A dual-path reference start-up circuit suitable for wide input voltage range

Abstract

The application discloses a dual-path reference starting circuit suitable for a wide input voltage range and belongs to the technical field of control and regulation. The dual-path reference starting circuit comprises an enable control unit, a low-voltage starting unit, a high-voltage maintaining unit, a voltage detection unit and a reference voltage unit. The application adds the low-voltage starting unit composed of a PMOS tube, and combines the voltage detection unit to enable the circuit to automatically switch the power supply path according to the detection result, forming an intelligent dual-path power supply system. When the power supply voltage is low and the reference voltage cannot be established, the circuit directly couples the power supply to the power supply node with an extremely low on-resistance, realizing fast and strong starting; when the reference is established and the power supply voltage exceeds the safety threshold, the circuit automatically switches to the high-voltage maintaining unit for micro-current power supply. Through the dual-path automatic switching mechanism of low-voltage PMOS strong starting and high-voltage NMOS micro-current maintaining, the technical problem that the traditional single-path architecture cannot simultaneously consider reliable starting in a wide voltage range and ultra-low static current is fundamentally solved.

Description

Technical Field

[0001] This invention discloses a dual-path reference start-up circuit suitable for a wide input voltage range, which relates to power management technology and belongs to the field of control and regulation technology. Background Technology

[0002] In high-voltage power management integrated circuits, it is often necessary to operate over an extremely wide power supply voltage range, from the low battery voltage of 2.5V to the high bus voltage of 60V. To achieve stable operation of the system under wide voltage conditions, not only must the reference circuit operate reliably across the entire voltage range, but stringent microampere-level requirements are also often imposed on its static power consumption. However, in traditional circuit architectures, there is an inherent contradiction between supporting a wide voltage range and achieving ultra-low quiescent current: extending the voltage range usually comes at the cost of increased power consumption, while designs that pursue low power consumption are difficult to cover high-voltage applications.

[0003] like Figure 1 The conventional reference startup circuit shown typically uses a single N-type transistor M4 as the power supply switch, with its gate driven by a bias circuit. This circuit has a significant drawback: to withstand high input voltages up to 60V, the fourth transistor M4 needs to be a high-voltage device. High-voltage NMOS transistors typically have a high threshold voltage VTH, and their conduction requires a sufficient gate-source drive voltage VGS. When the supply voltage VDD is low, for example, close to 2.5V, the bias circuit struggles to generate a sufficiently high voltage to fully power the fourth transistor M4. The fourth transistor M4 is weakly conducting at low voltages, and its on-resistance Ron is very large, failing to provide sufficient startup current for the subsequent reference voltage generation module, resulting in the internal reference voltage VREF failing to reliably establish at low input voltages. Conversely, if a low-threshold device is used to improve low-voltage startup performance, unacceptable leakage current will occur at high inputs, leading to a sharp increase in quiescent current and failing to meet low-power requirements.

[0004] Therefore, the existing single power supply path structure makes it difficult to simultaneously achieve the two key performance characteristics of "reliable low-voltage startup" and "ultra-low quiescent current at high voltage" within a wide input voltage range of 2.5V-60V. The industry urgently needs an innovative circuit architecture to resolve this contradiction. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a dual-path reference startup circuit suitable for a wide input voltage range. This circuit, through an innovative "dual-path architecture" and "intelligent switching logic," employs a strong drive path to ensure reliable reference establishment at low input voltages, and automatically switches to a micro-current sustaining path at high input voltages to achieve extremely low static power consumption, thereby achieving the invention's objective of optimizing the performance of the reference startup circuit across the entire voltage range.

[0006] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0007] A dual-path reference start-up circuit suitable for a wide input voltage range includes: an enable control unit, a low-voltage start-up unit, a high-voltage sustaining unit, a voltage detection unit, and a reference voltage unit; the enable control unit provides enable control signals for the low-voltage start-up unit and the high-voltage sustaining unit; the low-voltage start-up unit provides a low-voltage power supply path between the power supply voltage and the power supply node when the power supply voltage does not meet the reference voltage establishment requirement; the high-voltage sustaining unit provides a high-voltage power supply path between the power supply voltage and the power supply node after the reference voltage has been established and the power supply voltage exceeds a safety threshold; the voltage detection unit generates a switching control signal when it detects that the reference voltage has been established and the power supply voltage exceeds the safety threshold, and adjusts the node voltage output by the enable signal of the enable control unit according to the switching control signal; the reference voltage unit has its power supply terminal connected to the power supply node and provides the reference voltage.

