JPS61244267A - Power source circuit - Google Patents

Abstract

PURPOSE:To detect an accurate current value by sampling a current signal corresponding to an output current supplied to a load synchronously with a control signal of a switching circuit. CONSTITUTION:A power source 20 stabilizes an input from a nonstabilized power source 10, and supplies it to a load 30. Its switching circuit 21 switches an input from the power source 10 by a drive signal 103 fed through a controller 25 and a driver 26. In this case, a sample-holding circuit 27 and a peak-holding circuit 28 are provided, a current signal 104 and a control signal 102 are input, and the signal 104 is sampled synchronously with the signal 102. Further, its peak value is transmitted to a current detecting terminal 29. Thus, the signal 104 becomes a pulse synchronized with a switching current to obtain a sampled current signal 105 for the variation in the output current supplied to the load 30.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power supply circuit, and particularly to a power supply circuit having means for detecting an output current.

[Conventional technology]

2. Description of the Related Art Various power supply circuits are used in various devices constituting a combiner system and the like in order to supply stable power unaffected by disturbances during load fluctuations. Such power supply circuits are generally equipped with a means for detecting the output current in order to monitor fluctuations in the output current and to shut off the power supply to preserve the circuit when an overcurrent flows. There is.

That is, as shown in FIG. 2, the conventional power supply circuit 50 includes a switching circuit 51 that switches the input from the unregulated power supply 10 according to fluctuations in the load 30, and a pulse transformer 53 that transforms the output of the switching circuit 51. , a rectifying and smoothing circuit 54 that rectifies and smoothes the output of the pulse transformer 53 and supplies it to the load 30, and an output voltage 1 of the rectifying and smoothing circuit 54.
A control signal 112 for controlling the width of the power pulse sent out by the switching circuit 51 by detecting the fluctuation of the power pulse 11.
a control circuit 55 that sends out the above control signal 1;
a driver circuit 56 that inputs 12 and sends out a drive signal to drive the switching circuit 51; and a current detection circuit 52 that is inserted into the primary side of the pulse transformer and sends out a voltage proportional to the current supplied to the load 30. and current detection circuit 5
The current detection terminal 59 includes a resistor 57 and a capacitor 58, which lead the output of the current detection terminal 59 to a current detection terminal 59.

Therefore, a signal obtained by rectifying the output of the current detection circuit 52 by a resistor 57 and a capacitor 58 is led to the current detection terminal 59.

[Problem that the invention seeks to solve]

However, in such a conventional power supply circuit, the detected signal fluctuates according to changes in the power pulse sent out by the switching circuit 51, so there is a drawback that it cannot follow sudden fluctuations in the output current supplied to the load 30. .

[Means for solving problems]

The power supply circuit of the present invention is a power supply circuit that has a pulse transformer and stabilizes an unregulated power supply, and is inserted into the primary winding side of the pulse transformer to send out a current signal proportional to the output current of the power supply circuit. a current detection circuit that inputs a control signal for switching the unregulated power supply and the current signal and sends out a sampled current signal obtained by sampling the current signal in synchronization with the control signal; and a peak hold circuit that inputs a signal and sends out the peak value of the sampled current signal.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

The power supply circuit 20 shown in FIG. 1 stabilizes the input from the unregulated power supply 10 and supplies it to the load 30.

The switching circuit 21 switches the input from the unregulated power supply IO according to a drive signal 103 that changes according to fluctuations in the load 30.

The pulse transformer 23 transforms the power pulse sent out by the switching circuit 21 and sends it out.

The rectifying and smoothing circuit 24 rectifies and smoothes the output of the pulse transformer 23 and sends it to the load 30 .

The control circuit 25 inputs the voltage signal 101t sent out by the rectifying and smoothing circuit 24, compares it with the reference voltage, and controls the switch 7.7 so that the difference becomes "0".
A control signal 102 for switching the circuit 21 is sent out.

The driver circuit 26 inputs the control signal 102 described above, and in synchronization with it, sends out a drive signal 103 that drives the switching circuit 21 described above.

The current detection circuit 22 is inserted into the primary side of the pulse transformer 23, receives the power pulse sent out by the switching circuit 21, and sends out a current signal 104 proportional to the output current supplied to the load 3o.

The sample and hold circuit 27 inputs the current signal 104 and the control signal 102 described above, and generates a sample current signal 1 obtained by sampling the current signal 104 in synchronization with the control signal 102.
05 is sent.

The peak hold circuit 28 receives the above sample current signal 10.
5 is input, and its peak value is sent to the current detection terminal 29. Note that the peak hold circuit 28 is equipped with a reset terminal (not shown) for clearing the above peak value.

In such a power supply circuit 20, the current signal 104 sent out by the current detection circuit 22 is nine pulses synchronized with the switching current flowing through the primary side of the pulse transformer 23. Therefore, by sampling the current signal 104 described above in synchronization with the control signal 102 that controls the switching circuit 21 described above, a sampled current signal 105 corresponding to fluctuations in the output current supplied to the load 30 can be obtained.

Further, the peak value of the sample current signal 105 can be guided to the current detection terminal 29 by the peak hold circuit 28 .

〔Effect of the invention〕

Since the power supply circuit of the present invention samples the current signal corresponding to the output current supplied to the load in synchronization with the control signal for switching the switching circuit, accurate current that follows sudden fluctuations in the output current can be obtained. It has the effect of being able to detect values.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. 21... Switching circuit, 22...
Current detection circuit, 23...Pulse transformer, 24
...... Rectification and smoothing circuit, 25... Control circuit, 26... Driver circuit, 27...
...Sample hold circuit, 28...Peak hold circuit.

Claims (1)

[Claims] In a power supply circuit having a pulse transformer and stabilizing an unregulated power supply, the power supply circuit is inserted into the primary winding side of the pulse transformer to send out a current signal proportional to the output current of the power supply circuit. a current detection circuit; a sample hold circuit that inputs a control signal for switching the unregulated power supply and the current signal and sends out a sampled current signal obtained by sampling the current signal in synchronization with the control signal; and a peak hold circuit that inputs the peak value of the sample current signal and outputs the peak value of the sample current signal.