JPH1014220A - Dc-stabilizing power circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC-stabilizing power circuit, capable of operation with optimum efficiency in each of plural operation modes. SOLUTION: A DC-stabilizing power circuit 1 is constituted by providing it with a first drive circuit 16 and a second drive circuit 17 for driving switching elements 121 and 151 with high efficiency, corresponding to each of the two modes of a normal operation mode to supply load with a large current and a suspended mode, to supply the load with an indispensable minimum low current, and switching these drive circuits 16 and 17 corresponding to each mode. Hereby, high efficiency can be maintained at all times, and the power consumption in a portable electronic apparatus can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stabilized DC power supply circuit used for portable electronic equipment and the like, and more particularly to a stabilized DC power supply circuit for switching a drive circuit of a switching element according to an operation mode.

[0002]

2. Description of the Related Art Conventionally, in a DC stabilized power supply circuit built in a portable electronic device such as a notebook type personal computer, an input source is a battery. Is required. For this reason, a resistor having a high resistance value is used for the resistor used in the circuit, and a resistor having a low DC resistance value is selected for the coil.

In such efficiency improvement, a switching element for increasing the frequency of direct current occupies a large part of the efficiency improvement.

The switching element includes a transistor
Although FETs are generally used, since there is a storage time peculiar to the element, in order to make this storage time small and to perform a high-speed switching operation, one FET is used in one specific state according to an input voltage, a load current, or the like. The switching element driving circuit is adjusted so that the efficiency is improved.

In addition, when the efficiency is increased in two states, specifically, in the two modes of the normal operation and the suspend mode, the adjustment point is set to the point where the efficiency is improved.

That is, the power source of a portable electronic device is usually
There are a state in which the device is operated (normal operation mode) and a state in which the operation is interrupted but the minimum necessary functions such as a memory are maintained (suspend mode).

In the normal operation mode, the current consumption is larger than that in the suspend mode. For example, in a notebook personal computer, there is a difference in current value of several hundred times between these modes.

Further, when a large current flows through a load, the storage time of the switching element tends to increase, so that the switching element driving circuit has been configured with a low impedance.

[0009]

However, if the operation in the suspend mode state is performed by the drive circuit set at the best point in the normal operation mode state, the loss of the drive circuit increases and the efficiency decreases. In addition, when the operating point is adjusted to an efficient operation in both mode states, there is a problem that the efficiency is lower than when the optimum efficiency is set in each mode state.

An object of the present invention is to provide a stabilized DC power supply circuit that can operate with optimum efficiency in each of a plurality of operation modes in view of the above problems.

[0011]

In order to achieve the above object, the present invention comprises a switching element for controlling the output voltage at a constant voltage and a pulse width modulation (PWM) control circuit for supplying a large current to a load. An operation mode and a DC stabilized power supply circuit that switches an operation state of the switching element according to two modes of a suspend mode that supplies a minimum current required to a load,
An output signal of the PWM control circuit is input, a first switching element drive circuit that operates the switching element with high efficiency in the normal operation mode, and an output signal of the PWM control circuit are input, and the output signal of the PWM control circuit is input in the suspend mode. A second switching element driving circuit for operating the switching element with high efficiency; and a first switching element driving circuit when a normal operation mode is designated based on a mode switching signal for switching between the normal operation mode and the suspend mode. The second switching element driving circuit is set to the operating state, the second switching element driving circuit is set to the non-operating state, and when the suspend mode is designated, the second switching element driving circuit is set to the operating state and the first switching element driving circuit is turned off. Suggest DC stabilized power supply circuit provided with an operating circuit switching means for the non-operation state.

