JPH09167137A - Power supply controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably supply power to an electronic equipment main body without being affected by the load fluctuation of an external device in the power supply controller of the electronic equipment driven by a battery power source to which a memory card and a printer can be connected as external device. SOLUTION: When the external devices are connected through external device through power supply controllers 29a and 29b, supply power setting data is read from table data for supply power setting, which is previously stored in ROM 25 in accordance with the output voltage level of the battery power source 30, which is detected by a voltage detector 31, and it is set in supply power setting data latch parts in the external device in power supply controllers 29a and 29b. The combination of the respective resistance elements of a parallel/ serial resistance group operating as the restriction resistance of supply power is changed and set. When there is margin in power capacity, the restriction synthesis resistance is set to be low and external supply possible power is restricted by a high value. Wen there is no margin in power capacity, the restriction synthesis resistance is set to be high and the external supply possible power is restricted by the low value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply control device for an electronic device driven by a battery power supply to which, for example, a memory card or a printer can be connected as an external device.

[0002]

2. Description of the Related Art For example, a PDA (Personal Digital Assist)
Some portable information terminal devices, such as ants), can be connected to a memory card, printer, etc. as external devices, but if the terminal device body is driven by battery power, The drive voltage for external equipment is also supplied.

As described above, when an external device is connected to the terminal device main body, the driving voltage is supplied to the external device to increase the power consumption of the battery power source and reduce its power supply capability. If an external device is connected and used in a state where the power capacity of the battery is reduced to some extent due to the exhaustion of the battery power, the device main body and the external device will soon become inoperable due to insufficient power supply capability.

Therefore, when an external device is connected, the power supply capacity is checked by the output voltage of the battery power supply at that time.
Power is not supplied to external equipment.

[0005]

On the other hand, even if the power supply capacity of the battery power source in the main body of the apparatus is more than a predetermined level and the external equipment is connected and used, for example, at the time of starting the operation of the external equipment. When the power supply load is temporarily increased, the supply voltage to the apparatus main body may fall below the operable voltage, which may cause the operation of the entire apparatus to stop.

[0006] Such a problem becomes more prominent as the battery power is consumed to some extent and the power supply capacity thereof is reduced.
There is a problem that data processing is interrupted or memory data is destroyed.

The present invention has been made in view of the above problems, and even in an electronic device using a battery power source, the electronic device is stable with respect to the main body of the electronic device without being affected by the load fluctuation of the external device. It is an object of the present invention to provide a power supply control device capable of supplying power to a power supply.

[0008]

That is, a power supply control device according to claim 1 of the present invention is a power supply control device for an electronic device which is supplied with power from a battery and is connectable to an external device. To the electronic device main body and an external device connected to the electronic device main body, power supply means for detecting the output voltage of the battery power supply, and the battery power supply detected by the voltage detection means. According to the output voltage level of, the power supply limiting means for limiting the upper limit value of the power supplied to the external device via the power supply means is provided.

A power supply control device according to a second aspect of the present invention is the power supply control device according to the first aspect, wherein the supply power limiting means includes a resistance group formed by combining a plurality of resistance elements. Supply power for limiting the upper limit of the power supplied to the external device via the power supply means by selecting the combination of the resistance elements in this resistance group according to the output voltage level of the battery power supply. It is characterized in that it is a limiting means.

That is, in the power source control device according to the first aspect, the upper limit value of the electric power supplied to the external device is limited according to the output voltage level of the battery power source detected by the voltage detecting means. Even when the load on the side temporarily increases, the electric power above the limit value is not supplied to the external device side, and the operating voltage required on the electronic device body side can be secured.

Further, in the power supply control device according to the second aspect, the combination of the resistance elements in the resistance group formed by combining the plurality of resistance elements is selected according to the output voltage level of the battery power source detected by the voltage detection means. Therefore, the upper limit value of the electric power supplied to the external device is limited.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an external configuration of a compact information terminal device equipped with a power supply control device according to an embodiment of the present invention.

The device body 11 of the small-sized information terminal device is of a size that can be sufficiently held by a user with one hand, and a touch panel type display unit 12 is provided at the center of the front face of the device body 11, and this touch panel display unit is provided. A key input screen 13 is displayed at 12 in the key input mode.

