Classifications

• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03K—PULSE TECHNIQUE
  • H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
  • H03K19/0008—Arrangements for reducing power consumption
  • H03K19/0013—Arrangements for reducing power consumption in field effect transistor circuits
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03K—PULSE TECHNIQUE
  • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
  • H03K17/08—Modifications for protecting switching circuit against overcurrent or overvoltage
  • H03K17/081—Modifications for protecting switching circuit against overcurrent or overvoltage without feedback from the output circuit to the control circuit
  • H03K17/0812—Modifications for protecting switching circuit against overcurrent or overvoltage without feedback from the output circuit to the control circuit by measures taken in the control circuit
  • H03K17/08122—Modifications for protecting switching circuit against overcurrent or overvoltage without feedback from the output circuit to the control circuit by measures taken in the control circuit in field-effect transistor switches
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03K—PULSE TECHNIQUE
  • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
  • H03K17/16—Modifications for eliminating interference voltages or currents
  • H03K17/161—Modifications for eliminating interference voltages or currents in field-effect transistor switches
  • H03K17/162—Modifications for eliminating interference voltages or currents in field-effect transistor switches without feedback from the output circuit to the control circuit
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03K—PULSE TECHNIQUE
  • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
  • H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
  • H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
  • H03K17/687—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03K—PULSE TECHNIQUE
  • H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
  • H03K19/0175—Coupling arrangements; Interface arrangements

