JP5839781B2 - Semiconductor device - Google Patents

Description

  The present invention communicates data executed between a host device (also referred to as a host) such as a personal computer (hereinafter referred to as a PC) and peripheral devices such as a printer, a digital camera, and a digital audio player. The present invention relates to a semiconductor device that controls the above. In particular, the present invention relates to a semiconductor device suitable for a technique in which data communication between a host device and a peripheral device is performed using a universal serial bus (hereinafter referred to as USB). Furthermore, the present invention relates to the semiconductor device provided with the power supply voltage supply system and the power supply voltage supply method for supplying the power supply voltage to the semiconductor device provided with the power supply voltage supply system.

  In recent years, the demand for portable digital audio players and the like as peripheral devices has increased rapidly. Such a peripheral device mainly includes a mounting board and a slot to which a memory such as a USB connector and a Flash memory mounted on the mounting board can be connected. On this mounting board, a USB control circuit (also referred to as a USB transceiver), a microcontroller unit (hereinafter referred to as MCU), and an I / O block for interfacing with an external device such as a flash memory are provided as one chip. An integrated controller IC is mounted. This mounting board is built in the digital audio player.

  The USB connector can be connected to a USB, and a PC as a host device and a peripheral device are connected via the USB.

  The USB control circuit has a function of receiving data from the USB and a function of outputting data to the USB.

  The MCU gives a predetermined instruction to these circuits so that the USB control circuit and the I / O block execute a desired operation.

  A peripheral part, that is, a memory such as a flash memory for storing music data or the like is connected to the slot.

  The music data stored in the PC is transferred to the peripheral device via USB under the control of the PC, and the transferred music data is stored in the Flash memory via the USB control circuit under the control of the MCU. The data stored in the Flash memory is transferred to the PC via the MCU, the USB control circuit, and the USB based on the control of the MCU, and the transferred music data is stored in the PC. As described above, the USB is used to transfer content data such as music data between the PC and the peripheral device.

Since the peripheral device as described above is portable, it is driven by a battery. Therefore, in order to suppress battery consumption, the operating voltage in the peripheral device must be set low. The operating voltage means a power supply voltage supplied to the peripheral device. As prior art documents related to the present application, there are the following.
JP 2000-196945 A

  However, since the operating voltage of the USB control circuit and the operating voltage of the flash memory are standardized, for example, the operating voltage of the peripheral device cannot be lowered by ignoring the standardized operating voltage. That is, the minimum operating voltage of the peripheral device depends on the standardized operating voltage of the USB control circuit and the I / O block. Therefore, further reduction in power consumption cannot be expected for the entire peripheral device (the entire digital audio player). In particular, while data communication is being performed using the USB, the USB control circuit operates using a clock signal having a relatively high frequency, so that the battery is consumed heavily. Therefore, a semiconductor device with improved power consumption has been desired.

The present invention has been conceived in order to overcome the above problems. Among the inventions disclosed in the present application, outlines of typical ones are as follows. That is, a first power supply terminal to which a first power supply voltage is supplied, a second power supply terminal to which a second power supply voltage is supplied, a third power supply terminal to which a third power supply voltage is supplied, and a host device A first terminal that can be connected, a second terminal that can be connected to the peripheral device, and a first power supply terminal. Based on the first power supply voltage, the data output from the host device is the first terminal. A first circuit block capable of receiving via the first, a second terminal and a third power supply terminal, and receiving data output from the peripheral device based on the third power supply voltage And a third circuit block that is connected to the second power supply terminal and that controls the operation of the second circuit block based on a second power supply voltage lower than the third power supply voltage. Device.
Furthermore, the outline of another representative one is as follows. That is, a first terminal connectable to a host device, a second terminal connectable to a peripheral device, a first power supply terminal to which a first power supply voltage is supplied from the host device, and a second power source A second power supply terminal to which a voltage is supplied; a third power supply terminal to which a third power supply voltage is supplied from a power supply for driving the peripheral device; and the first power supply terminal; A first circuit block capable of receiving data output from the host device via the first terminal based on one power supply voltage; the second terminal; and the third power supply terminal And a second circuit block for receiving data output from the peripheral device based on the third power supply voltage, and a third circuit block connected to the second power supply terminal. The host device is connected to the first terminal, and In a state in which serial the first power supply voltage to the first power supply terminal is supplied, and generates based on the second power supply voltage to the first power supply voltage higher than the power supply voltage of the second voltage, In a state where the host device is disconnected from the first terminal and the first power supply voltage is not supplied to the first power supply terminal, the second power supply voltage is set to be higher than the second power supply voltage. A semiconductor device comprising: a second power supply voltage generation unit that generates a high voltage based on the third power supply voltage.

