Serial port to single bus transmission circuit

Abstract

The application discloses a serial port to single bus transmission circuit, including DC voltage line V+, DC voltage line V-, bus BUS, first system and second system, the first system and second system are connected through DC voltage line V+, DC voltage line V-, bus BUS three lines, when the Tx1 end of the first MCU chip is low level, the triode Q5, triode Q8 are turned on, the bus BUS voltage is pulled low, when the Tx1 end of the first MCU chip is high level, triode Q5, triode Q8 are cut off, the bus BUS voltage is pulled high. Through the first system and the second system which are basically symmetrical, when the bus BUS and the DC voltage line V- are short-circuited, the bus is pulled low BUS, and the circuit is not damaged; when the bus BUS and the DC voltage line V+ are short-circuited, the bus BUS is pulled high, and the circuit is not damaged, the condition that the transmission circuit is damaged is avoided in the lithium ion battery charging process, and charging safety is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of serial port to single bus conversion, and particularly relates to a serial port to single bus conversion transmission circuit. BACKGROUND

[0002] When charging a lithium battery using a charger, the voltage and current of the charger must match the lithium battery. In order to better protect the performance of the lithium battery, the charging process is generally required to be controlled according to four stages of trickle charging (low-voltage pre-charging), constant-current charging, constant-voltage charging, and charging termination. The basic requirement of a lithium battery charger is a specific charging current and charging voltage, thereby ensuring safe charging of the lithium battery. Additional charging auxiliary functions are added to improve battery life and simplify charger operation, including trickle charging for over-discharged batteries, battery voltage detection, input current limiting, turning off the charger after charging is complete, and automatically starting charging after partial discharge of the battery.

[0003] During the charging process of a lithium ion battery, the transmission circuit is prone to damage, affecting charging safety. SUMMARY

[0004] The present application aims to overcome the deficiencies in the prior art and provide a serial port to single bus conversion transmission circuit that can improve charging safety.

[0005] The present application is achieved by the following technical solutions:

[0006] A serial port to single bus conversion transmission circuit, comprising a direct current voltage line V+, a direct current voltage line V-, a bus BUS, a first system and a second system, the first system and the second system being connected by the direct current voltage line V+, the direct current voltage line V- and the bus BUS, the first system comprising a first MCU chip, a transistor Q1, a transistor Q3, a transistor Q5 and a transistor Q8, the Tx1 end of the first MCU chip being electrically connected to the base of the transistor Q5, the emitter of the transistor Q5 being connected to the voltage input end of the first MCU chip, the collector of the transistor Q5 being electrically connected to the base of the transistor Q8, the emitter of the transistor Q8 being grounded, when the Tx1 end of the first MCU chip is at a low level, the transistor Q5 and the transistor Q8 are turned on, and the bus BUS voltage is pulled low, when the Tx1 end of the first MCU chip is at a high level, the transistor Q5 and the transistor Q8 are turned off, and the bus BUS voltage is pulled high, the Rx1 end of the first MCU chip being electrically connected to the collector of the transistor Q1, the emitter of the transistor Q5 being connected to the voltage input end of the first MCU chip, the base of the transistor Q5 being electrically connected to the collector of the transistor Q3, and the emitter of the transistor Q3 being grounded.

[0007] Further, the first system is further provided with a resistor R3 and a diode D1, one end of the diode D1 is connected with a transmission circuit VCC end, the other end of the diode D1 is connected with the resistor R3.

[0008] Further, the second system includes a second MCU chip, a triode Q2, a triode Q4, a triode Q6, a triode Q7, the Tx2 end of the second MCU chip is electrically connected with the base of the triode Q6, the emitter of the triode Q6 is connected with the voltage input end of the second MCU chip, the collector of the triode Q6 is electrically connected with the base of the triode Q7, the emitter of the triode Q7 is grounded, when the Tx2 end of the second MCU chip is low, the triode Q6 and the triode Q7 are turned on, the bus BUS voltage is pulled low, when the Tx2 end of the second MCU chip is high, the triode Q6 and the triode Q7 are cut off, the bus BUS voltage is pulled high, the Rx2 end of the second MCU chip is electrically connected with the collector of the triode Q2, the emitter of the triode Q2 is connected with the voltage input end of the second MCU chip, the base of the triode Q2 is electrically connected with the collector of the triode Q4, the emitter of the triode Q4 is grounded.

