JP2007228407A - Double power source bidirectional level shifter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double power source bidirectional level shifter capable of converting a voltage level over a wide range. <P>SOLUTION: A double power source bidirectional level shifter includes: a first analog switch SW1 with which a first power supply voltage VCCA and a second power supply voltage VCCB are supplied through diodes D1 and D2 to a power supply terminal in parallel, respectively and a signal at a level of VCCB is output from an output terminal by connecting an input terminal to the output terminal when the VCCB is input to the input terminal and a signal at a level of VCCA is supplied to a control terminal; and a second analog switch SW2 with which VCCA and VCCB are supplied through diodes D3 and D4 to a power supply terminal in parallel, respectively and a signal at the level of VCCA is output from an output terminal by connecting an input terminal to the output terminal when the VCCA is input to the input terminal and a signal at the level of VCCB is supplied to a control terminal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a two-power supply bidirectional level shifter, and more particularly to a two-power supply bidirectional level shifter capable of converting a voltage level over a wide range.

  A two-power supply bidirectional level shifter exists as a device that serves as an interface between two devices and circuits having different power supply voltages. The two-power supply bidirectional level shifter inputs power supply voltages (VCCA and VCCB) for operating these two devices and circuits, and shifts the signal of the voltage VCCA level from one device or circuit to the voltage VCCB. The voltage level of the signal is bidirectionally converted, such as being sent to a device or circuit, and the voltage VCCB level signal from the other device or circuit is shifted to the voltage VCCA and sent to the one device or circuit. It is.

  The two power supply bidirectional level shifter that has been commercially available has a maximum voltage level conversion range of about 1.2V to 5.5V, and the maximum voltage that can be input as the power supply voltage (VCCA, VCCB) is about 6V. Met.

  However, today, various types of peripheral devices and parts having different power supply voltages are attached to information processing terminals such as personal computers and mobile phones, either internally or externally. Some of these peripheral devices and parts have a low power supply voltage of about 1.8V, and a high power supply voltage of about 12V.

  For example, assuming that the power supply voltage of the control side device (CPU, etc.) is 3 to 5 V, the voltage level is converted in a wide range of 3 to 5 V to 1.8 to 12 V in order to control those peripheral devices. Must. This range is beyond the conversion range of conventional commercially available dual power supply bidirectional level shifters. Depending on the power supply voltage level of each peripheral device, etc., multiple types of commercially available dual power supply bidirectional level shifters can be used. It is necessary to use a two-power supply bidirectional level shifter.

  FIG. 8 is a diagram illustrating a control method for peripheral devices and the like using such a conventional two-power supply bidirectional level shifter. A control device (CPU or the like) 31 having a power supply voltage of 3.3V includes a controlled device (peripheral device or the like) 32 having a power supply voltage of 1.8V, a controlled device 33 having a power supply voltage of 5V, and a controlled device having a power supply voltage of 12V. Are controlled, the controlled device 32 has a dedicated dual power supply level shifter 35 for 1.8V 市 販 3.3V conversion (for example, a commercial product) and the controlled device 33 has a dedicated 5V⇔3.3V conversion. 3 power supply bidirectional level shifter 36 (for example, commercially available product) and 2 power supply bidirectional level shifter 37 (for example, custom-made product) for conversion of 12V to 3.3V dedicated to controlled device 34 Was used.

  However, the use of a plurality of two-power supply bidirectional level shifters of different types in this way leads to an increase in the number of parts and an increase in manufacturing cost of information processing terminals such as personal computers and mobile phones.

  The applicant has also filed a patent application for a voltage conversion circuit for two-way communication in the past, but the voltage conversion circuit was not particularly concerned with the convertible range of the voltage level (Patent Document 1). .

JP 2000-307413 A (paragraph numbers 0011 to 12, FIG. 1)

  In view of such a point, an object of the present invention is to provide a dual power supply bidirectional level shifter capable of converting a voltage level over a wide range.

In order to solve this problem, the two-power supply bidirectional level shifter according to the first invention of the present application is characterized by including analog switches as described in the following (1) and (2).
(1) The first power supply voltage and the second power supply voltage are respectively supplied in parallel to the power supply terminal via the diode, the second power supply voltage is input to the input terminal, and the first power supply voltage level signal A first analog switch that connects the input terminal and the output terminal and outputs a signal of the level of the second power supply voltage from the output terminal when is supplied to the control terminal.
(2) The first power supply voltage and the second power supply voltage are respectively supplied in parallel to the power supply terminals via the diodes, the first power supply voltage is input to the input terminal, and the second power supply voltage level signal A second analog switch that connects the input terminal and the output terminal and outputs a signal of the first power supply voltage level from the output terminal when the signal is supplied to the control terminal.

  In this two-power supply bidirectional level shifter, when a signal of the first power supply voltage level from a device or circuit operating at the first power supply voltage is supplied to the control terminal of the first analog switch, the input terminal of the analog switch is applied. The input second power supply voltage is output from the output terminal of the analog switch. Therefore, if the output signal of the analog switch is sent to a device or circuit that operates at the second power supply voltage, a signal at the first power supply voltage level from the device or circuit that operates at the first power supply voltage is output. The power supply voltage can be shifted to a power supply voltage level of 2 and sent to a device or a circuit that operates at the second power supply voltage.