On the right side of the front of the apparatus body 11,
A button key 14 is provided, and this button key 14 has
An “ON” key for turning the power on / off, a “Key” key for setting a key input mode, an “Enter” key for instructing data input and command execution, a cursor movement operation on the touch panel display unit 12, A cursor key for selecting data is provided.

The device main body 11 includes a PCMC.
IA (Personal Computer Memory Card International A
A memory card 15 such as an ssociation) or a printer 17 via a Centronics interface 16 which is a printer interface having an 8-bit parallel data bus is connected as an external device as necessary.

The device body 11 of the small information terminal device is
Data can be input, registered, searched, and displayed by itself, and a memory card 15 can be connected to be used as an expansion memory, or desired data can be connected to a printer 17 for printing processing.

Here, the device main body 11 of the small-sized information terminal device is such that its drive voltage is supplied by a replaceable battery power source. However, the drive voltage is supplied by the power source mounted on the apparatus body 11.

FIG. 2 is a block diagram showing the configuration of an electronic circuit of the small information terminal device. The electronic circuit of this compact information terminal device includes a CPU 21. Control unit (CP
U) 21 is a system previously stored in the ROM 25 in response to a key operation signal input from the button key 14 or a touch operation signal input from the touch panel display unit 12 (22, 23) via the touch panel controller 24. The program is started and the operation of each part of the circuit is controlled.

The control unit (CPU) 21 includes the button keys 14, touch panel controller 24, ROM 2
5, the common driver 26 and the segment driver 27 for driving the common electrodes and the segment electrodes of the liquid crystal display screen 22 in the touch panel display unit 12 according to the display data, the RAM 28, and the external device power supply control device 29.
a and 29 are connected.

The touch panel display section 12 is constructed by stacking a touch panel 23 on a liquid crystal display screen 22, and a voltage signal corresponding to a touch position of the touch panel 23 is generated in response to a touch operation on the touch panel 23. Detected, the X and Y coordinates of the touch position corresponding to the liquid crystal display screen 22 are obtained.

The control unit (CPU) 21 displays touch position coordinates obtained by the touch panel controller 24 in response to a touch operation on the touch panel 23 of the touch panel display unit 12 and a display on the liquid crystal display screen 22 corresponding to the touch position coordinates. The content of the touch operation is determined based on the data.

The ROM 25 stores in advance a system program that governs the overall operation of the small-sized information terminal device, a mode processing program corresponding to each operation mode of data input, search, and display, a memory 15, a printer 17, and the like. Various subprograms such as an external device control program associated with the connection and use of the external device are stored in advance.

In the RAM 28, a work area in which the data input / output accompanying the control processing in the various operation modes in the control unit (CPU) 21 is temporarily stored, and the input data is registered for each various operation mode. A data memory such as a data registration area to be stored is provided.

Further, this small-sized information terminal device is provided with a battery power source 30, and the battery power source 31 supplies the power source voltage to each part of the circuit. The power source voltage output from this battery power source 31 is the system. The power is supplied to the electronic circuit inside the apparatus main body 11 as the power supply Vsys, and is also supplied as the external equipment power supply Vin to the memory card 15 and the printer 17 through the external equipment power supply control devices 29a and 29b.

A voltage detector 31 is connected in parallel to the battery power source 31, and the output voltage level thereof is detected. The voltage level detection signal of the battery power source 31 by the voltage detector 31 is the control unit ( CPU) 21.

The external equipment power supply control devices 29a and 29b are
When the corresponding external device (memory card 15, printer 17) is connected, the maximum value of the power supplied to the external device is limited according to the voltage level of the battery power source 30 detected by the voltage detector 31. If, for example, the voltage level of the battery power source 30 is high and there is a sufficient power source capacity, the limit value of the power that can be supplied to the external device is set high, and the voltage level of the battery power source 30 is low and the power source capacity has decreased. In this case, the limit value of the power that can be supplied to the external device is set low.

As a result, when the power supply capacity of the battery power source 30 is reduced, even if the power load of the external device is increased, the power supplied to the external device is kept low, and the circuit operation inside the apparatus main body 11 is suppressed. The power supply capacity of the system power supply Vsys required for the above is secured.