  The following is a brief description of an outline of the effects obtained by the typical inventions among the inventions disclosed in the present application. That is, according to the semiconductor device of the present invention, the first circuit block that receives data output from the host device, the second circuit block that receives data output from the peripheral device, and the first circuit block In addition, it is possible to supply independent power supply voltages to each block with the third circuit block that controls the operation of the second circuit block. Therefore, it is possible to obtain a semiconductor device capable of minimizing battery consumption while satisfying the operating voltage required for each block.

It is a figure explaining the outline of the semiconductor device of the present invention. It is a figure explaining an example of the usage method of the semiconductor device of this invention. It is a block diagram of a semiconductor device of the present invention. It is a detailed circuit diagram of a level shifter. It is a figure which shows the example which applied the semiconductor device of this invention to the digital audio player. It is a figure which shows the external appearance of a semiconductor device. It is a figure which shows 2nd Embodiment of the semiconductor device of this invention. It is a figure which shows the example which applied 2nd Embodiment of the semiconductor device of this invention to the digital audio player.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in order to make explanation easy, the same code | symbol is provided to the same structure. Further, the description of the duplicate configuration is omitted.

  FIG. 1 is a diagram for explaining the outline of a semiconductor device of the present invention.

  A semiconductor device 1001 of the present invention mainly includes an MCU block 1003, a USB control block 1005, an I / O block 1007, a power supply terminal 1009, a power supply terminal 1011 and a power supply terminal 1013.

  The MCU block 1003 is connected to the power supply terminal 1011. All the circuits in the MCU block 1003 operate based on the power supply voltage VDD2 supplied to the power supply terminal 1011. Here, the operation based on the power supply voltage VDD2 means that the power supply node of the circuit in the MCU block 1003 is connected to the power supply terminal 1011 but is not connected to the power supply terminal 1009 and the power supply terminal 1013. means. For example, taking a CMOS inverter as an example, it means that the source electrode of the PMOS transistor is connected to the power supply terminal 1011 but is not connected to the power supply terminal 1009 and the power supply terminal 1013.

  The USB control block 1005 is connected to the power supply terminal 1009. All the circuits in the USB control block 1005 operate based on the power supply voltage VDD1 supplied to the power supply terminal 1009. Here, the operation based on the power supply voltage VDD1 means that the power supply node of the circuit in the USB control block 1005 is connected to the power supply terminal 1009 but is not connected to the power supply terminal 1011 and the power supply terminal 1013. Means. For example, in the case of a CMOS inverter, it means that the source electrode of the PMOS transistor is connected to the power supply terminal 1009 but is not connected to the power supply terminal 1011 and the power supply terminal 1013.

  The I / O block 1007 is connected to the power supply terminal 1013. All circuits in the I / O block 1007 operate based on the power supply voltage VDD3 supplied to the power supply terminal 1013. Here, the operation based on the power supply voltage VDD3 means that the power supply node of the circuit in the I / O block 1007 is connected to the power supply terminal 1013 but is not connected to the power supply terminal 1009 and the power supply terminal 1011. Means that. For example, in the case of a CMOS inverter, it means that the source electrode of the PMOS transistor is connected to the power supply terminal 1013 but is not connected to the power supply terminal 1009 and the power supply terminal 1011. The level of the voltage supplied to each power supply terminal 1009, 1011, 1013 will be described later.