  Further, when a signal of the second power supply voltage level from a device or circuit operating at the second power supply voltage is supplied to the control terminal of the second analog switch, the first input to the input terminal of the analog switch is input. Is supplied from the output terminal of the analog switch. Therefore, if the output signal of the analog switch is sent to a device or circuit that operates at the first power supply voltage, a signal at the level of the second power supply voltage from the device or circuit that operates at the second power supply voltage is output. It is possible to shift to the level of one power supply voltage and send it to a device or circuit that operates at the first power supply voltage.

  Thus, the voltage level of the signal can be converted bidirectionally between the device or circuit operating with the first power supply voltage and the device or circuit operating with the second power supply voltage.

  Since the first power supply voltage and the second power supply voltage are supplied in parallel through the diodes to the power supply terminals of these analog switches, respectively, the first power supply voltage and the second power supply voltage are The higher voltage is supplied through a diode. Therefore, even if the lower limit of one of the first power supply voltage and the second power supply voltage is set lower than the minimum operating voltage of these analog switches, the lower limit of the other voltage is set to be equal to or higher than the minimum operating voltage. The minimum operating voltage of these analog switches can be ensured.

  In addition, the upper limit of the first power supply voltage and the second power supply voltage can be increased to the maximum voltage that can be supplied to these analog switches.

  Thus, since the lower limit of one of the first power supply voltage and the second power supply voltage can be lowered and the upper limit of the first power supply voltage and the second power supply voltage can be increased, the conventional two power supplies The voltage level can be converted in a wider range than the bidirectional level shifter.

  The dual power supply bidirectional level shifter can be configured using only easily available and inexpensive devices such as analog switches and diodes.

Next, a two-power supply bidirectional level shifter according to a second invention of the present application is characterized by including analog switches as described in the following (1) to (4).
(1) A first power supply voltage and a voltage obtained by transforming any one of the first power supply voltage and the second power supply voltage are respectively supplied to the power supply terminals in parallel through the diodes. When the voltage is input to the input terminal and the first power supply voltage level signal is supplied to the control terminal, the input terminal and the output terminal are connected to output the transformed voltage level signal from the output terminal. The first analog switch to do.
(2) The second power supply voltage and the transformed voltage are respectively supplied in parallel to the power supply terminal via the diode, the second power supply voltage is input to the input terminal, and this is output from the output terminal of the first analog switch. A second analog switch for connecting the input terminal and the output terminal and outputting a signal of the second power supply voltage level from the output terminal when a signal of the transformed voltage level is supplied to the control terminal;
(3) The second power supply voltage and the transformed voltage are respectively supplied in parallel to the power supply terminal via the diode, and the transformed voltage is input to the input terminal, and the signal of the second power supply voltage level is controlled. A third analog switch that, when supplied to the terminal, connects the input terminal and the output terminal and outputs a signal of the transformed voltage level from the output terminal.
(4) The first power supply voltage and the transformed voltage are respectively supplied in parallel to the power supply terminal via the diode, the first power supply voltage is input to the input terminal, and this is output from the output terminal of the third analog switch. A fourth analog switch for connecting the input terminal and the output terminal to output a first power supply voltage level signal from the output terminal when the transformed voltage level signal is supplied to the control terminal;

  In this two-power supply bidirectional level shifter, when a signal of the first power supply voltage level from a device or circuit operating at the first power supply voltage is supplied to the control terminal of the first analog switch, the input terminal of the analog switch is applied. The input voltage obtained by transforming the first power supply voltage or the second power supply voltage is output from the output terminal of the analog switch and supplied to the control terminal of the second analog switch.

  In the second analog switch, when the signal of the transformed voltage level is supplied to the control terminal, the second power supply voltage input to the input terminal is output from the output terminal.

  Therefore, if the output signal of the second analog switch is sent to a device or circuit that operates at the second power supply voltage, a signal at the level of the first power supply voltage from the device or circuit that operates at the first power supply voltage is sent. It is possible to shift to the level of the second power supply voltage and send it to a device or a circuit that operates with the second power supply voltage.

  Further, when a signal at the second power supply voltage level from a device or circuit operating at the second power supply voltage is supplied to the control terminal of the third analog switch, the signal is input to the input terminal of the analog switch. The transformed voltage is output from the output terminal of the analog switch and supplied to the control terminal of the fourth analog switch.

  In the fourth analog switch, when the transformed voltage level signal is supplied to the control terminal, the first power supply voltage input to the input terminal is output from the output terminal.

  Therefore, if the output signal of the fourth analog switch is sent to a device or circuit that operates at the first power supply voltage, a signal at the second power supply voltage level from the device or circuit that operates at the second power supply voltage is sent. The first power supply voltage level can be shifted to a device or a circuit that operates at the first power supply voltage.

  Thus, the voltage level of the signal can be converted bidirectionally between the device or circuit operating with the first power supply voltage and the device or circuit operating with the second power supply voltage.