[0008] As a further optimization scheme for a dual-path reference start-up circuit suitable for a wide input voltage range, the enable control unit includes: a first transistor, a fifth transistor, a second diode, a third diode, a fourth diode, and a fifth diode; the first transistor has its gate receiving an external enable signal and its source grounded; the fifth transistor has its gate connected to an external enable signal, its source grounded, and its drain connected to the power supply voltage via a low-voltage start-up unit; the second diode has its cathode connected to the drain of the first transistor; the third diode has its cathode connected to the anode of the second diode; the fourth diode has its cathode connected to the anode of the third diode; and the fifth diode has its cathode connected to the anode of the fourth diode, with its anode serving as the enable signal output node for the enable control unit.

[0009] As a further optimization of a dual-path reference start-up circuit suitable for a wide input voltage range, the low-voltage start-up unit includes: a sixth transistor, a seventh transistor, a third resistor, and a sixth diode; the gate of the sixth transistor is connected to the enable signal output node of the enable control unit, and its source is connected to the drain of the fifth transistor; the source of the seventh transistor is connected to the power supply voltage, and its drain is connected to the power supply node; one end of the third resistor is connected to the power supply voltage, and the other end is connected to the gate of the seventh transistor; the cathode of the sixth diode is connected to the power supply voltage, and its anode is connected to the gate of the seventh transistor.

[0010] As a further optimization of a dual-path reference start-up circuit suitable for a wide input voltage range, the high-voltage sustaining unit includes: a second transistor, a third transistor, a fourth transistor, a first resistor, a second resistor, and a first diode; the second transistor has its source connected to the power supply voltage and its drain connected to its gate; the third transistor has its source connected to the power supply voltage and its gate connected to the gate of the second transistor; the fourth transistor has its drain connected to the power supply voltage, its gate connected to the drain of the third transistor, and its source connected to the power supply node; the first resistor has one end connected to the drain of the second transistor and the other end connected to the enable signal output node of the enable control unit; the second resistor has one end connected to the drain of the third transistor and the other end grounded; the first diode has its cathode connected to the drain of the third transistor and its anode grounded.

[0011] As a further optimization of a dual-path reference start-up circuit suitable for a wide input voltage range, the voltage detection unit includes: a voltage detection module and an eighth transistor; the voltage detection module has its power supply terminal connected to the power supply node, one of its input terminals connected to the power supply voltage, and its other output terminal connected to the output terminal of the reference unit, generating a switching control signal when it detects that the reference voltage has been established and the power supply voltage exceeds the safe voltage threshold; the eighth transistor has its gate connected to the output terminal of the voltage detection module, its drain connected to the enable signal output node of the enable control unit, and its source grounded.

[0012] As a further optimization of a dual-path reference start-up circuit suitable for a wide input voltage range, the voltage detection module includes: a power supply voltage follower subunit, a power supply voltage detection subunit, and a reference voltage detection subunit; the power supply voltage follower subunit is used to output a power supply voltage follower signal when the power supply voltage does not exceed the safety threshold, and to output a constant safety threshold voltage when the power supply voltage exceeds the safety threshold; the power supply voltage detection subunit is used to generate a power supply voltage detection signal when the reference voltage has been established and the power supply voltage exceeds the safety voltage threshold; the reference voltage detection subunit is used to generate a reference voltage detection signal after the reference voltage is established, and to generate a switching control signal when both the reference voltage detection signal and the power supply voltage detection signal are valid.

[0013] As a further optimization of a dual-path reference startup circuit suitable for a wide input voltage range, the power supply voltage follower subunit includes: a tenth transistor, an eleventh transistor, a twelfth transistor, a thirteenth transistor, a seventeenth transistor, an eighteenth transistor, a fourteenth transistor, a fifteenth transistor, a sixteenth transistor, a tenth capacitor, an eleventh resistor, and a tenth resistor; the tenth transistor has its gate connected to its drain and its source grounded; the eleventh transistor has its gate connected to the gate of the tenth transistor and its source grounded; the twelfth transistor has its source connected to the drain of the eleventh transistor; the thirteenth transistor has its gate connected to a reference voltage and its source connected to the drain of the eleventh transistor; the seventeenth transistor has its gate connected to a bias voltage and its source connected to the twelfth transistor. Drain; the eighteenth transistor, whose gate is connected to a bias voltage, and whose source is connected to the drain of the thirteenth transistor; the fourteenth transistor, whose source is connected to a power supply voltage, and whose gate and drain are connected to the drain of the seventeenth transistor; the fifteenth transistor, whose source is connected to a power supply voltage, whose gate is connected to the gate of the fourteenth transistor, and whose drain is connected to the drain of the eighteenth transistor; the sixteenth transistor, whose source is connected to a power supply voltage, whose gate is connected to the drain of the fifteenth transistor, and whose drain outputs a power supply voltage follower signal; the tenth capacitor, one end of which is connected to the source of the eighteenth transistor, and the other end of which is connected to the drain of the sixteenth transistor; the eleventh resistor, one end of which is connected to the drain of the sixteenth transistor; the tenth resistor, one end of which is connected to the other end of the eleventh resistor and the gate of the twelfth transistor, and the other end of which is grounded.

