Circuit structure for realizing pin multiplexing

Abstract

The application relates to a circuit structure for realizing circuit pin multiplexing, which comprises an MCU module, a temperature sensing circuit and a functional module circuit, the output end of the temperature sensing circuit is connected with an enable signal port of the MCU module, the output voltage of the temperature sensing circuit is always higher than the threshold voltage of the enable signal, and the MCU module is connected with the functional module circuit. The circuit structure for realizing circuit pin multiplexing adopts the application, aiming at the problem of circuit pin multiplexing, a temperature sensing output curve is designed, analog signal output and digital signal transmission are influenced mutually, the problem of single pin multifunction multiplexing is solved, analog signal output and input signal can share a pin, the problem of pin quantity limitation is solved, signal transmission is effectively solved, and the performance-cost ratio of the circuit is improved.

Description

Technical Field

[0001] This invention relates to the field of circuit design, and more particularly to the field of signal transmission, specifically to a circuit structure for realizing pin multiplexing. Background Technology

[0002] With continuous technological advancements and improvements in design techniques, circuits are carrying increasingly more functions, requiring a corresponding increase in interfaces. Given the limited number of package pins, the challenge arises in pin reuse to address signal transmission. In some power drive circuits, due to high power consumption, continuous temperature monitoring is necessary to adjust the circuit's operating state and prevent overheating and damage. For example... Figure 1 The image shows the voltage curve output by the internal temperature sensing circuit, which is proportional to the temperature. Figure 2 The image shows one application scenario.

[0003] Figure 1 The output voltage is linearly related to the temperature. Different chips output different voltage values ​​according to their temperatures. Therefore, by reading the voltage value output by the temperature sensing circuit in the circuit, the temperature of the chips inside the circuit can be calculated.

[0004] Figure 2 The MCU detects the output of the temperature sensing signal to determine the circuit's operation. When the temperature is too high, it will change the circuit's operating state to reduce power consumption, lower the circuit temperature, and reduce the possibility of circuit damage. Simultaneously, the MCU also receives or detects other operating states. If an anomaly occurs, it sends an enable signal (EN) to the subsequent circuit, causing the circuit to stop operating, or restarts operation after the state returns to normal. For example... Figure 3 The diagram illustrates the typical way an enable signal is transmitted in a circuit.

[0005] Figure 2 This is a schematic diagram of the internal structure. When the external input signal EN is pulled down to a low level (below the threshold voltage Vth), the internal signal Y flips, thereby controlling the internal circuitry to perform the corresponding action. The actual internal structure may be an inverter, Schmitt trigger, comparator, multi-input gate circuit, etc. Regardless of the form, a threshold voltage Vth is required. When the EN voltage drops to this voltage, the enable signal is considered valid, and the corresponding action is performed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a circuit structure that is simple in structure, solves the limitation of the number of pins, and has a wide range of applications for realizing the reuse of circuit pins.

[0007] To achieve the above objectives, the circuit structure for implementing pin multiplexing in this invention is as follows:

[0008] The main feature of this circuit structure that enables pin multiplexing is that the circuit structure includes an MCU module, a temperature sensing circuit, and a functional module circuit. The output terminal of the temperature sensing circuit is connected to the enable signal port of the MCU module, and the output voltage of the temperature sensing circuit is always higher than the threshold voltage of the enable signal. The MCU module is connected to the functional module circuit.

[0009] Preferably, the MCU outputs a low-level signal and transmits the low-level signal to the temperature sensing circuit.

[0010] Preferably, the circuit structure further includes an overcurrent protection circuit and a temperature protection circuit, both of which are connected to the output terminal of the temperature sensing circuit, and the outputs of both the overcurrent protection circuit and the temperature protection circuit are configured as open-drain outputs.

[0011] Preferably, the temperature sensing circuit comprises a reference circuit unit, an inverting amplifier circuit, and a follower circuit, wherein the reference circuit unit outputs reference voltage Vf1 signals and reference voltage Vf2 signals, respectively.

[0012] The positive terminal of the inverting amplifier circuit is connected to the reference circuit unit, and the input of the positive terminal is the reference voltage Vf1. The inverting input signal of the inverting amplifier circuit is Vpn, and the output signal of the inverting amplifier circuit is Vout.

