Patent Description:
At present, with the development of lithium batteries as energy storage devices of many electronic devices toward high power, low costs, and low standby power consumption, power of a battery is likely to be exhausted in long-time standby mode, failing to meet a long-time standby function required for electronic devices. In the prior art, to avoid power consumption caused by long-time standby of a battery, the battery, after being switched off, needs to be switched on using some additionally provided mechanical switches such as a button.

Document <CIT> discloses an automatic boot circuit for electronic equipment. When electronic equipment is connected and has a power supply adapter to charge to battery unit, the automatic boot circuit triggers the operation of a power management chip performing auto power-on.

Embodiments of the present invention provide a battery switch-on circuit to achieve automatic switch-on of a battery power supply unit when a load is connected.

The present invention provides a battery switch-on circuit, the battery switch-on circuit including a power supply circuit and a switch circuit, where:.

Optionally, the battery switch-on circuit further includes a chip working power supply; and the dual-channel voltage comparison unit includes a dual-channel comparator, the reference voltage is preset in the dual-channel comparator, the dual-channel comparator includes a power supply terminal, and the power supply terminal is electrically connected to the chip working power supply.

Optionally, the dual-channel voltage comparison unit further includes a third voltage dividing resistor and a fourth voltage dividing resistor; the dual-channel comparator includes a first input terminal and a first output terminal;.

Optionally, the dual-channel voltage comparison unit further includes a reference voltage unit, and the dual-channel comparator includes a first reference voltage terminal and a second reference voltage terminal; and
an output terminal of the reference voltage unit is electrically connected to the first reference voltage terminal and the second reference voltage terminal respectively, and the reference voltage unit is configured to control both the first reference voltage terminal and the second reference voltage terminal to be kept at the reference voltage.

Optionally, the reference voltage unit includes a reference voltage device and a seventh resistor; and
the reference voltage device includes a reference terminal, the reference terminal is electrically connected to the chip working power supply by the seventh resistor, and the reference terminal is further electrically connected to the first reference voltage terminal and the second reference voltage terminal respectively.

Optionally, the switch control unit includes a first switch device, a second switch device, a third switch device, a pull-down resistor, and a pull-up resistor, where:.

Optionally, the first switch device is a p-channel metal-oxide-semiconductor (PMOS), and the second switch device, the third switch device, and the fourth switch device are all n-channel metal-oxide-semiconductors (NMOSs).

Optionally, an output voltage of the first voltage power supply is <NUM> V.

Optionally, an output voltage of the battery power supply unit is <NUM> V, and an initial floating voltage of the output terminal of the fourth switch device is <NUM> V.

The embodiments of the present invention disclose a battery switch-on circuit, including a power supply circuit and a switch circuit. The power supply circuit includes a battery power supply unit, a first voltage dividing resistor, a second voltage dividing resistor, and a fourth switch device. The switch circuit includes a dual-channel voltage comparison unit and a switch control unit. A first input terminal of the dual-channel voltage comparison unit is electrically connected to a positive electrode of the battery power supply unit. A second input terminal of the dual-channel voltage comparison unit is electrically connected to an output terminal of the fourth switch device. The dual-channel voltage comparison unit is configured to transmit, when a positive electrode voltage of the battery power supply unit is lower than a reference voltage, a first control signal to the first control terminal of the switch control unit to cause the switch control unit to control the fourth switch device to switch off, and is further configured to transmit, when an output terminal voltage of the fourth switch device is higher than the reference voltage, a second control signal to the second control terminal of the switch control unit to cause the switch control unit to control the fourth switch device to switch on. Whereby, automatic switch-on of the battery power supply unit is achieved when a load is connected.

The following further describes embodiments of the present invention in detail with reference to the accompanying drawings and embodiments. It may be understood that specific embodiments described herein are only used to explain the embodiments of the present invention, but not to limit the embodiments of the present invention. In addition, it should be further noted that, for ease of description, the accompanying drawings only show parts relevant to the embodiments of the present invention rather than the entire structure.

<FIG> is a diagram of a power supply circuit of a battery switch-on circuit according to an embodiment of the present invention, and <FIG> is a diagram of a switch circuit of a battery switch-on circuit according to an embodiment of the present invention. As shown in <FIG>, the battery switch-on circuit includes a power supply circuit and a switch circuit.

Referring to <FIG>, the power supply circuit includes a battery power supply unit <NUM>, a first voltage dividing resistor R1, a second voltage dividing resistor R2, and a fourth switch device Q4. A positive electrode of the battery power supply unit <NUM> is connected to a first terminal of the first voltage dividing resistor R1. A negative electrode of the battery power supply unit <NUM> is electrically connected to a first terminal of the second voltage dividing resistor R2 and an input terminal of the fourth switch device Q4 respectively. A second terminal of the first voltage dividing resistor R1 and a second terminal of the second voltage dividing resistor R2 are electrically connected to each other and are further connected in parallel to an output terminal of the fourth switch device Q4.