[0014] As a further optimization of a dual-path reference start-up circuit suitable for a wide input voltage range, the power supply voltage detection subunit includes: a twelfth resistor, a fourteenth resistor, a thirteenth resistor, a comparator, and a first inverter; the twelfth resistor has one end connected to the drain of the sixteenth transistor; the fourteenth resistor has one end connected to the other end of the twelfth resistor; the thirteenth resistor has one end connected to the other end of the fourteenth resistor, and the other end is grounded; the comparator has its non-inverting input connected to the junction of the twelfth and fourteenth resistors, and its inverting input connected to the reference voltage; the first inverter has its input connected to the comparator output, and its output outputs the power supply voltage detection signal.

[0015] As a further optimization of a dual-path reference start-up circuit suitable for a wide input voltage range, the reference voltage detection subunit includes: a sixteenth resistor, a twenty-first transistor, a fifteenth resistor, a second inverter, a twentieth transistor, a third inverter, and a NOR gate; the sixteenth resistor has one end connected to the power supply voltage; the twenty-first transistor has its gate connected to the reference voltage, and its drain connected to the other end of the sixteenth resistor; the fifteenth resistor has one end connected to the source of the twenty-first transistor, and its other end grounded; the second inverter has its input connected to the drain of the twenty-first transistor; the twentieth transistor has its drain connected to the source of the twenty-first transistor, its source grounded, and its gate connected to the output of the second inverter; the third inverter has its input connected to the input of the second inverter; and the NOR gate has one input connected to the output of the third inverter, its other input connected to the power supply voltage detection signal, and its output outputting the reference voltage detection signal.

[0016] As a further optimization of a dual-path reference start-up circuit suitable for a wide input voltage range, transistors 1, 4, 5, 6, 8, 10, 11, 12, 13, 17, 18, 19, 20, and 21 are N-type transistors, while transistors 2, 3, 7, 14, 15, and 16 are P-type transistors.

[0017] This invention adopts the above-mentioned technical solution, and through the dual-path automatic switching mechanism of 'low-voltage PMOS strong start-up and high-voltage NMOS micro-current maintenance', it fundamentally solves the technical problem that the traditional single-path architecture cannot simultaneously achieve reliable start-up over a wide voltage range and ultra-low quiescent current, and has the following beneficial effects:

[0018] 1. Achieved reliable reference establishment under low voltage: This invention creatively adds a low-voltage start-up unit composed of PMOS transistor M7. This unit can be fully turned on when the power supply voltage VDD is slightly higher than the threshold voltage of M7. The source voltage of M7 can be as low as 2.5V. With extremely low on-resistance, VDD is directly coupled to the power supply node VO, providing a strong drive current for the reference module. This fundamentally solves the technical problem that traditional circuits cannot reliably establish a reference under low input voltage.

[0019] 2. Achieves ultra-low quiescent current across the entire voltage range: After the reference is established and the input voltage increases, the circuit automatically and completely shuts off M7 through the voltage detection unit and switches to the high-voltage sustaining unit composed of the micro-current biased NMOS transistor M4. Since the current of all active paths under steady state is designed to be in the microampere level, and the first, second, and third resistors in the key nodes of the circuit use large-value resistors, the quiescent current can be stably maintained at the microampere level throughout the entire operating voltage range of 2.5V to 60V, overcoming the problem of large quiescent current in traditional circuits under high voltage. Based on the intelligent switching mechanism of the AND condition of VDD and VREF, it ensures reliable start-up of the circuit at input voltages as low as 2.5V and stable maintenance at input voltages as high as 60V, more effectively preventing malfunctions caused by unstable reference or power transients. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the working principle of a traditional high-voltage power supply circuit.

[0021] Figure 2 This is a circuit diagram of a wide voltage range, low power consumption power supply proposed in this invention.

[0022] Figure 3 for Figure 2 Internal circuit diagram of the voltage detection module.

[0023] Explanation of the labels in the diagram: M1~M8 are the first to eighth transistors, M10~M21 are the tenth to twenty-first transistors, R1~R3 ​​are the first to third resistors, R10~R16 are the tenth to sixteenth resistors, D1~D6 are the first to sixth diodes, C10 is the tenth capacitor, CMP is the comparator, INV1~INV3 are the first to third inverters, and NOR1 is the NOR gate. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only some, not all, of the embodiments of this invention.