Definitions

• the present invention relates to a coil load drive output circuit for driving a coil load such as a motor actuator.
• Patent Document 1 JP-A-6-152374
• Patent Document 2 JP-A-11 317653
• the current flows to the coil load 2 through the parasitic diode 113 existing in parallel with the second drive transistor 112. Therefore, at this time, the voltage at the output terminal OUT changes from the power supply potential V to the ground potential or less. Radiated noise.
• This radiation noise can usually be dealt with by mounting a noise suppression component such as a capacitor at a place where it is necessary. It is important in terms of performance and cost to reduce the power radiation noise itself.
• the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coil load drive output circuit that can reduce radiation noise due to switching. Means for solving the problem
• a coil load drive output circuit is connected in series between a power supply potential and a ground potential, and includes a midpoint power supply drive drive circuit.
• First and second control transistors that output transistor control voltages, first and second current limiting impedance elements that respectively limit currents flowing through the first and second control transistors, a power supply potential and a ground potential,
• the third and fourth control transistors which are connected in series between each other and output the midpoint force ground-side drive transistor control voltage, and the third and fourth control transistors, which limit the current flowing through the third and fourth control transistors, respectively.
• the fourth current limiting impedance element is connected in series between the power supply potential and the ground potential, and each is controlled by the power supply side drive transistor control voltage or the ground side drive transistor control voltage.
• the power supply side drive transistor and the ground side drive transistor that output the drive voltage for driving the coil load from the middle point are controlled by the power supply side drive transistor control voltage.
• the power supply side driving transistor is a P-type MOS transistor
• the ground side driving transistor is an N-type MOS transistor
• the second and third current limiting impedance elements are first and fourth current limiting impedance elements. Is larger than the resistance value.
• the power supply side driving transistor and the ground side driving transistor are both N-type MOS transistors, and the first and third current limiting impedance elements are the second and fourth current limiting impedance elements. Greater than the resistance value.
• the invention's effect since the coil load drive output circuit is provided with the current limiting impedance element that limits the current flowing through each control transistor, the power supply side drive transistor and the ground side drive transistor are gradually turned off. In addition, radiation noise due to switching can be reduced.
• FIG. 1 is a circuit diagram of a coil load drive output circuit according to a preferred embodiment of the present invention.
• FIG. 2 is a waveform chart showing waveforms generated in respective parts of the above.
• FIG. 3 is a circuit diagram of a coil load drive output circuit according to another preferred embodiment of the present invention.
• FIG. 4 is a circuit diagram illustrating a phenomenon during switching.
• FIG. 1 is a circuit diagram of a coil load drive output circuit 1 according to a preferred embodiment of the present invention.
• Reference numeral 11 denotes an inverter.
• This inverter 11 is a motor control circuit or an actuator control circuit (not shown). Inverts the input signal (PWM signal) of low level, low level, or low level input to the input terminal IN.
• 12, 13 are P-type MOS transistors and N-type MOS transistors.
• OS transistor 12 and N-type MOS transistor 13 are connected between power supply potential V and ground potential.
• Reference numeral 14 denotes a current limiting impedance element.
• the current limiting impedance element 14 limits a current flowing through the P-type MOS transistor 12.
• Reference numeral 15 denotes a ground-side detection transistor which is an N-type MOS transistor. This ground-side detection transistor 15 is connected to a node A, and is controlled by a voltage at a node D described later, that is, a ground-side drive transistor control voltage. .
• Reference numeral 16 denotes a buffer, and the buffer 16 shapes the voltage waveform of the node A.
• Reference numerals 17 and 18 denote a first control transistor which is a P-type MOS transistor and a second control transistor which is an N-type MOS transistor.
• the first control transistor 17 and the second control transistor 18 are connected to a power supply potential. Connected in series between V and ground potential
• Reference numerals 19 and 20 denote first and second current-limiting impedance elements. These first and second current-limiting impedance elements 19 and 20 are first and second control transistors 17 and 20, respectively.
• 21 and 22 are a P-type MOS transistor and an N-type MOS transistor.
• OS transistor 21 and N-type MOS transistor 22 are connected between power supply potential V and ground potential.
• Reference numeral 23 denotes a current limiting impedance element.
• the current limiting impedance element 23 limits the current flowing through the N-type MOS transistor 22.
• Reference numeral 24 denotes a power-supply-side detection transistor that is a P-type MOS transistor.
• the power-supply-side detection transistor 24 is connected to the node C, and is controlled by a voltage at the node B, that is, a power-supply-side drive transistor control voltage.
• 25 is a buffer, and this buffer 25 shapes the voltage waveform of the node C.
• Reference numerals 26 and 27 denote a third control transistor which is a P-type MOS transistor and a fourth control transistor which is an N-type MOS transistor.The third control transistor 26 and the fourth control transistor 27 Connected in series between the
• Reference numerals 28 and 29 denote third and fourth current limiting impedance elements, respectively.
• the third and fourth current limiting impedance elements 28 and 29 respectively control the current flowing through the third and fourth control transistors 26 and 27, respectively. Restrict.
• reference numerals 30 and 31 denote a power-side drive transistor as a P-type MOS transistor and a ground-side drive transistor as an N-type MOS transistor. These power-side drive transistor 30 and ground-side drive transistor 31 Connected in series between the potential V and the ground potential,
• Each is controlled by the power-side drive transistor control voltage or the ground-side drive transistor control voltage, and outputs a drive voltage for driving the coil load 2 from the middle point via the output terminal OUT.
• the parasitic capacitance 32 between the drain and the gate of the power supply side driving transistor 30 and the parasitic capacitance 33 between the drain and the gate of the ground side driving transistor 31 are shown. Is shown.
• a circuit similar to the coil load drive output circuit 1 is provided on one side (not shown) of the coil load 2.
• the current limiting impedance elements 14, 19, 20, 23, 28, 29 are resistors.
• the current-limiting impedance element 14 has such a resistance that the voltage at the node A can be kept at a low level even when the P-type MOS transistor 12 is on when the ground-side detection transistor 15 is on.
• the current limiting impedance element 23 has such a resistance that the voltage at the node C can be maintained at a high level even when the power supply side detection transistor 24 is turned on and the N-type MOS transistor 22 is turned on! It is.
• the resistance values of the first current limiting impedance element 19 and the fourth current limiting impedance element 29 are the same or substantially the same (for example, 1K to 2 ⁇ ), and the second current limiting impedance element 20 and the third current limiting impedance Is smaller than the resistance value of the sensing element 28 (for example, 10K to 30K ⁇ ).
