Charging circuit for interphone

Abstract

The utility model provides a charging circuit for an interphone, which comprises a charging interface, a sampling resistor, a charging module, a first-stage comparison module, a second-stage comparison module, a switch module and an indication module, one end of the sampling resistor is connected with the output end of the charging interface, the other end of the sampling resistor is connected with the input end of the charging module, and the output end of the charging module is connected with a battery. The non-inverting input end of the first-stage comparison module is connected with the output end of the charging interface, the inverting input end of the first-stage comparison module is connected with the input end of the charging module, the output end of the first-stage comparison module is connected with the inverting input end of the second-stage comparison module, the non-inverting input end of the second-stage comparison module is connected with the output end of the charging interface, and the output end of the second-stage comparison module is connected with the control end of the switch module. The charging state can be accurately displayed, the circuit is simple, and the cost is low.

Description

Technical Field

[0001] The utility model relates to a charging circuit for a walkie-talkie. Background Art

[0002] A walkie-talkie is a two-way mobile communication tool. It allows calls without any network support and does not incur phone charges. It is suitable for relatively fixed and frequent calls. With the development of battery technology, the battery life is getting better and better, and the performance of batteries has also improved a lot. In order to meet the market demand for lighter and thinner walkie-talkies, walkie-talkies with built-in batteries have appeared. The batteries of such walkie-talkies are charged through a special charging module. In order to intuitively indicate the status of charging or charging completion, the charging chip in the charging module displays different indication signals through the control indication mechanism.

[0003] However, in actual use, it is found that existing charging chips often give inaccurate indications. For example, the battery has been fully charged, but the charging chip does not promptly control the indication mechanism to switch the indication signal. This not only greatly reduces the user experience, but also loses the meaning of the charging indication. Utility Model Content

[0004] The utility model provides a charging circuit for a walkie-talkie, which can accurately display the charging state and has a simple circuit and low cost.

[0005] The utility model is realized by the following technical solutions:

[0006] A charging circuit for a walkie-talkie, comprising a charging interface, a sampling resistor, a charging module, a first-level comparison module, a second-level comparison module, a switch module and an indication module, wherein one end of the sampling resistor is connected to an output end of the charging interface, and the other end is connected to an input end of the charging module, the output end of the charging module is connected to a battery, a positive-phase input end of the first-level comparison module is connected to an output end of the charging interface, an inverting input end is connected to an input end of the charging module, and an output end is connected to an inverting input end of a second-level comparison module, a positive-phase input end of the second-level comparison module is connected to an output end of the charging interface, and an output end is connected to a control end of a switch module, the charging module controls fast charging or trickle charging of the battery, the second-level comparison module outputs a voltage value corresponding to fast charging or trickle charging, and the switch module controls the indication module to act according to the voltage value to send different indication signals corresponding to fast charging or trickle charging. A sampling resistor is used to create a voltage difference between the output end of the charging interface and the input end of the charging module. The charging currents of fast charging and trickle charging are different, which makes the voltage difference different, and thus makes the voltage value output by the second set of comparison modules different. The switch module can control the action of the indication module according to the different voltage values ​​in the two cases to send out different indication signals. In this way, it can be ensured that when the charging current changes, the indication signal sent by the indication module also changes, thereby accurately displaying the charging status. The circuit is simple and the cost is low.

[0007] Furthermore, the sampling resistor has a resistance of 0.08Ω-0.15Ω, which can reduce the load effect of too large a resistance on the charging power supply connected to the charging interface, avoiding affecting the normal operation of the charging module, while at the same time not entering the offset voltage range of the operational amplifier due to too small a resistance, thereby ensuring the normal operation of the operational amplifier.

[0008] Furthermore, the first-stage comparison module includes a first operational amplifier, a first resistor having one end connected to the non-phase input terminal of the first operational amplifier, a second resistor connected between the non-phase input terminal of the first operational amplifier and ground, a third resistor having one end connected to the inverting input terminal of the first operational amplifier, and a fourth resistor connected between the output terminal and the inverting input terminal of the first operational amplifier. The other end of the first resistor serves as the non-phase input terminal of the first-stage comparison module, the other end of the third resistor serves as the inverting input terminal of the first-stage comparison module, and the output terminal of the first operational amplifier serves as the output terminal of the first-stage comparison module, so that the comparison function is realized with a simple circuit.