[0025] like Figure 2 As shown, the dual-path reference start-up circuit applicable to a wide input voltage range proposed in this invention includes: an enable control unit, a low-voltage start-up unit, a high-voltage sustaining unit, a voltage detection unit, and a reference voltage unit.

[0026] The enable control unit, connected between the enable signal EN and the power supply voltage VDD, provides enable control signals for the high-voltage sustaining unit and the low-voltage startup unit. The enable control unit includes a first transistor M1, a fifth transistor M5, and second to fifth diodes D2-D5. The first transistor M1 and the fifth transistor M5 are N-type transistors. The gates of the first transistor M1 and the fifth transistor M5 receive the enable signal EN. The source of the first transistor M1 is grounded, and its drain is connected to the cathode of the second diode D2. The source of the fifth transistor M5 is grounded, and its drain is connected to the power supply voltage VDD via the low-voltage startup unit. The anode of the second diode D2 is connected to the cathode of the third diode D3, the anode of the third diode D3 is connected to the cathode of the fourth diode D4, and the anode of the fourth diode D4 is connected to the cathode of the fifth diode D5. The anode of the fifth diode D5 is denoted as node N3, which is the enable signal output node. When the EN signal is valid, the enable control unit generates a high-level signal at node N3.

[0027] A low-voltage startup unit is connected between the power supply voltage VDD and the power supply node VO of the reference startup circuit. It provides a low-voltage power supply path between the power supply voltage and the power supply node when the power supply voltage does not meet the reference voltage establishment requirements. The low-voltage startup unit includes: a sixth transistor M6, a seventh transistor M7, a third resistor R3, and a sixth diode D6. The sixth transistor M6 is an N-type transistor, and the seventh transistor M7 is a P-type transistor. The source of the seventh transistor M7 is connected to the power supply voltage VDD, the drain is connected to the power supply node VO of the reference startup circuit, and the gate is connected to VDD through the third resistor R3 and the sixth diode D6, and is controlled by the signal from node N3. The sixth diode D6 is used to clamp the gate-source voltage of the seventh transistor M7 to ensure safety in high-voltage applications. The gate of the sixth transistor M6 is connected to node N3, the source is connected to the drain of the fifth transistor M5, and the drain is connected to the gate of the seventh transistor M7. When node N3 is high, the sixth transistor M6 conducts, pulling the gate of the seventh transistor M7 low, and the seventh transistor M7 conducts.

[0028] A high-voltage sustaining unit, connected in parallel with the low-voltage startup unit between the power supply voltage VDD and the power supply node VO of the reference startup circuit, provides a high-voltage power supply path between the power supply voltage and the power supply node after the reference voltage has been established and the power supply voltage exceeds a safe threshold. The high-voltage sustaining unit includes a second transistor M2, a third transistor M3, a fourth transistor M4, a first resistor R1, a second resistor R2, and a first diode D1. The second transistor M2 and the third transistor M3 are P-type transistors, and the fourth transistor M4 is an N-type transistor. The second transistor M2 and the third transistor M3 form a current mirror to bias the gate of the fourth transistor M4. The sources of the second transistor M2 and the third transistor M3 are connected to the power supply voltage VDD. The drain and gate of the second transistor M2 and the gate of the third transistor M3 are connected to form node N1, and the drain of the third transistor M3 is denoted as node N2. The second resistor R2 and the first diode D1 are connected in parallel between the gate of the fourth transistor M4 and ground. The second resistor R2 is the pull-down resistor for the gate of the fourth transistor M4. The first diode D1 is used to clamp the gate-source voltage of the fourth transistor M4. One end of the second resistor R2 and the cathode of the first diode D1 are both connected to node N2, and the other end of the second resistor R2 and the anode of the first diode D1 are both grounded. The first resistor R1 is used for current limiting, with one end connected to node N1 and the other end connected to node N3. The drain of the fourth transistor M4 is connected to VDD, the source is connected to VO, and the gate is connected to node N2.

[0029] The voltage detection unit monitors the power supply voltage VDD and the reference voltage VREF, and switches between the high-voltage and low-voltage power supply paths. When the reference voltage is established and the power supply voltage exceeds a safety threshold, it generates a switching control signal and adjusts the enable signal output node voltage of the enable control unit according to the switching control signal. The voltage detection unit includes a voltage detection module and an eighth transistor M8, which is an N-type transistor. The voltage detection module monitors the power supply voltage VDD and the reference voltage VREF and outputs a switching control signal VOK. Under the action of the switching control signal VOK, the eighth transistor M8 switches between the high-voltage and low-voltage power supply paths. The power supply terminal of the voltage detection module is connected to the power supply node VO of the reference startup circuit. Its two input terminals are connected to the power supply voltage VDD and the reference voltage VREF, respectively, and its output terminal is connected to the gate of the eighth transistor M8. The drain of the eighth transistor M8 is connected to node N3, and its source is grounded. The internal circuit structure of the voltage detection module is as follows: Figure 3 As shown, it specifically includes a power supply voltage follower unit, a power supply voltage detection unit, and a reference voltage detection unit.

