JP3348117B2 - Voltage-voltage converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage-to-voltage converter, and more particularly, to a voltage-to-voltage converter operating from an input voltage of 1 volt.

[0002]

2. Description of the Related Art Voltage-to-voltage converters are used for transmitting signals between two different measuring instruments. That is, the input and output are DC-insulated, and the transformer-insulated type has a relatively simple circuit configuration, high accuracy, high speed,
Low power consumption is guaranteed, and the input signal (DC) is converted to alternating current by using a rectangular wave alternating voltage as the gate drive voltage of the transistor, and the signal transmission isolation transformer (pulse transformer) is used.
Thus, a signal can be transmitted.

[0003]

The above-mentioned voltage-to-voltage converter is required to drive a transformer having a high impedance and operate at an input voltage of 1 volt. For example, as can be seen from the input / output characteristics of the generally available voltage-to-voltage converter in FIG. 5, the range in which stable characteristics can be obtained is limited to 1.5 to 10 volts DC. The present invention has been made in view of such technical problems, and has an input voltage of 1 to 10 volts,
It is an object of the present invention to provide an insulation-type voltage-voltage converter that operates from an input voltage of 1 volt or less, with an output voltage of 1 to 10 volts and a current consumption of 1 mA (ampere) / volt.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above technical object, the present invention provides an N-MO that converts an input signal (DC) into an alternating current to operate an insulating transformer for signal transmission.
An auxiliary power supply circuit capable of generating a gate drive voltage used for the S-type FET with an input voltage of at least 1 volt was prepared. That is, the circuit comprises a rectangular wave oscillating circuit that operates at an input voltage of 1 volt and generates a rectangular wave voltage with a duty ratio of 50%, and an auxiliary voltage generating circuit that includes the rectangular wave voltage and a pulse transformer that operates using a transistor. The gate drive voltage from the auxiliary power supply circuit causes the N-MO
The present invention proposes an insulation type voltage-to-voltage converter that operates from an input voltage of 1 volt by operating an isolation transformer for signal transmission via an S-type FET.

That is, the present invention comprises an auxiliary power supply circuit and a signal transmission circuit, wherein the auxiliary power supply circuit operates at a minimum of 1 volt and oscillates a rectangular wave voltage with a duty ratio of 50%, A pulse transformer that applies the rectangular wave voltage to the primary side through push-pull via the PNP and NPN transistors and outputs the gate drive voltage of the N-MOS type FET of ± 2.5 V or more to the secondary side. form more structure to the voltage generating circuit, the signal transmitting circuit, the signal transmitting insulating transformer (high impedance pulse transformer)
And a voltage-voltage conversion circuit comprising a pair of N-MOS type FETs operated by the gate drive voltage and connected in series to the primary side and the secondary side of the transformer; those were more structure forms <br/> an output circuit for obtaining an output. Also, three terminals are provided on the input side of the auxiliary power supply circuit.
A stabilizing voltage switching circuit consisting of
The range of the input voltage input to the auxiliary voltage circuit
Divided into upper and lower parts based on the value
The voltage below a specified value via a three-terminal regulator.
By using the stabilizing voltage, the N-MOS type FE
Push the gate drive voltage of T below the rated voltage ± 20 volts
I got it .

[0006]

According to the above technical means, a pulse transformer having a high impedance is driven by using a rectangular wave oscillating circuit which operates at an input voltage of 1 volt, and ± 2.5 volts (turn ratio of the pulse transformer = 2. 5) It is possible to generate the voltage and drive the N-MOS type FET of the voltage-to-voltage conversion circuit that operates at 2 to 2.5 volts, and to operate from an input voltage of 1 volt. A conversion device can be obtained. In addition, the input voltage range is divided into upper and lower ranges, and a stabilized voltage (5 volts) is used for a value equal to or higher than a predetermined value via a three-terminal regulator. The gate drive voltage can be suppressed to a rated voltage of ± 20 volts or less. Further, the current consumption can be suppressed to 1 mA / volt or less by using the ultra-low current consumption type three-terminal regulator and using a high impedance pulse transformer of several kilo-ohms.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, a public embodiment of the present invention will be illustratively described in detail. However, unless otherwise specified, dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Only. FIG. 1 is a circuit diagram showing one embodiment of the voltage-voltage converter of the present invention. In the figure, 1 is an auxiliary power supply circuit, 2
Is a signal transmission circuit, 11 is a stabilized voltage switching circuit, 12
Is a rectangular wave oscillation circuit, 13 is an auxiliary voltage generation circuit, 14 is a voltage-voltage conversion circuit, and 15 is an output circuit.

