated circuit (IC5) that pulls up the OC terminal using the power supply voltage (5V) of the high-side switch IC, rather than pulling it up with the power supply voltage supplied to the subsequent optional device, as is the case with open-drain outputs.

[0048] Figure 8(A) is a timing chart showing the signals at each terminal of IC4. As shown in Figure 8(A), when the power supply voltage V_rec is input at timing t1, the voltage at the OC terminal of IC4 rises to the same value as the power supply voltage V_rec. On the other hand, Figure 8(B) is a timing chart showing the signals at each terminal of IC5. As shown in Figure 8(B), from timing t1 when the power supply voltage V_rec is input to timing t2 when 5V is input to the VIN terminal, the voltage at the OC terminal of IC5 becomes an intermediate potential. This is because IC5 uses the power supply voltage (5V) of the high-side switch IC to pull up the OC terminal. If the overcurrent signal (OC_Sig2) is at an intermediate potential, power supply to the IC of the subsequent optional device may stop, or the overcurrent protection function may not be properly implemented.

[0049] Therefore, when IC5 is implemented, a resistor-integrated PNP transistor 1302 and a resistor-integrated NPN transistor 1303 are implemented so that the overcurrent signal (OC_Sig2) is adjusted to a predetermined voltage value. The resistor-integrated PNP transistor 1302 is supplied with the power supply voltage (5V) of IC5. As a result, in the high-side switch on which IC5 is implemented, the output of IC5's OC terminal is pulled up with the power supply voltage (5V) of IC5, and the resistor-integrated NPN transistor 1303 outputs an open-drain signal. Thus, a normal overcurrent signal (OC_sig2) can be input to CPU203 (Figure 3). Note that when IC5 is implemented, the short resistor 1301 is not implemented. On the other hand, when IC4 is implemented, the resistor-integrated PNP transistor 1302 and the resistor-integrated NPN transistor 1303 are not implemented.

[0050] Figure 9 is a schematic diagram of the main components of a circuit board on which IC4 and short resistor 1301 and IC5, resistor-integrated PNP transistor 1302, and resistor-integrated NPN transistor 1303 can be exclusively mounted. As shown in Figure 9, only one side of the circuit board is shown, but the circuit board of this embodiment may be a single-sided board, a double-sided board, or a multilayer board.

[0051] The mounting surface of the circuit board has a mounting section Z2IC on which an integrated circuit (IC4 or IC5) is exclusively mounted, a mounting section Z11 on which a short resistor 1301 is mounted, and a plurality of vias. The mounting surface further has a mounting section Z12 on which a resistor-integrated PNP transistor 1302 is mounted, and a mounting section Z13 on which a resistor-integrated NPN transistor 1303 is mounted.

[0052] Multiple terminals of the integrated circuit to be mounted on mounting section Z2IC are connected to pads, which are conductive parts formed on the mounting surface. The pad for the terminals of the integrated circuit has a pad Pvin2, which is a conductive part to which the VIN terminal is connected, a pad Pvout2, which is a conductive part to which the VOUT terminal is connected, and a pad Poc2, which is a conductive part to which the OC terminal is connected.

[0053] Mounting section Z11, where the short resistor 1301 is mounted, is provided with two pads that serve as conductors to which the terminals of the short resistor 1301 are connected. Similarly, mounting section Z12, where the resistor-integrated PNP transistor 1302 is mounted, is provided with three pads that serve as conductors to which the terminals of the resistor-integrated PNP transistor 1302 are connected. Likewise, mounting section Z13, where the resistor-integrated NPN transistor 1303 is mounted, is provided with three pads that serve as conductors to which the terminals of the resistor-integrated NPN transistor 1303 are connected.

[0054] As shown in Figure 9, the pad Poc2 for the OC terminal and one of the pads for the terminal of the resistor-integrated PNP transistor 1302 are electrically connected via a conductor pattern. Furthermore, this conductor pattern extends to one of the pads of the short resistor 1301. As a result, the pad Poc2 for the OC terminal and one of the pads of the short resistor 1301 are also electrically connected. Note that if the short resistor 1301 is not installed, the space between the two pads of the short resistor 1301 is open to prevent conductivity.

[0055] Furthermore, one of the other terminal pads of the resistor-integrated PNP transistor 1302 is electrically connected to one of the terminal pads of the resistor-integrated NPN transistor 1303 via a conductor pattern. Another terminal pad of the resistor-integrated NPN transistor 1303 is also electrically connected to the other pad of the short resistor 1301 via a conductor pattern. Note that if the resistor-integrated PNP transistor 1302 is not installed, its three pads are left open to prevent conduction. Similarly, if the resistor-integrated NPN transistor 1303 is not installed, its three pads are left open to prevent conduction.