[0030] The power supply voltage follower subunit is connected between the power supply voltage VDD and ground. It tracks the power supply voltage and outputs a power supply voltage follower signal VDR. When the power supply voltage VDD does not exceed the safety threshold, VDR = VDD; when the power supply voltage VDD exceeds the safety threshold, the value of VDR is the safety threshold. The power supply voltage follower subunit includes transistors M10 through M18, capacitor C10, resistor R10, and resistor R11. Transistors M14, M15, and M16 are P-type transistors, while transistors M10, M11, M12, M13, M17, and M18 are N-type transistors.Among them, the tenth transistor M10 and the eleventh transistor M11 form a current mirror structure to provide bias current. The drain and gate of the tenth transistor M10 and the gate of the eleventh transistor M11 are all connected to an external current source for bias. The source of the tenth transistor M10 and the source of the eleventh transistor M11 are grounded. The twelfth transistor M12 and the thirteenth transistor M13 form an input pair to prevent damage to the low-voltage input pair composed of the twelfth transistor M12 and the thirteenth transistor M13 when the VDD voltage is high. The source of the twelfth transistor M12 and the source of the thirteenth transistor M13 are both connected to the drain of the eleventh transistor M11. 13. The gate of transistor M14 is connected to the reference voltage VREF; transistors M15 and M14 are load current mirrors. The source of transistor M14 and the source of transistor M15 are connected to the power supply voltage VDD. The gate and drain of transistor M14 are connected to the gate of transistor M15; transistors M17 and M18 are high-voltage isolation transistors, protecting transistors M12 and M13. The drain of transistor M17 is connected to the drain of transistor M14. The gate of transistor M17 is connected to the bias voltage VB. The source of transistor M17 is connected to the reference voltage VREF; transistor M14 and M15 are load current mirrors. The source of transistor M14 and M15 is connected to the power supply voltage VDD. The gate and drain of transistor M14 are connected to the gate of transistor M15. The drain of the 12th transistor M12 is connected to the gate of the 18th transistor M18, which is connected to the drain of the 15th transistor M15. The gate of the 18th transistor M18 is connected to the bias voltage VB, and the source of the 18th transistor M18 is connected to the drain of the 13th transistor M13. The 16th transistor M16 is the output regulation transistor, with its source connected to the power supply voltage VDD, its gate connected to the drain of the 15th transistor M15 and the drain of the 18th transistor M18, and its drain being the output terminal of the power supply voltage follower signal VDR. Transistors M11 to M15 form a five-transistor amplifier structure, and the five-transistor amplifier and the 16th transistor M16 constitute a... This is a VDD voltage follower structure. The tenth capacitor, C10, is a Miller compensation capacitor. The tenth resistor, R10, and the eleventh resistor, R11, are feedback resistors. One terminal of the tenth capacitor, C10, is connected to the source of the eighteenth transistor, M18, and the drain of the thirteenth transistor, M13. The other terminal of the tenth capacitor, C10, is connected to the drain of the sixteenth transistor, M16. One end of the eleventh resistor, R11, is connected to the drain of the sixteenth transistor, M16. The other end of the eleventh resistor, R11, and one end of the tenth resistor, R10, form a power supply voltage detection signal feedback point. The gate of the twelfth transistor, M12, is connected to the power supply voltage detection signal feedback point. The other end of the tenth resistor, R10, is grounded. This power supply voltage follower unit uses the reference voltage VREF as a reference. When VDD is initially powered on, the drain voltage VDR of M16 rises with the VDD voltage. After VREF is established, if the power supply voltage VDD continues to rise and exceeds the safe voltage threshold, the power supply voltage follower signal VDR remains constant at a safe voltage of 5V and no longer follows VDD, preventing damage to the circuit due to high VDD voltage.

