JPH08331036A - Power supply circuit for portable equipment - Google Patents

Abstract

PURPOSE: To obtain the power supply circuit for a portable equipment using a battery for a power supply and requiring plural different power supply voltages. CONSTITUTION: The power supply circuit is provided with a stabilizing voltage generator 12 comprising a regulator circuit connecting to a battery 10, a switching power supply circuit 1, and a fixed frequency oscillator 7 applying a clock signal to a switching pulse generating circuit 1-5 as an external synchronizing signal of the switching power supply circuit 1. An output voltage of the stabilizing voltage generator 12 is fed to the switching power supply circuit 1 and a prescribed circuit block (control section 6) and an output voltage from the switching power supply circuit 1 is fed to the prescribed circuit block (high frequency section) whose load current is constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit suitable for portable equipment using a battery as a power supply, and more particularly to a power supply circuit for generating a plurality of different regulated constant voltages from a battery, for example, a cellular phone, a PHS, etc. It can be used as a power supply circuit of a mobile device such as a mobile phone which requires generation of different stabilized power supply voltages such as a high frequency circuit block and a control block by a battery power supply.

[0002]

2. Description of the Related Art When a plurality of stabilized constant voltages are generated by using a battery as a power source, regulator circuits are connected in series by the number of the voltages, and DC / DC converter circuits are required by the number. An example is shown in FIG. 3, and a stabilized voltage generator using a DC / DC converter circuit 13 is connected in parallel to the battery 10.

[0003]

However, when the regulator circuits are connected in series as described above, the energy of the battery is consumed as heat in order to stabilize the voltage, resulting in poor efficiency and shortened battery life. . FIG.
In the case of using the DC / DC converter as described above, the circuit becomes complicated and, in the case of being used in a mobile phone, if the switching frequency is free, a beat failure is likely to occur.

The present invention has been made in view of the above points, and eliminates the above-mentioned problems, improves efficiency and extends battery life, simplifies the circuit, and causes a reception failure when used in a mobile phone. The purpose is to prevent it from happening.

[0005]

In order to solve the above-mentioned problems, the present invention is designed to generate a plurality of different regulated constant voltage power supplies using a battery as a power supply and supply them to predetermined circuit blocks. In a power supply circuit of a portable device, a stabilized voltage generator (regulator circuit 12 or DC / DC converter) of an arbitrary system for generating a constant voltage connected to a battery 10 as shown in the principle block diagram of FIG. A simplified switching power supply circuit 1 for generating, a switching frequency signal generating means (switching pulse generation circuit 1-5), and a clock signal as an external synchronization signal of the switching power supply circuit 1 fixed to the switching pulse generation circuit 1-5. An oscillator 7 is provided, and the output of the stabilized voltage generator (12) is the switching power supply circuit 1
In addition, the power is supplied to a predetermined circuit block (for example, the control unit 6), and the output of the switching power supply circuit 1 is supplied to the power for a predetermined circuit block (for example, a high frequency unit) having a constant load current.

[0006]

In the present invention, since it is premised that the constant voltage is supplied to the circuit block whose load current is constant, the switching power supply circuit 1 which outputs the constant voltage to the desired stabilized voltage generator (12) in series is The switching power supply circuit 1 can be simplified, and the triangular wave generation circuit, the pulse width comparator, the error amplifier, etc. are omitted as compared with the case of using a normal pulse width modulation type switching power supply circuit, and the circuit can be simplified. .