  In addition, one of the first power supply voltage and the second power supply voltage and a voltage obtained by transforming the first power supply voltage or the second power supply voltage are respectively connected to the power supply terminals of these analog switches via diodes. Therefore, even if both the first power supply voltage and the second power supply voltage are less than the minimum operating voltage of these analog switches, the first power supply voltage or the second power supply voltage is set to the minimum power supply voltage. If the voltage is transformed beyond the operating voltage, the minimum operating voltage of these analog switches can be secured.

  In addition, the upper limit of the first power supply voltage and the second power supply voltage can be increased to the maximum voltage that can be supplied to these analog switches.

  As described above, the lower limits of both the first power supply voltage and the second power supply voltage can be lowered and the upper limits of the first power supply voltage and the second power supply voltage can be increased. The voltage level can be converted in a wider range than the dual power supply bidirectional level shifter according to the first aspect of the invention.

  The dual power supply bidirectional level shifter according to the first invention of the present application has an effect that the voltage level can be converted over a wide range using only an easily available and inexpensive device such as an analog switch or a diode. It is done.

  According to the dual power supply bidirectional level shifter according to the second invention of the present application, the voltage level can be converted in a wider range using the analog switch or the diode than the dual power supply bidirectional level shifter according to the first invention of the present application. The effect that it can be obtained.

Embodiments of the present invention will be specifically described below with reference to the drawings.
[First Embodiment of the Present Invention]
FIG. 1 is a circuit diagram showing a configuration example of a two-power supply bidirectional level shifter to which the first invention of the present application is applied. This two-power supply bidirectional level shifter includes devices and circuits that operate at power supply voltage VCCA: 3 to 5 V (hereinafter referred to as devices on the VCCA side) and devices and circuits that operate at power supply voltage VCCB: 1.8 to 18 V (hereinafter referred to as “devices on the VCCA side”). The voltage level of the signal is bidirectionally converted between the device and the device on the VCCB side).

  A signal input from the VCCA side device to the dual power supply bidirectional level shifter via the bus (VCCA_BUS) 11 is supplied to the control terminal “4” of the analog switch SW1 via the buffer B1. The analog switch SW1 is an analog switch that operates in a power supply voltage range of 3 to 18 V, and is generally commercially available. The power supply voltage VCCA and the power supply voltage VCCB are supplied in parallel to the power supply terminal “5” of the analog switch SW1 via the diodes D1 and D2, respectively. The power supply voltage VCCB is input to the input terminal “1” of the analog switch SW1. The terminal “3” of the analog switch SW1 is a ground terminal.

  When a high level signal is supplied to the control terminal “4”, the analog switch SW1 is connected to the input terminal “1” and the output terminal “2”, and outputs a signal of the level of the power supply voltage VCCB to the output terminal “ 2 ”. On the other hand, when a low level signal is supplied to the control terminal “4”, the input terminal “1” and the output terminal “2” are not connected, and the output signal becomes low level (ground level by the pull-down resistor R1). The output signal of the analog switch SW1 is input to a buffer B2 having a configuration as described later.

  A signal input to the two-power supply bidirectional level shifter from the device on the VCCB side via the bus (VCCB_BUS) 12 is supplied to the control terminal “4” of the analog switch SW2. The analog switch SW2 has the same configuration as the analog switch SW1. The power supply voltage VCCA and the power supply voltage VCCB are supplied in parallel to the power supply terminal “5” of the analog switch SW2 via the diodes D3 and D4, respectively. The power supply voltage VCCA is input to the input terminal “1” of the analog switch SW2.

  When the high level signal is supplied to the control terminal “4”, the analog switch SW2 is connected to the input terminal “1” and the output terminal “2”, and outputs a signal of the level of the power supply voltage VCCA. Output from terminal “2”. On the other hand, when a low level signal is supplied to the control terminal “4”, the input terminal “1” and the output terminal “2” are not connected, and the output signal becomes low level (ground level by the pull-down resistor R2). The output signal of the analog switch SW2 is input to a buffer (a three-state gate whose gate is negative logic) B3.

  The two power supply bidirectional level shifter is supplied with a signal whose high level is the level of the power supply voltage VCCA via the control signal line 13 as a control signal for switching the voltage level conversion direction. This control signal is supplied to the gate of the buffer B3 and also to the control terminal “4” of the analog switch SW3 via the buffer B4.

  The buffer B3 enters a high impedance state when a high level control signal is supplied, and outputs a signal having the same level as the input signal when a low level control signal is supplied. The output signal of the buffer B3 is sent from the dual power supply bidirectional level shifter to the VCCA device via the bus 11.

  The analog switch SW3 is for converting the control signal at the level of the power supply voltage VCCA into the level of the power supply voltage VCCB, and has the same configuration as the analog switch SW1. The power supply voltage VCCA and the power supply voltage VCCB are supplied in parallel to the power supply terminal “5” of the analog switch SW3 via the diodes D5 and D6, respectively. The power supply voltage VCCB is input to the input terminal “1” of the analog switch SW3.