[0031] The power supply voltage detection subunit is used to generate a power supply voltage detection signal when a reference voltage has been established and the power supply voltage exceeds a safe voltage threshold. The power supply voltage detection subunit includes a comparator CMP, resistors 12 to 14 (R12-R14), a nineteenth transistor M19, and a first inverter INV1. The nineteenth transistor M19 is an N-type transistor. Resistors R12, R13, and R14 form a resistor divider network to divide the power supply voltage detection signal VDR. One end of resistor R12 is connected to VDR, one end of resistor R14 is connected to the other end of resistor R12, and the other end of resistor R14 is connected to one end of resistor R13, with the other end of resistor R13 grounded. The non-inverting input of comparator CMP is connected to the junction of resistors R12 and R13, and the inverting input is connected to the reference voltage VREF. The output of comparator CMP, after passing through the first inverter INV1, outputs the power supply voltage detection signal VDOK. The output of the reference voltage detection unit is connected to the NOR gate NOR1, which outputs the switching control signal VOK. The nineteenth transistor M19 is a hysteresis feedback transistor, with its drain connected to the junction of the fourteenth resistor R14 and the thirteenth resistor R13, its gate connected to the output of the first inverter INV1, and its source grounded. The power supply voltage detection unit detects the VDD voltage by determining whether VDR has reached the safe voltage threshold. When the VDD voltage is less than 5V, the VDR voltage completely follows the VDD voltage. The safe voltage threshold can be set at a voltage value that allows the circuit to start normally and safely. For example, if VDD = 4.5V, that is, when VDR follows VDD to reach 4.5V, due to the setting of the resistor voltage divider network, the voltage at the non-inverting input of the comparator CMP exceeds the voltage at the inverting input VREF, and the output VDOK of this unit will flip.

[0032] The reference voltage detection subunit is used to generate a reference voltage detection signal after the reference voltage is established, and to generate a switching control signal when both the reference voltage detection signal and the power supply voltage detection signal are valid. The reference voltage detection subunit includes a twentieth transistor M20, a twenty-first transistor M21, a second inverter INV2, a third inverter INV3, and a NOR gate NOR1. The twentieth transistor M20 and the twenty-first transistor M21 are N-type transistors. The gate of the 21st transistor M21 is connected to the reference voltage VREF, its drain is connected to one end of the 16th resistor R16, and its source is connected to one end of the 15th resistor R15. The 16th resistor R16 is the load resistor, and the 15th resistor R15 is the hysteresis resistor. The other end of the 16th resistor R16 is connected to the power supply voltage VDD, and the other end of the 15th resistor R15 is grounded. The input of the second inverter INV2 is connected to the drain of the 21st transistor M21, and the input of the third inverter INV3 is connected to the output of the second inverter INV2. The gate of the 20th transistor M20 is connected to the output of the second inverter INV2, and its drain is connected to the source of the 21st transistor M21, with the source grounded. The drain voltage of the 21st transistor M21 is fed into one input of the NOR gate NOR1 after passing through two stages of inverting buffers, namely the second inverter INV2 and the third inverter INV3. The 21st transistor M21 acts as a single-transistor amplifier with source negative feedback, used to detect whether the reference voltage VREF has been successfully established. The 20th transistor M20 is a hysteresis feedback transistor. One input of the NOR gate NOR1 is connected to the reference voltage VREF detection signal VROK output from the third inverter INV3, and the other input is connected to the power supply voltage detection signal VDOK. When VREF is established, the 21st transistor M21 turns on, pulling the input voltage of the second inverter INV2 low. This causes the output signal VROK of the third inverter INV3 to flip to a low level. When both VDOK and VROK signals flip to low levels, the VOK signal flips to a high level, thus realizing the detection function of VDD and VREF voltages and controlling the switching between the dual power supply paths.

[0033] The dual-path reference startup circuit proposed in this invention comprises two operating stages: a low-voltage startup stage and a high-voltage, low-power maintenance stage. The following describes... Figure 2 and Figure 3 The working principles of the two working stages are explained.

[0034] Low-voltage strong start-up phase: When the enable signal EN is valid (high level), the first transistor M1 is turned on, and the second transistor M2 in the high-voltage sustaining unit is in a weakly conducting state. Current flows from VDD through the second transistor M2 into the first resistor R1, charging node N3 and making it high level, thus turning on the sixth transistor M6. The sixth transistor M6 pulls down its drain voltage, which in turn pulls down the gate voltage of the seventh transistor M7. As long as the VDD voltage is higher than the threshold voltage of the seventh transistor M7, the seventh transistor M7 turns on, strongly transferring the VDD potential to the VO node, supplying power to the reference voltage unit and the voltage detection module. The power supply voltage VDD rises from 0V, and the node VO voltage follows suit. When VDD reaches 2.5V, the VO voltage also rises to 2.5V, meeting the voltage requirement for VREF establishment. Once VDD reaches the minimum operating voltage of the reference cell, 2.5V, VREF is established. VREF rises from 0V to 1.2V, and the 21st transistor M21 changes from off to on. The 21st transistor M21 pulls the input of the second inverter INV2 from high to low, and finally, the reference voltage VREF detection signal VROK flips from high to low. This stage is the low-voltage startup stage, powered by the 7th transistor M7.

