JPH06202769A - Power source device - Google Patents

Abstract

PURPOSE:To easily detect the decrease of a voltage at the early time of starting the operation of a power source part and to exactly detect the state of the shortage of the voltage by detecting the voltage of the power source part not only at the time of the start of the operation but also after a prescribed time since the start of the operation by a voltage detecting means. CONSTITUTION:A voltage detecting and comparator circuit 5 detects the voltage level of a battery 2, and compares in with a threshold level. When the voltage level of the battery 2 is more than the threshold level a power source control circuit 6 outputs an H as a main power source control signal (c) to the control terminal CNT of a main power source circuit 3 based on a power source control signal (b), and the main power source circuit 3 is operated. Then, a reset signal (d) is outputted from a reset generating circuit 8, and a new reset signal (e) is outputted from the power source control circuit 6. After the time interval of 50-100ms, the output of the reset signal (d) is stopped, and the voltage level of the battery 2 is detected, and compared with the threshold level again by the voltage detecting and comparator circuit 5. When the voltage level of the battery 2 is less than the threshold level, a detect level signal (a) is outputted to the power source control circuit 6, and the operation of the main power source circuit 3 is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device, and more particularly to a power supply device for a battery-powered portable information processing device.

[0002]

2. Description of the Related Art With recent advances in semiconductor technology,
For example, various small-sized and high-performance portable information processing devices typified by electronic notebooks are provided. In such portable information processing devices, batteries such as dry batteries or storage batteries are used for the purpose of portable use. It is generally provided with a power supply device by driving.

In such a power supply device, a device to which power is supplied (in this case, a portable information processing device as an example)
In order to secure a reference potential for stable operation of the device, a circuit is normally added to the power supply device for determining whether or not sufficient power can be supplied to the device to which the power is supplied.

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

The power supply device 1 includes a battery 2, a main power supply circuit 3, a sub power supply circuit 4, a voltage detection / comparison circuit 5, a power supply control circuit 6, and C.
It is composed of the PU 7.

The battery 2 is a main power source which can be attached to and detached from the main body of the apparatus, and is a power supply source for each circuit in the portable information processing apparatus.

The main power supply circuit 3 is a power supply circuit used when starting up and operating the power supply device 1, and the sub power supply circuit 4 is a power supply circuit for starting up the power supply device 1 and for memory backup. In FIG. 3, IN is an input terminal, OUT is an output terminal, and CN is shown in the main power supply circuit 3 and the sub power supply circuit 4.
T is a control terminal and GND is a ground terminal.

The voltage detection / comparison circuit 5 detects the voltage level of the battery 2 and compares the voltage level of the battery 2 with a preset device operable voltage level, which is a threshold value.
If the voltage level of the power supply control circuit 6 is equal to or lower than the device operable voltage level,
(In this case, "L") is output, and it is checked whether or not the battery 2 has a sufficient voltage supply capability.

The power supply control circuit 6 is provided with an AND gate AND inside, and is based on the logical product of the detect level signal a output from the voltage detection / comparison circuit 5 and the power supply control signal b output from the CPU 7. The main power supply control signal c is output to the control terminal CNT of the power supply circuit 3.

The CPU 7 controls the entire power supply device 1. For example, when the power supply device 1 is operating, such as when a power switch is turned on, the power supply control signal b (in this case, " H ") is generated.

Hereinafter, a battery voltage detecting operation when the power supply device 1 shown in FIG. 3 is applied to a portable information processing device will be described with reference to a flow chart shown in FIG.

FIG. 4 is a flowchart showing an operation example of the conventional example.

First, when the battery 2 is attached to the portable information processing device (step P1), a power supply voltage is supplied from the battery 2 to the sub power supply circuit 4 to activate the sub power supply circuit 4 (step P1).
2).

When the sub power supply circuit 4 is activated, the sub power supply circuit 4
Supply a predetermined voltage to the CPU 7 from the C
The PU 7 activates the power supply control signal b output to the power supply control circuit 6 (“H”) (step P3).

Here, in the voltage detection / comparison circuit 5, the battery 2
The voltage level of the battery 2 is detected, and whether the detected voltage level is higher than a preset threshold value is compared (step P4). Detect level signal a
By outputting ("L"), the power supply control circuit 6 sets the main power supply control signal c output to the control terminal CNT of the main power supply circuit 3 to "L", so that the main power supply circuit 3 does not operate, The portable information processing device does not start (step P5).

On the other hand, when the voltage of the battery 2 is higher than the threshold value, the power supply control circuit 6 controls the main power supply circuit 3 based on the power supply control signal b ("H") output from the power-on terminal PW of the CPU 7. Since "H" is output as the main power supply control signal c to the terminal CNT, the main power supply circuit 3 operates and activates the entire portable information processing device (step P5).

[0017]

However, in such a conventional power supply device, the battery 2 is activated when the device is started.
If the voltage level of the battery 2 is less than or equal to a predetermined threshold value, the start of the entire device is stopped, and
Since the configuration is such that the entire device is activated when the threshold value is exceeded, there are the following problems.