[0009] Further, the first system further includes a diode D2 and a diode D8, one end of the diode D2 is connected with the collector of the triode Q3, the other end of the diode D2 is connected with a resistor R5.

[0010] Further, the second system further includes a diode D3 and a diode D9, one end of the diode D3 is connected with the collector of the triode Q4, the other end of the diode D3 is connected with a resistor R4

[0011] Further, the first system is further provided with an anti-ESD circuit, the anti-ESD circuit includes a diode D6, a diode D7, a resistor R8 and a resistor R10, one end of the diode D6 is connected with one end of the resistor R8, the other end of the diode D6 is grounded, one end of the diode D7 is connected with one end of the resistor R10, the other end of the diode D7 is grounded, the other end of the resistor R8 is connected with the other end of the resistor R10 through the bus BUS.

[0012] Further, the triode Q1, the triode Q5, the triode Q2, the triode Q6 are all PNP triodes.

[0013] Further, the triode Q3, the triode Q8, the triode Q4, the triode Q7 are all NPN triodes.

[0014] Compared with the prior art, the application has the following advantages and beneficial effects:

[0015] The application prevents the short circuit of the bus BUS and the direct voltage line V+ from damaging the circuit, prevents the short circuit of the bus BUS and the direct voltage line V- from damaging the circuit, and prevents the voltage of the direct voltage line V+ from being transmitted to the circuit VCC, thereby avoiding the damage of the transmission circuit during the charging of the lithium ion battery and improving the charging safety. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a transmission circuit diagram of serial port to single bus. DETAILED DESCRIPTION

[0017] It should be understood that the specific embodiments described herein are merely exemplary and do not limit the present application.

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0019] It should be noted that the terms "include", "contain" and "have" in the specification and claims of the present application and the above-mentioned drawings are intended to cover the inclusions without exclusivity. For example, the processes, methods, systems, products or devices containing a series of steps or units are not limited to the listed steps or units, but can optionally further include the steps or units not listed, or can optionally further include other steps or units inherent to these processes, methods, products or devices. The terms such as "first" and "second" and the like in the claims, specification and drawings of the present application are only used to distinguish one entity / operation / object from another entity / operation / object, and do not necessarily require or imply any actual relationship or order between the entities / operations / objects.

[0020] As Figure 1The serial port to single bus transmission circuit shown, including DC voltage line V+, DC voltage line V-, bus BUS, the first system 1 and the second system 2, the first system 1 and the second system 2 are connected by DC voltage line V+, DC voltage line V-, bus BUS three wire, the first system 1 includes the first MCU chip, triode Q1, triode Q3, triode Q5, triode Q8, the Tx1 end of the first MCU chip is electrically connected with the base of triode Q5, the emitter of triode Q5 is connected with the voltage input end of the first MCU chip, the collector of triode Q5 is electrically connected with the base of triode Q8, the emitter of triode Q8 is grounded, the Tx1 end and the Rx1 end of the first MCU chip in the first system 1, the level control of Tx1 end: when the Tx1 end of the first MCU chip is low, triode Q5, triode Q8 are turned on, the bus BUS voltage is pulled low, when the Tx1 end of the first MCU chip is high, triode Q5, triode Q8 are cut off, the bus BUS voltage is pulled up to VCC; the level control of RX1 end: when the bus BUS is low, triode Q3 is cut off, triode Q1 is cut off, the Rx1 end is low. When the bus BUS voltage is high, triode Q3 is turned on, triode Q1 is turned on, the RX1 end is high; the Rx1 end of the first MCU chip is electrically connected with the collector of triode Q1, the emitter of triode Q5 is connected with the voltage input end of the first MCU chip, the base of triode Q5 is electrically connected with the collector of triode Q3, the emitter of triode Q3 is grounded; the first system 1 is also provided with resistance R3 and diode D1, one end of diode D1 is connected with transmission circuit VCC end, the other end of diode D1 is connected with resistance R3, the embodiment can realize TTL serial communication conversion: TTL serial port Tx line and Rx line <----> single bus BUS <----> TTL serial port Tx line and Rx line, realize bidirectional transmission, without worrying about the communication line and other lines short circuit will damage the circuit, the communication between the first MCU chip and the second MCU chip does not need each high level matching, through the basic symmetry of the first system and the second system, when the bus BUS and DC voltage line V- are short-circuited, the bus is pulled low BUS, which will not damage the circuit; when the bus BUS and DC voltage line V+ are short-circuited, the bus BUS is pulled up, which will not damage the circuit, diode D1 prevents the DC voltage line V+ voltage from being back-feeding the transmission circuit VCC end, avoids the damage of the transmission circuit in the lithium ion battery charging process, improves the charging safety.

