JPH09200955A - Power surge noise suppression method - Google Patents

Abstract

The present invention relates to a noise suppression circuit in a communication device, and an object thereof is to provide a power supply surge noise suppression method effective in a power supply device of a digital circuit of the communication device. In a power supply device (4) of a communication device, a broadband blocking filter (13) is inserted between the power supply and the power supply device (4), and clamp elements (11, 15) are connected in parallel between the power supply inputs and between the inputs of the power supply device (4), respectively. To do.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise countermeasure circuit in a communication device, and more particularly to a power supply surge noise suppression system effective in a power supply device for a digital circuit of the communication device.

[0002] In recent years, with the development of digital technology and the advance of transmission technology, the expansion of communication networks has been remarkable. In particular, information devices and communication devices have been fused to enable various data to be communicated at high speed and with high multiplexing. In this case,
There is a demand for improving reliability by preventing malfunction of an information communication device due to changes in the external environment.

Therefore, conventionally, various Es have been used in communication devices.
MC (Electro Magnetic Compatibility) measures have been taken, but in order to further strengthen these measures, in addition to the EMC measures of the digital circuit itself, noise measures should also be taken in the power supply circuit that supplies power to the digital circuit. Is required.

[0004]

2. Description of the Related Art FIG. 9 shows a power supply circuit of a conventional communication device. In the figure, 1 is a power supply line on the high potential side of the power supply (G), 2 is a power supply line on the low potential side of the power supply (-48V), 3 is a ground for maintenance (E), and 4A is a switching power supply for converting the power supply voltage. The power supply device 5 is a digital circuit serving as a load of the power supply circuit.

In the power supply device 4, reference numeral 41 is a noise removing capacitor on the input side. Reference numeral 42 is a transformer, which performs voltage conversion for 48V to 5V, for example, according to the winding ratio. 43 is a switching transistor, 44 is a secondary winding, 45 is a rectifying diode, and 46 is a noise removing capacitor on the output side. In the digital circuit 5, 51 is a + 5V terminal and 52 is a ground terminal. The ground terminal 52 is connected to the maintenance ground 3.

In the power supply circuit of the conventional communication device shown in FIG. 9, the high-potential-side power supply line 1 for power supply input is grounded, and the ground terminal 52 of the load digital circuit 5 is connected to the maintenance ground ( E) 3 is grounded to stabilize the potential of the digital circuit 5 and prevent its malfunction.

[0007]

In the conventional power supply circuit shown in FIG. 9, common mode noise is generated between the power supply line and the ground, and a power supply fluctuation that causes noise is generated between the power supply line and the ground. Occurs.

When voltage fluctuations that cause noise occur between the power supply line and the ground, the noise also propagates to the + 5V power supply of the digital circuit, causing a malfunction in the digital circuit 5.

The present invention is intended to solve the above-mentioned problems of the prior art, and combines surge noise generated in a power supply line due to lightning, a momentary power interruption, etc., with a clamp element and a broadband blocking filter. It is intended to surely prevent the malfunction of the digital circuit of the communication device by gradually suppressing the digital circuit of the communication device.

Further, according to the present invention, it is possible to efficiently suppress surge noise in a composite power supply in which different power supply voltages are mixed and mounted, which is expected to increase in the future, and to prevent malfunction of a digital circuit of a communication device. It is an object of the present invention to provide a power supply surge noise suppression method that can be prevented at low cost.

[0011]

FIG. 1 shows a principle configuration (1) of the present invention, in which the same elements as those in FIG. 9 are designated by the same reference numerals, 11 and 12 are clamping elements, and
Reference numerals 3 and 14 are broadband blocking filters, and 15 and 16 are clamp elements. The clamp element 11 is connected between the high potential side power supply line 1 and the low potential side power supply line 2, and the clamp element 15 is
It is connected between the output side of the broadband blocking filter 13 and the low potential side power supply line 2. The clamp element 12 is connected between the high-potential-side power supply line 1 and the maintenance ground 3, and the clamp element 16 is connected.
Are connected between the output side of the wideband blocking filter 13 and the output side of the wideband blocking filter 14.

FIG. 2 illustrates the operating principle of the method of the present invention. In the figure, indicates the occurrence of surge noise. Indicates the operation of the clamp elements 11 and 12 on the input side, and the leading portion of the surge noise remains as it is based on the delay of the operation of the clamp elements, but after the operation of the clamp elements, it may be clamped to a constant voltage. It is shown.

Shows the operation of the broadband blocking filters 13 and 14, and it is shown that the high frequency components in the outputs of the clamp elements 11 and 12 are removed, resulting in a blunt surge voltage waveform. Is a clamp element 15 on the output side,
16 shows that the outputs of the wide band rejection filters 13 and 14 are further clamped to have a small value waveform.