As shown in FIG. 1, the voltage-voltage converter of the present invention comprises an auxiliary power supply circuit 1 and a signal transmission circuit 2. The auxiliary power supply circuit 1 includes a stabilized voltage switching circuit 1
1, a rectangular wave oscillation circuit 12 and an auxiliary voltage generation circuit 13, and the signal transmission circuit 2 includes a voltage-voltage conversion circuit 14 and an output circuit 15.

The stabilizing voltage switching circuit 11 includes a photo-MOS relay P.0 connected to a resistor R0 and a terminal a.
C and a series circuit formed by the variable input voltage type micropower voltage element IC0 connected via the terminal b thereof is connected in parallel between the input terminals Vin and E, and the terminal Vin and the photoMOS relay P.C. C terminal c is connected. The downstream terminal e of the three-terminal regulator IC1 of the stabilized voltage circuit provided in series with the input terminal Vin and the photomos relay P. C, and the input voltage V1 <Vx, where Vx = (6.0-6.
5) In the case of volts, the photomos relay P. The switching terminals c and d of C are placed in a conductive state, and the three-terminal regulator IC1 is configured to be short-circuited. When the input voltage V1 is Vx ≦ V1 ≦ 10 volts, the input terminal Vin → the resistor R0 → the photoMOS relay P. C → IC
0 → the current flowing in the series circuit of the input terminal E increases, and the photomos C operates (OFF between terminals c and d),
The short circuit between the input and output of the three-terminal regulator IC1 is released, the three-terminal regulator IC1 outputs a constant voltage of 5 volts, and the voltage between the point e and the terminal E is 5 times higher than the input voltage V1.
It is configured so that it can be switched to a constant voltage of volts. The three-terminal regulator IC1 uses an ultra-low current consumption type (1-2 μA) and a rated input / output voltage difference of 30 mV. The rectangular wave oscillation circuit 12 includes an oscillation IC 2
And a resistor R2 and a capacitor C2 having a small temperature change, so as to generate a rectangular wave having a duty ratio of 50% at several KHz. The oscillation frequency f is 1 / C2
X proportional to R2. R2 is selected to have a high resistance as long as oscillation is possible in order to reduce current consumption.

The auxiliary voltage generation circuit 13 includes PNP transistors Tr1 and N having a current amplification factor of several hundreds or more.
It comprises a PN transistor Tr2, a pulse transformer T1 having a frequency of several Khz and an impedance of several KΩ, and capacitors C4 and C5. On the primary side of the pulse transformer T1, two windings n1, n2 are provided.
Similarly, n3 and n4 are provided on the next side.
Have the same polarity and n2 has the opposite polarity, and the collector of the PNP transistor Tr1 is connected to n1.
Is connected to the collector of the NPN transistor Tr2. As shown in FIG. 2, rectangular winding alternating voltages are obtained independently on the secondary windings n3 and n4. The gate drive voltage described later is low and the ON resistance is low. A rectangular wave having an amplitude of ± 2.5 × (V1 to 5) volts or more necessary for driving the N-MOS type FET is generated. Further, the secondary winding n3 is subjected to voltage doubler rectification to obtain a DC voltage of ± V2 via capacitors C4 and C5, and is used as an auxiliary power supply for an operational amplifier IC3 (current consumption 100 μA) described later. is there. The windings n1, n2, n
The turn ratio between n3 and n4 is n1 = n2, n3 = n4, and n3 / n4
n1 is set to 2.5 or more.