  When the high level control signal is supplied to the control terminal “4”, the analog switch SW3 is connected to the input terminal “1” and the output terminal “2”, and outputs a signal of the level of the power supply voltage VCCB. Output from “2”. On the other hand, when the low-level control signal is supplied to the control terminal “4”, the input terminal “1” and the output terminal “2” are not connected, and the output signal becomes the low level (the ground level by the pull-down resistor R3). . The output signal of the analog switch SW3 is supplied to the buffer B2.

  The buffer B2 is configured by an analog switch having the same configuration as the analog switches SW1 to SW3. As shown in FIG. 2, the output signal of the analog switch SW1 is input to the input terminal “1” of the analog switch. The output signal of the analog switch SW3 is supplied to the control terminal “4” of the analog switch. A power supply voltage VCCA and a power supply voltage VCCB are supplied in parallel to the power supply terminal “5” of the analog switch via diodes D7 and D8, respectively.

  When a high level signal is supplied to the control terminal “4”, the analog switch is connected to the input terminal “1” and the output terminal “2”, and is a signal having the same level as the output signal of the analog switch SW1. Is output from the output terminal “2”. As shown in FIG. 1, this output signal is sent from the dual power supply bidirectional level shifter to the VCCB side device via the bus 12. On the other hand, when a low level signal is supplied to the control terminal “4”, the input terminal “1” and the output terminal “2” are not connected to the analog switch, and the output is in a high impedance state.

  Next, how the dual power supply bidirectional level shifter converts the voltage level of the signal bidirectionally between the VCCA device and the VCCB device will be described. When a signal is sent from the VCCA side device to the VCCB side device, a high level control signal is sent to the two-power supply bidirectional level shifter. When a VCCA level signal is sent from the VCCA device to the dual power supply bidirectional level shifter via the bus 11, a high level (VCCA level) signal is supplied to the control terminal “4” of the analog switch SW1. Therefore, VCCB input to the input terminal “1” of the analog switch SW1 is output from the output terminal “2” of the analog switch SW1 and input to the buffer B2 (the input terminal “1” of the analog switch in FIG. 2). To do.

  At this time, the signal supplied from the analog switch SW3 to the buffer B2 (the control terminal “4” of the analog switch in FIG. 2) by the high level control signal becomes the high level, so that the buffer B2 (the analog switch of FIG. 2) A signal of VCCB level is output from the output terminal “2”), and this signal is sent to the VCCB side device via the bus 12. As a result, the VCCA level signal from the VCCA device is shifted to the VCCB level and sent to the VCCB device. Further, the buffer B3 is in a high impedance state.

  When a signal is sent from the VCCB side device to the VCCA side device, a low-level control signal is sent to the two-power supply bidirectional level shifter. When a VCCB level signal is sent from the VCCB side device to the dual power supply bidirectional level shifter via the bus 12, a high level (VCCB level) signal is supplied to the control terminal “4” of the analog switch SW2. Therefore, VCCA inputted to the input terminal “1” of the analog switch SW2 is outputted from the output terminal “2” of the analog switch SW2 and inputted to the buffer B3.

  At this time, since the buffer B3 outputs a signal of the same level as the input signal by the low level control signal, a signal of the VCCA level is output from the buffer B3, and this signal is sent to the VCCA device via the bus 11. . Thereby, the VCCB level signal from the VCCB side device is shifted to the VCCA level and sent to the VCCA side device. Further, since the signal supplied from the analog switch SW3 to the buffer B2 (the control terminal “4” of the analog switch in FIG. 2) is at a low level, the buffer B2 is in a high impedance state.

  In this way, the voltage level of the signal can be converted bidirectionally between the VCCA side device and the VCCB side device.

  In this two-power supply bidirectional level shifter, the power supply voltage VCCA and the power supply voltage VCCB are respectively connected to the power supply terminals of the analog switches (analog switches SW1 to SW3 and the analog switch of FIG. 2 constituting the buffer B2) via diodes. Since they are supplied in parallel, the higher voltage of VCCA and VCCB is supplied via the diode. Therefore, the minimum operating voltage of these analog switches can be ensured even though 1.8 V, which is the lower limit of VCCB, is less than the minimum operating voltage (3 V) of these analog switches.

  FIG. 3 is a diagram showing how the minimum operating voltage is secured. As shown in FIG. 3A, when VCCA = 3V and VCCB = 5V, 5V VCCB is supplied to the power supply terminals of these analog switches. As shown in FIG. 3B, when VCCA = 5V and VCCB = 3V, 5V VCCA is supplied to the power supply terminals of these analog switches. As shown in FIG. 3C, when VCCA = 5V and VCCB = 12V, 12V VCCB is supplied to the power supply terminals of these analog switches. As shown in FIG. 3D, when VCCA = 3V and VCCB = 1.8V, 3V VCCA is supplied to the power supply terminals of these analog switches. Therefore, in any case, 3 V, which is the minimum operating voltage of these analog switches, is secured.

  Further, although the upper limit of VCCB is a high voltage of 18V, the power supply voltage range of these analog switches is 3 to 18V, so that 18V VCCB can also be supplied to the power supply terminals of these analog switches.