FIG. 3 is a circuit diagram showing the configuration of the external equipment power supply control devices 29a and 29b provided in the compact information terminal device. The external device power supply Vin supplied from the battery power supply 30 of the apparatus main body 11 is the IO from the control unit (CPU) 21.
It is supplied through a transistor 41 that is switched by an ON signal.

At the power output terminal of the transistor 41, a series resistance group consisting of four resistance elements 3a to 3d and 3 are provided.
A parallel resistance group including one resistance element 3f to 3h is connected in series, and a power supply voltage having a limited maximum power that can be supplied through each resistance group circuit is output as an external device drive voltage Vout.

The series resistance groups 3a to 3d and the parallel resistance groups 3f to 3h have resistance elements 3a, 3b, 3c and 3d.
Of the bypass switch 2 to each of the resistor elements 3f to 3h.
a to 2e are connected, and disconnection switches 2f, 2g and 2h are connected to the individual resistance elements 3f, 3g and 3h of the parallel resistance groups 3f to 3h.

The switches 2a to 2h supply power setting data D0 latched to the latch circuits 1a to 1h of the supply power setting data latch unit 42 in synchronization with the IOCK signal from the control unit (CPU) 21. ON / OFF control (“1” → ON / “0” → OFF) according to -7, and the supply power setting data D0-7 is externally supplied via the external device power supply control devices 29a, 29b. Set according to the output voltage level of the battery power source 30 detected by the voltage detector 31 when the device is connected, based on the table data (see FIG. 4) for power supply setting stored in the ROM 25 in advance. To be done.

FIG. 4 shows the ROM 25 of the small information terminal device.
It is a figure which shows an example of the table data for power supply setting beforehand memorize | stored in (or RAM28). In this case, for example, when the output voltage level of the battery voltage 30 detected by the voltage detector 31 is as high as "4.5V" and the power supply capacity is sufficient, the power supply setting of the external device power supply control devices 29a, 29b is set. Supply data setting data D0-7 "F3h" is set in the data latch section 42, and each latch circuit 1a
Since "11110011" is written in to 1h, the bypass switches 2a to 2d and the connection / disconnection switches 2g and 2h are written.
Turns on, and A to B with respect to the external device drive voltage Vout
The power limiting resistance between them is only the parallel resistance group of the resistance elements 3g and 3h. Therefore, the maximum power that can be supplied by the external device drive voltage Vout is set high.

On the other hand, for example, when the output voltage level of the battery voltage 30 detected by the voltage detector 31 becomes as low as "3.3V" and the power supply capacity thereof drops, the external equipment power supply control devices 29a, 29b are supplied. Supply power setting data D0-7 "94h" is set in the power setting data latch section 42, and "100101" is set in each of the latch circuits 1a to 1h.
00 "is written, bypass switches 2a and 2d
Also, only the disconnection switch 2f is turned on, and the power limiting resistance between A and B for the external device drive voltage Vout becomes a series resistance group of the resistance elements 3b, 3c, 3f. Therefore, the maximum power that can be supplied by the external device drive voltage Vout is set low.

Furthermore, for example, when the output voltage level of the battery voltage 30 detected by the voltage detector 31 is "2.9V", which is the minimum voltage level required for the system power supply Vsys, and the power supply capacity is significantly reduced, Since there is not enough power supply to the external device, the supplied power setting data latch unit 42 of the external device power supply control device 29a, 29b.
Is set to supply power setting data D0-7 "00h", and "00000000" is set in each of the latch circuits 1a to 1h.
Is written, the bypass switches 2a to 2d and the connection / disconnection switches 2e to 2h are all turned off, and the power supply to the external device is cut off.

A voltage detector 43 is connected to the output terminal of the external device drive voltage Vout, and the power consumption of the external device is monitored at the voltage level of the external device drive voltage Vout. The voltage detection signal DET of the external device drive voltage Vout from the detector 43 is supplied to the control unit (CPU) 21.

When the voltage detector 43 detects a voltage level of the external device drive voltage Vout which is equal to or lower than a predetermined value and the voltage detection signal DET is supplied to the control unit (CPU) 21, the ION signal is output to the transistor 41. Is stopped, and the power supply to external equipment is cut off.