The voltage-voltage conversion circuit 14 includes a pulse transformer T2 for transmitting a signal, and Rs and Cs provided in parallel with the primary and secondary windings N and N (N = N), respectively.
And a N-MOS type FE of a signal transmitting transistor connected to the primary side and the secondary side winding.
T, Tr3 and Tr4. The resonance frequency between the snubber and the winding N is set to be twice the value of the rectangular wave frequency having a duty ratio of 50%, so that voltage-voltage conversion with high accuracy and excellent temperature characteristics can be performed. Constitute. The transistors Tr3 and Tr4 use N-MOS type FETs having a low gate drive voltage and a low ON resistance,
A rectangular wave alternating voltage of the terminal B of the secondary winding n4 of the pulse transformer T1 is applied to the gate G3 of the transistor Tr3, and the secondary winding n3 of the pulse transformer T1 is applied to the gate G4 of the transistor Tr4. A rectangular wave alternating voltage of the terminal A is applied. The magnitude of the rectangular wave alternating voltage has an amplitude of ± 2.5 × (V1 to 5) volts, and the other ends of the terminals A and B and the transistor Tr
The sources S3 and S4 of the transistors Tr3 and Tr4 are connected to the ground to be at zero potential. Further, the pulse transformer T2
Denotes the impedance at the frequency (several KHz) to be used is several KΩ, and the turns ratio between the primary side and the secondary side is N: N.

The output circuit 15 includes a filter 16 and an operational amplifier IC3 that uses ± V2 volts output to the output side of the auxiliary voltage generation circuit 13 as an auxiliary power supply.

The operation of the circuit shown in FIG. 1 will be described below. When the input voltage V1 is [1- (6.0-6.
5)] In the case of volts, in the stabilizing voltage switching circuit 11, the photomos By operation of C, the point Vin →
Since the point c → point d → point e becomes conductive, the stabilizing voltage circuit IC1 is short-circuited and the input voltage V1 is applied to the downstream rectangular wave oscillation circuit 12 and the auxiliary voltage generation circuit 13 below the point e as the applied voltage. used. Note that when the input voltage V1 is [(6.
0 to 6.5) to 10] volts, the photomos relay P.O. Since the terminals c and d of C are turned off, the stabilized voltage circuit IC1 operates to generate a constant voltage of 5 volts, and the downstream rectangular wave oscillation circuit 12 and the auxiliary voltage generation circuit 1 below the point e.
3, the constant voltage of 5 volts is applied.

Next, upon receiving the input voltage or the constant voltage, the rectangular wave oscillation circuit 12 generates a rectangular wave voltage having an oscillation frequency of several KHz determined by the resistors R2 and C2 and a duty ratio of 50% as an auxiliary voltage. The signal is input to the circuit 13 to activate the PNP transistor Tr1 and the NPN transistor Tr2, and the primary winding n1 of the pulse transformer 1
And n2 is applied with the input voltage V1 or a constant voltage of 5 volts. As a result, the secondary windings n3 and n4
A rectangular wave alternating voltage having an amplitude of ± 2.5 × (V1 volt to 5 volt) is output between the terminal E (zero potential) and A and between the terminals E and B. On the other hand, the rectangular wave alternating voltage output between the terminals A and E is connected to the capacitors C4 and C5.
To output a DC voltage of ± V2.

On the other hand, the input voltage V1 input to the signal transmission circuit 2 is input to a voltage-voltage conversion circuit 14, and is input to the primary side of a pulse transformer T2 for signal transmission to apply the voltage V1. The gates G3 and G4 of the NMOS transistors Tr3 and Tr4 connected to the primary and secondary windings of the pulse transformer are connected to the terminals of the secondary windings n3 and n4 of the auxiliary voltage generating circuit 13. A rectangular wave alternating voltage having an amplitude of ± 2.5 × (V1 volt to 5 volt) shown in FIG. The amplitude of the applied voltage is a) V1 =
For [1 (6.0 to 6.5)] volts, ± (2.5
-15) volts, and the current consumption is 1 mA / volt or less for a load having an input impedance of 10 KΩ or more.
The amplitude of the applied voltage is b) V1 = [(6.0-6.5)
-10] volt, the stabilized voltage circuit IC1 operates, so that the voltage is suppressed within ± 15 volts, and the N-MOS
The absolute rated voltage between the gate and the source of the type FET can be satisfied ± 20 volts. As shown in FIG. 4, the current consumption satisfies 1 mA / volt or less for a load having an input impedance of 10 KΩ or more.