• the operation of the coil load drive output circuit 1 will be described based on the waveform diagram of FIG. First, a case where a current flows from the output terminal OUT to the coil load 2 will be described.
• the waveform of OUT indicates the voltage waveform of the output terminal OUT in this case, and OUT and the voltage waveform of the output terminal OUT when a current flows from the coil load 2 described later in the direction of the output terminal OUT. Is shown.
• the node A goes to a low level, and the voltage at the node B turns on the first control transistor 17, so that the resistance value of the impedance element 19 and the parasitic With a capacity value of 32 It rises at the determined time constant.
• the on-resistance of the power supply side drive transistor 30 gradually increases, and the coil load 2 tries to keep flowing current due to the inductive property, so that the voltage of the output terminal OUT gradually decreases. Therefore, the voltage at the output terminal OUT does not drop sharply, and radiation noise is reduced.
• the power supply side detection transistor 24 since the power supply side detection transistor 24 is turned on, the node C is kept at a high level and the node D is kept at a low level. Therefore, the ground side drive transistor 31 is connected to the input terminal IN from the input terminal IN. It is forcibly turned off regardless of the input signal. Then, when the voltage at the node B further rises and the gate-source voltage of the power supply side driving transistor 30 becomes smaller than a value (threshold), the power supply side driving transistor 30 becomes a sub-threshold region. And the on-resistance rises sharply and begins to turn off. Then, the power supply side detection transistor 24 also starts to turn off at the same time, so that the node C becomes low level. Since the third control transistor 26 is turned on, the voltage at the node D rises with a time constant determined by the resistance value of the impedance element 28 and the capacitance value of the parasitic capacitance 33.
• the impedance of the impedance element 28 is larger than the resistance of the impedance element 19, the voltage at the node D rises more slowly than the voltage at the node B.
• the power supply side driving transistor 30 through which a small amount of current flows is completely turned off, and the power also flows through the ground side driving transistor 31, and these two transistors 30, 31 At the same time.
• the voltage at the node B must rise to the power supply potential V relatively quickly, so the impedance element 19
• the level changes to a high level
• the voltage at the node D changes the resistance value of the impedance element 29 because the fourth control transistor 27 is turned on.
• the time constant determined by the capacitance value of the parasitic capacitance 33.
• the on-resistance of the ground-side drive transistor 31 gradually increases according to the voltage change at the node D, and the coil load 2 tries to continue to flow current due to the inductive property, so that the voltage at the output terminal OUT drops slightly. However, it is clamped by a parasitic diode (not shown) existing in parallel with the ground side drive transistor 31.
• the ground-side detection transistor 15 since the ground-side detection transistor 15 is on, the node A is kept at a low level and the node B is kept at a high level.
• the source side drive transistor 30 is forcibly turned off regardless of the input signal of the input terminal IN.
• the voltage at the node D further decreases and the voltage between the gate and the source of the ground-side drive transistor 31 becomes smaller than the threshold! /, The value (threshold), the ground-side drive transistor 31 becomes in the sub-threshold region. Then, the on-resistance rises rapidly and starts to turn off. Then, the ground side detection transistor 15 also starts to be turned off at the same time, so that the node A becomes high level.
• the second control transistor 18 Since the second control transistor 18 is turned on, the voltage at the node B gradually decreases with a time constant determined by the resistance value of the impedance element 20 and the capacitance value of the parasitic capacitance 32. The voltage at the output terminal OUT gradually increases according to the voltage at the node B. Therefore, radiation noise is reduced.
• Each part other than the output terminal OUT (waveform OUT 'in Fig. 2) operates in the same manner as described above.
• the voltage at the output terminal OUT gradually decreases or rises according to the voltage at the node D. That is, the voltage of the output terminal OUT starts to decrease after the ground-side drive transistor 31 starts to turn on, and starts to increase when the ground-side drive transistor 31 starts to turn off. In this case as well, radiation noise is reduced.
• the power supply drive transistor 30 which is a P-type MOS transistor in the coil load drive output circuit 1 is replaced with a power supply drive transistor 56 which is an N-type MOS transistor. Things.
• the power supply side detection transistor 24, which is a P-type MOS transistor is connected to the power supply side detection transistor 55, which is an N-type MOS transistor; Is relatively large (for example, 10K to 30 ⁇ ), the second current limiting impedance element 20 is connected to the second current limiting impedance element 53 for relatively small resistance (for example, 1K to 2 ⁇ ).
• Each is replaced by an impedance element 54.
• the coil load drive output circuit 51 performs the same operation as the coil load drive output circuit 1, although the voltage waveform of the node B is upside down in FIG. 2 described above, and radiation noise is reduced.
• the coil load drive output circuit 1 or 51 is provided with the ground-side detection transistor 15 and the power-side detection transistor 24 or 55 so that if the power-side drive transistor 30 or 56 is turned on, The drive transistor 31 is forcibly turned off, and if the ground drive transistor 31 is on, the power drive transistor 30 is forcibly turned off so that the power drive transistor 30 or 56 and the ground drive transistor are turned off. Force that automatically suppresses through current in 31 It is also possible to individually control the gates of the first to fourth control transistors 17, 18, 26, and 27 to suppress the through current.
• the coil load drive output circuit according to the embodiment of the present invention has been described above.
• the present invention is not limited to the circuit described in the embodiment, but may be implemented in various forms within the scope of the claims.
• Various design changes are possible.
• the current limiting impedance elements 14, 19 (or 53), 20 (or 54), 23, 28, and 29 are resistors, but these can be used as constant current sources.
• the parasitic capacitances 32 and 33 it is possible to positively add capacitance.

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• Engineering & Computer Science (AREA)
• Computer Hardware Design (AREA)
• Physics & Mathematics (AREA)
• Computing Systems (AREA)
• General Engineering & Computer Science (AREA)
• Mathematical Physics (AREA)
• Electronic Switches (AREA)

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Citations (4)

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• 2004
  • 2004-06-02 JP JP2004164291A patent/JP4014048B2/ja not_active Expired - Lifetime
• 2005
  • 2005-06-01 WO PCT/JP2005/010039 patent/WO2005119912A1/ja not_active Ceased
  • 2005-06-01 KR KR1020067024760A patent/KR20070029178A/ko not_active Withdrawn
  • 2005-06-01 CN CNA2005800178268A patent/CN1961481A/zh active Pending
  • 2005-06-01 US US11/569,946 patent/US20080018365A1/en not_active Abandoned
  • 2005-06-02 TW TW094118095A patent/TW200614667A/zh not_active IP Right Cessation

Patent Citations (4)

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