That is, the series-parallel resistance groups 3a to 3d, 3
Even when the driving voltage Vout is supplied to the external device through the power limiting resistance due to the combination of f to 3h, if the power consumption of the external device temporarily increases due to the load fluctuation, Based on the voltage detection signal DET from the voltage detector 43, the power supply to the external device is cut off, and the system power supply Vsys inside the device main body 11 is cut off.
The required voltage is secured.

Next, the power control operation associated with the connection of external equipment of the small-sized information terminal device having the above-mentioned configuration will be described.
FIG. 5 is a flowchart showing a power supply control process associated with connection of an external device in the small information terminal device.

When an external device is connected to the apparatus main body 11 by the memory card 15 or the printer 17, the power supply control process in FIG. 5 is started, and it is first confirmed whether or not the external device is securely connected. (Steps S1 and S2).

When it is confirmed that the printer 17 is securely connected to the apparatus main body 11 as an external device, the output voltage level of the battery power source 30 detected by the voltage detector 31 is controlled. It is read by the unit (CPU) 21 (steps S2 → S3).

Here, for example, the battery power source 30 has already been consumed to some extent, and the voltage detector 31 causes the control unit (CP
U) When the power supply output voltage level read by 21 is lower than a certain value and it is determined that power supply to the external device is impossible, a message to the user that the connection of the external device is unavailable Data and message data prompting replacement of the battery power source 30 are displayed on the touch panel display unit 12.
Displayed on the (liquid crystal display screen 22) (step S4 → S)
5).

On the other hand, from the voltage detector 31 to the control unit (CP
U) When the power supply output voltage level read by 21 is abnormal by a constant value and it is determined that power can be supplied to the external device, the ROM 25 is previously stored in the ROM 25 in accordance with the detected power supply voltage level. The supplied power setting data D0-7 is read from the stored table data for setting the supplied power to the external device, and the supplied power setting data latch unit 4 in the external device power control device 29b for the printer is read.
2 is written (steps S4 → S6, S7).

Then, from the control unit (CPU) 21 to the IOO
The N signal is output and supplied to the transistor 41 of the external device power supply control device 29b, and the power supply voltage output from the battery power supply 30 is input as the external device power supply Vin and written in the supplied power setting data latch unit 42. It is output as the external device drive voltage Vout via the power limiting resistance combined in accordance with the supplied power setting data D0-7 (step S8).

In this case, when the output voltage level of the battery power source 30 is high and the power source capacity has a margin, the power limiting resistors are combined by the power supply setting data D0-7 written in the power supply setting data latch section 42. Sufficient power is supplied to the printer 17 whose resistance is set to a low value and which is connected via the external device power supply control device 29b.

Even if the battery power source 30 has a sufficient power capacity and a sufficient amount of power is supplied to the connected external device, the power source is not changed in accordance with the printing operation of the printer 17, for example. If the load temporarily increases and the system power supply Vsys in the apparatus main body 11 may drop, the external device drive voltage Vout may drop due to the increased power load on the printer 17. The voltage is detected by the voltage detector 43 and the control unit (CP
U) 21 is notified, and I to the transistor 41 is notified.
The output of the OON signal is stopped.

As a result, the power supply to the printer 17 due to a heavy load is cut off and the system power supply Vsys is prevented from being adversely affected. On the other hand, when the output voltage level of the battery power source 30 is low and there is no margin in the power source capacity, the combined power resistance setting value D0-7 written in the supplied power setting data latch section 42 causes the combined resistance of the power limiting resistors to be high. And the maximum power that can be supplied to the printer 17 connected via the external device power control device 29b is suppressed to a low level.

In this case as well, similar to the above, for example, the printer 17
If there is a risk that the power supply load will be temporarily increased due to the printing operation of No. 1 and the system power supply Vsys in the apparatus main body 11 will be lowered, the external power supply by the printer 17 is increased. The voltage detector 43 detects the voltage drop of the drive voltage Vout, and the control unit (C
PU) 21 is notified, and the output of the ION signal to the transistor 41 is stopped. And printer 1
The power supply accompanying the high load to 7 is cut off, and the adverse effect on the system power supply Vsys is prevented.