The transistor Tr of the rectangular wave alternating voltage
3 and Tr4, the Tr3, T4
r4 turns ON and OFF at the same time, and the pulse transformer T2 operates. That is, the primary current flows from the terminal Vin to the primary winding of the pulse transformer T2 → the transistor Tr3 (drain D3 → source S3) → E1. The secondary current flows from the capacitor C3 to the transistor Tr4 (source 4 to drain D) from the winding start point g of the secondary winding of the pulse transformer T2.
4) → The winding end m of the secondary winding flows, and a voltage substantially equal to the input voltage V1 is stored in the capacitor C3. Since the voltage of the capacitor C3 has many ripples, the output circuit 15
, The impedance is converted by the operational amplifier IC3, the offset is adjusted by the trimmer VR2, and the resistance R is adjusted.
5 and the trimmer VR1 are used to adjust the span.
Is output from the output terminal Vout.

The transistors Tr3 and Tr4 are turned off.
, The drain current becomes zero, but a back electromotive voltage is generated in the primary winding, and the inductance of the winding, the snubber Rx,
A series resonance occurs with Cx. As shown in FIG. 3, if the resonance frequency is twice the rectangular wave frequency, the variation of the output voltage with temperature can be reduced.

[0018]

As described above, according to the present invention, voltage-voltage conversion of an input voltage (1 to 10) volts and an output voltage (1 to 10) volts can be performed, and current consumption is suppressed to 1 mA / volt or less. Thus, a voltage-to-voltage converter operating at an input voltage of at least 1 volt can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram according to an embodiment of a voltage-voltage converter of the present invention.

FIG. 2 is a diagram showing a rectangular wave alternating voltage generated on a secondary side of a pulse transformer T1 in FIG. 1;

3 is a diagram showing a voltage waveform applied to a gate and a voltage waveform of a drain of a transistor Tr3 in FIG. 1;

FIG. 4 is a diagram showing a relationship between an input voltage and an input current in the voltage-voltage converter of the present invention.

FIG. 5 is an input / output characteristic diagram of a conventional voltage-voltage converter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Auxiliary power supply circuit 2 Signal transmission circuit 11 Stabilized voltage switching circuit 12 Oscillation circuit 13 Auxiliary voltage generation circuit 14 Voltage-voltage conversion circuit 15 Voltage output circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02M 3/28 H02M 7/538

Claims (1)

(57) [Claims] An auxiliary power supply circuit operating at the same input voltage;
A voltage-to-voltage converter comprising a signal transmission circuit, wherein the auxiliary power supply circuit operates at a minimum of 1 volt.
Square wave oscillating circuit that oscillates a square wave voltage with a 50% ratio
And the rectangular wave power via PNP and NPN transistors.
Pressure is applied to the primary side by push-pull and ± 2.5
N-MOS FETs over volts (field-effect transistors
A pulse transformer that outputs the gate drive voltage
And an auxiliary voltage generating circuit for transmitting a signal.High impedancePal
Transformer and the primary and secondary sides of the transformer in series
N-MOS type operating with a pair of the gate drive voltages
A voltage-voltage conversion circuit having an FET and a converted voltage;
An output circuit that converts voltage to impedance to obtain a voltage output
Composed ofWith A three-terminal regulator is provided on the input side of the auxiliary power supply circuit.
A stable voltage switching circuit, and
The range of input voltage to be input
And three-terminal regulation
Use a stabilized voltage that is lower than the specified voltage
The gate drive voltage of the N-MOS type FET
Rated voltage is kept below ± 20 volts Specially
A voltage-to-voltage converter.