According to the DC stabilized power supply circuit, when the normal operation mode is designated by the mode switching signal, the operation circuit switching means causes the first circuit to switch to the first operation mode.
The second switching element drive circuit is inactive while the second switching element drive circuit is in operation,
The switching element is driven by the first switching element drive circuit in synchronization with the output signal of the PWM control circuit, the output voltage is controlled at a constant voltage, and a large current is supplied to the load. Further, when the suspend mode is designated by the mode switching signal, the first switching element drive circuit is set to the non-operation state and the second switching element drive circuit is set to the operation state by the operation circuit switching means. The second switching element drive circuit drives the switching elements in synchronization with the output signal of the PWM control circuit, controls the output voltage at a constant voltage, and supplies a minimum necessary low current to the load.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing a stabilized DC power supply circuit according to the first embodiment of the present invention. This DC stabilized power supply circuit is a step-down type power supply circuit that generates a low output voltage Vout from a high input voltage Vin.

In the figure, 1 is a stabilized DC power supply circuit,
Capacitor 11, first chopper circuit 12, smoothing circuit 1
3, the voltage detection circuit 14, the second chopper circuit 15, the first
, A second drive circuit 17, a pulse width modulation (hereinafter simply referred to as PWM) control IC 18, and a constant voltage generation circuit 19, and the capacitor 11 is connected between the input terminal IN and the ground. Have been.

The first chopper circuit 12 has a P-channel F
A switching element 121 made of ET, an NPN transistor 122, a PNP transistor 123, and a resistor 124,
Consists of 125.

The source of the switching element 121 is connected to the input terminal IN, and the gate is connected to the emitter of the transistor 122 and the emitter of the transistor 123. The collector of the transistor 122 is connected to the input terminal IN, and the transistors 122 and 123 are connected via the resistor 124.
Connected to each base. Further, the collector of the transistor 123 is grounded via the resistor 125.

The smoothing circuit 13 is a freewheel type smoothing circuit composed of a commutation diode 131, a smoothing reactor 132, and a smoothing capacitor 133. The input is connected to the drain of the switching element 121, and the output is the output terminal OUT. It is connected to the.

The voltage detection circuit 14 includes resistors 141 and 142 connected in series between the output terminal OUT and the ground, and detects the voltage Vout output to the output terminal OUT by the resistors 141 and 142.
To output a voltage V1.

The second chopper circuit 15 has an N-channel F
ET switching element 151, NPN transistor 152, PNP transistor 153, and resistor 154
It is composed of

The drain of the switching element 151 is connected to the drain of the switching element 121, and the source is grounded. Further, the gate of the switching element 151 is connected to the respective emitters of the transistors 152 and 153. The collector of the transistor 152 is connected to the input terminal IN, and the collector of the transistor 153 is grounded via the resistor 154.

The first drive circuit 16 includes a first delay circuit 16
1, second delay circuit 162, NPN transistor 163,
And a resistor 164.

The first delay circuit 161 operates according to the input voltage Vin, and outputs the PWM signal outputted from the PWM control IC.
The M signal Vpwm is input via the transistor 163, and the PWM signal Vpwm is delayed by a predetermined time and output to the bases of the transistors 122 and 123 of the first chopper circuit 12. The collector of the transistor 163 is the first
Of the PWM signal V
pwm is input, and a switching signal Vsusp is input to the base via a resistor 164.

The second delay circuit 162 is connected to the input voltage Vin.
And the switching signal Vsusp, and the switching signal Vsusp
Operates at a high level of the TTL level, receives a PWM signal Vpwm output from the PWM control IC, delays the PWM signal Vpwm by a predetermined time, and outputs a signal to each of the transistors 152 and 153 of the second chopper circuit 15. Output to base.

The second drive circuit 17 includes a PNP transistor 171, an NPN transistor 172, and a resistor 173.
~ 175.

The 5V voltage generated by the constant voltage generation circuit 19 is applied to the emitter of the transistor 171, and the switching signal Vsusp is input to the base via the resistor 173. Further, the collector of the transistor 171 is connected to the base of the transistor 172 via the resistor 174. The emitter of the transistor 172 has a PWM
The signal Vpwm is input, and the collector is connected to the respective bases of the transistors 122 and 123 of the first chopper circuit 12 via the resistor 175.