By assembling the clamp element, the broadband blocking filter, and the clamp element in this order from the power source input side, the steep voltage fluctuation of surge noise is suppressed on the primary power source side of the communication device, and the secondary power source is suppressed. It is possible to suppress the propagation of the noise voltage to the side and effectively prevent the occurrence of malfunction in the digital circuit.

One of the causes of surge noise is lightning. As a measure against surge noise due to lightning, a method such as connecting a clamp element such as a varistor between the power supply potential and the ground to reduce the noise voltage has been conventionally performed. Measures to reduce surge noise in stages have also been taken so far.

The rising speed of surge noise due to lightning is generally said to be 1 μS to 10 μS. In recent years, the rising speed of surge noise, which has been a problem in digital circuits and the like, is about 5 nS. Then, it cannot respond to such a sudden voltage change, and the noise voltage at the rising change point of noise is
Even if the clamp elements are stacked in multiple stages, they cannot be removed.

According to a special clamp element developed for military purposes, it is possible to cope with high-speed voltage change and completely suppress surge noise. The device is extremely expensive and is not available on the open market.

However, as in the present invention, when the rising edge of the surge noise cannot be clamped by the primary clamp element, the noise waveform is blunted by the broadband blocking filter connected between the primary clamp element and the secondary clamp element. By removing the abrupt voltage change, the surge noise voltage can be completely reduced without using a special clamp element.

Further, by electrically connecting the high-potential side (ground side) of the power source and the maintenance ground, fluctuations in the power source such as surge noise can occur in the same phase and on the high-potential side power line and the ground line. Since the electric potential fluctuations of the respective electric wires are synchronized with each other, the relative voltage between the two electric wires remains stable even if the respective voltages change. Based on these principles, it becomes possible to effectively suppress the malfunction of the digital circuit of the communication device.

FIG. 3 shows the basic configuration (2) of the present invention, showing the case of a composite power source. In the power supply device 4, the same parts as those in FIG.
42A is a transformer, 44 is a secondary winding for high voltage output, 4
7 is a secondary winding for low voltage output, 48 is a rectifying diode connected to the secondary winding 47, 49 is a rectifying diode 4
It is a noise removing capacitor on the 8th side. Further, in the digital circuit 5, 51 is a high power supply voltage terminal, 53 is a low power supply voltage terminal, 54 is a circuit of an element driven by a high power supply voltage, 55 is a circuit of an element driven by a low power supply voltage, and 56.
Is a capacitor.

In the case of FIG. 3, the digital circuit 5 includes a circuit 54 composed of elements driven by a high power supply voltage and a circuit 55 composed of elements driven by a low power supply voltage. The power supply device 4 rectifies the outputs of the winding wire 44 and the winding wire 47,
The high power supply voltage and the low power supply voltage are generated to generate the circuit 54 and the circuit 5.
5 is being supplied. In this case, in the circuit 54 on the high power supply voltage side of the digital circuit 5, a large number of capacitors 56 are connected between the high power supply voltage terminal and the ground terminal as AC impedance lowering elements.

In the case of the composite power source, the capacitors as the noise suppressing circuit are concentratedly mounted on the high power source voltage side, so that the malfunction of the digital circuit of the communication device can be efficiently prevented.

FIG. 4 shows a development trend regarding the power supply voltage of the semiconductor element. As shown in the figure, the power supply voltage of the semiconductor element tends to gradually decrease in order to realize high-speed operation and low power of the semiconductor element. However, as a communication device, the + 5V system circuit is left as it is in order to interface with other devices. Therefore, it is considered that the composite power supply will become the mainstream in the future. When using a combined power supply, there are more points to take noise countermeasures than when using a single power supply.

FIG. 5 is a power supply impeder in the case of a composite power supply.
To explain the situation. In the figure, (a) is surge noise
The relationship between the power generation source and the power source impedance of the device was shown.
Which is the power source of the device for the surge source 101
The impedance of 102 is Z _INAnd the
Iz voltage is V_INAnd (B) is the impeder of the entire device
It shows the relationship between the impedance and the impedance of the composite power supply.
You. In the case of combined power source consisting of device power sources 103 and 104
And the impedance of each is Z₁ ^', Z_Two ^'To be
And the impedance Z of the entire device_INIs as follows
You. Z_IN= Z₁ ^'・ Z_Two ^'/ (Z₁ ^'+ Z_Two ^')