[0009] Furthermore, the second-stage comparison module includes a second operational amplifier, a fifth resistor having one end connected to the non-phase input terminal of the second operational amplifier, a sixth resistor connected between the non-phase input terminal of the second operational amplifier and ground, a seventh resistor having one end connected to the inverting input terminal of the second operational amplifier, and an eighth resistor connected between the output terminal and the inverting input terminal of the second operational amplifier. The other end of the fifth resistor serves as the non-phase input terminal of the second-stage comparison module, the other end of the seventh resistor serves as the inverting input terminal of the second-stage comparison module, and the output terminal of the second-stage comparator serves as the output terminal of the second-stage comparison module, so that the comparison function is realized with a simple circuit.

[0010] Furthermore, the switch module includes a single-pole double-throw analog switch chip, the single-pole double-throw analog switch chip has a control pin, a common pin, a first output pin and a second output pin, the output end of the second-level comparison module is connected to the control pin, and the single-pole double-throw analog switch chip controls the common pin to be connected to the first output pin or the second output pin according to the voltage of the control pin.

[0011] Furthermore, the indication module includes a first light-emitting diode and a second light-emitting diode, the anode of the first light-emitting diode and the cathode of the second light-emitting diode are connected to the first output pin of the single-pole double-throw analog switch chip, the cathode of the first light-emitting diode and the anode of the second light-emitting diode are connected to the second output pin of the single-pole double-throw analog switch chip, the single-pole double-throw analog switch chip controls the on and off of the two light-emitting diodes, and the circuit is simple and reliable.

[0012] Furthermore, the indication module also includes a ninth resistor connected between the first output pin of the single-pole double-throw analog switch chip and the ground, and a tenth resistor connected between the second output pin of the single-pole double-throw analog switch chip and the ground.

[0013] Furthermore, the charging module includes a charging chip.

[0014] Furthermore, a first capacitor is connected between the non-inverting input terminal and the inverting input terminal of the first operational amplifier, and a second capacitor is connected between the non-inverting input terminal and the inverting input terminal of the second operational amplifier to filter out common-mode interference of high-frequency components. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0016] Figure 1 This is a circuit schematic diagram of the utility model.

[0017] Among them, 1. charging interface; 2. charging module; 3. first-level comparison module; 4. second-level comparison module; 5. switch module; 6. indication module; 7. battery; R1-R10, first resistor to tenth resistor; R11, sampling resistor; C1, first capacitor; C2, second capacitor; U1-1, first operational amplifier; U1-2, second operational amplifier; U2, single-pole double-throw analog switch chip; D1, first light-emitting diode; D2, second light-emitting diode. DETAILED DESCRIPTION

[0018] like Figure 1 As shown, the charging circuit for the intercom includes a charging interface 1, a sampling resistor R11, a charging module 2, a first-level comparison module 3, a second-level comparison module 4, a switch module 5 and an indication module 6. One end of the sampling resistor R11 is connected to the output end of the charging interface 1, and the other end is connected to the input end of the charging module 2. The output end of the charging module 2 is connected to the positive electrode of the battery 7. The positive input end of the first-level comparison module 3 is connected to the output end of the charging interface 1, the inverting input end is connected to the input end of the charging module 2, and the output end is connected to the inverting input end of the second-level comparison module 4. The positive input end of the second-level comparison module 4 is connected to the output end of the charging interface 1, and the output end is connected to the control end of the switch module 5. The charging module 2 controls the fast charging or trickle charging of the battery 7. The second-level comparison module 4 outputs a voltage value corresponding to the fast charging or trickle charging, and the switch module 5 controls the indication module 6 to act according to the voltage value to send different indication signals corresponding to the fast charging or trickle charging. In order not to affect the normal operation of the charging module 2, the resistance range of the sampling resistor R11 is 0.08Ω-0.15Ω. In this embodiment, the resistance of the sampling resistor R11 is 0.1Ω. In this embodiment, the charging module 2 includes a charging chip, the specific model is ETA6072.

