JPS59162734A - Power source circuit of small-sized electronic device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a power supply circuit for small electronic equipment.

This is a power supply circuit for a small bubble electronic device that can use two types of power sources: an external power source and an internal power source, and has a dedicated converter for each power source, and can operate by switching between the two chamber sources depending on the usage conditions. A conventional embodiment is shown in FIG. In FIG. 1, an external power supply 1 is connected to an internal power supply circuit of an electronic device through a connector 2, and a power supply switching relay 7 turns the relay contact 8 ON to the α side. When the power switch 3 is turned on and off from the above state, the voltage changes at the contact A1 of the power switch 3 and the contact B of the back amplifier capacitor 9 at the time of power switching are shown in Figure 2. In other words, when the power switch 3 is turned on, The external power supply converter 4 is activated, charging begins in the backup capacitor f9, and the voltage V required for the load 10 is reached with a rise time of several hundred milliseconds. If the load circuit 10 is a circuit using a microprocessor, the power-on clear circuit of the load circuit 10 will not operate if the rise time of the power supply voltage is several hundred milliseconds as shown in Figure 2. It often happens that the microprocessor goes out of control.

The present invention overcomes the above drawbacks by providing a delay relay contact between the power switching backup capacitor and the load electrical circuit.

The present invention will be described in detail below with reference to an embodiment shown in FIG. As in the embodiment shown in FIG. 1, when the external power supply 1 is connected to the internal power supply circuit of the electronic device through the cover 2, the power supply switching relay 7 turns the relay contact 8 ON to the α side. From the above state, turn off the power switch 3.
FIG. 4 shows the voltage changes at the contact B of the backup capacitor 9 and the input terminal 0 of the power input section of the load circuit 10 when the power source is switched to contact A1 of the power switch 3. That is, if the power switch 3 is turned on in the above state, the external power converter 4 is activated and the backup capacitor 9 is charged, but as long as the contact 13 of the relay 12 is on the b side, power is not supplied to the load circuit 10. The voltage at the zero point remains zero. When the delay time of the delay circuit 11 is reached after the power switch is turned on, the relay 12 is activated, and the contact 13 of the relay is turned on to the α side. Here, the delay time of the delay circuit 11 is determined by the backup capacitor 9.
Set to several hundred milliseconds or more, which is the voltage rise time of n.
For example, the rising voltage at input terminal 0 of load circuit 10 is applied to input terminal C of load circuit 10 because relay contact 13 moves from side b to side α after charging of backup capacitor 9 is completed. The rise of the voltage is the fourth
As described above, according to the present invention, by delaying the output of the power supply to the load, charging of the backup capacitor is completed to a specified voltage, and then the voltage is input to the load circuit. The voltage applied to the load circuit rises steeply, allowing the power-on clear circuit of the load circuit to operate normally. At the same time, there is also the effect of canceling out the chattering of the power switch.

[Brief explanation of the drawing]

Figure 12 is a power supply system diagram of a conventional small electronic device that has an FU circuit that can use two types of power supplies. FIG. 2 is a diagram showing changes in voltage at contact A1 and contact B in the circuit of FIG. 1 when power switch 3 is turned on at 077. FIG. 3 is a power supply system diagram of a small electronic device having an OPU circuit according to the present invention. Figure 4 shows contact A1 contact B and terminal 0 of the power supply circuit in Figure 3.
FIG. 3 is a diagram showing changes in voltage when the power switch 3 is turned on and off. 1. External power supply 20. Connector 30. Power switch 40. Comparator 5° for external power supply, built-in battery - Taro. Built-in battery converter 7. Power switching relay 80. Relay connection 9. Backup capacitor points 10,. Load 11° with OPU circuit. Delayed entrance/road [20. Power output relay 13
0. Relay [2 contacts 140. Discharge resistance of backup capacitor 9 Applicant: Daini Seikosha Co., Ltd. Patent attorney Tsutomu Mogami

Claims (1)

[Claims] It uses two types of power sources, an external power source and a built-in battery, and has a dedicated converter for each power source, making it possible to switch between the two power sources without affecting the operation of the device even while the device is in operation. A power supply circuit for a small electronic device, characterized in that a power output delay circuit is provided between a power output section and a load circuit section.