(C) shows the relationship between the transformer winding ratio and the power source impedance. The winding ratio of the high power supply voltage system is n ₁ (= N ₂ / N ₁ ), the winding ratio of the low power supply voltage system is n ₂ (= N ₃ / N ₁ ), and the load of the high power supply voltage system is Z _{1 ,}
Assuming that the load of the low power supply voltage system is Z ₂ , the respective impedances seen from the primary side are as follows. Z ₁ '= Z ₁ / n ₁ ² Z ₂ ' = Z ₂ / n ₂ ²

FIG. 6 shows an example of calculation of the power source impedance in the case of the composite power source. In the figure, (a) shows a configuration example of a composite power supply, and illustrates an example in which the power supply voltage is 48V, the high power supply voltage system voltage is + 5V, and the low power supply voltage system voltage is + 1V. (B) shows the impedance Z _IN of the entire device when the impedance Z ₁ of the high power supply voltage system is changed while the impedance Z ₂ of the low power supply voltage system is fixed at 10Ω, and (c) shows the impedance of the high power supply voltage system. Z
Impedance Z _{IN of the} entire device when impedance Z ₂ of the low power supply voltage system is changed with ₁ = 10Ω fixed
Is shown.

As is clear from the calculation result of FIG. 6, the change rate of the input impedance Z _IN when the power source impedance becomes small is the impedance Z of the high power source voltage system.
_The case where ₁ is changed is larger than the case where the impedance Z ₂ of the low power supply voltage system is changed.

Therefore, in the case of a composite power source, if the measures are taken so as to reduce the AC impedance by concentrating on the high power voltage system, the impedance Z _IN with respect to the overall surge noise can be easily and inexpensively. Can be reduced to However, it is assumed that the passband characteristic of the transformer with respect to the surge noise frequency is the same as that with respect to the switching frequency.

Specific means for solving the problems of the present invention will be listed below.

(1) In the power supply device 4 of the communication device, the broadband blocking filter 13 is inserted between the power supply and the power supply device 4, and the clamp elements 11 and 15 are provided in parallel between the power supply inputs and between the inputs of the power supply device 4, respectively. Connect.

(2) In the case of (1), the ground side of the power supply is electrically connected to the maintenance ground 3 connected to one end of the output of the power supply device 4.

(3) In the case of (2), the broadband blocking filter 14 is inserted between one end of the output of the power supply device 4 and the maintenance earth 3, and between the ground side of the power source and the maintenance earth 3.
The clamp elements 12 and 16 are respectively connected between the input of the power supply device 4 and one end of the output of the power supply device 4.

(4) In a communication device using a plurality of power supply voltages of different voltages, a capacitor 56 is connected as an AC impedance lowering element to both ends of a high voltage power supply of the plurality of power supply voltages.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 7 shows an embodiment (1) of the present invention and corresponds to the principle configuration (1) of the present invention shown in FIG. In FIG. 7, the same parts as those in FIG. 1 are indicated by the same numbers, and the case where the power supply voltage is +5 V is illustrated.

In the embodiment shown in FIG. 7, a zinc oxide varistor 11A is connected between the high potential side power supply line 1 and the low potential side power supply line 2 as a clamp element on the input side.
A surge noise voltage is roughly clamped by connecting a strontium titanate varistor or a barium titanate varistor 12A between the high-potential-side power supply line 1 and the protective maintenance earth 3.

Next, as a broadband blocking filter, a feed-through filter 13A is inserted between the high-potential side power supply line 1 and one end of the input of the power supply device 4, and the maintenance ground 3 and the other end of the input of the switching power supply 4A are connected. The feed-through filter 14A is inserted between the two to slow the rise of the surge noise voltage in a wide band. The through-type filter has a characteristic of allowing 100 Hz or less to pass, but attenuating 40 dB or more from 100 Hz to 1 GHz. Further, as a clamp element on the output side, a Zener diode 15A is connected between the output side of the feedthrough filter 13A and the low potential side power supply line 2 to connect the output side of the feedthrough filter 13A and the output side of the feedthrough filter 14A. A zener diode 16A is connected between the two to clamp the surge noise voltage to a voltage that does not affect the digital circuit.

In the circuit of FIG. 7, a capacitor 17 is further connected between the output side of the feedthrough filter 13A and the low potential side power supply line 2, and the + of the digital circuit 5 is added.
The Zener diode 18 is connected as a clamp element between the 5V terminal 51 and the ground terminal 52 to reduce the surge noise voltage.

FIG. 8 shows an embodiment (2) of the present invention, which corresponds to the principle configuration (2) of the present invention shown in FIG. In FIG. 8, the same parts as those in FIGS. 3 and 7 are indicated by the same numbers, and the case where the high power supply voltage is +5 V and the low power supply voltage is +2.5 V is illustrated.