[0056] Furthermore, the other pad of the short resistor 1301 is connected to the CPU 203 (Figure 3) via a conductor pattern. The circuit board has a via Via3 for inputting an overcurrent signal (OC_Sig2) to the CPU 203 (Figure 3). The overcurrent signal (OC_Sig2) output via Via3 is input to the CPU 203 (Figure 3) via a conductor pattern not shown. Via3 functions as an output conductor that outputs the overcurrent signal (OC_Sig2). The conductor pattern that electrically connects Via3 and the other pad of the short resistor 1301 is referred to as the output conductor pattern.

[0057] In the circuit board shown in Figure 9, when IC4 is mounted on the circuit board, the short resistor 1301 is mounted, and the resistor-integrated PNP transistor 1302 and resistor-integrated NPN transistor 1303 are not mounted. On the other hand, when IC5 is mounted on the circuit board, the resistor-integrated PNP transistor 1302 and resistor-integrated NPN transistor 1303 are mounted, and the short resistor 1303 is not mounted.

[0058] As described above, the circuit board described in this embodiment allows for the switching and mounting of electrical components according to the characteristics of the high-side switch, so IC4 can be easily replaced with an interchangeable IC5 (or an interchangeable IC4) for IC5. Furthermore, since the circuit board of this embodiment is configured to mount integrated circuits on a common mounting section Z2IC, there is no need to provide separate mounting sections for mounting integrated circuits, thus enabling space saving for the circuit board. [Explanation of Symbols]

[0059] ZIC mounting part Pren1 mounting section Z1~Z5 Mounting section

Claims

1. A circuit board on which a first set comprising at least a first integrated circuit and a first electrical component, or a second set comprising at least a second integrated circuit and a second electrical component, is exclusively mounted, An IC mounting section to which the first integrated circuit or the second integrated circuit is attached, A first mounting portion is configured to allow mounting of a first electrical component, and includes at least a first pad and a second pad. A second mounting portion is configured to allow mounting of a second electrical component, and includes at least a third pad and a fourth pad. A first conductor pattern electrically connects the IC mounting portion and the first pad of the first mounting portion, A second conductor pattern electrically connects the IC mounting portion and the third pad of the second mounting portion, It has a third conductor pattern that electrically connects the second pad of the first mounting portion and the fourth pad of the second mounting portion, When the first electrical component is not mounted, the first pad and the second pad of the first mounting portion are left open so as not to be electrically connected to each other. A circuit board characterized in that, when the second electrical component is not mounted, the third pad and the fourth pad of the second mounting portion are left open so as not to conduct electricity with each other.

2. The IC mounting portion is formed on the first surface of the circuit board. The circuit board according to claim 1, characterized in that the first mounting portion and the second mounting portion are formed on the second surface of the circuit board opposite to the first surface.

3. The circuit board according to claim 1, characterized in that the IC mounting portion, the first mounting portion, and the second mounting portion are formed on the mounting surface of the circuit board.

4. The circuit board according to claim 1, characterized in that an input section is formed between one end of the third conductor pattern and the other end of the third conductor pattern to which an electrical signal is input.

5. The circuit board according to claim 4, characterized in that the electrical signal is an enable signal for switching whether or not to enable a predetermined function.

6. The first integrated circuit or the second integrated circuit receives an enable signal to switch whether or not to enable a predetermined function. If the first integrated circuit is implemented, the voltage of the enable signal is compared with the first threshold voltage. The circuit board according to claim 1, characterized in that, when the second integrated circuit is mounted, the voltage of the enable signal is compared with a second threshold voltage different from the first threshold voltage.

7. A circuit board on which a first set comprising at least a first integrated circuit and a first electrical component, or a second set comprising at least a second integrated circuit and a second electrical component, is exclusively mounted, An IC mounting section to which the first integrated circuit or the second integrated circuit is attached, A first mounting portion is configured to allow mounting of a first electrical component, and includes at least a first pad and a second pad. A second mounting portion is configured to allow mounting of a second electrical component, and includes at least a third pad and a fourth pad. The IC mounting portion, and a first conductor pattern that electrically connects the first pad of the first mounting portion and the third pad of the second mounting portion, It has a second conductor pattern that electrically connects the second pad of the first mounting portion and the fourth pad of the second mounting portion, The first pad and the second pad of the first mounting portion are left open so that they do not conduct electricity to each other when the first electrical component is not mounted. A circuit board characterized in that the third pad and the fourth pad of the second mounting portion are open so that they do not conduct electricity to each other when the second electrical component is not mounted.

8. An output unit that outputs the electrical signal output from the IC mounting section to another signal processing unit, The circuit board according to claim 7, further comprising a third conductor pattern that electrically connects the output section, the second pad of the first mounting section, and the fourth pad of the second mounting section.

9. The circuit board according to claim 8, characterized in that the electrical signal is an overcurrent signal that changes from a first state to a second state when an overcurrent is detected.

10. When the first integrated circuit is mounted, the voltage value of the overcurrent signal output from the IC mounting section when no overcurrent is detected is the first voltage value. The circuit board according to claim 7, characterized in that when the second integrated circuit is mounted, the voltage value of the overcurrent signal output from the IC mounting portion when no overcurrent is detected is a second voltage value different from the first voltage value.

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