JPH0693645B2 - Power control circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless terminal device used for wireless mobile communication, and more particularly to on / off control of a power source in a portable wireless terminal device.

[Conventional technology]

Wireless mobile communication is widely used in various fields as a means for transmitting information of a mobile body that changes temporally and locationally, despite varying characteristics such as radio wave propagation and external noise. The development of electronics has brought about a change in the communication system, and in particular, the use of semiconductors has improved the quality of communication, and devices have become smaller and lighter. Recently, many mobile wireless terminal devices that use the characteristics of semiconductors and that use a dry battery or a storage battery as a power source have become more popular, and their usability has improved further. There are various types of semiconductors used regardless of whether they are analog or digital. However, a microcomputer is generally used to control the equipment and appropriately processes various signals. Therefore, when turning on / off the power supply of such a wireless terminal device, not only a mechanical switch but also a so-called soft switch using this microcomputer is used.

For this mechanical switch, use a slide switch or a rotary switch to insert these switches into the power line that connects the power supply and each circuit, and simply "connect" this power line.
Alternatively, the power supply to each circuit is turned on / off by turning it off. In addition, the soft switch is operated by the push button of the keyboard provided on the operation panel of the device, and the power is turned on based on the command from the microcomputer.
It is something to turn off.

[Problems to be solved by the invention]

There are various problems in the prior art in which the power supply of the portable wireless terminal device is turned on / off by a mechanical switch or a soft switch. In particular, there are many restrictions on devices in the portable car telephone system in which demand has rapidly increased.

Generally, in a car telephone system, the base station side and the mobile station side mutually monitor the transmission output level emitted from the other station side in consideration of the radio wave propagation characteristics, etc., and see if the situation changes due to movement. I try to respond immediately. Therefore, if the mobile station turns off the power without performing a normal call termination operation, it is considered that the base station is in a call and, for example, the mobile station temporarily moved to a tunnel where radio waves do not reach. It is decided that the line is held for a certain period of time. Since this fixed time extends to about 10 seconds, for example, the more devices are operated, the lower the line usage efficiency becomes. Therefore, conventionally, by arranging a large-capacity capacitor in the power supply circuit, even if the mechanical switch is "disconnected", the power supply voltage is held with sufficient charge accumulated in this capacitor, and the mechanical Detecting that the target switch was "disconnected", the call was ended.

Even in equipment that uses a lot of semiconductors, the power supply capacity corresponding to the transmission output is required, and since the power supply voltage must be maintained even when the mechanical switch is "disconnected", the space occupied by the quiescent capacitor is large. Inevitably, it is necessary to use parts that have a margin in terms of power supply capacity, especially the whole device is small, lightweight, low power consumption, and cheap, like portable wireless terminal devices. However, it becomes difficult to dispose such a large-capacity capacitor.

Also, when using a microcomputer installed in a car telephone system to turn on / off the power by software by pressing a push-button on the keyboard, the microcomputer controls the on / off of the power, so that external noise When the operation of the micro computer becomes abnormal due to such reasons, the power cannot be turned off.

[Means for solving problems]

SUMMARY OF THE INVENTION The present invention, in a power supply control circuit used for a mobile wireless terminal device in mobile communication, solves such a problem of the prior art by a mechanical switch and a constant value after the mechanical switch is turned off. An oscillation control circuit that outputs a delayed clock pulse after a lapse of time, a delay flip-flop that outputs a signal that turns off the power supply based on the state of the mechanical switch and the delayed clock pulse, and a logic circuit to which a signal from an external device is input A soft switch consisting of
An OR circuit for ORing the output of the delay flip-flop and the output of the soft switch, and a transistor circuit for turning on / off the power supply by the output of the OR circuit are provided.