  Thus, since the lower limit of VCCB is lowered and the upper limit is raised, the voltage level can be converted in a wider range than the conventional two-power supply bidirectional level shifter.

  In FIG. 4, “FIG. 1” is shown so that the convertible area of this two-power supply bidirectional level shifter can be compared with various conventional two-power supply bidirectional level shifters (four types shown as “conventional”). Show. In addition, as each analog switch, a convertible region when a power supply voltage range of 3 to 12 V (also a commercial product) is used instead of a power supply voltage range of 3 to 18 V is also shown in FIG. In the case of a switch)). In either case, the VCCB range is significantly wider than the conventional one.

  The dual power supply bidirectional level shifter can be configured using only easily available and inexpensive devices such as analog switches and diodes.

  Here, as shown in FIG. 8, the control device 31 having the power supply voltage 3.3V is controlled by the controlled device 32 (power supply voltage 1.8V), the controlled device 33 (power supply voltage 5V), and the controlled device 34 (power supply voltage 12V). ), A method of controlling these controlled devices 32 to 34 using the two-power supply bidirectional level shifter shown in FIG. 1 will be described.

  In this case, the control device 31 is a device on the VCCA side, the controlled devices 32 to 34 are devices on the VCCB side, and the power supply terminals (in the analog switch SW2) of each analog switch of the two-power supply bidirectional level shifter shown in FIG. While supplying 3.3V as VCCA to the power supply terminal and the input terminal), VCCB supplied to the power supply terminal of each analog switch of the two power supply bidirectional level shifter (the power supply terminal and the input terminal in the case of the analog switches SW1 and SW3) is 1 .Switch alternately between 8V, 5V and 12V. Then, as shown in FIG. 5, the controlled devices 32 to 34 are alternately controlled using the single two-power supply bidirectional level shifter 21.

  In this way, by using a single dual power supply bidirectional level shifter composed of inexpensive devices, it is possible to control a plurality of peripheral devices with different power supply voltages, so that a large number of peripheral devices can be built-in or removed. It is possible to reduce the number of parts of an information processing terminal such as a personal computer or a mobile phone attached, and to reduce the manufacturing cost.

[Second Embodiment of the Present Invention]
Next, FIG. 6 is a circuit diagram showing a configuration example of a two-power supply bidirectional level shifter to which the second invention of the present application is applied. This two-power supply bidirectional level shifter includes devices and circuits that operate at a power supply voltage VCCA: 1.8 to 18V (hereinafter referred to as devices on the VCCA side) and devices and circuits that operate at a power supply voltage VCCB: 1.8 to 18V. (Hereinafter, referred to as a VCCB side device) to convert the voltage level of the signal bidirectionally.

  Each analog switch in the dual power supply bidirectional level shifter has the same configuration as the analog switch in the dual power supply bidirectional level shifter shown in FIG. The same reference numerals as those in FIG. 1 are also applied to the buses and control signal lines between the VCCA device and the VCCB device.

  A signal input from the VCCA side device to the dual power supply bidirectional level shifter via the bus 11 is supplied to the control terminal “4” of the analog switch SW11. The power supply voltage VCCA, 3 to 5 V is supplied in parallel to the power supply terminal “5” of the analog switch SW11 via the diodes D11 and D12, respectively. The voltage of 3 to 5 V is supplied to the two-power supply bidirectional level shifter by transforming one of the power supply voltage VCCA and the power supply voltage VCCB with a regulator (not shown). The transformed voltage of 3 to 5 V is input to the input terminal “1” of the analog switch SW11.

  When a high level signal is supplied to the control terminal “4”, the analog switch SW11 is connected to the input terminal “1” and the output terminal “2”, and outputs a signal having a level of 3 to 5 V to the output terminal “ 2 ". On the other hand, when a low level signal is supplied to the control terminal “4”, the input terminal “1” and the output terminal “2” are not connected, and the output signal becomes low level (ground level by the pull-down resistor R11). The output signal of the analog switch SW11 is supplied to the control terminal “4” of the analog switch SW12 via the buffer B11.

  The power supply terminal “5” of the analog switch SW12 is supplied with the transformed voltage of 3 to 5 V and the power supply voltage VCCB in parallel through the diodes D13 and D14, respectively. The power supply voltage VCCB is input to the input terminal “1” of the analog switch SW12.

  When a high level signal is supplied to the control terminal “4”, the analog switch SW12 is connected to the input terminal “1” and the output terminal “2”, and outputs a signal at the level of the power supply voltage VCCB to the output terminal “ 2 ". On the other hand, when a low level signal is supplied to the control terminal “4”, the input terminal “1” and the output terminal “2” are not connected, and the output signal becomes low level (ground level by the pull-down resistor R12). The output signal of the analog switch SW12 is input to a buffer B12 having a configuration as described later.

  A signal input from the VCCB side device to the dual power supply bidirectional level shifter via the bus 12 is supplied to the control terminal “4” of the analog switch SW13. The power supply terminal “5” of the analog switch SW13 is supplied with the power supply voltage VCCB and the aforementioned transformed voltage of 3 to 5 V in parallel via the diodes D15 and D16, respectively. The transformed voltage of 3 to 5 V is input to the input terminal “1” of the analog switch SW13.