That is, for example, even if the electric capacity stored in the battery 2 is very small, the voltage detection / comparison circuit 5 detects and compares the voltage level by the voltage detection / comparison circuit 5.
If the voltage level is larger than the threshold value (device operable voltage level) set in step 1, the main power supply circuit 3 operates and the entire device is activated, and then the supply voltage drops due to exhaustion of the battery 2, and There is a possibility that the circuit in the information processing device for malfunction will malfunction.

In general, the main power supply circuit 3 and the sub power supply circuit 4 are provided with capacitors for stably supplying a constant voltage. However, the power supply control is performed immediately after the battery 2 is removed by replacing the battery or the like. When the signal b becomes active, the voltage detection / comparison circuit 5 determines that the voltage of the battery 2 is a voltage level higher than the threshold value (device operable voltage level) due to the electric energy accumulated so far in the capacitor. However, the main power supply circuit 3 operates and the entire device starts up, but since the battery 2 has already been removed, the above-mentioned capacitor is immediately discharged, and the circuit in the portable information device may malfunction. is there.

An object of the present invention is to reliably detect a voltage shortage condition.

[0021]

The means of the present invention are as follows.

According to the present invention, a power supply unit for supplying a predetermined power supply voltage required by the circuit to an arbitrary circuit, and a power supply unit of the power supply unit at the start of operation of the circuit and after a predetermined time from the start of operation of the circuit. Voltage detection means for detecting a voltage value, and voltage supply determination means for determining whether to supply the power supply voltage from the power supply portion to the circuit based on the detection result of the voltage detection means,
It is characterized by having.

In this case, it is desirable to apply a predetermined load to the power supply unit from the start of the operation of the circuit to a predetermined time after the start of the operation of the circuit, and the load should be in the reset state. Can be considered.

[0024]

The operation of the means of the present invention is as follows.

According to the present invention, not only at the time of starting the operation but also at the time of starting the operation, the voltage value of the power source unit is detected by the voltage detecting means, so that it is easy to detect the voltage drop at the beginning of the operation of the power source unit. The voltage shortage state is reliably detected.

That is, the unstable supply of the power supply voltage in the state of insufficient voltage is suppressed, and the malfunction of the power supply destination is prevented in advance.

[0027]

EXAMPLES Examples will be described below with reference to FIGS.

FIGS. 1 and 2 are views showing an embodiment of the power supply device according to the present invention.

First, the structure will be described. FIG. 1 is a block diagram showing a circuit example of the power supply device of this embodiment. 1, a power supply device 1 includes a battery 2, a main power supply circuit 3, a sub power supply circuit 4, a voltage detection / comparison circuit 5, a power supply control circuit 6, and a CPU.
7 and a reset generation circuit 8.

The battery 2 is, for example, a NiCd battery (Ni-
Cd battery), dry battery, etc., and is a main power source detachably provided in the portable information processing device body, and is a power supply source for each circuit in the portable information processing device.

The main power supply circuit 3 is a power supply circuit used when starting up and operating the power supply device 1, and the sub power supply circuit 4 is a power supply circuit for starting up the power supply device 1 and for memory backup. In FIG. 1, IN is an input terminal, OUT is an output terminal, and CN is shown in the main power supply circuit 3 and the sub power supply circuit 4.
T is a control terminal and GND is a ground terminal.

The voltage detection / comparison circuit 5 detects the voltage level of the battery 2 and compares the voltage level of the battery 2 with a preset device operable voltage level, which is a threshold value.
If the voltage level of the power supply control circuit 6 is equal to or lower than the device operable voltage level,
(In this case, "L") is output, and it is checked whether or not the battery 2 has a sufficient voltage supply capability.

The power supply control circuit 6 is connected to the control terminal CNT of the main power supply circuit 3 based on the logical product of the detect level signal a output from the voltage detection / comparison circuit 5 and the power supply control signal b output from the CPU 7. The power supply control signal c is output, and at the end of the reset signal d output from the reset generation circuit 8, when the detect level signal a output from the voltage detection comparison circuit 5 is "H", CP
A new reset signal e (in this case, "H") for releasing the reset state is output to U7, and when the detect level signal a output from the voltage detection / comparison circuit 5 is "L", As the power supply control signal c, an output indicating a detect (in this case, "L") is performed. In addition,
In FIG. 1, in the power supply control circuit 6, VCC is a voltage terminal, GND is a ground terminal, PW is a power-on terminal, and L
BT is a level input terminal, PC is a power supply control output terminal, RS
T is a reset terminal and NRST is a new reset terminal.

The CPU 7 controls the entire power supply device 1. For example, the power control signal b (in this case, " H ") is generated.

The reset generation circuit 8 is for outputting the reset signal d to the power supply control circuit 6 for a fixed time after the main power supply circuit 3 starts operating.

Next, the operation of this embodiment will be described.

First, the battery voltage detection operation when the power supply device 1 in FIG. 1 is applied to a portable information processing device will be described with reference to the flowchart shown in FIG.

FIG. 2 is a flow chart showing an operation example of this embodiment.