Referring to <FIG>, the switch circuit includes a dual-channel voltage comparison unit <NUM> and a switch control unit <NUM>. The dual-channel voltage comparison unit <NUM> includes a first input terminal PACK+ and a first output terminal a7 disposed opposite to each other and a second input terminal PACK- and a second output terminal a1 disposed opposite to each other. With reference to <FIG>, the first input terminal PACK+ is electrically connected to the positive electrode of the battery power supply unit <NUM>, the first output terminal a7 is electrically connected to a first control terminal of the switch control unit <NUM>, the second input terminal PACK- is electrically connected to the output terminal of the fourth switch device Q4, the second output terminal a1 is electrically connected to a second control terminal of the switch control unit <NUM>, and an output terminal 12V POWR_SEC of the switch control unit <NUM> is electrically connected to a control terminal of the fourth switch device Q4.

The dual-channel voltage comparison unit <NUM> is configured to transmit, when a positive electrode voltage of the battery power supply unit <NUM> is lower than a reference voltage, a first control signal to the first control terminal of the switch control unit <NUM> to cause the switch control unit <NUM> to control the fourth switch device Q4 to switch off, and is further configured to transmit, when an output terminal voltage of the fourth switch device Q4 is higher than the reference voltage, a second control signal to the second control terminal of the switch control unit <NUM> to cause the switch control unit <NUM> to control the fourth switch device Q4 to switch on.

When no load is connected, the fourth switch device Q4 is off, a voltage signal of the battery power supply unit <NUM> is divided by the first voltage dividing resistor R1 and the second voltage dividing resistor R2, and then the output terminal of the fourth switch device Q4 outputs an initial floating voltage. For example, the battery power supply unit <NUM> supplies a voltage of <NUM> V, and the initial floating voltage is <NUM> V.

When a load is connected, the positive electrode and the negative electrode of the battery power supply unit <NUM> are short-circuited, a voltage outputted by the output terminal of the fourth switch device Q4 is equal to the positive electrode voltage of the battery power supply unit <NUM>, the output terminal voltage of the fourth switch device Q4 is higher than the reference voltage, and the dual-channel voltage comparison unit <NUM> transmits the second control signal to the second control terminal of the switch control unit <NUM> to cause the fourth switch device Q4 to switch on. When the positive electrode voltage of the battery power supply unit <NUM> is insufficient, i.e., the positive electrode voltage of the battery power supply unit <NUM> is lower than the reference voltage, the dual-channel voltage comparison unit <NUM> transmits the first control signal to the first control terminal of the switch control unit <NUM> to cause the fourth switch device Q4 to switch off. In this way, when a load is connected and the output terminal voltage of the fourth switch device Q4 is equal to the positive electrode voltage of the battery power supply unit <NUM>, the battery power supply unit <NUM> is connected to an external load, and when electric power in the battery power supply unit <NUM> is insufficient or when no load is connected, the battery power supply unit <NUM> is disconnected from the external load. Whereby, automatic switch-on of the battery power supply unit <NUM> is achieved when a load is connected, thereby avoiding power consumption caused by long-time standby of the battery.

Further, based on the foregoing embodiment, optionally, the battery switch-on circuit further includes a chip working power supply P3V3 STBY.

Still referring to <FIG>, the dual-channel voltage comparison unit <NUM> includes a dual-channel comparator U2. The reference voltage is preset in the dual-channel comparator U2. The dual-channel comparator U2 includes a power supply terminal a8. The power supply terminal a8 is electrically connected to the chip working power supply P3V3 STBY.

The chip working power supply P3V3 STBY is electrically connected to the power supply terminal a8 of the dual-channel comparator, and is configured to supply power to the dual-channel comparator U2. For example, the chip working power supply P3V3 STBY supplies a <NUM> V direct current to continuously supply power to the dual-channel comparator U2, so that the dual-channel comparator U2 keeps working without consuming electric power in the battery power supply unit.

Optionally, the dual-channel voltage comparison unit <NUM> further includes a reference voltage unit <NUM>, and the dual-channel comparator U2 includes a first reference voltage terminal a2 and a second reference voltage terminal a5; and
an output terminal of the reference voltage unit <NUM> is electrically connected to the first reference voltage terminal a2 and the second reference voltage terminal a5 respectively, and the reference voltage unit <NUM> is configured to control both the first reference voltage terminal a2 and the second reference voltage terminal a5 to be kept at the reference voltage.