  One of the features of the semiconductor device 1001 of the present invention is that a power source node of a circuit constituting the MCU block 1003, a power source node of a circuit constituting the USB control block 1005, and a power source of a circuit constituting the I / O block 1007 The nodes are electrically isolated from each other. Such a configuration is hereinafter referred to as a separate power supply system. A method of supplying a power supply voltage to such a separate power supply type semiconductor device is referred to as a separate power supply method.

  The semiconductor device 1001 of the present invention is connected to a PC 1015 which is a host device via, for example, a USB 1019 and is connected to a flash memory 1017 which is a peripheral component via a slot or a data bus 1021. The semiconductor device 1001 controls data transfer performed between the PC 1015 and the flash memory 1017, for example.

  The MCU block 1003, the USB control block 1005, and the I / O block 1007 are integrated on one semiconductor chip. The integrated semiconductor chip is packaged through a resin sealing process or the like to become a semiconductor device 1001 as shown. Note that the MCU block 1003, the USB control block 1005, and the I / O block 1007 are not necessarily integrated on one semiconductor chip. For example, the MCU block 1003 and the I / O block 1007 may be integrated on the first semiconductor chip, and the USB control block 1005 may be integrated on the second semiconductor chip. In this case, the first semiconductor chip and the second semiconductor chip are packaged through a resin sealing process or the like, so that a semiconductor device 1001 as illustrated is formed. An overview of the packaged semiconductor device 1001 will be described later.

  FIG. 2 is a diagram illustrating an example of a method of using the semiconductor device 1001 of the present invention.

  In FIG. 2, a diode 2001 as a power supply voltage drop means is connected between the power supply terminal 1009 and the power supply terminal 1011 in order to realize the separate power supply method, and between the power supply terminal 1011 and the power supply terminal 1013. An example in which diodes 2003 and 2005 as power supply voltage drop means are connected is shown.

  For example, when 3.3 V is supplied to the anode of the diode 2001 and the anode of the diode 2005, 3.3 V is supplied to the USB control block 1005 and the I / O block 1007, respectively. Therefore, the USB control block 1005 and the I / O block 1007 each operate at 3.3V.

  On the other hand, the higher voltage of the following formula (1) or formula (2) appears at the power supply terminal 1011. That is, the diodes 2001, 2003, and 2005 function as switching elements that select one of the two power supply voltages supplied from the outside. “Selecting one of the two power supply voltages supplied from the outside” means whether the path A or the path B shown in FIG. 2 is selected.

(Voltage of anode of diode 2001) − (forward voltage drop Vf of diode 2001) (1)
(Anode voltage of diode 2005) − (forward drop voltage Vf of diode 2003 + forward drop voltage Vf of diode 2005) Equation (2)
Here, it is assumed that the forward drop voltage Vf of the diode is about 0.45V.

  Now, since the voltage of the anode of the diode 2001 and the voltage of the anode of the diode 2005 are both 3.3 V, the voltage level calculated by the above equation (1) appears at the power supply terminal 1011. (Route A is selected.) That is, 3.3V−0.45V = 2.85V appears at the power supply terminal 1011. When 2.85V is supplied to the power supply terminal 1011, the MCU block 1003 operates at 2.85V. A state in which the power supply voltage is supplied to all of the power supply terminals 1009, 1011 and 1013 is referred to as a first mode.

  On the other hand, when the anode voltage of the diode 2001 is 0V and the anode voltage of the diode 2005 is 3.3V, the voltage level calculated by the above equation (2) appears at the power supply terminal 1011. (Route B is selected.) That is, 3.3 V− (0.45 V + 0.45 V) = 2.4 V appears at the power supply terminal 1011. When 2.4V is supplied to the power supply terminal 1011, the MCU block 1003 operates at 2.4V. A state in which a power supply voltage is supplied to the power supply terminals 1011 and 1013 but no power supply voltage is supplied to the power supply terminal 1009 is referred to as a second mode.

  The following example can be considered as a method of using the semiconductor device 1001 in FIG. In the following example, it is assumed that the semiconductor device 1001 is incorporated in a portable device such as a digital audio player and is connected to a PC as a host device via USB.