Further, in the present invention, since the switching frequency signal is synchronized with the frequency-divided signal obtained by dividing the clock signal by the frequency dividing circuit 8, the clock signal has a fixed frequency output by a crystal oscillator of a temperature compensation type or the like. Since it is a signal, the frequency hardly changes as in the prior art due to changes in environmental conditions such as temperature. Therefore, the clock signal is divided by the frequency dividing circuit 8
With proper frequency division, mutual interference with the intermediate frequency signal of the receiving section 2 does not occur and it is possible to prevent deterioration of the communication quality.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of a power supply circuit of a portable device showing the principle of the present invention. The regulator circuit 12 (or DC / DC converter), which is an arbitrary type stabilized voltage generator connected to the 7.2V battery 10, has a voltage of 4.5.
Generate a constant voltage of V. Switching pulse generation circuit 1
Switching power supply circuit 1 having -5 and generating a constant voltage
Produces a voltage of 3.3V. The clock signal of the fixed oscillator 7 is supplied to the switching pulse generating circuit 1-5 as an external synchronizing signal after being frequency-divided by the frequency dividing circuit 8 (a frequency division ratio of 1: 1 is also possible). Switching pulse generation circuit 1-
Reference numeral 5 is a so-called external synchronizing signal duty adjusting means for appropriately adjusting the duty of the output signal of the frequency divider 8 to generate a switching pulse synchronized with the system clock. The switching power supply circuit 1 is supplied with the 4.5V output voltage of the regulator circuit 12 and the switching pulse generated by the switching pulse generation circuit 1-5.
The 4.5V output from the regulator circuit 12 is the switching power supply circuit 1 and a predetermined circuit block (for example,
The output of the switching power supply circuit 1 is supplied as the power supply of the control unit 6) and is supplied as the power supply of a predetermined circuit block (for example, a high frequency unit) having a constant load current.

An embodiment in which this is applied to a mobile phone will be described below. FIG. 2 is a diagram showing a configuration example of a mobile phone using the switching power supply circuit of the present invention. As shown, a mobile phone using the switching power supply circuit of the present invention generates a switching power supply circuit 1, a receiving unit 2, a receiver 3, a transmitting unit 4, a transmitter 5, a control unit 6 for controlling the whole, and a clock signal. An oscillator 7 such as a crystal oscillator, a frequency dividing circuit 8 for dividing a clock signal, an antenna 9, a battery 10,
It is composed of a regulator circuit 12.

The receiving unit 2 and the transmitting unit 4 are controlled by the control unit 6, and the receiving unit 2 receives the radio wave signal received from the antenna 9 as a first signal.
The intermediate frequency signal and the second intermediate frequency signal are converted and demodulated and output as a voice output from the handset 3, and the transmitting unit 4 modulates the voice signal input from the handset 5 and outputs it as a radio wave signal from the antenna 9. The 3.3V output of the switching power supply circuit 1 is supplied to the receiver 2 and the transmitter 4.

Control unit 6 having a CPU (central processing unit)
Is supplied with a constant voltage output of 4.5 V of the regulator circuit 12. The CPU operates with a clock signal (about 4.8 MHz) generated by the oscillator 7 which is a crystal oscillator. The clock signal is frequency-divided from the control unit 6 through the frequency dividing circuit 8 and input as an external synchronizing signal of the switching power supply circuit 1 through the switching pulse generating circuit 1-5. Here, the switching pulse generation circuit 1-5 generates the switching frequency pulse signal in synchronization with the external synchronization signal,
This signal is input to the switching power supply circuit 1.

The switching power supply circuit 1 adjusts the output voltage supplied from the regulator circuit 12 and supplies a predetermined constant voltage to the receiver 2, transmitter 4, and controller 6. Next, the switching power supply circuit 1 will be described.

As shown in FIG. 1, a switching power supply circuit 1
Is FET (Field Effect Transistor) 1-1, reactor 1
-2, the diode 1-3, and the capacitor 1-4, the voltage output from the battery 10 is applied to the input terminal S (source) of the FET (field effect transistor) 1-1 and to the gate terminal G. Output from the output terminal D (drain), and is smoothed by a smoothing circuit composed of the diode 1-3, the reactor 1-2, and the capacitor 1-4, and the output is supplied as a DC constant voltage source. .

As described above, since the switching power supply circuit 1 of the present invention uses the frequency-divided signal obtained by dividing the clock signal used by the CPU of the control unit 6 by the frequency dividing circuit 8 as the external synchronizing signal, it is possible to control the temperature and the like. The output voltage hardly changes due to changes in the environmental conditions, and mutual interference with the intermediate frequency of the transmission / reception circuit does not cause beat disturbance or sensitivity suppression disturbance, so that the communication quality is improved. For example, if the clock signal used by the CPU is 4.8 MHz, the frequency of the synchronizing signal in the telephone call state is 4.8 MHz 16
The frequency may be divided to 300 KHz.