[0035] High-voltage, low-power maintenance phase: As VDD continues to rise, the power supply voltage detection signal VDR is divided by resistors R11 and R10 and then supplied to the gate of transistor M12. The input pair composed of transistors M12 and M13 compares VDD with VREF. The final comparison signal controls transistor M16 via transistors M14 and M15, ultimately adjusting the VDR voltage to track VDD. When VDD is less than 5V, VDR tracks VDD equally; when VDD exceeds 5V, VDR remains constant at 5V. To ensure the reference startup circuit can withstand high voltage, high-voltage transistors M16, M17, and M18 are used. When VDD rises to 60V, the low-voltage circuit remains unaffected. When VDD rises continuously from 2.5V to 4V-5V, VDR also tracks VDD to rise to 4V-5V. At this time, the voltage connected to the non-inverting input of CMP is the same as VREF. The output of CMP flips from 0V to 5V, and VDOK flips from 5V to 0V, that is, it is detected that VDD has reached 4V-5V, thus realizing the detection of VDD voltage. When the voltage detection module detects that VDD exceeds its internal threshold (e.g., 4.8V) and VREF has reached a stable value (e.g., 1.2V), it outputs a valid switching control signal VOK. At this time, VOK is high, turning on the eighth transistor M8, pulling the potential of node N3 low, causing the sixth transistor M6 to turn off. The gate voltage of the seventh transistor M7 is pulled up to VDD by the third resistor R3, turning off the seventh transistor M7, thus cutting off the low-voltage startup unit. Simultaneously, the valid VOK pulls the potential of node N3 low, pulling the gate potential of the second transistor M2 low, thereby turning on the second transistor M2 completely, establishing a current mirror bias. The current mirror formed by M2 and M3 operates, providing a microampere bias current to the second resistor R2 and the first diode D1 connected to the gate of the fourth transistor M4, causing the fourth transistor M4 to turn on. Subsequently, the fourth transistor M4 provides the sustaining current for the VO node. This stage is the high-voltage, low-power sustaining stage, entirely powered by the fourth transistor M4.

[0036] In summary, this invention cleverly resolves the contradiction between reliable startup and ultra-low quiescent current under wide voltage input by employing a dual-path automatic switching mechanism of "M7 startup and M4 maintenance," demonstrating high practical value and promising industrial prospects.

[0037] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the specific embodiments described above. The specific embodiments and descriptions in the specification are merely for further illustrating the principles and preparation effects of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A dual-path reference start-up circuit suitable for a wide input voltage range, characterized in that, include: The enable control unit is used to provide enable control signals for the low-voltage start-up unit and the high-voltage maintenance unit. The low-voltage startup unit is used to provide a low-voltage power supply path between the power supply voltage and the power supply node when the power supply voltage does not meet the requirements for establishing the reference voltage. The high-voltage sustaining unit is used to provide a high-voltage power supply path between the power supply voltage and the power supply node after the reference voltage has been established and the power supply voltage exceeds the safety threshold. A voltage detection unit is used to generate a switching control signal when a reference voltage is established and the power supply voltage exceeds a safety threshold, and to adjust the enable signal output node voltage of the enable control unit according to the switching control signal. and, The reference voltage unit has its power supply terminal connected to the power supply node to provide a reference voltage.

2. The dual-path reference start-up circuit suitable for a wide input voltage range according to claim 1, characterized in that, The enabling control unit includes: The first transistor has an external enable signal at its gate and its source grounded. The fifth transistor has its gate connected to an external enable signal, its source grounded, and its drain connected to the power supply voltage via the low-voltage startup unit. The cathode of the second diode is connected to the drain of the first transistor. The cathode of the third diode is connected to the anode of the second diode; A fourth diode, the cathode of which is connected to the anode of the third diode; and, The fifth diode has its cathode connected to the anode of the fourth diode, and its anode is the enable signal output node of the enable control unit.

3. The dual-path reference start-up circuit suitable for a wide input voltage range according to claim 2, characterized in that, The low-voltage start-up unit includes: The sixth transistor has its gate connected to the enable signal output node of the enable control unit, and its source connected to the drain of the fifth transistor. The seventh transistor has its source connected to the power supply voltage and its drain connected to the power supply node. The third resistor has one end connected to the power supply voltage and the other end connected to the gate of the seventh transistor; and, The sixth diode has its cathode connected to the power supply voltage and its anode connected to the gate of the seventh transistor.

4. The dual-path reference start-up circuit suitable for a wide input voltage range according to claim 3, characterized in that, The high-voltage maintenance unit includes: The second transistor has its source connected to the power supply voltage and its drain connected to the gate. The third transistor has its source connected to the power supply voltage and its gate connected to the gate of the second transistor. The fourth transistor has its drain connected to the power supply voltage, its gate connected to the drain of the third transistor, and its source connected to the power supply node. The first resistor has one end connected to the drain of the second transistor and the other end connected to the enable signal output node of the enable control unit. The second resistor has one end connected to the drain of the third transistor and the other end grounded; and, The first diode has its cathode connected to the drain of the third transistor and its anode grounded.