  The output of the first regulator that is driven by the battery and outputs the power supply voltage of 3.3V is connected to the power supply terminal 1013, and the output of the second regulator that is driven by the USB power supply bus and outputs the power supply voltage of 3.3V. Connect to power supply terminal 1009. When both the first and second regulators output 3.3V, the semiconductor device 1001 enters the first mode.

  In this first mode, since the path A is selected, the MCU block 1003 and the USB control block 1005 operate based on the power supply voltage of the USB power supply bus, but operate based on the electromotive force of the battery. Is the I / O block 1007 only. The USB control block 1005 operates using a clock signal having a relatively high frequency. However, since the power supply voltage of the USB control block 1005 is not supplied from the battery, it is possible to suppress battery consumption. In other words, since the USB power supply bus, which is the power supply voltage of the USB control block 1005, is supplied from the host computer, the battery electromotive force is not consumed by the MCU block 1003 and the USB control block 1005. Absent.

  When the first regulator outputs 3.3V and the second regulator outputs 0V, that is, when the semiconductor device 1001 is disconnected from the host device, the USB power supply bus is connected to the semiconductor device 1001. Supply of power supply voltage is stopped. The semiconductor device 1001 is in the second mode.

  In this second mode, since the power supply voltage is not supplied to the power supply terminal 1009, the USB control block 1005 stops its operation. In the second mode, the semiconductor device 1001 is disconnected from the PC that is the host device. Since the second mode is a mode in which data transmission / reception (or data communication) is not executed between the semiconductor device 1001 and the PC, the USB control block 1005 does not need to operate. Accordingly, the power supply voltage need not be supplied to the power supply terminal 1009.

  The power supply terminal 1011 is supplied with 2.4V, and the power supply terminal 1013 is supplied with 3.3V. The power supply voltage supplied to the power supply terminals 1011 and 1013 is supplied from the battery via the first regulator. In the second mode, in addition to the I / O block 1007, the MCU block 1003 operates based on the electromotive force of the battery. However, the power supply voltage 2.4 V of the MCU block 1003 is lower than the power supply voltage 3.3 V of the I / O block 1007.

  Therefore, when the separate power supply method according to the present invention is employed, battery consumption can be further suppressed as compared with the case where the power supply voltage of the MCU block 1003 is the same as the power supply voltage of the I / O block 1007.

  Furthermore, when the separate power supply method according to the present invention is employed, the power supply voltage based on the electromotive force of the battery is not supplied to the USB control block 1005 that transmits / receives data to / from the host device. Therefore, compared to a general portable device in which a power supply voltage based on the electromotive force of the battery is supplied to all circuits such as the USB control block, MCU block, and I / O block, the battery consumption is reduced. It can be suppressed more. This is because the power supply voltage is supplied only to the circuit blocks necessary for the operation.

  In the above usage example, an example in which the power supply voltage supplied to the power supply terminal 1009 is supplied from the USB power supply bus is described. However, the power supply voltage supplied to the power supply terminal 1009 is not limited to the USB power supply bus. The power supply voltage supplied to the power supply terminal 1009 may be any power supply voltage supplied from the host device. In other words, the power supply voltage supplied to the power supply terminal 1009 may be other than the power supply voltage supplied from the battery and may be any power supply voltage supplied from the host device.

  In the above usage example, the power supply voltage VDD1 supplied to the power supply terminal 1009 is 3.3V, the power supply voltage VDD2 supplied to the power supply terminal 1011 is 2.4V to 2.85V, and the power supply voltage supplied to the power supply terminal 1013. An example in which VDD3 is 3.3V is described. However, the separate power supply method of the present invention is not construed as being limited to these power supply voltage values. Any supply method may be used as long as the power supply voltage supplied to the MCU block is lower than the power supply voltage supplied to any other block at least in the second mode.

  Further, in the usage example of FIG. 2, diodes 2003 and 2005 are disclosed as means for making the power supply voltage VDD2 appearing at the power supply terminal 1011 lower than the power supply voltage VDD3 appearing at the power supply terminal 1013. However, the separate power supply method of the present invention is not construed as being limited to the above configuration. A regulator that outputs a power supply voltage of 2.4 V and a power supply voltage of 3.3 V based on the electromotive force of the battery may be connected to the power supply terminal 1011 and the power supply terminal 1013. In short, it is sufficient that the relationship of VDD2 <VDD3 can be generated based on the electromotive force of the battery. In this case, however, it is desirable to provide a diode for preventing backflow between the power supply terminal 1011 and the output terminal of the regulator.

