JPS60176417A - Power interruption detector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a power failure detection device used in a switching type DC stabilized power supply or the like.

Conventional configuration and its problems Traditionally, when the input of a stabilized DC power supply is turned on or off, or when there is a momentary power outage, the output drops and unstable voltage is applied to the central processing unit (hereinafter referred to as CPU) of the load, causing malfunction. Therefore, a power failure detection device was required to send a signal from the power supply side to the CPU in the event of an abnormal output.

FIG. 1 shows a circuit of a conventional power failure detection device.

In Figure 1, 1 is a diode that rectifies the input AC voltage, 2 is a capacitor that smoothes the rectified voltage, 3 is a switching transistor that converts the DC voltage into a high-frequency pulse, and 4 is a transmitter that transmits the high-frequency pulse to the secondary side. Trance,
5 is a diode that rectifies high-frequency pulses, 6 is a capacitor that smoothes the rectified voltage, and 7 is a photocoupler that transmits the output signal of the primary side power failure detection circuit 8 to the secondary side power failure detection circuit 9. Sometimes it is a frequency transformer.

First, when an AC voltage is applied to the input terminal 10, it is also applied to the input of the primary side power failure detection circuit 80, where the waveform is shaped and transmitted to the secondary side power failure detection circuit 9 by the photocoupler 7. The secondary side power failure detection circuit 9 outputs a power failure detection output to the power failure detection terminal 11 in response to a signal from the primary side. That is, it detects that the primary side input AC voltage level is too low or the instantaneous power outage time is long, and issues a power outage detection signal.

However, in the configuration shown in Figure 1, if Otokagura 7 is used for transmission to the secondary side and mounted on a printed circuit board, the mounting area will increase if the consumption distance of the primary side power failure detection circuit 8 does not meet the safety standard. Also, the photocoupler 7 must be able to withstand the dielectric strength voltage between the primary and secondary.

If a low frequency transformer is used in place of the photocoupler 7, the primary side power failure detection circuit 8 becomes unnecessary, but the use of the low frequency transformer increases weight, mounting area, and cost. In addition, in the case of a power supply with dual inputs of 100V and 20OV, it is necessary to change the transformer specifications or change the taps of the windings.

OBJECTS OF THE INVENTION In view of the above-mentioned drawbacks, the present invention provides a power failure detection device that can reduce the circuit mounting area in order to downsize the device.

Structure of the Invention In order to achieve this object, the power failure detection device of the present invention has a configuration in which an input AC voltage is detected by a flybank winding provided on the secondary side of the transformer, and a power failure detection circuit is arranged on the secondary side. DESCRIPTION OF EMBODIMENTS OF THE INVENTION Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows the configuration of a power failure detection device in an embodiment of the present invention. In Figure 2, 12 and 13 are diodes, 14 and 15 are capacitors, 16 are transistors,
Reference numeral 17 denotes a transformer, which has the same structure as that shown in FIG. 18 is a diode that rectifies the flyback winding output;
19 is a capacitor for smoothing the rectified voltage, and 21 is a power failure detection circuit.b The operation of the circuit configured as described above will be explained below. First, when an input AC voltage is applied to the input terminal 2o, it is rectified and smoothed by the diode 12 and the capacitor 14, and a DC voltage proportional to the input AC voltage is applied to the capacitor 14.

Next, a pulse is applied to the primary winding Ni of the transformer 17 by the switching action of the transistor 16, and a voltage having the waveform shown in FIG. 3A is induced in the secondary forward winding Nf. The voltage is then rectified and smoothed by a diode 18 and a capacitor 19, and a voltage having a waveform shown in FIG. 3 is applied to the input of the power failure detection circuit 210. Here, the voltage level shown in Figure 3 is proportional to the input AC' turtle pressure level, and by detecting this level, the power failure detection output is sent to the power failure detection terminal 22.
can be obtained.

Effects of the Invention As described above, the present invention provides a forward winding on the secondary side of the transformer to detect a voltage proportional to the input AC voltage, and simplifies the circuit by arranging the power failure detection circuit on the secondary side.
This means that the printed circuit board mounting area can be reduced. In addition,
Although the flyback circuit has been described in this embodiment, the Ford side diode output may be detected for the feedforward circuit.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram of a conventional power failure detection device, FIG. 2 is an electrical circuit diagram of an embodiment of the power failure detection device of the present invention, and FIGS. It is a voltage waveform diagram. 12, , 13, 18...Diode, 14
, 15゜19...- Capacitor, 16 Old... Transistor, 17... Transformer, 21 Old...
Power failure detection circuit.

Claims (1)

[Claims] A forward winding is provided separately from the secondary side load output winding of the flyback converter transformer so that the input AC voltage level of the flyback converter can be detected on the secondary side.
A power failure detection device consisting of a diode and a capacitor.