The PWM control IC 18 receives the input voltage V
The voltage V1 output from the voltage detection circuit 14 is input, the pulse width of the PWM signal Vpwm is changed based on the voltage V1, negative output control is performed, and the output voltage Vout is maintained at a predetermined value. I do.

The constant voltage generation circuit 19 generates a DC 5 V voltage from the input voltage Vin and supplies it to the second drive circuit 17.

Next, the operation of the stabilized DC power supply circuit 1 having the above configuration will be described. This power supply circuit 1 is used, for example, in a notebook personal computer and has an input terminal I
A battery is connected to N and the input voltage Vin is supplied. The switching signal Vsusp is output from the CPU of the personal computer.

When a large current is supplied to the load circuit (in the normal operation mode), the switching signal Vsusp is set to T
It is set to the high level of the TL level. As a result, the first drive circuit 16 becomes active, and the transistor
Since the switches 171 and 172 are turned off, the second drive circuit 17 is turned off.

That is, when the switching signal Vsusp is set to a high level, the transistor 163 of the first drive circuit 16
Is turned on and the PWM signal Vpwm is
The signal is input to the first delay circuit 161 via 3 and is supplied to the first chopper circuit 12 after being delayed for a predetermined time. Also,
The second delay circuit 162 is activated, and the second delay circuit
The PWM signal Vpwm input to 162 is supplied to the second chopper circuit 15 after being delayed for a predetermined time.

In the first chopper circuit 12, when the PWM signal Vpwm is low, the transistor 123 is turned on, the transistor 122 is turned off, and the transistor 122 is turned off.
The gate of the switching element 121 is pulled down to a low level (ground level) via 123, and the switching element
When the PWM signal Vpwm is at a high level, the transistor 122 is turned on and the transistor 121 is turned on.
3 is turned off, the gate of the switching element 121 is pulled up to a high level (Vin) via the transistor 122, and the switching element 121 is turned off.

In the second chopper circuit 15, PW
When the M signal Vpwm is at a high level, the transistor 152 is turned on and the transistor 153 is turned off. The gate of the switching element 151 is pulled up to a high level (Vin) via the transistor 152, and the switching element is turned on.
When the PWM signal Vpwm is at a low level, the transistor 152 is turned off, and the transistor 151 is turned off.
3 is turned on, the gate of the switching element 151 is pulled down to a low level (ground level) via the transistor 153, and the switching element 151 is turned off.

Thus, when the PWM signal Vpwm is at a low level, the voltage Vin input to the input terminal IN is input to the smoothing circuit 13 via the switching element 121, and is smoothed and output by the smoothing reactor 132 and the smoothing capacitor 133. Output to terminal OUT.

When the PWM signal Vpwm is at the high level, the input voltage Vin is cut off by the switching element 121 and the current of the smoothing reactor 132 is
1 and the switching element 151, and a constant voltage is output to the output terminal OUT.

At this time, the PWM control IC 18 changes the pulse width of the PWM signal Vpwm for controlling on / off of the switching elements 121 and 151 in accordance with the change of the output terminal voltage Vout so that the output terminal voltage Vout becomes constant. Perform feedback control.

Further, in order to prevent a cross current in which the two switching elements 121 and 151 are simultaneously turned on, a predetermined dead time t _DET after one of the switching elements is turned off from on by the delay circuits 161 and 162. And after the dead time t _DET elapses,
The other switching element is turned on.

Accordingly, when the load supplied to the load (not shown) connected to the output terminal OUT is a heavy load and the switching element 121 is off, the energy stored in the smoothing reactor 132 can be reduced even when the switching element 121 is off. Since the light is discharged via the switching element 151, the forward voltage loss due to the commutation diode 131 does not occur, and efficient synchronous rectification is performed.

On the other hand, when supplying the minimum necessary current to the load circuit (in the suspend mode), the switching signal Vsusp
Are set to the low level of the TTL level. As a result, the first drive circuit 16 enters a non-operation state, and the second drive circuit 17 enters an operation state.