5. The dual-path reference start-up circuit suitable for a wide input voltage range according to claim 4, characterized in that, The voltage detection unit includes: A voltage detection module, whose power supply terminal is connected to a power supply node, has one input terminal connected to the power supply voltage, and its other output terminal connected to the output terminal of the reference unit. When it detects that a reference voltage has been established and the power supply voltage exceeds a safe voltage threshold, it generates a switching control signal; and... The eighth transistor has its gate connected to the output terminal of the voltage detection module, its drain connected to the enable signal output node of the enable control unit, and its source grounded.

6. The dual-path reference start-up circuit suitable for a wide input voltage range according to claim 5, characterized in that, The voltage detection module includes: The power supply voltage follower subunit is used to output a power supply voltage follower signal when the power supply voltage does not exceed the safety threshold, and to output a constant safety threshold voltage when the power supply voltage exceeds the safety threshold. A power supply voltage detection subunit is used to generate a power supply voltage detection signal when a reference voltage has been established and the power supply voltage exceeds a safe voltage threshold; and, A reference voltage detection subunit is used to generate a reference voltage detection signal after the reference voltage is established, and to generate a switching control signal when both the reference voltage detection signal and the power supply voltage detection signal are valid.

7. The dual-path reference start-up circuit suitable for a wide input voltage range according to claim 6, characterized in that, The power supply voltage follower subunit includes: The tenth transistor has its gate connected to its drain and its source grounded. The eleventh transistor has its gate connected to the gate of the tenth transistor, and its source is grounded. The twelfth transistor has its source connected to the drain of the eleventh transistor; The thirteenth transistor has its gate connected to a reference voltage and its source connected to the drain of the eleventh transistor. The seventeenth transistor has its gate connected to a bias voltage and its source connected to the drain of the twelfth transistor. The eighteenth transistor has its gate connected to a bias voltage and its source connected to the drain of the thirteenth transistor. The fourteenth transistor has its source connected to the power supply voltage, and its gate and drain are connected to the drain of the seventeenth transistor. The fifteenth transistor has its source connected to the power supply voltage, its gate connected to the gate of the fourteenth transistor, and its drain connected to the drain of the eighteenth transistor. The sixteenth transistor has its source connected to the power supply voltage, its gate connected to the drain of the fifteenth transistor, and its drain outputs a power supply voltage follower signal. The tenth capacitor has one terminal connected to the source of the eighteenth transistor and the other terminal connected to the drain of the sixteenth transistor; The eleventh resistor, one end of which is connected to the drain of the sixteenth transistor; and, The tenth resistor has one end connected to the other end of the eleventh resistor and the gate of the twelfth transistor, and its other end is grounded.

8. The dual-path reference start-up circuit suitable for a wide input voltage range according to claim 7, characterized in that, The power supply voltage detection subunit includes: The twelfth resistor has one end connected to the drain of the sixteenth transistor; The fourteenth resistor has one end connected to the other end of the twelfth resistor; The thirteenth resistor has one end connected to the other end of the fourteenth resistor, and the other end is grounded. The comparator has its non-inverting input connected to the junction of the twelfth and fourteenth resistors, and its inverting input connected to a reference voltage; and, The first inverter has its input connected to the output of the comparator, and its output outputs a power supply voltage detection signal.

9. The dual-path reference start-up circuit suitable for a wide input voltage range according to claim 8, characterized in that, The reference voltage detection subunit includes: The sixteenth resistor has one end connected to the power supply voltage; The twenty-first transistor has its gate connected to a reference voltage and its drain connected to the other end of the sixteenth resistor. The fifteenth resistor has one end connected to the source of the twenty-first transistor and the other end grounded. The second inverter has its input terminal connected to the drain of the twenty-first transistor; The drain of the twentieth transistor is connected to the source of the twentieth eleventh transistor, the source of which is grounded, and the gate of which is connected to the output of the second inverter. A third inverter, the input of which is connected to the input of the second inverter; and, The NOR gate has one input connected to the output of the third inverter, another input connected to the power supply voltage detection signal, and an output output of the reference voltage detection signal.

10. The dual-path reference start-up circuit suitable for a wide input voltage range according to claim 9, characterized in that, The first, fourth, fifth, sixth, eighth, tenth, eleventh, twelfth, thirteenth, seventeenth, eighteenth, nineteenth, twentieth, and twenty-first transistors are N-type transistors, and the second, third, seventh, fourteenth, fifteenth, and sixteenth transistors are P-type transistors.

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