Optionally, the reference voltage unit <NUM> includes a reference voltage device U1 and a seventh resistor R7; and
the reference voltage device U1 includes a reference terminal, the reference terminal b1 is electrically connected to the chip working power supply P3V3 STBY by the seventh resistor R7, and the reference terminal b1 is further electrically connected to the first reference voltage terminal a2 and the second reference voltage terminal a5 respectively.

The chip working power supply P3V3 STBY is electrically connected to the reference terminal b1 of the reference voltage device U1 by the seventh resistor R7, and is configured to supply power to the reference voltage device U1. For example, the chip working power supply P3V3 STBY supplies a <NUM> V direct current, and the chip working power supply P3V3 STBY serves as a backup power supply to avoid consuming electric power in the battery power supply unit <NUM>, and continuously supplies power to the reference voltage device U1.

The reference voltage unit <NUM> supplies a reference voltage of <NUM> V, the output terminal of the reference voltage unit <NUM> is electrically connected to the first reference voltage terminal a2 and the second reference voltage terminal a5 respectively, and the first reference voltage terminal a2 and the second reference voltage terminal a5 in the dual-channel comparator U2 are kept at a reference voltage value of <NUM> V.

Referring to <FIG>, optionally, the dual-channel voltage comparison unit <NUM> further includes a third voltage dividing resistor R3 and a fourth voltage dividing resistor R4.

The dual-channel comparator U2 includes a first input terminal a6 and a first output terminal a7 disposed opposite to each other.

A first terminal of the third voltage dividing resistor R3 is electrically connected to the positive electrode of the battery power supply unit <NUM>, a first terminal of the fourth voltage dividing resistor R4 is connected to a ground terminal, and a second terminal of the third voltage dividing resistor R3 and a second terminal of the fourth voltage dividing resistor R4 are electrically connected to each other and are connected to the first input terminal a6 of the dual-channel comparator U2.

The dual-channel comparator U2 is configured to transmit the first control signal to the first control terminal of the switch control unit <NUM> through the first output terminal a7 of the dual-channel comparator U2 when it is detected that a voltage at the first input terminal a6 of the dual-channel comparator U2 is lower than the reference voltage.

Optionally, the dual-channel voltage comparison unit <NUM> further includes a fifth voltage dividing resistor R5 and a sixth voltage dividing resistor R6.

A first terminal of the fifth voltage dividing resistor R5 is electrically connected to the output terminal of the fourth switch device Q4, and a first terminal of the sixth voltage dividing resistor R6 and a second terminal of the fifth voltage dividing resistor R5 are electrically connected to each other and are connected to a second input terminal a3 of the dual-channel comparator U2.

The dual-channel comparator U2 is configured to transmit the second control signal to the second control terminal of the switch control unit <NUM> through the second output terminal a1 of the dual-channel comparator U2 when it is detected that a voltage at the second input terminal a3 of the dual-channel comparator U2 is higher than the reference voltage.

Optionally, the switch control unit <NUM> includes a first switch device Q1, a second switch device Q2, a third switch device Q3, a pull-down resistor R8, and a pull-up resistor R9.

A gate of the second switch device Q2 is electrically connected to the second output terminal a1 of the dual-channel voltage comparison unit <NUM>, a source of the second switch device Q2 is connected to a ground terminal, and a drain of the second switch device Q2 is connected to a first terminal of the pull-down resistor R8.

A gate of the third switch device Q3 is electrically connected to the first output terminal a7 of the dual-channel voltage comparison unit <NUM>, a source of the third switch device Q3 is connected to the ground terminal, and a drain of the third switch device Q3 is electrically connected to the second output terminal a1 of the dual-channel voltage comparison unit <NUM>.

A second terminal of the pull-down resistor R8 is electrically connected to a first terminal of the pull-up resistor R9 and a gate of the first switch device Q1 respectively, a source of the first switch device Q1 and a second terminal of the pull-up resistor R9 are electrically connected to each other and are connected to a first voltage power supply 12V POWR, and a drain 12V POWR_SEC of the first switch device Q1 is electrically connected to the control terminal of the fourth switch device Q4.

The pull-down resistor R8 and the pull-up resistor R9 provide a current limiting function.