[0019] More specifically, the first comparison module includes a first-level comparison module 3 including a first operational amplifier U1-1, a first resistor R1 having one end connected to the positive input terminal of the first operational amplifier U1-1, a second resistor R2 connected between the positive input terminal of the first operational amplifier U1-1 and ground, a third resistor R3 having one end connected to the inverting input terminal of the first operational amplifier U1-1, a fourth resistor R4 connected between the output terminal and the inverting input terminal of the first operational amplifier U1-1, and a first capacitor C1 connected between the positive input terminal and the inverting input terminal of the first operational amplifier U1-1, the other end of the first resistor R1 serves as the positive input terminal of the first-level comparison module 3, the other end of the third resistor R3 serves as the inverting input terminal of the first-level comparison module 3, and the output terminal of the first operational amplifier U1-1 serves as the output terminal of the first-level comparison module 3. The second-stage comparison module 4 includes a second operational amplifier U1-2, a fifth resistor R5 having one end connected to the non-inverting input terminal of the second operational amplifier U1-2, a sixth resistor R6 connected between the non-inverting input terminal of the second operational amplifier U1-2 and ground, a seventh resistor R7 having one end connected to the inverting input terminal of the second operational amplifier U1-2, an eighth resistor R8 connected between the output terminal and the inverting input terminal of the second operational amplifier U1-2, and a second capacitor C2 connected between the non-inverting input terminal and the inverting input terminal of the second operational amplifier U1-2, the other end of the fifth resistor R5 serves as the non-inverting input terminal of the second-stage comparison module 4, the other end of the seventh resistor R7 serves as the inverting input terminal of the second-stage comparison module 4, and the output terminal of the second-stage comparator serves as the output terminal of the second-stage comparison module 4. In this embodiment, the first operational amplifier U1-1 and the second operational amplifier U1-2 are dual operational amplifier chips of model BA2904.

[0020] The switch module 5 includes a single-pole double-throw analog switch chip U2, which has a control pin, a common pin, a first output pin and a second output pin. The output end of the second-stage comparison module 4 is connected to the control pin, and the single-pole double-throw analog switch chip U2 controls the common pin to be connected to the first output pin or the second output pin according to the voltage of the control pin. The indication module 6 includes a first light-emitting diode D1, a second light-emitting diode D2, a ninth resistor R9 and a tenth resistor R10. The anode of the first light-emitting diode D1 and the cathode of the second light-emitting diode D2 are connected to the first output pin of the single-pole double-throw analog switch chip U2, the cathode of the first light-emitting diode D1 and the anode of the second light-emitting diode D2 are connected to the second output pin of the single-pole double-throw analog switch chip U2, the ninth resistor R9 is connected between the first output pin of the single-pole double-throw analog switch chip U2 and the ground, and the tenth resistor R10 is connected between the second output pin of the single-pole double-throw analog switch chip U2 and the ground. In this embodiment, the selected single-pole double-throw analog switch chip U2 model is CS3157.

[0021] In this embodiment, the resistance of the first resistor R1 is 150KΩ, the resistance of the second resistor R2 is 300KΩ, the resistance of the third resistor R3 is 300KΩ, the resistance of the fourth resistor R4 is 150KΩ, the resistance of the fifth resistor R5 is 100KΩ, the resistance of the sixth resistor R6 is 1KΩ, the resistance of the seventh resistor R7 is 1MΩ, and the resistance of the eighth resistor R8 is 10KΩ.

[0022] In this embodiment, the charging interface 1 provides a 5V voltage and a fast charging current I 充 Set to 1.5A, trickle charge current I 充 Let's take 0.12A as an example to explain the working principle:

[0023] First, the voltage of the battery 7 is rapidly increased by a fast charge current. When the voltage of the battery 7 reaches the fully charged potential, the battery 7 is continuously charged by a very small trickle charge current to increase the saturation of the battery 7.

[0024] Assume that the output voltage of charging interface 1 is U 参考点 =5V, the voltage after sampling resistor R11 is U 采样点 =5-0.1*I 充 , the output U of the first stage comparison module 3 1 =2*(U 参考点 –U 采样点 )=2*[5-(5-0.1*I 充 )]=0.2*I 充 , the output of the second level comparison module

[0025]

[0026] During fast charging,

[0027] The output U of the second stage comparison module 2 =5-20*1.5, the inverting voltage of the second operational amplifier U1-2 is greater than the positive voltage, and the output is low level, the common pin (pin 4) of the single-pole double-throw analog switch chip U2 is connected to the first output pin (pin 3), 5U supplies power to the first light-emitting diode D1 through the pin 3 of the single-pole double-throw analog switch chip U2, and the first light-emitting diode D1 is forward-conducted and lights up, indicating that the battery 7 is charging;

[0028] When the water is filled,

[0029] The output U of the second stage comparison module 2 =5-20*0.12=2.6V, this voltage reaches the switching threshold of the single-pole double-throw analog switch chip U2, the common pin of the single-pole double-throw analog switch chip U2 is turned on to the second output pin (pin 1), 5U supplies power to the second light-emitting diode D2 through pin 1 of the single-pole double-throw analog switch chip U2, the second light-emitting diode D2 is forward-conducted and lights up, indicating that the battery 7 is fully charged and is being trickle-charged.