  FIG. 3 is a block diagram of the semiconductor device 1001 of the present invention. FIG. 3 is a diagram for explaining the semiconductor device 1001 shown in FIG. 1 in more detail.

  The semiconductor device 1001 is provided with data terminals 3001 and 3003, a ground terminal 3007, and a bus connection detection terminal 3009 in addition to the power supply terminal 1009, the power supply terminal 1011, and the power supply terminal 1013 described above. The semiconductor device 1001 has many other terminals, but not all terminals are disclosed in order to facilitate the description of the present invention.

  The data terminals 3001 and 3003, the power supply terminal 1009, and the ground terminal 3007 correspond to four lines constituting the USB. Data terminals 3001 and 3003 are connected to the USB control block 1005.

  The data terminal 3001 is a terminal for receiving data D + from the host device transferred via the first USB data line. Further, the data terminal 3001 is a terminal for transmitting data D + received from the peripheral parts such as a flash memory (not shown) received via the I / O block 1007 to the first data line of the USB. The data D + from the peripheral parts includes data processed by the MCU block 1003.

  The data terminal 3003 is a terminal for receiving data D− from the host device transferred via the USB second data line. The data terminal 3003 is a terminal for transmitting data from peripheral parts such as a flash memory (not shown) received via the I / O block 1007 as data D- to the second data line of the USB. is there. The data from the peripheral parts may be data processed by the MCU block 1003. Data D + and data D- are complementary to each other. Therefore, one bus of the USB connected to the data terminal 3001 and one bus of the USB connected to the data terminal 3003 are referred to as a data bus pair.

  The USB control block 1005 includes, for example, a PLL circuit 3011 that multiplies a 6 MHz clock signal to a 48 MHz clock signal. The USB control block 1005 receives data from the data bus pair based on the output of the PLL circuit 3011. The received data is transferred to another circuit, for example, the DMA block 3013 in the MCU block 1003 based on an instruction from the CPU. Furthermore, the USB control block 1005 transfers the data stored in another circuit, for example, the DMA block 3013 to the host device via the data bus pair based on an instruction from the CPU.

  Data transfer using USB is executed at a speed of 12 Mbps (full speed) and 1.5 Mbps (slow speed). In order to realize data transfer at such a speed, the USB control block 1005 is required to operate at a relatively high frequency of 48 MHz. On the other hand, the MCU block 1003 is operated at a relatively low frequency of 12 MHz, thereby reducing the power consumption of the entire semiconductor device. In particular, this effect is significant in the second mode as described above.

  As shown in the figure, the MCU block 1003 includes a CPU and peripheral circuits such as an interrupt request generation circuit INT, a timer, a PWM, an AD converter, a ROM, and a RAM. Since these CPU and peripheral circuits are general ones, their detailed description is omitted. However, the description regarding the interrupt request generation circuit INT will be described later.

The MCU block 1003 has a direct circuit as a direct circuit.
Memory Access block (hereinafter referred to as DMA block) is included. The DMA block 3013 temporarily stores the data D + and D− transferred from the USB control block 1005, and transfers the stored data to peripheral components such as a flash memory connected to the I / O block 1007. . Further, the DMA block 3013 temporarily stores data transferred from peripheral components such as a flash memory connected to the I / O block 1007 and transfers the data to the USB control block 1005.

  Data transfer from the USB control block 1005 to the DMA block 3013 is not sequentially executed in accordance with an instruction from the CPU. Therefore, data transfer is executed at high speed. Such data transfer is known as DMA transfer.

  The MCU block 1003 further has a function of generating a control signal for controlling the operation of a predetermined circuit in the MCU block 1003 based on the data D + and D− transferred from the USB control block 1005.