It should be noted that the working principle of the battery switch-on circuit is as follows: when a load is connected, the positive electrode and the negative electrode of the battery power supply unit <NUM> are short-circuited, and the output terminal of the fourth switch device Q4 outputs a relatively large voltage signal, which is then divided by the third voltage dividing resistor R3 and the fourth voltage dividing resistor R4 and transmitted to the second input terminal a3 of the dual-channel comparator U2. In this way, the voltage at the second input terminal a3 of the dual-channel comparator U2 is higher than the voltage at the second reference voltage terminal a2, and the second output terminal a1 of the dual-channel comparator U2 outputs a high level, to drive the second switch device Q2 to switch on and pull down the voltage at the gate of the first switch device. In this case, the first switch device Q1 is on, the voltage signal of the first voltage power supply 12V POWR is outputted to the gate of the fourth switch device Q4 through the first switch device Q1, and the fourth switch device is on, thereby achieving automatic switch-on of the battery power supply unit. When electric power in the battery power supply unit <NUM> is insufficient, i.e., when the positive electrode voltage of the battery power supply unit <NUM> is insufficient, the voltage signal is divided by the fifth voltage dividing resistor R5 and the sixth voltage dividing resistor R6 and then transmitted to the first input terminal a6 of the dual-channel comparator U2. In this case, the voltage at the first input terminal a6 of the dual-channel comparator U2 is higher than the voltage at the first reference voltage terminal a2, and the first output terminal a7 of the dual-channel comparator U2 outputs a high level, to drive the third switch device Q3 to switch on and pull down the voltage at the gate of the second switch device Q2. In this case, the second switch device Q2 is off, the pull-up resistor R9 pulls up the voltage at the gate of the first switch device, the first switch device Q1 is off, the first switch power supply 12V POWR_SEC cannot transmit the voltage signal to the fourth switch device Q4, the fourth switch device Q4 is off, and the battery power supply unit is in an off state.

Optionally, the first switch device Q1 is a PMOS, and the second switch device Q2, the third switch device Q3, and the fourth switch device Q4 are all NMOSs.

Optionally, an output voltage of the battery power supply unit <NUM> is <NUM> V.

According to this technical solution, when no load is connected, the fourth switch device Q4 is off; when a load is connected, the voltage at the output terminal of the fourth switch device Q4 increases, and after voltage comparison by the dual-channel comparator U2, the second output terminal a1 of the dual-channel comparator U2 outputs a high voltage, to control the second switch device Q2 to switch on, so as to pull down the voltage at the gate of the first switch device Q1, and the first switch device Q1 is on. Then the first voltage power supply 12V POWR outputs a voltage signal to the gate of the fourth switch device Q4 through the first switch device Q1 to control the fourth switch device Q4 to switch on, thereby achieving a connection between the battery power supply unit and the load. When electric power in the battery power supply unit <NUM> is insufficient, i.e., when the positive electrode voltage of the battery power supply unit <NUM> is lower than the reference voltage, the first output terminal a7 of the dual-channel comparator U2 outputs a high level after voltage comparison by the dual-channel comparator U2, to control the third switch device to switch on, so as to pull down (the voltage of) the control terminal of the second switch device, then the second switch device and the first switch device are off, the first voltage power supply 12V POWR cannot output the voltage signal to the gate of the fourth switch device Q4, and the fourth switch device Q4 is off, thereby achieving automatic switch-on of the battery power supply unit when a load is connected, and avoiding power consumption caused by long-time standby of the battery.

Claim 1:
A battery switch-on circuit, comprising: a power supply circuit and a switch circuit, wherein:
the power supply circuit comprises a battery power supply unit (<NUM>), a first voltage dividing resistor (R1), a second voltage dividing resistor (R2), and a fourth switch device (Q4), wherein a positive electrode of the battery power supply unit (<NUM>) is connected to a first terminal of the first voltage dividing resistor (R1), a negative electrode of the battery power supply unit (<NUM>) is electrically connected to a first terminal of the second voltage dividing resistor (R2) and an input terminal of the fourth switch device (Q4) respectively, and a second terminal of the first voltage dividing resistor (R1) and a second terminal of the second voltage dividing resistor (R2) are electrically connected to each other;
the switch circuit comprises a dual-channel voltage comparison unit (<NUM>) and a switch control unit (<NUM>), the dual-channel voltage comparison unit comprises a first input terminal (PACK+) and a first output terminal (a7) and a second input terminal (PACK-) and a second output terminal (a1), the first input terminal (PACK+) is electrically connected to the positive electrode of the battery power supply unit (<NUM>), the first output terminal is electrically connected to a first control terminal of the switch control unit, the second input terminal (PACK-) is electrically connected to the output terminal of the fourth switch device (Q4), the second output terminal is electrically connected to a second control terminal of the switch control unit, and an output terminal (12V POWR_SEC) of the switch control unit is electrically connected to a control terminal of the fourth switch device (Q4); and
the dual-channel voltage comparison unit is configured to transmit, when a positive electrode voltage of the battery power supply unit (<NUM>) is lower than a reference voltage, a first control signal to the first control terminal of the switch control unit to cause the switch control unit to control the fourth switch device (Q4) to switch off, and is further configured to transmit, when an output terminal voltage of the fourth switch device (Q4) is higher than the reference voltage, a second control signal to the second control terminal of the switch control unit to cause the switch control unit to control the fourth switch device (Q4) to switch on.