[0030] The above description is only a preferred embodiment of the present utility model, and therefore cannot be used to limit the scope of implementation of the present utility model. That is, equivalent changes and modifications made according to the scope of the patent application of the present utility model and the contents of the specification should still fall within the scope covered by the patent of the present utility model.

Claims

1. A charging circuit for a walkie-talkie, characterized in that: The invention comprises a charging interface, a sampling resistor, a charging module, a first-level comparison module, a second-level comparison module, a switch module and an indication module. One end of the sampling resistor is connected to the output end of the charging interface, and the other end is connected to the input end of the charging module. The output end of the charging module is connected to the battery. The positive input end of the first-level comparison module is connected to the output end of the charging interface, the negative input end is connected to the input end of the charging module, and the output end is connected to the negative input end of the second-level comparison module. The positive input end of the second-level comparison module is connected to the output end of the charging interface, and the output end is connected to the control end of the switch module. The charging module controls fast charging or trickle charging of the battery. The second-level comparison module outputs voltage values ​​corresponding to fast charging or trickle charging respectively. The switch module controls the indication module to act according to the voltage value to send different indication signals corresponding to fast charging or trickle charging respectively.

2. A charging circuit for a walkie-talkie according to claim 1, characterized in that: The resistance of the sampling resistor is 0.08Ω-0.15Ω.

3. A charging circuit for a walkie-talkie according to claim 1, characterized in that: The first-stage comparison module includes a first operational amplifier, a first resistor having one end connected to the non-inverting input terminal of the first operational amplifier, a second resistor connected between the non-inverting input terminal of the first operational amplifier and ground, a third resistor having one end connected to the inverting input terminal of the first operational amplifier, and a fourth resistor connected between the output terminal and the inverting input terminal of the first operational amplifier. The other end of the first resistor serves as the non-inverting input terminal of the first-stage comparison module, the other end of the third resistor serves as the inverting input terminal of the first-stage comparison module, and the output terminal of the first operational amplifier serves as the output terminal of the first-stage comparison module.

4. A charging circuit for a walkie-talkie according to claim 3, characterized in that: The second-stage comparison module includes a second operational amplifier, a fifth resistor having one end connected to the non-inverting input terminal of the second operational amplifier, a sixth resistor connected between the non-inverting input terminal of the second operational amplifier and ground, a seventh resistor having one end connected to the inverting input terminal of the second operational amplifier, and an eighth resistor connected between the output terminal and the inverting input terminal of the second operational amplifier. The other end of the fifth resistor serves as the non-inverting input terminal of the second-stage comparison module, the other end of the seventh resistor serves as the inverting input terminal of the second-stage comparison module, and the output terminal of the second-stage comparator serves as the output terminal of the second-stage comparison module.

5. A charging circuit for a walkie-talkie according to claim 1, 2, 3 or 4, characterized in that: The switch module includes a single-pole double-throw analog switch chip, which has a control pin, a common pin, a first output pin and a second output pin. The output end of the second-stage comparison module is connected to the control pin, and the single-pole double-throw analog switch chip controls the common pin to be connected to the first output pin or the second output pin according to the voltage of the control pin.

6. A charging circuit for a walkie-talkie according to claim 5, characterized in that: The indication module includes a first light emitting diode and a second light emitting diode, wherein the anode of the first light emitting diode and the cathode of the second light emitting diode are connected to the first output pin of the single-pole double-throw analog switch chip, and the cathode of the first light emitting diode and the anode of the second light emitting diode are connected to the second output pin of the single-pole double-throw analog switch chip.

7. A charging circuit for a walkie-talkie according to claim 6, characterized in that: The indication module further includes a ninth resistor connected between the first output pin of the single-pole double-throw analog switch chip and the ground, and a tenth resistor connected between the second output pin of the single-pole double-throw analog switch chip and the ground.

8. A charging circuit for a walkie-talkie according to claim 1, 2, 3 or 4, characterized in that: The charging module includes a charging chip.

9. A charging circuit for a walkie-talkie according to claim 4, characterized in that: A first capacitor is connected between the non-inverting input terminal and the inverting input terminal of the first operational amplifier, and a second capacitor is connected between the non-inverting input terminal and the inverting input terminal of the second operational amplifier.

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