In the embodiment shown in FIG. 8, a zinc oxide varistor 11A is connected between the high potential side power supply line 1 and the low potential side power supply line 2 as a clamp element on the input side.
A surge noise voltage is roughly clamped by connecting a strontium titanate varistor or a barium titanate varistor 12A between the high-potential-side power supply line 1 and the protective maintenance earth 3.

Next, as a broadband blocking filter, a feed-through filter 13A is inserted between the high-potential side power supply line 1 and one end of the input of the power supply device 4, and the maintenance earth 3 and the other end of the input of the switching power supply 4A are connected. The feed-through filter 14A is inserted between the two to slow the rise of the surge noise voltage in a wide band. Further, as a clamp element on the output side, a Zener diode 15A is connected between the output side of the feedthrough filter 13A and the low potential side power supply line 2 to connect the output side of the feedthrough filter 13A and the output side of the feedthrough filter 14A. Zener diode 16A is connected between
Clamp to a voltage where digital circuits are unaffected.

In the circuit of FIG. 8, a capacitor 17 is further connected between the output side of the feedthrough filter 13A and the low potential side power supply line 2, and the digital circuit 5 has a + voltage.
The Zener diode 18 is connected as a clamp element between the 5V terminal 51 and the ground terminal 52 to reduce the surge noise voltage, and in the circuit 54 on the high power supply voltage side, the AC voltage is applied between the + 5V terminal 51 and the ground terminal 52. A large number of capacitors 56 are connected as impedance lowering elements to absorb surge noise.

[0042]

As described above, according to the present invention, the surge noise generated in the power supply line can be sequentially suppressed by using the clamp element and the wide band blocking filter in combination, and therefore the communication device. It is possible to effectively prevent malfunctions in the digital circuit.

Further, according to the present invention, in the composite power source in which different power source voltages are mixedly mounted, the surge noise can be efficiently eliminated by performing a measure to concentrate on the high power source voltage system and reduce the AC impedance. Therefore, it is possible to prevent malfunction of the digital circuit of the communication device at low cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a principle configuration (1) of the present invention.

FIG. 2 is a diagram for explaining the operation principle of the method of the present invention.

FIG. 3 is a diagram showing a basic configuration (2) of the present invention.

FIG. 4 is a diagram showing a development trend regarding a power supply voltage of a semiconductor element.

FIG. 5 is a diagram for explaining the power source impedance in the case of a composite power source, where (a) is the relationship between the surge noise source and the power source impedance of the device, and (b) is the impedance of the entire device and the impedance of the composite power source. Relationship, (c)
Indicates the relationship between the winding ratio of the transformer and the power source impedance.

FIG. 6 is a diagram showing an example of calculation of power source impedance in the case of a composite power source, where (a) is a configuration example of the composite power source, and (b).
As the impedance Z ₂ = 10 [Omega constant low power supply voltage system, the input impedance Z _IN of the whole device when changing the impedance Z ₁ of the high power supply voltage system, (c) the impedance Z ₁ = 10 [Omega high power supply voltage system The impedance Z _IN of the entire device when the impedance Z ₂ of the low power supply voltage system is changed is shown as constant.

FIG. 7 is a diagram showing an embodiment (1) of the present invention.

FIG. 8 is a diagram showing an embodiment (2) of the present invention.

FIG. 9 is a diagram showing a power supply circuit of a conventional communication device.

[Explanation of symbols]

 3 Ground for Maintenance 4 Power Supply Device 11 Clamp Element 12 Clamp Element 13 Broadband Blocking Filter 14 Broadband Blocking Filter 15 Clamping Element 16 Clamping Element 56 Capacitor

Claims (4)

[Claims] 1. A power supply device for a communication device, wherein a wide-band blocking filter is inserted between the power supplies, and clamp elements are connected in parallel between the power supply inputs and between the inputs of the power supply device. Power surge noise suppression method. 2. The power supply surge noise suppression system according to claim 1, wherein the ground side of the power supply is electrically connected to a maintenance earth connected to one end of the output of the power supply device. Surge noise suppression method. 3. The power supply surge noise suppression system according to claim 2, wherein a broadband blocking filter is inserted between one end of the output of the power supply device and a maintenance ground, and between the ground side of the power supply and the maintenance ground. , And a clamp element connected between the input of the power supply device and one end of the output of the power supply device, respectively. 4. A power supply surge noise, characterized in that, in a communication device using a plurality of power supply voltages of different voltages, an AC impedance lowering element is connected to both ends of a high voltage power supply of the plurality of power supply voltages. Suppression method.