  A power supply bus 5001 (referred to as Vbus) constituting the USB is connected to the bus connection detection terminal 3009 via a USB connector. The interrupt request generation circuit INT is connected to the terminal 3009 and monitors the potential level of the terminal 3009. The interrupt request generation circuit INT detects that the USB is connected to the semiconductor device 1001 by monitoring the potential level of the terminal 3009 and outputs an interrupt request to the CPU. By this interrupt request, the CPU recognizes that the semiconductor device 1001 is connected to the PC that is the host device.

  The I / O block 1007 has a function of outputting data in the semiconductor device 1001 to peripheral components such as a flash memory and a function of inputting data of the flash memory. The I / O block 1007 is mainly composed of an input / output buffer. The power supply voltage VDD3 of the input / output buffer can be set corresponding to the operating voltage of the peripheral components independently of the power supply voltage VDD2 of the MCU block 1003 and the power supply voltage VDD1 of the USB control block 1005. That is, the above-described separate power supply method is adopted for the semiconductor device 1001.

  Specifically, since the operating voltage of the flash memory, which is a peripheral component, is 3.3 V, 3.3 V can be supplied to the input / output buffer.

  The I / O block 1007 is further provided with an oscillation circuit 3015. The oscillation circuit 3015 generates an oscillation signal of 12 MHz, for example, and outputs a clock signal based on this oscillation signal. This clock signal is output to the MCU block 1003 via the level shifter 3017. The MCU block 1003 operates based on this 12 MHz clock signal. The 12 MHz clock signal is supplied to the 1/2 frequency dividing circuit 3023 and is divided into a 6 MHz clock signal. The 6 MHz clock signal is transmitted to the PLL circuit 3011 in the USB control block 1005 via the level shifter 3019. The PLL circuit 3011 multiplies the 6 MHz clock signal by 8 and outputs a 48 MHz clock signal. The USB control block 1005 operates based on this 48 MHz clock signal.

  A level shifter 3019 is provided between the USB control block 1005 and the MCU block 1003. Level shifters 3017 and 3021 are provided between the MCU block 1003 and the I / O block 1007. Thus, a level shifter must be provided between blocks having different power supply voltages. This is a well-known technique in this technical field.

  However, a special level shifter is employed in the semiconductor device 1001 of the present invention. In particular, the level shifter 3019 requires a special structure. This is because the USB control block 1005 receives power supply via the USB power bus when the USB is connected to the semiconductor device 1001, but power supply is cut off when the USB is removed from the semiconductor device 1001. It is. Therefore, it is necessary to provide a special level shifter that not only converts the voltage level but also supports when the power supply is cut off.

  FIG. 4 shows a detailed circuit diagram of the level shifter 3019.

  The level shifter 3019 includes inverters 4001, 4003, 4005, and 4007. The power supply nodes of the inverters 4001 and 4003 are connected to the power supply terminal VI connected to the power supply terminal 1009, and the power supply nodes of the inverters 4005 and 4007 are connected to the power supply terminal VO connected to the power supply terminal 1011.

  Furthermore, the level shifter 3019 has an input terminal IN that receives data from the USB control block 1005 and an output terminal OUT that outputs data to the MCU block 1003.

  Further, the level shifter 3019 includes an inverter INV1 composed of a PMOS 4013 and an NMOS 4015, and an inverter INV2 composed of a PMOS 4017 and an NMOS 4019. These inverters INV1 and INV2 are cross-connected to each other to constitute a latch circuit.

  Further, the level shifter 3019 includes an NMOS 4009 connected to the node N1 and an NMOS 4011 connected to the node N2.

  Since the power supply node of the inverters 4001 and 4003 is supplied with VDD1 which is the operation power supply of the USB control block 1005, the inverters 4001 and 4003 operate at a power supply voltage of 3.3V. Accordingly, the inverters 4001 and 4003 output a logic L level of 0V and a logic H level of 3.3V.

  Since the power supply node of the inverters 4005 and 4007 is supplied with VDD2 which is the operation power supply of the MCU block 1003, the inverters 4005 and 4007 operate at the power supply voltage of 2.85 V in the first mode, and the second mode At 2.4V. Therefore, the inverters 4001 and 4003 output 0V logic L level and 2.85V logic H level in the first mode, and 0V logic L level and 2.4V logic in the second mode. H level is output.