That is, when the switching signal Vsusp is set to a low level, the transistor 163 of the first drive circuit 16
Is turned off, and P supplied to the first delay circuit 161
The WM signal Vpwm is cut off. Further, a second delay circuit
The second delay circuit 162 outputs a low-level voltage, and the switching element 151 is turned off.

The transistor of the second drive circuit 17
Since a low level is applied to the base of the transistor 171, the transistor 171 is turned on, and the base of the transistor 172 becomes high via the transistor 171 and the resistor 174, so that the transistor 172 is turned on.

Thus, the PWM control IC 18
The PWM signal Vpwm output from the
, And supplied to the first chopper circuit 12 via the resistor 175.

The first chopper circuit 12 receives the supplied PW
The same operation as described above is performed by the M signal Vpwm, and the output terminal O
A predetermined constant voltage Vout is output from the UT.

Therefore, in the suspend mode, the operations of the second chopper circuit 15 and the first drive circuit 16 are stopped, and the power consumption in these circuits is reduced.

As described above, according to the first embodiment,
The first and second modes for driving the switching elements 121 and 151 with high efficiency correspond to the two modes of a normal operation mode for supplying a large current to the load and a suspend mode for supplying a required minimum low current to the load. Drive circuits 16 and 17 are provided, and the drive circuit 1 corresponding to each mode is provided.
Since the switching elements 121 and 151 are driven by switching between the switching elements 6 and 17, high efficiency can be always maintained, and power consumption in the portable electronic device can be reduced.

Next, a second embodiment of the present invention will be described. FIG. 2 is a configuration diagram illustrating a DC stabilized power supply circuit according to the second embodiment. This power supply circuit is a circuit that does not perform synchronous rectification unlike the first embodiment.

In the figure, reference numeral 2 denotes a stabilized DC power supply circuit,
It comprises a capacitor 21, a chopper circuit 22, a smoothing circuit 23, a voltage detection circuit 24, a first drive circuit 25, a second drive circuit 26, a PWM control IC 27, and a constant voltage generation circuit 28, and the capacitor 21 has an input terminal IN And ground.

The chopper circuit 22 includes a switching element 221 composed of a P-channel FET and a resistor 222. The source of the switching element 221 is connected to the input terminal IN and to the gate of the switching element 221 via the resistor 222. ing.

The smoothing circuit 23 is a freewheel type smoothing circuit composed of a commutation diode 231, a smoothing reactor 232 and a smoothing capacitor 233, the input of which is connected to the drain of the switching element 221 and the output of which is the output terminal OUT. It is connected to the.

The voltage detection circuit 24 includes resistors 241 and 242 connected in series between the output terminal OUT and ground.
The voltage Vout output to the output terminal OUT is connected to the resistors 241 and 242
To output a voltage V1.

The first drive circuit 25 comprises PNP transistors 251, 252, NPN transistors 253, 254, 255, and resistors 256a to 256f.

The emitter of the transistor 251 is connected to the input terminal I.
N, and the base is connected to the collector of transistor 254 via resistor 256a. Further, the collector of the transistor 251 is connected to the collector of the transistor 253, and the transistors 252 and 25 are connected via the resistor 256b.
3 connected to each base.

The emitter of the transistor 252 is connected to the emitter of the transistor 253 and the gate of the switching element 221, and the collector is grounded via the resistor 256c.

A resistor 256d is provided at the base of the transistor 254.
, A switching signal Vsusp is applied, and the emitter is grounded. Further, the switching signal Vsusp is applied to the base of the transistor 255 via the resistor 256e, the PWM signal Vpwm is input to the emitter, and the collector is connected to the gate of the switching element 221 via the resistor 256f.

The second drive circuit 26 includes an NPN transistor 261, a PNP transistor 262, and a resistor 263,
It consists of 264,265.