Therefore, according to the power supply control device in the small-sized information terminal device having the above configuration, when the external device such as the memory card 15 or the printer 17 is connected through the external device power supply control devices 29a and 29b, the voltage detection is performed. The power supply setting data D0-7 is read from the table data for power supply setting stored in advance in the ROM 25 in accordance with the output voltage level of the battery power supply 30 detected by the battery charger 31, and the external device power supply control device 29a is read. , 29b are set in the supply power setting data latch unit 42, the combination of the resistance elements of the series-parallel resistance groups 3a to 3d, 3f to 3h is changed and set, and when the power supply capacity has a margin, the limited combined resistance is low. If the maximum value of the power that can be supplied to the external device is set to a high value and there is not enough power capacity, the limit Since the maximum resistance is set to a high value and the maximum value of the electric power that can be supplied to the external device is limited to a low value, the system power supply Vsys inside the device body 11 is changed even if the power load changes with the operation of the external device. The adverse effect on is suppressed to the minimum, and stable circuit operation on the main body side can be secured.

Therefore, the voltage required for the internal system power supply Vsys cannot be secured due to the power supply to the external equipment, and the data processing is interrupted or the memory is destroyed due to the unexpected system operation stop. It can be prevented.

[0050]

As described above, according to the power supply control device according to the first aspect of the present invention, the upper limit of the electric power supplied to the external device according to the output voltage level of the battery power supply detected by the voltage detection means. Because the value is limited, even if the load on the external device side becomes temporarily large, for example, the power above the limit value will not be supplied to the external device side, and the necessary operation on the electronic device body side The voltage can be secured.

According to the second aspect of the power supply control device of the present invention, the resistance in the resistance group formed by combining a plurality of resistance elements according to the output voltage level of the battery power supply detected by the voltage detection means. A combination of elements is selected,
The upper limit value of the electric power supplied to the external device comes to be limited.

Therefore, even in an electronic device using a battery power source, it is possible to stably supply power to the main body of the electronic device without being affected by the load fluctuation of the external device.

[Brief description of the drawings]

FIG. 1 is a diagram showing an external configuration of a small information terminal device equipped with a power supply control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an electronic circuit of the small-sized information terminal device.

FIG. 3 is a circuit diagram showing a configuration of an external device power supply control device provided in the small information terminal device.

FIG. 4 is a diagram showing an example of supply power setting table data stored in advance in a ROM or a RAM of the small-sized information terminal device.

FIG. 5 is a flowchart showing a power supply control process associated with connection of an external device in the small information terminal device.

[Explanation of symbols]

 11 ... Small information terminal device main body, 12 ... Touch panel display unit, 13 ... Key input screen, 14 ... Button key, 15 ... Memory card, 16 ... Centronics interface, 17 ... Printer, 21 ... Control unit (CPU), 22 ... Liquid crystal Display screen, 23 ... Touch panel, 24 ... Touch panel controller, 25 ... ROM, 26 ... Common driver, 27 ... Segment driver, 28 ... RAM, 29a ... Memory card external device power control device, 29b ... Printer external device power control device , 30 ... Battery power source, 31 ... Battery power source voltage detector, 41 ... External device power source input transistor, 42 ... Supply power setting data latch section, 43 ... External device drive voltage detector, 1a-1h ... Latch circuit, 2a ~ 2d ... Bypass switch for limiting resistance setting, E～2h ... disconnecting switch limiting resistor setting, 3 a to 3 d ... series resistor group, 3f~3h ... parallel resistor group.

Claims (2)

[Claims] 1. A power supply control device for an electronic device, which is supplied with power from a battery and is connectable to an external device, wherein the battery supplies power to the electronic device main body and an external device connected to the electronic device main body. Supply means, voltage detection means for detecting the output voltage of the battery power supply, and power supplied to an external device via the power supply means according to the output voltage level of the battery power supply detected by the voltage detection means. And a supply power limiting means for limiting the upper limit of the power supply control device. 2. The power supply limiting means comprises a resistance group formed by combining a plurality of resistance elements, and selecting the combination of the resistance elements in the resistance group according to the output voltage level of the battery power supply. The power supply control device according to claim 1, wherein the power supply control device is a supply power limiting device that limits an upper limit value of the power supplied to the external device via the power supply device.