Next, the operation of the level shifter 3019 will be described.
(When the semiconductor device 1001 is in the first mode)
When a signal of logic H level (3.3V) is supplied from the USB control block 1005 to the input terminal IN, the NMOS 4009 is turned on and the node N1 becomes 0V. When the node N1 becomes 0V, the PMOS 4017 is turned on, so that the node N2 becomes a logic H level of 2.85V. When the node N2 becomes a logic H level, the output terminal OUT becomes a logic H level. When the node N2 becomes a logic H level, the NMOS 4015 is turned on. Thus, the 3.3 V logic H level output from the USB control block 1005 is transferred to the MCU block 1003 as the 2.85 V logic H level.

(When the semiconductor device 1001 is in the second mode)
In this state, when the semiconductor device 1001 is disconnected from the host device, the power supply from the host device is cut off. That is, the semiconductor device 1001 enters the second mode. When the semiconductor device 1001 enters the second mode, the level of the power supply terminal VI enters a floating state. However, a power supply voltage of 2.4 V is supplied from the power supply terminal VO to the inverters INV1 and INV2 constituting the latch circuit. Therefore, the logic H level output from the USB block 1005 in the first mode is stored in this latch circuit. Therefore, the logic H level of the output terminal OUT is maintained.

  If the level shifter 3019 is a circuit having only a function for performing a level shift, the level of the output terminal OUT becomes indefinite in the second mode. As a result, an unnecessary through current is generated in the circuit unit in the MCU block 1003 that receives an indefinite level, and the current consumption increases.

  By adopting the level shifter of the present invention, the current consumption of the USB control block 1005 can be cut off completely. As a result, the current consumption of the entire semiconductor device 1001 can be reduced.

  A plurality of level shifters having the structure shown in FIG. 4 are provided. A level shifter in which the input terminal IN is connected to the MCU block 1003, the output terminal OUT is connected to the USB control block 1005, the power supply terminal VI is connected to the power supply terminal 1011, and the power supply terminal VO is connected to the power supply terminal 1009 is also available. , A level shifter 3019 is provided. This is because data is transferred bi-directionally between the MCU block 1003 and the USB control block 1005.

  FIG. 5 is a diagram showing an example in which the semiconductor device 1001 of the present invention is applied to a digital audio player.

  In FIG. 5, all the components except the flash memory 1017 as a peripheral part, a battery 5009 having an electromotive force of 1.5 V, a power supply bus 5001, a ground voltage bus 5003, and a data bus pair 5005 are illustrated. Not mounted on the mounting board. The mounting board is built in the digital audio player.

  The flash memory 1017 can be attached to and detached from the slot 1021. The battery 5009 is detachable from a battery box (not shown). The USB is in the form of a cable and is detachable from the USB connector.

  A regulator 5011 for converting a 5V power supply voltage supplied from the USB to 3.3V is connected between the power supply terminal 1009 and a USB connector terminal corresponding to the power supply bus 5001. The terminal of the USB connector corresponding to the power supply bus 5001 and the bus connection detection terminal 3009 are connected by a wiring formed on the mounting substrate, and this wiring is grounded through a resistance element 5013 of 1 M ohm, for example. That is, the bus connection detection terminal 3009 is pulled down by the resistance element 5013.

  For example, a 22 ohm resistance element 5015 is connected between the data terminal 3001 and the USB connector.

  For example, a 22 ohm resistance element 5017 is connected between the data terminal 3003 and the USB connector.

  The ground terminal 3007 and the USB connector terminal corresponding to the ground voltage bus 5003 are connected by a wiring formed on a mounting board that is thicker than the other wiring, and this wiring is grounded. The reason for using a thicker wiring than the other wiring is to reduce noise.

  A diode 2001 as a power supply voltage drop element is connected between the power supply terminal 1009 and the power supply terminal 1011.

  Between the power supply terminal 1011 and the power supply terminal 1013, a diode 2003 and a diode 2005 as voltage drop elements are connected in series.