The PWM signal Vpwm is input to the emitter of the transistor 261, and the collector is connected to the gate of the switching element 221 via the resistor 263. Also,
The collector of the transistor 262 is connected to the base of the transistor 261 via the resistor 264.
The switching signal Vsusp is input via the switch 5. Further, a constant voltage generating circuit 2 is connected to the emitter of the transistor 262.
The 5V voltage generated by 8 is applied.

The PWM control IC 27 has the input voltage V
In operation, the voltage V1 output from the voltage detection circuit 24 is input, the pulse width of the PWM signal Vpwm is changed based on the voltage V1, negative output control is performed, and the output voltage Vout is maintained at a predetermined value. I do.

The constant voltage generation circuit 28 generates a DC 5 V voltage from the input voltage Vin and supplies it to the second drive circuit 26.

Next, the operation of the stabilized DC power supply circuit 2 having the above-described configuration will be described. The power supply circuit 2 is used in, for example, a notebook personal computer as in the first embodiment, and a battery is connected to the input terminal IN to supply an input voltage Vin. Also, the switching signal Vsusp
Is output from the CPU of the personal computer.

When a large current is supplied to the load circuit (in the normal operation mode), the switching signal Vsusp
It is set to the high level of the TL level. As a result, the first drive circuit 25 is activated and the transistor
Since the transistors 261 and 262 are turned off, the second drive circuit 26 is turned off.

That is, when the switching signal Vsusp is set to the high level, the transistors 254 and 254 of the first drive circuit 25
255 is turned on, the PWM signal Vpwm is supplied to the bases of the transistors 252 and 253 via the transistor 255 and the resistor 256f, and the base of the transistor 251 is set to the low level (ground level) via the transistor 254 and the resistor 256a. The transistor 251 is turned on by pulling down, and the voltage V is applied to the collector of the transistor 253.
in is applied.

As a result, when the PWM signal Vpwm is at the low level, the transistor 253 is turned off,
252 is turned on, and the gate of the switching element 221 is at the low level (ground level) via the transistor 252.
And the switching element 221 is turned on. When the PWM signal Vpwm is at a high level, the transistor 253 is turned on, the transistor 252 is turned off, and the gate of the switching element 221 is at a high level (Vin) via the transistor 253. And the switching element 221 is turned off.

Thus, when the PWM signal Vpwm is at a low level, the voltage Vin input to the input terminal IN is input to the smoothing circuit 23 via the switching element 221 and is output after being smoothed by the smoothing reactor 232 and the smoothing capacitor 233. Output to terminal OUT.

When the PWM signal Vpwm is at a high level, the input voltage Vin is cut off by the switching element 221 and the current of the smoothing reactor 232 is
1 and a constant voltage is output to the output terminal OUT.

At this time, the PWM control IC 27 changes the pulse width of the PWM signal Vpwm for controlling ON / OFF of the switching element 221 according to the change of the output terminal voltage Vout so that the output terminal voltage Vout becomes constant. Perform feedback control.

Thus, when the load supplied to the load (not shown) connected to the output terminal OUT is a heavy load, the switching elements 22 and 253 are provided by the transistors 252 and 253.
The on / off state of 1 is switched at high speed, and a stable voltage can be supplied efficiently.

On the other hand, when the minimum necessary current is supplied to the load circuit (in the suspend mode), the switching signal Vsusp
Are set to the low level of the TTL level. As a result, the first drive circuit 25 becomes inactive and the second drive circuit 26 becomes active.

That is, when the switching signal Vsusp is set to a low level, the transistors 251,
254, 255 are turned off, the PWM signal Vpwm supplied to the first drive circuit 25 is cut off, and the voltage supply to the first drive circuit 25 is cut off by the transistor 251.

The transistor of the second drive circuit 26
Since a low level is applied to the base of the transistor 262, the transistor 262 is turned on, the base of the transistor 261 is turned to a high level via the transistor 262 and the resistor 264, and the transistor 261 is turned on.

Thus, the PWM control IC 27
The PWM signal Vpwm output from the
And the gate of the switching element 221 via the resistor 263.