[Action]

The present invention has a mechanical switch and a soft switch, and when the mechanical switch is turned off, the power is turned off after a certain period of time regardless of the control operation of the microcomputer, and when the power is on. The power is turned off by setting the control terminal to the active level.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings. In addition,
Elements common to the drawings are designated by the same reference numerals. FIG. 1 is a block diagram of a power supply control circuit showing an embodiment of the present invention. Oscillation circuit 1 composed of resistors and capacitors
The clock pulse generated by is divided by the frequency dividing circuit 2 provided with the clock pulse input terminal CK, the reset terminal R and the output terminal Qn into a clock pulse having a predetermined pulse width. These clock pulses are further input to the delay flip flops 3 and 4 connected in cascade. In addition to this, the oscillation control circuit for generating the delayed clock pulse has a set of delay flip-flop 6 and delay flip-flop 4 in which the NOT circuit 5 is connected to the clock pulse input terminal CK and the output terminal is connected to the reset terminal R of the frequency dividing circuit 2. It is composed of a NOT circuit 7 whose output is connected to the terminal S. The mechanical switch 8 is connected to the input terminal D of the delay flip-flop 10 via the NOT circuit 9, and its output terminal becomes one input of the OR circuit 11, and its clock pulse input terminal CK is connected to the output terminal Q of the delay flip-flop 3. It is connected. The output of the OR circuit 11 is connected to the base of a PNP transistor 12 that turns the power supply on and off, and its emitter is grounded via a capacitor 13. The soft switch is configured such that the output of the AND circuit 15 having the output of the NOT circuit 14 as one input becomes the other input of the OR circuit 11. A power control command for a microcomputer, which is an external device (not shown) Is a command to turn off the power when it is at "L" level and is input to the NOT circuit 14 through the control terminal P1. The reset signal of this computer is at "L" level. Is a signal for stopping the operation of (1) and becomes the other input of the AND circuit 15 via the reset signal control terminal P2. The power is turned on / off by an on / off terminal P3 connected to the emitter of the transistor 12. Then, the oscillation control of the oscillation circuit 1, the frequency dividing circuit 2, the delay flip-flops 3, 4, 6 and the negation circuit 5 and the negation circuit 7 outputs a delayed clock pulse after a certain time has elapsed since the mechanical switch 8 was turned off. It constitutes the circuit. FIG. 2 is a waveform diagram showing the signal waveform of each part in the block diagram shown in FIG. 1. (a) is the operation of the switch 8, (b) is the state of the output terminal of the delay flip-flop 10, and (c). Is a state of the on / off terminal P3, (d) is a state of the control terminal P1, and (e) is a state of the reset signal control terminal P2. The mechanical switch 8 of (a) and the mechanical switch 8 of (c) are shown. Both of the control terminals P1 which are soft switches,
First, the power is on, and then the power is off. (A) to (c) show the action of a mechanical switch, and (c) to (e) show the action of a soft switch.

Now, the operation of the embodiment of the present invention thus constructed will be described. It is assumed that power is constantly supplied to each circuit, but since each circuit is composed of a CMOS type integrated circuit that requires low current consumption, power is not supplied to a microcomputer computer system (not shown). The current in the unsupplied state is almost negligible. First, the operation of the mechanical switch 8 side will be described assuming that the side of the soft switch composed of the NOT circuit 14 and the logical circuit 15 is not functioning, that is, the output of the AND circuit 15 is at the "L" level.

Delay flip-flop when power is on now
Since the output terminal of 10 is at "L" level and the output of the AND circuit 15 is also at "L" level, the output of the OR circuit 11 is at "L" level and the transistor 12 is on.
Therefore, as shown in FIG. 2 (c), the output voltage of the on / off terminal P3 is "+ V".