  When a high level signal is supplied to the control terminal “4”, the analog switch SW13 is connected to the input terminal “1” and the output terminal “2”, and outputs a signal having a level of 3 to 5 V to the output terminal “ 2 ". On the other hand, when a low level signal is supplied to the control terminal “4”, the input terminal “1” and the output terminal “2” are not connected, and the output signal becomes low level (ground level by the pull-down resistor R13). The output signal of the analog switch SW13 is supplied to the control terminal “4” of the analog switch SW14 via the buffer B13.

  The power supply terminal “5” of the analog switch SW14 is supplied with the transformed voltage of 3 to 5 V and the power supply voltage VCCA in parallel via the diodes D17 and D18, respectively. The power supply voltage VCCA is input to the input terminal “1” of the analog switch SW14.

  When a high level signal is supplied to the control terminal “4”, the analog switch SW14 is connected to the input terminal “1” and the output terminal “2”, and outputs the signal at the level of the power supply voltage VCCA to the output terminal “4”. 2 ". On the other hand, when a low level signal is supplied to the control terminal “4”, the input terminal “1” and the output terminal “2” are not connected, and the output signal becomes low level (ground level by the pull-down resistor R14). The output signal of the analog switch SW14 is input to a buffer B14 having a configuration as described later.

  A control signal (a signal whose high level becomes the level of the power supply voltage VCCA) input via the control signal line 13 is supplied to the buffer B14 and to the control terminal “4” of the analog switch SW15.

  An analog switch SW15 and an analog switch SW16, which will be described later, are for converting a control signal of the level of the power supply voltage VCCA into a level of the power supply voltage VCCB. The power supply terminal “5” of the analog switch SW15 is supplied with the power supply voltage VCCA and the aforementioned transformed voltage of 3 to 5 V in parallel via the diodes D19 and D20, respectively. The transformed voltage of 3 to 5 V is input to the input terminal “1” of the analog switch SW15.

  When a high level control signal is supplied to the control terminal “4”, the analog switch SW15 is connected to the input terminal “1” and the output terminal “2”, and outputs a signal having a level of 3 to 5 V as an output terminal. Output from “2”. On the other hand, when the low level control signal is supplied to the control terminal “4”, the input terminal “1” and the output terminal “2” are not connected, and the output signal becomes low level (ground level by the pull-down resistor R15). . The output signal of the analog switch SW15 is supplied to the control terminal “4” of the analog switch SW16 via the inverter I1 and the buffer B15.

  The power supply terminal “5” of the analog switch SW16 is supplied with the transformed voltage of 3 to 5 V and the power supply voltage VCCB in parallel through the diodes D21 and D22, respectively. The power supply voltage VCCB is input to the input terminal “1” of the analog switch SW16.

  When a high level signal is supplied to the control terminal “4”, the analog switch SW16 is connected to the input terminal “1” and the output terminal “2”, and outputs a signal at the level of the power supply voltage VCCB to the output terminal “ 2 ”. On the other hand, when a low level signal is supplied to the control terminal “4”, the input terminal “1” and the output terminal “2” are not connected, and the output signal becomes low level (ground level by the pull-down resistor R16). The output signal of the analog switch SW16 is supplied to the buffer B12.

  The buffer B12 is configured by an analog switch having the same configuration as the analog switches SW11 to SW16. As shown in FIG. 7A, the output signal of the analog switch SW12 is input to the input terminal “1” of the analog switch. The output signal of the analog switch SW16 is supplied to the control terminal “4” of the analog switch. The power supply terminal “5” of the analog switch is supplied with the transformed voltage of 3 to 5 V and the power supply voltage VCCB in parallel via the diodes D23 and D24, respectively.

  When a high level signal is supplied to the control terminal “4”, the analog switch is connected to the input terminal “1” and the output terminal “2”, and is a signal having the same level as the output signal of the analog switch SW12. Is output from the output terminal “2”. As shown in FIG. 6, this output signal is sent from the two-power supply bidirectional level shifter to the VCCB side device via the bus 12. On the other hand, when a low level signal is supplied to the control terminal “4”, the input terminal “1” and the output terminal “2” are not connected to the analog switch, and the output is in a high impedance state.

  The buffer B14 includes an analog switch having the same configuration as the analog switches SW11 to SW16. As shown in FIG. 7B, the output signal of the analog switch SW14 is input to the input terminal “1” of the analog switch. The control signal is supplied to the control terminal “4” of the analog switch. The power supply terminal “5” of the analog switch is supplied with the transformed voltage of 3 to 5 V and the power supply voltage VCCA in parallel via the diodes D25 and D26, respectively.

  When a high-level control signal is supplied to the control terminal “4”, the analog switch is connected to the input terminal “1” and the output terminal “2”, and has the same level as the output signal of the analog switch SW14. The signal is output from the output terminal “2”. As shown in FIG. 6, the output signal is sent from the dual power supply bidirectional level shifter to the VCCA device via the bus 11. On the other hand, when a low-level control signal is supplied to the control terminal “4”, the input terminal “1” and the output terminal “2” are not connected to the analog switch, and the output is in a high impedance state.