First, as in the conventional example shown in FIG. 4, when the battery 2 is attached to the portable information processing device (step S1),
A power supply voltage is supplied from the battery 2 to the sub power supply circuit 4 to activate the sub power supply circuit 4 (step S2).

When the sub power supply circuit 4 is activated, the sub power supply circuit 4
Supply a predetermined voltage to the CPU 7 from the C
The PU 7 activates the power supply control signal b output to the power supply control circuit 6 (“H”) (step S3).

In the voltage detection / comparison circuit 5, the battery 2
The voltage level of the battery 2 is detected, and whether or not the detected voltage level is higher than a preset threshold value is compared (step S4). Detect level signal a
By outputting ("L"), the power supply control circuit 6 sets the main power supply control signal c output to the control terminal CNT of the main power supply circuit 3 to "L", so that the main power supply circuit 3 does not operate, The portable information processing device does not start (step S5).

On the other hand, when the voltage of the battery 2 is higher than the threshold value, the power supply control circuit 6 controls the main power supply circuit 3 based on the power supply control signal b ("H") output from the power-on terminal PW of the CPU 7. Since "H" is output as the main power supply control signal c to the terminal CNT, the main power supply circuit 3 operates (step S5).

When the main power supply circuit 3 starts operating, the reset signal d ("H") from the reset generation circuit 8 and the new reset signal e ("L") from the power supply control circuit 6 are output (steps). S6). In this state, C
The PU 7 is in the reset state, and the battery 2 is under a load of about 50%.

Then, after a time interval of 50 ms to 100 ms, the output of the reset signal d is stopped (step S
7) Then, the voltage detection / comparison circuit 5 detects the voltage level of the battery 2 again, and compares whether the detected voltage level is larger than a preset threshold value (step S8) to determine the voltage of the battery 2 Is less than or equal to the threshold,
Detect level signal a to the power supply control circuit 6
By outputting ("L"), the main power supply control signal c output from the power supply control circuit 6 to the control terminal CNT of the main power supply circuit 3 is set to "L", and the operation of the main power supply circuit 3 is stopped ( In step S9), the portable information processing device does not start.

On the other hand, when the voltage of the battery 2 is higher than the threshold value, the new reset signal e output from the power supply control circuit 6 to the CPU 7 is stopped (step S10), and the CPU 7 is applied by resetting it. The power-supply control signal b (“H”) output from the power-on terminal PW of the CPU 7, the power-supply control circuit 6 supplies the control terminal CNT of the main power-supply circuit 3 with “H” as the main power-supply control signal c. , The main power supply circuit 3 operates as it is, and the entire portable information processing device is activated.

That is, until the main power supply circuit 3 is operated, it is the same as the conventional example, but after the operation of the main power supply circuit 3,
The reset signal d is released and the voltages of the batteries are compared again. At this time, if the potential of the batteries 2 is low, the supply of the power supply voltage to the main power supply circuit 3 is stopped. In this case, new reset signal 1
Since 2 is not released, malfunction can be prevented.

As described above, in this embodiment, immediately after the power is turned on, the CPU 7 is set in the reset state without supplying the power supply voltage from the battery 2 to the circuit, thereby applying a load,
Whether or not to activate the circuit is determined by determining the battery voltage at this time.

Therefore, the CPU is consumed by the exhausted battery 2.
7 and other circuits can be prevented from malfunctioning, which can prevent malfunctions due to insufficient remaining battery capacity and non-mounting of the battery, and can be used for power control circuits of all portable information equipment devices.

In the above embodiment, the load is applied by setting the CPU 7 in the reset state, but the present invention is not limited to this, and the load may be applied by other means. . However, in this case, it is necessary to add a special means for applying a load.

[0050]

According to the present invention, the voltage detection means detects not only the voltage value at the start of operation but also the voltage value of the power supply unit after a predetermined time from the start of operation, so that the voltage drop at the initial time of operation start in the power supply unit. Can be easily detected, and the state of voltage shortage can be reliably detected.

Therefore, it is possible to suppress the unstable supply of the power supply voltage when the voltage is insufficient, and it is possible to prevent the malfunction due to the insufficient voltage of the power supply destination.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a circuit example of a power supply device according to an embodiment.

FIG. 2 is a flowchart showing an operation example of one embodiment.

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

FIG. 4 is a flowchart showing an operation example of a conventional example.

[Explanation of symbols]

 1 power supply device 2 battery 3 main power supply circuit 4 sub power supply circuit 5 voltage detection comparison circuit 6 power supply control circuit 7 CPU 8 reset generation circuit IN input terminal OUT output terminal CNT control terminal VCC voltage terminal GND ground terminal PW power-on terminal LBT level input Terminal PC Power supply control output terminal RST Reset terminal NRST New reset terminal

Claims (1)

[Claims] 1. A power supply unit for supplying a predetermined power supply voltage required by the circuit to an arbitrary circuit, and detecting a voltage value of the power supply unit at the start of operation of the circuit and after a predetermined time from the start of operation of the circuit. And a voltage supply determining means for determining whether to supply the power supply voltage from the power supply unit to the circuit based on the detection result of the voltage detecting means. .