Next, when the mechanical switch 8 is turned off to turn off the power, the input of the negation circuit 9 becomes "H" level as shown in FIG. 2 (a), and the output of the negation circuit 9 becomes "L". At the level, the output of the negation circuit 5 becomes the "H" level. That is,
Since the clock pulse is input to the delay flip-flop 6, the output terminal of the delay flip-flop 6 becomes "L" level. When the power is turned on, this output terminal is at the “H” level, that is, the reset terminal R of the frequency dividing circuit 2 is at the “H” level, and the frequency dividing circuit 2 has stopped operating. The frequency dividing circuit 2 starts operating when it becomes the “L” level.

The frequency dividing circuit 2 outputs a clock pulse from the output terminal Qn after a preset fixed time T ₀ . Then, the delay flip-flop 3 outputs the delayed clock pulse which is the output of the oscillation control circuit from the output terminal Q when the clock pulse is input.

Next, since this delayed clock pulse is input to the clock pulse input terminal CK of the delay flip-flop 10, the output terminal of the delay flip-flop 10 becomes "H" level as shown in FIG. 2 (b). Then, the output of the OR circuit 11 becomes "H" level, the transistor 12 is turned off, and the output voltage of the on / off terminal P3 is turned off as shown in FIG. 2 (c).

Therefore, as shown in FIG. 2, since the power is turned off after a fixed time T ₀ has passed since the mechanical switch 8 was turned off, the call termination process can be performed during the fixed time T ₀ , and a large capacity is required. It is not necessary to hold the power supply voltage with a capacitor. Next, as a soft switch, when power is supplied to a microcomputer (not shown), the control terminal P1 is set to "L" as shown in FIG.
By setting the level, the output of the AND circuit 15 becomes "H".
At the level, the output of the OR circuit 11 becomes "H" level,
The transistor 12 can be turned off and the output voltage of the on / off terminal P3 can be turned off. When power is not supplied to this microcomputer system, the reset signal control terminal P2 is at "L" level, and during this period, even if the control terminal P1 is in any state, it is an on / off terminal.
It does not affect the control of P3. Therefore, the power can be turned off by the mechanical switch 8 regardless of the control operation of the microcomputer.

The negation circuit 7 is designed so that the outputs of the delay flip-flops 6 and 10 are in the initial state when the power which is constantly supplied to the above circuits is turned on.

〔The invention's effect〕

According to the present invention, an oscillation control circuit for outputting a delayed clock pulse is provided after a lapse of a certain time after the mechanical switch is turned off, and an OR circuit is further provided to operate even with a soft switch. In addition to eliminating the need for a holding capacitor, by turning off the mechanical switch, the output voltage of the power supply control circuit can be turned off after an accurate fixed time regardless of the operation of the microcomputer. It is also possible to deal with various wireless terminal devices having different specifications with respect to the standard of the instantaneous interruption time. It is also possible to turn off the power according to a command from the microcomputer, for example, the power may be turned off after executing the call end processing.

[Brief description of drawings]

FIG. 1 is a block diagram of a power supply control circuit showing an embodiment of the present invention, and FIG. 2 is a waveform diagram showing signal waveforms of respective parts in this block diagram. 1 ... Oscillation circuit, 2 ... Dividing circuit, 3,4,6,10 ... Delay flip-flop, 5,7,9,14 ... Negation circuit, 8 ... Switch, 11 ... OR circuit, 12 …… Transistor, 13 …… Capacitor, 15 …… AND circuit.

Claims (1)

[Claims] 1. A power supply control circuit for use in a mobile wireless terminal device for mobile communication, comprising a mechanical switch and a soft switch for turning on / off a power supply, wherein the mechanical switch and the mechanical switch are provided. An oscillation control circuit that outputs a delayed clock pulse after a certain period of time after turning off, a delay flip-flop that outputs a signal that turns off the power supply based on the state of the mechanical switch and the delayed clock pulse, and an external device A soft switch composed of a logic circuit to which the signal of (1) is input, a logical sum circuit that takes the logical sum of the output of the delay flip-flop and the output of the soft switch, and the output of this logical sum circuit turns on / off the power supply. A power supply control circuit comprising a transistor circuit for performing the operation.