  Next, how the two-power supply bidirectional level shifter converts the voltage level of the signal bidirectionally between the VCCA side device and the VCCB side device will be described. When a signal is sent from the VCCA side device to the VCCB side device, a low-level control signal is sent to the two-power supply bidirectional level shifter. When a VCCA level signal is sent from the VCCA device to the dual power supply bidirectional level shifter via the bus 11, a high level (VCCA level) signal is supplied to the control terminal “4” of the analog switch SW11. Therefore, the voltage of 3 to 5 V input to the input terminal “1” of the analog switch SW11 is output from the output terminal “2” of the analog switch SW11 and supplied to the control terminal “4” of the analog switch SW12. .

  Thus, when the high level (3 to 5 V level) signal is supplied to the control terminal “4” of the analog switch SW12, the VCCB input to the input terminal “1” of the analog switch SW12 becomes the analog switch. The signal is output from the output terminal “2” of the SW12 and input to the buffer B12 (the analog switch input terminal “1” in FIG. 7A).

  At this time, the output signal of the analog switch SW15 becomes low level by the low level control signal, and the high level signal inverted by the inverter I1 is supplied to the control terminal “4” of the analog switch SW16, thereby the analog switch SW16. To the buffer B12 (the control terminal “4” of the analog switch in FIG. 7A) becomes a high level (the level of the power supply voltage VCCB), so the buffer B12 (the output terminal “of the analog switch in FIG. 2” 2)), a VCCB level signal is output, and this signal is sent to the VCCB side device via the bus 12. As a result, the VCCA level signal from the VCCA device is shifted to the VCCB level and sent to the VCCB device.

  Further, since the low level control signal is supplied to the buffer B14 (the control terminal “4” of the analog switch in FIG. 7B), the buffer B14 enters a high impedance state.

  When a signal is sent from the VCCB side device to the VCCA side device, a high level control signal is sent to the two-power supply bidirectional level shifter. When a VCCB level signal is sent from the VCCB side device to the dual power supply bidirectional level shifter via the bus 12, a high level (VCCB level) signal is supplied to the control terminal “4” of the analog switch SW13. Therefore, the voltage of 3 to 5 V input to the input terminal “1” of the analog switch SW13 is output from the output terminal “2” of the analog switch SW13 and supplied to the control terminal “4” of the analog switch SW14. .

  In this way, when the high level (3 to 5 V level) signal is supplied to the control terminal “4” of the analog switch SW14, the VCCA input to the input terminal “1” of the analog switch SW14 becomes the analog switch. The signal is output from the output terminal “2” of the SW 14 and input to the buffer B 14 (the analog switch input terminal “1” in FIG. 7B).

  At this time, since a high-level control signal is supplied to the buffer B14 (the control terminal “4” of the analog switch in FIG. 7B), the buffer B14 (the output terminal “2” of the analog switch in FIG. 7B). )), A VCCA level signal is output, and this signal is sent to the VCCA device via the bus 11. Thereby, the VCCB level signal from the VCCB side device is shifted to the VCCA level and sent to the VCCA side device.

  Further, the output signal of the analog switch SW15 becomes high level (3 to 5V) by the high level control signal, and the low level signal inverted by the inverter I1 is supplied to the control terminal “4” of the analog switch SW16. As a result, the signal supplied from the analog switch SW16 to the buffer B12 (the control terminal “4” of the analog switch in FIG. 7A) becomes the low level, so that the buffer B12 enters the high impedance state.

  In this way, the voltage level of the signal can be converted bidirectionally between the VCCA side device and the VCCB side device.

  In this two-power supply bidirectional level shifter, one of the power supply voltage VCCA and the power supply voltage VCCB is connected to the power supply terminal of each analog switch (analog switches SW11 to SW16 and the analog switches of FIG. 7 constituting the buffers B12 and B14). And 3 to 5 V (3 V or more which is the minimum operating voltage of these analog switches) obtained by transforming VCCA or VCCB are supplied in parallel through the diodes, respectively, so that VCCA or VCCB and 3 to 5 V The higher voltage is supplied through the diode. Therefore, the minimum operating voltage of these analog switches is ensured even though both the lower limit of VCCA, 1.8V, and the lower limit of VCCB, 1.8V, are less than the minimum operating voltage of these analog switches. be able to.

  Moreover, although the upper limit of VCCA and VCCB is a high voltage of 18V, since the power supply voltage range of these analog switches is 3 to 18V, 18V VCCA and VCCB can be supplied to the power supply terminals of these analog switches. .

  Thus, since the lower limits of both VCCA and VCCB are lowered and the upper limits thereof are increased, the voltage level can be converted in a wider range than the two-power supply bidirectional level shifter shown in FIG. .

  FIG. 4 shows that the convertible region of this two-power supply bidirectional level shifter can be compared with various conventional two-power supply bidirectional level shifters and the two-power supply bidirectional level shifter shown in FIG. As shown.

[Additional notes]
Finally, supplementary matters for the embodiment of the invention described above will be described.