Since the clock signal is a fixed frequency signal output from a crystal oscillator of temperature compensation type or the like, the frequency hardly changes due to changes in environmental conditions such as temperature, and the frequency divider circuit is divided. If the ratio is appropriately selected, the reception section does not cause mutual interference with the intermediate frequency signal as in the conventional case, and the deterioration of the communication quality can be prevented.

Although one embodiment of the present invention has been described above, the present invention is not limited to this. For example, the regulator circuit 12 can be configured by a switching power supply circuit like the switching power supply circuit 1, and a frequency divider and a switching pulse generation circuit are separately provided, and the clock signal from the control unit 6 is divided at a predetermined frequency division ratio. 1 and 2, an external synchronization signal (illustrated by a dotted line 11 drawn from the frequency dividing circuit 8 in FIGS. 1 and 2) is generated and supplied to the switching pulse generating circuit. In this case, the switching power supply circuit 1
It is possible to synchronize with the switching power supply circuit, and it is possible to prevent occurrence of a beat failure due to a difference in switching frequency between the two switching power supply circuits.

Further, the above embodiment is an example of the configuration of the control unit 6 which receives the power supply of 4.5V and the transmitting unit 2 and the receiving unit 2 which receive the power supply of 3.3V. An example in which two circuit blocks are supplied with voltage has been shown, but the present invention is not limited to this, and switching power supply circuits can be connected in series or in parallel by the required number of voltages. is there. A switching pulse generating circuit and a frequency dividing circuit are connected to each switching power supply circuit, and a frequency dividing signal having a predetermined frequency dividing ratio is supplied to the switching pulse generating circuit as an external synchronizing signal.

[0018]

The circuit is simplified and the current consumption is reduced as compared with the case of using a normal pulse width modulation type DC / DC converter circuit.

Efficiency is improved and battery life is extended as compared with the case where regulator circuits are connected in series and used.

If the stabilized voltage generator is composed of a DC / DC converter and its switching frequency can be synchronized with an external signal, the system clock output from the frequency dividing circuit 8 can be used for switching. It is possible to avoid a beat failure due to a difference in switching frequency between the power supply circuit 1 and the power supply circuit 1.

[Brief description of drawings]

FIG. 1 is a block diagram showing the principle of the present invention.

FIG. 2 is a diagram showing a configuration example of a mobile phone using the present invention.

FIG. 3 is a block diagram of a power supply circuit showing a conventional example.

[Explanation of symbols]

1: Switching Power Supply Circuit 1-1: FET (Field Effect Transistor) 1-2: Reactor 1-3: Diode 1-4: Capacitor 1-5: Switching Pulse Generating Circuit 2: Receiving Unit 3: Receiving Unit 4: Transmitting Unit 5: Transmitter section 6: Control section 7: Oscillator 8: Frequency divider circuit 9: Antenna 10: Battery 12: Regulator circuit (stabilized voltage generator) 13: DC / DC converter circuit (stabilized voltage generator)

Claims (2)

[Claims] 1. A power supply circuit of a portable device adapted to generate a plurality of different regulated constant voltage sources using a battery as a power source and to supply a constant voltage output to a predetermined circuit block, respectively. A stabilized voltage generator of an arbitrary system, one or a plurality of switching power supply circuits for generating a constant voltage, a switching frequency generating means for supplying an external synchronizing signal to the switching power supply circuit, and a clock signal for the switching frequency generating means. The output of the stabilized voltage generator is supplied as the power supply for the switching power supply circuit and the predetermined circuit block, and the output of the switching power supply circuit is the power supply for the predetermined circuit block whose load current is constant. A power supply circuit for a portable device, characterized in that it is supplied as 2. A frequency dividing circuit is provided, which divides a clock signal and supplies it to the switching frequency generating means as each external synchronizing signal of the one or more switching power supply circuits, and the switching frequency generating means supplies the divided frequency. The power supply circuit for a portable device according to claim 1, wherein an output of which the duty of the frequency signal is adjusted is supplied to the switching power supply circuit.