Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific current responsive fault sensor
Reexamination Certificate
2000-04-27
2003-04-01
Huynh, Kim (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific current responsive fault sensor
C361S018000, C363S089000, C323S908000
Reexamination Certificate
active
06542344
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a switching regulator that is capable of reducing a rush current that flows at the time of starting.
2. Description of the Related Art
In general, a chopper type step-up switching regulator is mainly made up of, as shown in a circuit diagram of
FIG. 4
, an inductor
403
, a rectifying device
404
, a smoothing capacitor
405
, a switching device
407
and a control circuit
406
. In the switching regulator thus structured, even if the switching device
407
is turned off to stop the step-up operation, an energy is unavoidably supplied to a load device
402
from an input power supply
401
through the inductor
403
and the rectifying device
404
.
Under the above circumstances, there has been conventionally known, as shown in
FIG. 3
, a switching regulator in which a switch
310
is disposed between an input power supply
301
and an inductor
303
, a switch
311
is disposed between the inductor
303
and a switching device
307
, a switch
312
is disposed between the switching device
307
and a rectifying device
304
, a switch
313
is disposed between the rectifying device
304
and a smoothing capacitor
305
, and a switch
314
is disposed between a smoothing capacitor
305
and a device
302
, wherein those respective switches are turned off in order to interrupt the supply of an energy to the device
302
from the input power supply
301
when step-up operation stops.
However, in the conventional switching regulator, when the switch
310
, the switch
311
, the switch
312
, the switch
313
or the switch
314
are turned on to start the step-up operation, a large rush current unavoidably flows into the smoothing capacitor
305
and a capacitor
309
added to the device from the input power supply
301
with an adverse effect that an input supply voltage drops or the rectifying device, the smoothing capacitor and so on are damaged by the rush current.
SUMMARY OF THE INVENTION
In view of the above, an object of the present invention is to solve the above problems with the conventional switching regulator.
Another object of the present invention is to provide a switching regulator which is capable of suppressing a rush current in which a switch for interrupting the supply of an energy to a device from an input power supply is not suddenly changed over from an inconductive state to a conductive state to permit a current to flow infinitely as soon as the switch turns on as in the conventional switching regulator, but a switch that limits a current or a switch that limits a current which flows for a given period of time, is employed.
In order to achieve the above objects, according to the present invention, there is provided a switching regulator, comprising:
an input power supply connected to an input of the switching regulator;
at least one input/output disconnection switch disposed between the input power supply and a device connected to an output of the switching regulator, for interrupting the supply of an energy to the device from the input power supply; and
means for limiting a rush current that flows into an output capacitor from the input power supply when the input/output disconnection switch turns on to start step-up operation.
Also, according to the present invention, in the switching regulator, the rush current limiting means of the input/output disconnection switch has a current limit function added to the output disconnection switch to set a limit value of a current that is allowed to flow.
Further, according to the present invention, in the switching regulator, the rush current limiting means of the input/output disconnection switch has a transistor as the output disconnection switch, the transistor operating in the same manner as that of an integral amplifying circuit to limit a current that flows for a given period of time.
Still further, according to the present invention, in the switching regulator, the rush current limiting means of the input/output disconnection switch repeats the on/off operation of the output disconnection switch to control an on-time and off-time, thereby limiting a current that is allowed to flow.
REFERENCES:
patent: 5350997 (1994-09-01), Ghotbi et al.
patent: 5420780 (1995-05-01), Bernstein et al.
patent: 5834924 (1998-11-01), Konopka et al.
patent: 6094036 (2000-07-01), Rampold
Adams & Wilks
Huynh Kim
Seiko Instruments Inc.
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