  Between the power supply terminal 1013 and the battery 5009, a regulator 5007 for converting a voltage of 1.5V supplied from the battery 5009 into 3.3V is connected. The output of the regulator 5007 is also supplied to the power supply terminal 5019 of the flash memory 1017.

  FIG. 6 is a diagram illustrating an appearance of the semiconductor device 1001.

In FIG. 6, the terminal to which “VBUS” is assigned corresponds to the power supply terminal 1009 in FIG. 5, the terminal to which “P90 / VBUSIN” is assigned corresponds to the bus connection detection terminal 3009 in FIG. A terminal to which “D +” is assigned corresponds to the data terminal 3001 in FIG. 5, a terminal to which “D−” is assigned corresponds to the data terminal 3003 in FIG. 5, and a terminal to which “VDD CORE” is assigned. Corresponds to the power supply terminal 1011 in FIG. 5, and a terminal to which “VDD IO” is assigned corresponds to the power supply terminal 1013 in FIG. In FIG. 6, “VDD”
There are a plurality of terminals to which “CORE” is assigned, but these are all commonly connected in the semiconductor device 1001. The same applies to the terminals to which “VDD IO” is assigned.

  When the USB cable is connected to the digital audio player as described above, the operation (first mode) when this player is connected to the PC that is the host device, and the USB cable is removed, this The operation (second mode) when the player becomes usable away from the PC will be easily understood from the above description.

  FIG. 7 is a diagram showing a second embodiment of the semiconductor device 1001 of the present invention.

  The difference between the second embodiment and the first embodiment is that a regulator 5011 for converting a 5V power supply voltage supplied from the USB to 3.3V is built in the semiconductor device 1001. Since other configurations are substantially the same, description thereof is omitted.

  FIG. 8 is a diagram showing an example in which the semiconductor device 1001 of the present invention is applied to a digital audio player. The operation of the digital audio player shown in FIG. 8 will be easily understood by the description of the application example shown in FIG.

DESCRIPTION OF SYMBOLS 1001 ... Semiconductor device 1003 ... MCU block 1005 ... USB control block 1007 ... I / O block 1009 ... Power supply terminal 1011 ... Power supply terminal 1013 ... Power supply terminal

Claims (5)

A first terminal connectable to a host device;
A second terminal connectable to the peripheral device;
A first power supply terminal to which a first power supply voltage is supplied from the host device;
A second power supply terminal to which a second power supply voltage is supplied;
A third power supply terminal to which a third power supply voltage is supplied from a power supply for driving the peripheral device;
A first circuit block connected to the first power supply terminal and capable of receiving the data output from the host device via the first terminal based on the first power supply voltage; A second circuit block connected to the second terminal and the third power supply terminal and receiving data output from the peripheral device based on the third power supply voltage;
A third circuit block connected to the second power supply terminal,
In a state where the host device is connected to the first terminal and the first power supply voltage is supplied to the first power supply terminal, the second power supply voltage is set to be higher than the second power supply voltage. generated based on the first power supply voltage of the high voltage, wherein the first terminal host device is disconnected, and, in a state where the first power supply voltage to the first power supply terminal is not supplied a semiconductor device characterized in that it comprises a second power supply voltage generator for generating based on the second power supply voltage to the third power supply voltage higher than the power supply voltage of the second voltage.   The semiconductor device according to claim 1, wherein the third circuit block is a circuit block capable of controlling the first circuit block based on the second power supply voltage. 3. The semiconductor device according to claim 1, wherein a power source for driving the peripheral device is a battery. Said second power supply voltage generating section, is stepped down to the first power supply voltage to generate the second power supply voltage, the first connected between the second power supply terminal and the first power supply terminal and the supply voltage step-down means, said third power supply voltage is stepped down to generate the second power supply voltage, a second power supply connected between said second power supply terminal and the third power supply terminal the semiconductor device according to any one of claims 1 to 3, characterized in that it comprises a voltage step-down unit. The semiconductor device according to claim 1, wherein the second circuit block is an input / output circuit, and the peripheral device is a flash memory.