  (A) The dual power supply bidirectional level shifter according to the present invention is not limited to an analog switch having a power supply voltage range of 3 to 18 V or an analog switch having a power supply voltage range of 3 to 12 V, but includes various commercially available analog switches. Basically, any analog switch can be used.

  (B) In a device in which VCCA and VCCB are set as an external supply power supply and a backup power supply, not limited to a two-power supply bidirectional level shifter, VCCCA and VCCB are usually supplied in parallel via diodes, respectively. When VCCA supply is stopped due to a power failure or the like, VCCB may be automatically supplied when VCCA drops below a certain voltage.

  (C) Since the operating voltage of the semiconductor can be adjusted if the two-power supply bidirectional level shifter is made into an LSI, the operating voltage of the analog switch is lowered (for example, the minimum operating voltage is set to 1.2 V or less). Is possible. Thereby, even if the lower limit of VCCA or VCCB is a low voltage of about 1.2 V, the voltage level of the signal can be converted bidirectionally by the two-power supply bidirectional level shifter according to the present invention.

It is a circuit diagram which shows the structural example of the 2 power supply bidirectional | two-way level shifter to which 1st invention of this application is applied. It is a circuit diagram which shows the structure of buffer B2 of FIG. It is a figure which shows a mode that the minimum operating voltage of each analog switch of FIG. 1 is ensured. It is a figure for comparing the convertible area | region of the 2 power supply bidirectional level shifter of FIG.1 and FIG.6 with the convertible area | region of the conventional 2 power supply bidirectional level shifter. It is a figure which illustrates the control method of a peripheral device etc. which used the 2 power supply bidirectional | two-way level shifter of FIG. It is a circuit diagram which shows the structural example of the 2 power supply bidirectional | two-way level shifter to which 2nd invention of this application is applied. It is a circuit diagram which shows the structural example of buffer B12 and B14 of FIG. It is a figure which illustrates the control method of the peripheral equipment etc. which used the conventional 2 power supply bidirectional | two-way level shifter.

Explanation of symbols

  SW1 to SW3, SW11 to SW16 Analog switch, D1 to D8, D11 to D26 diode, B1 to B4, B11 to B15 buffer, I1 inverter, 11, 12 bus, 21 2 power supply bidirectional level shifter

Claims (4)

The first power supply voltage and the second power supply voltage are respectively supplied in parallel to the power supply terminal via the diode, the second power supply voltage is input to the input terminal, and a signal at the level of the first power supply voltage is received. A first analog switch that, when supplied to the control terminal, connects the input terminal and the output terminal and outputs a signal of the level of the second power supply voltage from the output terminal;
The first power supply voltage and the second power supply voltage are respectively supplied in parallel to a power supply terminal via a diode, the first power supply voltage is input to the input terminal, and the level of the second power supply voltage is A second analog switch that connects the input terminal and the output terminal and outputs a signal of the first power supply voltage level from the output terminal when the signal of the signal is supplied to the control terminal; A two-power supply bidirectional level shifter characterized by that. The dual power supply bidirectional level shifter according to claim 1,
One voltage range of the first power supply voltage and the second power supply voltage includes a range less than a minimum operating voltage of the first analog switch and the second analog switch. Power supply bidirectional level shifter. A first power supply voltage and a voltage obtained by transforming one of the first power supply voltage and the second power supply voltage are respectively supplied in parallel to the power supply terminal via a diode, and the transformed voltage is When input to the input terminal and the first power supply voltage level signal is supplied to the control terminal, the input terminal and the output terminal are connected, and the transformed voltage level signal is output from the output terminal. A first analog switch for outputting;
The second power supply voltage and the transformed voltage are respectively supplied in parallel to the power supply terminal via the diode, the second power supply voltage is input to the input terminal, and the output terminal of the first analog switch A second analog switch that connects the input terminal and the output terminal and outputs the signal of the second power supply voltage level from the output terminal when a signal having a transformed voltage level is supplied to the control terminal. When,
The second power supply voltage and the transformed voltage are respectively supplied in parallel to a power supply terminal via a diode, the transformed voltage is input to an input terminal, and a signal of the second power supply voltage level is a control terminal. A third analog switch that is connected to the input terminal and the output terminal and outputs a signal of the transformed voltage level from the output terminal;
A first power supply voltage and the transformed voltage are respectively supplied to a power supply terminal in parallel through a diode, the first power supply voltage is input to an input terminal, and the output terminal of the third analog switch A fourth analog switch that connects the input terminal and the output terminal and outputs the signal of the first power supply voltage level from the output terminal when a signal having a transformed voltage level is supplied to the control terminal; And a dual power supply bidirectional level shifter. The dual power supply bidirectional level shifter according to claim 3,
The voltage ranges of both the first power supply voltage and the second power supply voltage are the lowest operation of the first analog switch, the second analog switch, the third analog switch, and the fourth analog switch. Including the range below the voltage,
Both the two power sources characterized in that the transformed voltage is a voltage equal to or higher than a minimum operating voltage of the first analog switch, the second analog switch, the third analog switch, and the fourth analog switch. Directional shifter.

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