[0013] The positive terminal of the follower circuit is connected to the reference circuit unit, and the input of the positive terminal is the reference voltage Vf2. The negative terminal of the follower circuit is connected to the reference circuit unit.

[0014] The temperature sensing circuit also includes a current source and a diode. The negative end of the diode is grounded, and the positive end is connected to the current source. The other end of the current source is grounded. The current source generates a negative temperature characteristic voltage Vpn through the diode and is input to the inverting terminal of the inverting amplifier circuit.

[0015] Preferably, the inverting amplifier circuit includes a first operational amplifier, a first resistor, a second resistor, a third resistor, and a current-limiting resistor. The positive terminal of the first operational amplifier is connected to the first resistor, the third resistor is connected between the inverting terminal and the output terminal, the other end of the first resistor is connected to a reference circuit, the output terminal of the first operational amplifier is connected to the current-limiting resistor, and the second resistor is connected to the inverting terminal of the first operational amplifier and a follower circuit.

[0016] Preferably, the follower circuit includes a second operational amplifier and a MOS transistor. The positive terminal of the second operational amplifier is connected to a reference circuit unit, and the negative terminal is connected to a second resistor. The gate of the MOS transistor is connected to the output terminal of the second operational amplifier, and the source and drain are respectively connected to the two sides of a diode.

[0017] The circuit structure of this invention, which enables multiplexing of circuit pins, addresses the issue of pin multiplexing by designing a temperature sensing output curve. This resolves the mutual influence between analog signal output and digital signal transmission, thus solving the problem of multi-functional multiplexing of a single pin. It allows analog signal output and input signals to share pins, not only solving the problem of pin quantity limitation but also effectively solving signal transmission and improving the circuit's cost-effectiveness. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the voltage curve output by a temperature sensing circuit in the prior art, which is proportional to the temperature.

[0019] Figure 2 This is a schematic diagram of the circuit structure for the application scenario of the voltage curve of the existing technology.

[0020] Figure 3 This is a schematic diagram illustrating the conventional transmission method of enable signals in circuits in the prior art.

[0021] Figure 4 This is a schematic diagram of the output voltage curve of the circuit structure for realizing pin multiplexing in this invention.

[0022] Figure 5 The figure shows the V1 voltage curve as the temperature drops to T1 in the circuit structure that enables pin reuse according to the present invention.

[0023] Figure 6 This is a schematic diagram of a pin multiplexing circuit structure for implementing pin multiplexing in this invention.

[0024] Figure 7 This is a schematic diagram of a pin multiplexing circuit, representing an embodiment of the circuit structure for implementing pin multiplexing according to the present invention.

[0025] Figure 8 This is a schematic diagram of a pin multiplexing circuit, representing another embodiment of the circuit structure for implementing pin multiplexing according to the present invention.

[0026] Figure 9 This is a schematic diagram of the temperature sensing output circuit structure for implementing the circuit pin multiplexing circuit structure of the present invention. Detailed Implementation

[0027] To more clearly describe the technical content of the present invention, the following description is provided in conjunction with specific embodiments.

[0028] In existing technologies, the large number of pins in miniaturized packages of integrated circuits limits functional expansion due to the excessive functionality they carry. Therefore, pin multiplexing is one way to address this issue. This invention combines analog signal output with digital signal input to achieve pin multiplexing, thus avoiding pin limitations caused by functional expansion.

[0029] The circuit structure involved in this invention realizes the mutual influence between analog signal output and digital signal transmission, outputs a temperature sensing output curve, and solves the problem of multi-functional multiplexing of a single pin.

[0030] Typically, circuits infer the temperature of internal chips by reading the output voltage of a temperature sensing module. In practical applications, excessively high temperatures can damage circuits and cause other safety issues; therefore, circuits primarily detect high-temperature regions, while low-temperature regions are not considered effective. The circuit structure of this invention prevents the output voltage from decreasing further after reaching V1. By controlling the threshold voltage Vth of the input signal below V1, pin multiplexing for two functions is achieved, such as... Figure 5 As shown.

