Electricity: power supply or regulation systems – Output level responsive – Using a three or more terminal semiconductive device as the...
Reexamination Certificate
2000-07-26
2001-08-21
Berhane, Adolf Deneke (Department: 2838)
Electricity: power supply or regulation systems
Output level responsive
Using a three or more terminal semiconductive device as the...
Reexamination Certificate
active
06278265
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a switching regulator, and more particularly to a switching regulator suitable for mobile devices such as mobile phones, and note-type personal computers.
The requirements for size-down and weight reduction of mobile devices such as mobile phones, and note-type personal computers have been on the increase. In order to realize the above requirements, it is effective to reduce the number of batteries mounted on the mobile device and to use a power circuit provided therein, wherein a booster switching regulator is often used. For the power circuit using a series regulator, a voltage-down switching regulator may be used in view of a high efficiency.
FIG. 1
is a circuit diagram illustrative of a first conventional switching regulator.
FIG. 2
is a diagram illustrative of waveforms of j-point potential, f-point potential, d-point potential and g-point output of the first conventional switching regulator of FIG.
1
. The first conventional switching regulator is of a pulse width modulation system wherein in place of simple comparison of a reference voltage to a comparative voltage, a potential difference between the reference voltage and the comparative voltage is amplified to obtain an amplified voltage, so that the amplified voltage is then compared with an output voltage of a triangle waveform by use of a comparator, whereby ON-OFF operations of switching transistors are made in accordance with a result of an output from the comparator.
Namely, the first conventional switching regulator has the following circuit elements. A power source
14
is provided for supplying a reference voltage to the first conventional switching regulator. An error-amplifier
19
is provided which has two inputs connected to an f-point which is connected to the power source
14
for receiving the reference voltage from the power source
14
and also connected to a d-point for receiving a comparative voltage, so that the error-amplifier
19
amplifies a difference in potential between the f-point and the d-point namely between the reference voltage from the power source
14
and the comparative voltage at the d-point to generate an amplified potential difference. A triangle-waveform generator
18
is also provided for generating a triangle waveform. The triangle-waveform generator
18
is connected to an h-point. A comparator
12
is also provided which has two inputs connected through the h-point to the triangle-waveform generator
18
for receiving the triangle waveform from the triangle-waveform generator
18
and also connected through a j-point to an output from the error-amplifier
19
for receiving the amplified potential difference from the error-amplifier
19
, so that the comparator
12
compares the amplified potential difference with the triangle waveform. The comparator
12
has an output terminal connected to a g-point. A series connection of a p-channel output switching transistor
10
and an n-channel output switching transistor
9
is provided between an input terminal IN
1
and a ground line, wherein the p-channel output switching transistor
10
is connected in series between the input terminal IN
1
and the n-channel output switching transistor
9
, whilst the n-channel output switching transistor
9
is connected in series between the ground line and the p-channel output switching transistor
10
. Gates of the p-channel output switching transistor
10
and the n-channel output switching transistor
9
are connected through the g-point to the output terminal of the comparator
12
. A k-point is a middle point between the p-channel output switching transistor
10
and the n-channel output switching transistor
9
. A coil
5
is connected in series between the k-point and an output terminal OUT
2
. A load
3
is further provided which is connected between the output terminal OUT
2
and the ground line, so that the load
3
is connected in series through the output terminal OUT
2
to the coil
5
. A capacitor
4
is also provided which is connected between the output terminal OUT
2
and the ground line, so that the capacitor
4
is connected in series through the coil
5
to the k-point and also connected in series through the output terminal OUT
2
to the load
3
. A series connection of first and second resistances
7
and
8
is also connected between the ground line and a middle point between the coil
5
and the output terminal OUT
2
, so that the series connection of first and second resistances
7
and
8
is connected through the output terminal OUT
2
to the load
3
and also connected through the coil
5
to the k-point. An intermediate point between the first and second resistances
7
and
8
is also connected through the d-point to the error-amplifier
19
, so that the intermediate point between the first and second resistances
7
and
8
supplies the comparative voltage to the error-amplifier
19
. The first resistance
7
is connected between the second resistance and the intermediate point between the coil
5
and the output terminal OUT
2
, whilst the second resistance
8
is connected between the ground line and the first resistance
7
.
A potential difference between the reference voltage supplied through the f-point from the power source
14
and the comparative voltage supplied through the d-point from the intermediate point between the first and second resistances
7
and
8
is amplified by the error amplifier
19
to obtain an amplified potential difference, so that the amplified potential difference is then compared with the output voltage of the triangle waveform supplied through the h-point from the triangle waveform generator
18
by the comparator
12
, whereby ON-OFF operations of the p-channel and n-channel switching transistors
10
and
9
are made in accordance with a result of the output from the comparator
12
, wherein a duty ratio of the output waveform at the g-point connected to the output terminal of the comparator
12
is variable to realize a precise control thereof, whereby an output voltage with a small ripple appears at the output terminal OUT
2
.
The above first conventional switching regulator has the following disadvantages. The triangle waveform generator
18
and the error-amplifier
19
are essential for the above first conventional switching regulator. Further, a protection circuit is also necessary when the h-point potential and the g-point potential are outside the comparable range. This means that it is difficult to scale-down the circuit configuration of the first conventional switching regulator, and also that the circuit configuration is complicated whereby the power consumption is large. The efficiency of the voltage transformation as the power source circuit is also deteriorated.
FIG. 3
is a circuit diagram illustrative of a second conventional switching regulator. The second conventional switching regulator is of a pulse frequency modulation system wherein in place of simple comparison of a reference voltage to a comparative voltage, a potential difference between the reference voltage and the comparative voltage is amplified to obtain an amplified voltage, so that the amplified voltage is then compared with an output voltage of a triangle waveform by use of a comparator, whereby ON-OFF operations of a single switching transistor are made in accordance with a result of an output from the comparator.
Namely, the second conventional switching regulator has the following circuit elements. A power source
14
is provided for supplying a reference voltage to the first conventional switching regulator. An error-amplifier
19
is provided which has two inputs connected to an f-point which is connected to the power source
14
for receiving the reference voltage from the power source
14
and also connected to a d-point for receiving a comparative voltage, so that the error-amplifier
19
amplifies a difference in potential between the f-point and the d-point namely between the reference voltage from the power source
14
and the comparative voltage at the d-point to gen
Berhane Adolf Deneke
NEC Corporation
Young & Thompson
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