As a result, the switching element 221
When the WM signal Vpwm is at a low level, the transistor is turned on, and when the PWM signal Vpwm is at a high level, the transistor is turned off. The same operation as described above is performed, and a predetermined constant voltage Vout is output from the output terminal OUT.

Therefore, in the suspend mode, the operation of the first drive circuit 25 is stopped, and the power consumption in this operation is reduced.

As described above, according to the second embodiment,
The first and second modes for driving the switching element 221 with high efficiency correspond to the two modes of a normal operation mode for supplying a large current to a load and a suspend mode for supplying a minimum necessary low current to the load. Are provided, and the driving circuits 25 and 26 are provided corresponding to each mode.
Since the switching element 26 is switched to drive the switching element 221, high efficiency can always be maintained, and power consumption in the portable electronic device can be reduced.

The configurations in the first and second embodiments described above are merely examples, and the present invention is not limited to these configurations.

[0074]

As described above, according to the present invention, there are provided two modes: a normal operation mode for supplying a large current to a load, and a suspend mode for supplying a minimum necessary low current to a load. Therefore, a switching element driving circuit for driving the switching element with high efficiency is provided, and the switching element is driven by switching the driving circuit corresponding to each mode, so that high efficiency can be maintained at all times. This is a very excellent effect that the power consumption of the electronic device can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a stabilized DC power supply circuit according to a first embodiment of the present invention;

FIG. 2 is a configuration diagram illustrating a stabilized DC power supply circuit according to a second embodiment of the present invention;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... DC stabilized power supply circuit, 11 ... Capacitor, 12 ... First chopper circuit, 121 ... Switching element, 122 ... N
PN type transistor, 123 ... PNP type transistor, 12
4,125 ... resistor, 13 ... smoothing circuit, 131 ... commutation diode, 132 ... smoothing reactor, 133 ... smoothing capacitor, 1
DESCRIPTION OF SYMBOLS 4 ... Voltage detection circuit, 141, 142 ... Resistor, 15 ... Second chopper circuit, 151 ... Switching element, 152 ... NPN transistor, 153 ... PNP transistor, 154 ... Resistor, 16 ... First drive circuit, 161 ... the first delay circuit,
162 ... second delay circuit, 163 ... NPN type transistor,
164: resistor, 17: second drive circuit, 171: PNP transistor, 172: NPN transistor, 173 to 17
5 ... resistor, 18 ... PWM control IC, 19 ... constant voltage generation circuit, 2 ... DC stabilized power supply circuit, 21 ... capacitor, 22 ... chopper circuit, 221 ... switching element,
222 ... resistor, 23 ... smoothing circuit, 231 ... commutation diode, 232 ... smoothing reactor, 233 ... smoothing capacitor, 2
4: Voltage detection circuit, 241, 242: resistor, 25: first drive circuit, 251, 252: PNP transistor, 253, 254, 25
5 ... NPN transistor, 256a-256f ... resistor, 26
... Second driving circuit, 261... NPN transistor, 262
... PNP transistor, 263,264,265 ... Resistor, 27
... PWM control IC, 28 ... constant voltage generation circuit.

Claims (1)

[Claims] 1. A normal operation mode comprising a switching element for controlling an output voltage at a constant voltage and a pulse width modulation (PWM) control circuit for supplying a large current to a load, and a suspend for supplying a minimum necessary low current to a load. A DC stabilized power supply circuit for switching an operation state of the switching element according to two modes, wherein an output signal of the PWM control circuit is input, and the switching element is operated with high efficiency in the normal operation mode. A first switching element drive circuit, a second switching element drive circuit that receives an output signal of the PWM control circuit, and operates the switching element with high efficiency in the suspend mode, and a normal operation mode and a suspend mode. Cut Based on the mode switching signal to be changed, the first switching element drive circuit is set to the operating state when the normal operation mode is designated, and the second switching element drive circuit is set to the non-operating state when the suspend mode is designated. An operating circuit switching means for setting a second switching element drive circuit to an operation state and for setting the first switching element drive circuit to a non-operation state.