[0031] The circuit structure of this invention that implements pin multiplexing, such as... Figure 6 As shown, it includes an MCU module, a temperature sensing circuit, and a functional module circuit. The output terminal of the temperature sensing circuit is connected to the enable signal port of the MCU module. The MCU module is connected to the functional module circuit. The output voltage of the temperature sensing circuit is always higher than the threshold voltage of the enable signal. The MCU outputs a low-level signal and transmits the low-level signal to the temperature sensing circuit.

[0032] When the MCU is normally detecting the output voltage of the temperature sensing circuit, the output voltage is always higher than the threshold voltage of the enable signal, and no erroneous enable signal will be generated. When needed, the MCU pulls the port signal low to transmit the enable signal to the internal circuit. At this time, the low level will not be incorrectly identified as a high temperature state.

[0033] like Figure 7 As shown, the circuit structure also includes an overcurrent protection circuit and a temperature protection circuit. Both the overcurrent protection circuit and the temperature protection circuit are connected to the output terminal of the temperature sensing circuit, and the outputs of both the overcurrent protection circuit and the temperature protection circuit are set to open-drain output mode. Placing the outputs of other protection functions at this port, and setting the outputs of functions such as overcurrent protection and temperature protection to open-drain output mode, will not affect each other, achieving the effect of pin multiplexing.

[0034] The temperature sensing circuit of this invention consists of a reference circuit unit, an inverting amplifier circuit, and a follower circuit. The reference circuit unit outputs reference voltage signals Vf1 and Vf2 respectively. The positive terminal of the inverting amplifier circuit is connected to the reference circuit unit, and the input of the positive terminal is the reference voltage Vf1. The inverting input signal of the inverting amplifier circuit is Vpn, and the output signal of the inverting amplifier circuit is Vout. The positive terminal of the follower circuit is connected to the reference circuit unit, and the input of the positive terminal is the reference voltage Vf2. The inverting terminal of the follower circuit is connected to the reference circuit unit. The temperature sensing circuit also includes a current source If1 and a diode. The negative terminal of the diode is grounded, and the positive terminal is connected to the current source If1. The other end of the current source If1 is grounded. The current source If1 generates a negative temperature characteristic voltage Vpn through the diode and inputs it to the inverting terminal of the inverting amplifier circuit.

[0035] The inverting amplifier circuit includes a first operational amplifier AMP1, a first resistor R1, a second resistor R2, a third resistor Rf, and a current-limiting resistor. The positive terminal of the first operational amplifier AMP1 is connected to the first resistor R1. The third resistor Rf is connected between the inverting terminal and the output terminal. The other end of the first resistor R1 is connected to the reference circuit. The output terminal of the first operational amplifier AMP1 is connected to the current-limiting resistor. The second resistor R2 is connected to the inverting terminal of the first operational amplifier AMP1 and the follower circuit.

[0036] In the inverting amplifier circuit, the non-inverting terminal is the reference voltage Vf1, the inverting input signal is Vpn, Rt is the current-limiting resistor, and Vf1 and Vf2 are generated by the reference circuit. A stable current source If1 flows through diodes D1 and D2, or a single diode as an example, to generate a negative temperature characteristic voltage Vpn, which is then input to the second resistor R2.

[0037] The follower circuit includes a second operational amplifier AMP2 and a MOSFET P1. The positive terminal of the second operational amplifier AMP2 is connected to the reference circuit unit, and the negative terminal is connected to the second resistor R2. The gate of the MOSFET P1 is connected to the output terminal of the second operational amplifier AMP2, and the source and drain are connected to the two sides of the diode, respectively.

[0038] like Figure 9 As shown, due to the effect of the reference voltage Vf2, the highest value of the inverted input signal Vpn is clamped, i.e., Vpn≤Vf2.

[0039] The value of Vot can be represented as:

[0040] Vot=–Rf / R2×Vpn+(Rf / R2+1)Vf1

[0041] Where (Rf / R2+1)Vf1 is a fixed value. Since Vpn exhibits a negative temperature characteristic, Vot exhibits a positive temperature characteristic.

