JP3061943B2 - Power control circuit - Google Patents

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 circuit for controlling power supplied to a portable terminal.

[0002]

2. Description of the Related Art A conventional power supply control circuit includes a switching element (Tr, FET, etc.) for controlling power supply to a circuit section of a portable terminal, a control LSI for controlling the switching element, and a control LSI. And a reference voltage generator serving as a reference. In addition, since a battery is used as a power source, the control LSI is provided with a power supply prohibition function when the battery voltage drops, and a battery voltage when the battery operates. A power alarm signal generation function is provided as a battery voltage monitoring signal by software when the battery voltage drops.

FIG. 2 is a block diagram showing an example of a conventional power supply control circuit. In the conventional example, 11 is a Ni-Cd battery,
12 is a reference voltage generation IC, 13 is a power control LSI, 14
Is a power switch, 15 is a power ON / OFF control block inside 13, 16 is a power alarm generation block inside 13,
17 is a power switching transistor, 18 is a portable terminal logic circuit unit, and 19 is an LCD panel unit. The supply of power from 11 to each unit device of the portable terminal such as 18 and 19 is controlled by 13 LSIs. 13 is 12 reference voltage generation ICs
All the power supply controls are executed based on the reference voltage generated by. 14 is turned on, the LO
The W-level pulse signal is input to 13, and 13 turns on the 17 transistor to supply power from 11 to 18 and 19. At this time, the 15 block sections inside 13 monitor the collector output voltage (supply voltage to 18 and 19) of 17 based on the reference voltage from 12, and if the collector voltage value is lower than a certain voltage level, 18 Turn off 17 transistors to avoid abnormal operation at low voltage of 19 and 19
To stop the power supply. That is, when the battery voltage level of 11 is below a certain voltage level, control is performed so that the power of the portable terminal body is not turned on. In addition, when the power supply is supplied to the switches 18 and 19 by the SW ON of the switch 14 and the voltage level of the switch 11 is reduced due to the consumption of the battery 11, the block 16 of the block 13 based on the reference voltage generated by the switch 12 is turned on. Has a function of generating a power supply alarm signal when the collector output voltage is monitored and becomes lower than a certain voltage level. Several types of power supply alarm signals are generated according to the monitoring voltage level. (The two types of ALM1 and ALM2 are shown in Fig. 2.) This alarm signal is monitored by software, and the operation of the Logic circuit of the main unit is limited or stopped for each alarm signal generation voltage level, thereby reducing the low power supply voltage level. It is possible to prevent a malfunction of the main body Logic circuit system at the time.

As described above, in the conventional example, since the twelve reference voltage generating ICs are directly connected to the battery power source of 11, the current is always consumed at 12 even when the portable terminal body is in the power-off state, and the consumption of the battery 11 is expedited. Would.

[0005]

In this conventional power supply control circuit, when the battery power supply is in a connected state in the reference voltage generation unit serving as the operation base of the control LSI, the current is constantly consumed. There is a problem that the battery is constantly consumed even in the OFF state, and the actual operation time of the main body is shortened.

[0006]

According to the present invention, there is provided a power supply control circuit for a portable terminal operated by a battery, comprising : a reference voltage for outputting a reference voltage for control;
Generating circuit and a tri-state output when the power switch is turned on.
Power from the battery by the power signal and the reference voltage.
The power supply control circuit for supplying to the portable terminal
And holds the trigger signal and outputs it as a high-level signal
A latch circuit that operates by the high-level signal and
A battery for supplying power from the battery to the reference voltage generating circuit;
And a buffer circuit.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of one embodiment of the present invention.

In this embodiment, 21 is a Ni-Cd battery, 22 is a power switch (SW), 23 is a latch circuit,
24 is a buffer IC, 25 is a reference voltage generation IC, 26 is a power control LSI, 27 is a power control unit, 28 is a power alarm generation block, 29 is a power switching transistor, 30 is a portable terminal logic circuit, and 31 is an LCD It is a panel.

When the power switch 22 is turned on, the power control LS
The transistor 29 is turned ON by I26, and the logic circuit 3
0 and the LCD panel unit 31 are supplied with power. Battery 2
1 when the power supply voltage level is low (Log
ic) A power-on prohibition function under the control of the power supply control unit 27 for protection of malfunctions of the circuit units 30 and 31 and a main unit Logic when the collector 29 output voltage of the transistor 29 decreases due to the consumption of the battery 21 during operation of the main unit. The operations of a series of units of the power supply alarm signal generation function under the control of the alarm generation unit 28 for protecting the circuit units 30 and 31 from malfunctioning are the same as those of the above-described conventional power supply control circuit.

In the method of supplying power to the reference voltage generating IC according to the present embodiment, when the power switch 22 is turned on, it is turned on.
The signal is input to the power supply control LSI 26 and becomes a trigger signal for activating the main body power supply control.
3 is input. The power supply SW22 of the latch circuit 23 is ON.
It has a function of latching an ON signal and continuously outputting a HIGH level signal from when the signal is turned off until the signal is turned off next time. The HIGH level signal output from the latch circuit 23 is input to the buffer IC 24 and
5 supplies power to the reference voltage generating IC 25 while the HIGH level signal of the latch circuit 23 is output.

In this case, the power is supplied to the reference voltage generation IC 25 only when the power switch 22 is turned on and the power supply of the portable terminal body is in the ON state. Thus, current is not always consumed. The logic circuit 3
0 and the power supply control LSI 26 have a C-MOS device configuration, and the current consumption when not operating (portable terminal main body power OFF state) is very small in the order of μA. , The actual operation time can be lengthened.

[0012]

The present invention described above, according to the present invention, in the reference voltage generating circuit unit which consumes the current always in the power supply control circuit, la only when the power ON of the portable terminal body
Since the switch circuit and the buffer circuit supply power from the battery, current consumption when the main body is turned off becomes extremely small, the load on the battery as the power source is reduced, and the actual operation time of the main body is extended. Has an effect.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a conventional power supply control circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Battery 22 Power supply SW 23 Latch circuit 24 Buffer IC 25 Reference voltage generation IC 26 Power supply control LSI 27 Power supply control unit 28 Power supply alarm generation unit 29 Transistor 30 Logic circuit unit 31 LCD panel

Claims (1)

(57) [Claims] A power supply control circuit of a portable terminal operated by a battery outputs a reference voltage for control.
Output when the power supply switch conducts
From the battery by the trigger signal and the reference voltage
The power supply for supplying power to the portable terminal
A control circuit, which holds the trigger signal and outputs a high-level signal;
And a latch circuit that outputs
Operates and supplies power from the battery to the reference voltage generation circuit.
And a buffer circuit for supplying power.