[0021] The second system 2 comprises a second MCU chip, a transistor Q2, a transistor Q4, a transistor Q6, a transistor Q7, the Tx2 end of the second MCU chip is electrically connected with the base of the transistor Q6, the emitter of the transistor Q6 is connected with the voltage input end of the second MCU chip, the collector of the transistor Q6 is electrically connected with the base of the transistor Q7, the emitter of the transistor Q7 is grounded, when the Tx2 end of the second MCU chip is low, the transistor Q6 and the transistor Q7 are turned on, the bus BUS voltage is pulled low, when the Tx2 end of the second MCU chip is high, the transistor Q6 and the transistor Q7 are cut off, the bus BUS voltage is pulled high; the Rx2 end of the second MCU chip is electrically connected with the collector of the transistor Q2, the emitter of the transistor Q2 is connected with the voltage input end of the second MCU chip, the base of the transistor Q2 is electrically connected with the collector of the transistor Q4, the emitter of the transistor Q4 is grounded, the MCU voltages of the first system 1 and the second system 2 are different, for example, the MCU-1-VCC end voltage of the first system 1 is 3.3V, the MCU-2-VCC end voltage of the second system 2 is 5V, the first system 1 and the second system 2 are basically symmetrical, the principles are the same, and the difference is that the bus BUS pull-up voltage VCC is placed in the position of the first system 1, which can be placed according to the specific design situation, and the voltage value of the bus BUS pull-up voltage VCC can be designed according to the specific system power supply, and the resistance value of the transistor control resistor in the circuit also needs to be adjusted during design.

[0022] In one embodiment, the first system 1 further comprises a diode D2 and a diode D8, one end of the diode D2 is connected with the collector of the transistor Q3, the other end of the diode D2 is connected with a resistor R5, the second system 2 further comprises a diode D3 and a diode D9, one end of the diode D3 is connected with the collector of the transistor Q4, the other end of the diode D3 is connected with a resistor R4, the diodes D2, D8, D3 and D9 are used for isolating high voltage in the transmission circuit, the diodes are forwardly conducted and reversely cut off, and isolation protection of the transmission circuit is realized, because of the unidirectional conductivity of the diodes, the diodes can quickly cut off the reverse current in the transmission circuit, so that the isolation protection of the transmission circuit is realized.

[0023] The first system 1 is further provided with an ESD prevention circuit, which comprises a diode D6, a diode D7, a resistor R8 and a resistor R10; one end of the diode D6 is connected with one end of the resistor R8, and the other end of the diode D6 is grounded; one end of the diode D7 is connected with one end of the resistor R10, and the other end of the diode D7 is grounded; the other end of the resistor R8 is connected with the other end of the resistor R10 through a bus BUS, the bus voltage can be self-defined, the anti-interference performance is high, the ESD protection is reliable, ESD (Electro-Static discharge) is static discharge, the scale of modern semiconductor devices is larger and larger, and the working voltage is lower and lower, so that the sensitivity of the semiconductor devices to external electromagnetic disturbance is greatly improved. Through the electrostatic protection, the damage of the interference caused by the circuit, the CMOS circuit and the interface circuit to the components can be greatly reduced, and the damage of the components can be reduced.

[0024] The triode Q1, the triode Q5, the triode Q2 and the triode Q6 are PNP triodes, the PNP triode can amplify signals: the PNP triode can amplify current and voltage signals, so that weak signals become stronger, and can be used in amplifiers, power amplifiers and the like; switch control: the PNP triode can be used as a switch control device, can control the on-off of the circuit, realize various logic functions, and has wide application in computers, communications and the like; the PNP triode can also control the stability of the output voltage by adjusting the base voltage, and has an important role in various voltage stabilizers; the PNP triode can also be used as a protection device, which automatically cuts off the circuit under overload, overcurrent and the like to protect other components from being damaged. The triode Q3, the triode Q8, the triode Q4 and the triode Q7 are NPN triodes, the NPN triode can amplify current and voltage signals, so that weak signals become stronger, and can be used in amplifiers, power amplifiers and the like, the transmission circuit is all discrete components, which is composed of resistors, diodes and triodes, and is simple, safe and reliable.