[0042] The maximum value of the inverting input signal Vpn is limited by the clamping effect of the follower, Vpn,max = Vf2. Therefore, the minimum value of Vot is expressed as:

[0043] Vot,min=–Rf / R2×Vf2+(Rf / R2+1)Vf1.

[0044] The circuit structure of this invention employs a suitable reference voltage and resistance value, and the temperature-voltage relationship curve is shown below. Figure 4 As shown, at a certain temperature, the output voltage no longer decreases with temperature.

[0045] The circuit structure of this invention, which enables multiplexing of circuit pins, addresses the issue of pin multiplexing by designing a temperature sensing output curve. This resolves the mutual influence between analog signal output and digital signal transmission, thus solving the problem of multi-functional multiplexing of a single pin. It allows analog signal output and input signals to share pins, not only solving the problem of pin quantity limitation but also effectively solving signal transmission and improving the circuit's cost-effectiveness.

[0046] In this specification, the invention has been described with reference to specific embodiments thereof. However, it will be apparent that various modifications and variations can be made without departing from the spirit and scope of the invention. Therefore, the specification and drawings should be considered illustrative rather than restrictive.

Claims

1. A circuit structure for realizing pin multiplexing, characterized in that, It includes an MCU module, a temperature sensing circuit, and a functional module circuit. The output terminal of the temperature sensing circuit is connected to the enable signal port of the MCU module, and the MCU module is connected to the functional module circuit. The enable signal port of the MCU module is used as a multiplexed pin. When the MCU module detects the output voltage of the temperature sensing circuit normally through the multiplexed pin, the output voltage will always be higher than the threshold voltage of the enable signal port, and the multiplexed pin will be pulled low when needed. The temperature sensing circuit includes: a follower circuit, a reference circuit unit, an inverting amplifier circuit, a current source (If1), and a diode, wherein, The follower circuit includes a second operational amplifier (AMP2) and a MOSFET (P1). The positive terminal of the second operational amplifier (AMP2) is connected to the reference circuit unit, and the negative terminal is connected to the second resistor (R2) of the inverting amplifier circuit. The gate of the MOSFET (P1) is connected to the output terminal of the second operational amplifier (AMP2). The source and drain are connected to the two sides of a diode, respectively. The negative terminal of the diode is grounded, and the positive terminal is connected to a current source (If1). The other end of the current source (If1) is grounded. The current source (If1) generates a negative temperature characteristic voltage Vpn through the diode and is input to the inverting terminal of the inverting amplifier circuit.

2. The circuit structure for realizing pin multiplexing according to claim 1, characterized in that, The MCU outputs a low-level signal and transmits the low-level signal to the temperature sensing circuit.

3. The circuit structure for realizing pin multiplexing according to claim 1, characterized in that, It also includes an overcurrent protection circuit and a temperature protection circuit, both of which are connected to the output terminal of the temperature sensing circuit, and the outputs of the overcurrent protection circuit and the temperature protection circuit are both set to open-drain output mode.

4. The circuit structure for realizing pin multiplexing according to claim 1, characterized in that, The reference circuit unit outputs reference voltage Vf1 signal and reference voltage Vf2 signal respectively; The positive terminal of the inverting amplifier circuit is connected to the reference circuit unit, and the input of the positive terminal is the reference voltage Vf1. The inverting input signal of the inverting amplifier circuit is Vpn, and the output signal of the inverting amplifier circuit is Vout. The positive terminal of the follower circuit is connected to the reference circuit unit, and the input of the positive terminal is the reference voltage Vf2. The negative terminal of the follower circuit is connected to the reference circuit unit.

5. The circuit structure for realizing pin multiplexing according to claim 4, characterized in that, The inverting amplifier circuit further includes a first operational amplifier (AMP1), a first resistor (R1), a third resistor (Rf), and a current-limiting resistor. The positive terminal of the first operational amplifier (AMP1) is connected to the first resistor (R1), the third resistor (Rf) is connected between the inverting terminal and the output terminal, the other end of the first resistor (R1) is connected to the reference circuit, the output terminal of the first operational amplifier (AMP1) is connected to the current-limiting resistor, and the second resistor (R2) is connected to the inverting terminal of the first operational amplifier (AMP1) and the follower circuit.

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