Electric power conversion systems – Current conversion – Including automatic or integral protection means
Patent
1990-01-12
1991-11-05
Beha, Jr., William H.
Electric power conversion systems
Current conversion
Including automatic or integral protection means
340663, 361 92, 363 21, H02M 3335
Patent
active
050634917
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATION
The present application may be related to U.S. application Ser. No. 07/363,515.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a switching regulator used as a power source for an industrial electronic machine and the like, and more particularly, to a voltage drop detecting circuit for detecting a drop in an output voltage and issuing a voltage drop warning by outputting a signal to the outside.
2. Description of the Related Art
Switching regulators, in contrast with other regulators, are small-sized, light in weight, and highly efficient, and can cope with a wide range of input voltages, and thus are currently widely used as power sources for industrial electronic machines, such as computers, and servomotors, etc. Nevertheless, an erroneous operation of these industrial electronic machines may occur or the components thereof may be damaged if a drop in the supply voltage due to a malfunction of the power supply is not corrected. Therefore, a voltage drop detection circuit is provided on the power-supply side, separately from a voltage stabilizing circuit, to thereby improve the reliability of the whole system using the power supply. Namely, if a drop in the voltage occurs, the voltage drop detection circuit outputs a signal to the outside, to thereby quickly give an alarm or cut off the power supply.
FIG. 4 shows a circuit diagram of a forward-type switching regulator having a conventional voltage drop detecting circuit. In FIG. 4, A1 and A2 designate input terminals, which are connected to a DC power source, and B1 and B2 designate output terminals to which a stabilized DC voltage is delivered.
The voltage drop detection circuit is denoted as 5 and includes a comparator IC2, which compares the output voltage with a reference voltage of a Zener diode ZD1, and delivers a signal to terminals G1 and G2 when a drop in the output voltage occurs. H1 and H2 designate power supply terminals for the comparator IC2, and are connected to a DC power source.
The comparator IC2, however, cannot operate normally unless constantly supplied with a stabilized voltage, and thus the output of the switching regulator to be detected cannot be used as the power source for the comparator IC2. Namely, a separate power source to ensure a stabilized voltage is required. Moreover, a reference voltage source, such as the Zener diode ZD1, must be provided to set the detection level.
SUMMARY OF THE INVENTION
The present invention was created in consideration of the above circumstances, and an object thereof is to provide a voltage drop detection circuit which does not require a special power source for ensuring a stabilized voltage, and has a simple circuit configuration.
To solve the problem described above, according to the present invention, there is provided a voltage drop detection circuit able to detect a drop in the output voltage of a switching regulator which includes an error detection circuit arranged so that a current or voltage is increased and output when the output voltage rises above a predetermined value, and that a current or voltage is not output when the output voltage falls below the predetermined value, and a feedback circuit for controlling a control circuit of a switching transistor in response to a signal output from the error detection circuit. The voltage drop detection circuit comprises a detector operated by the output of the error detection circuit used as a control input.
Namely, the occurrence of a drop in the output voltage is detected by using the output of the error detector of the switching regulator as an input to the voltage drop detection circuit.
Therefore, if the output voltage of the switching regulator is higher than the predetermined value, the output voltage of the error detector is at a fixed value other than 0, and accordingly, a current flows to thereby activate the detector of the voltage drop detection circuit. If the output voltage of the switching regulator falls below the predetermined value, the cur
REFERENCES:
patent: 3679965 (1972-07-01), Wilkinson
patent: 4323961 (1982-04-01), Josephson
patent: 4717997 (1988-01-01), Hata
Beha Jr. William H.
Fanuc Ltd.
LandOfFree
Switching regular undervoltage detector does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Switching regular undervoltage detector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Switching regular undervoltage detector will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-502912