[0025] It should be noted that the above specific embodiments only serve as the preferred embodiments of the present application and the technical principles applied, and any modification, modification, replacement, combination, simplification made by those skilled in the art without departing from the spirit and principle of the present application should be an equivalent replacement method, which should be covered within the protection scope of the present application.

Claims

1. A serial-to-single-bus transmission circuit, characterized in that: The application relates to a three-wire connection system, which comprises a direct-current voltage line V+, a direct-current voltage line V-, a bus BUS, a first system and a second system, the first system and the second system are connected through the direct-current voltage line V+, the direct-current voltage line V- and the bus BUS, the first system comprises a first MCU chip, a transistor Q1, a transistor Q3, a transistor Q5, a transistor Q8, the Tx1 end of the first MCU chip is electrically connected with the base of the transistor Q5, the emitter of the transistor Q5 is connected with the voltage input end of the first MCU chip, the collector of the transistor Q5 is electrically connected with the base of the transistor Q8, the emitter of the transistor Q8 is grounded, when the Tx1 end of the first MCU chip is low, the transistor Q5 and the transistor Q8 are turned on, the bus BUS voltage is pulled low, when the Tx1 end of the first MCU chip is high, the transistor Q5 and the transistor Q8 are cut off, the bus BUS voltage is pulled high; the Rx1 end of the first MCU chip is electrically connected with the collector of the transistor Q1, the emitter of the transistor Q5 is connected with the voltage input end of the first MCU chip, the base of the transistor Q5 is electrically connected with the collector of the transistor Q3, the emitter of the transistor Q3 is grounded; The first system is further provided with a resistor R3 and a diode D1, one end of the diode D1 is connected with the transmission circuit VCC end, the other end of the diode D1 is connected with the resistor R3; The second system comprises a second MCU chip, a transistor Q2, a transistor Q4, a transistor Q6 and a transistor Q7, the Tx2 end of the second MCU chip is electrically connected with the base of the transistor Q6, the emitter of the transistor Q6 is connected with the voltage input end of the second MCU chip, the collector of the transistor Q6 is electrically connected with the base of the transistor Q7, the emitter of the transistor Q7 is grounded, when the Tx2 end of the second MCU chip is low, the transistor Q6 and the transistor Q7 are turned on, the bus BUS voltage is pulled low, when the Tx2 end of the second MCU chip is high, the transistor Q6 and the transistor Q7 are cut off, the bus BUS voltage is pulled high; the Rx2 end of the second MCU chip is electrically connected with the collector of the transistor Q2, the emitter of the transistor Q2 is connected with the voltage input end of the second MCU chip, the base of the transistor Q2 is electrically connected with the collector of the transistor Q4, the emitter of the transistor Q4 is grounded.

2. The serial-to-parallel bus conversion transmission circuit according to claim 1, wherein: The first system further comprises a diode D2 and a diode D8, one end of the diode D2 is connected with the collector of the transistor Q3, the other end of the diode D2 is connected with the resistor R5.

3. The serial-to-parallel bus conversion transmission circuit according to claim 1, wherein: The second system further comprises a diode D3 and a diode D9, one end of the diode D3 is connected with the collector of the transistor Q4, the other end of the diode D3 is connected with the resistor R4.

4. The serial-to-parallel bus conversion transmission circuit according to claim 1, wherein: The first system is also provided with an ESD prevention circuit, which comprises a diode D6, a diode D7, a resistor R8 and a resistor R10; one end of the diode D6 is connected with one end of the resistor R8, and the other end of the diode D6 is grounded; one end of the diode D7 is connected with one end of the resistor R10, and the other end of the diode D7 is grounded; the other end of the resistor R8 is connected with the other end of the resistor R10 through a bus BUS.

5. The serial-to-parallel bus conversion transmission circuit according to claim 1, wherein: The triode Q1, the triode Q5, the triode Q2 and the triode Q6 are all PNP triodes.

6. The serial-to-parallel bus conversion transmission circuit according to claim 1, wherein: The triode Q3, the triode Q8, the triode Q4 and the triode Q7 are all NPN triodes.

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