A protection circuit based on ultra-high voltage polysilicon resistor and switching power supply

Abstract

The application discloses a protection circuit based on superhigh-voltage polysilicon resistance and a switching power supply. LVDD The protection circuit based on superhigh-voltage polysilicon resistance has four ports, namely a VDD port, a V DD1 port, a V DD1 port and a GND port. The protection circuit based on superhigh-voltage polysilicon resistance comprises a voltage divider and a clamping device. The protection circuit based on superhigh-voltage polysilicon resistance provided by the application can realize 0-100V superwide voltage range operation on the VDD port through special polysilicon resistance structure technology, so that it can not only provide a low voltage V LVDD for monitoring VDD, but also provide a low voltage V DD1 for internal circuit, thereby saving the area and cost of the chip itself and removing the 40V clamping device in the traditional switching power supply, so that the switching power supply system of the application saves the use cost to the maximum.

Description

Technical Field

[0001] The present invention relates to the technical field of fast-charging switching power supplies, and in particular to a protection circuit and a switching power supply based on an ultra-high voltage polysilicon resistor. Background Art

[0002] Fast-charging switching power supplies have become the most popular charging device for current electronic devices. The fast-charging standard has also been quickly upgraded to PD3.0, and the output voltage has been upgraded from 5V to 15V to 3.3 to 20V. Therefore, the maximum output voltage of the transformer power supply auxiliary winding at the VDD port of the switching power supply system has increased from the traditional 40V to 80 to 100V. In order to cope with such a high operating voltage of VDD, most traditional switching power supplies are forced to add a 40V clamper 13 after the rectifier tube D2 of the transformer auxiliary winding La to prevent the VDD port voltage from exceeding the maximum rated voltage of 40V and burning the switching power supply controller integrated circuit. Therefore, the added 40V clamper 13 adds a lot of cost to users.

[0003] Traditional fast charging switching power supply such as Figure 1 As stated, Figure 1 A conventional fast-charging switching power supply 10 is depicted, and its operating waveform is as follows Figure 5 As shown. By sampling the secondary output voltage Vo of the transformer TR to the FB pin port of the power converter 11 through the feedback device 12 and the current Ip in the primary coil of the transformer through the power tube M1 and the current limiting resistor Rcs to the CS pin port of the power converter 11, a square wave signal (Vsw) with a varying pulse width is generated to control the opening and closing of the power tube (M1) to complete the transmission of the transformer TR energy. The VDD port of the traditional switching power supply 10 has a withstand voltage of only 40V, so a 40V clamp 13 is connected in series externally and then connected to the resistor R1, the rectifier tube D2, and the auxiliary winding La. The waveform of the process from startup to normal operation of the traditional switching power supply 10 is as follows Figure 5 As shown, each time VDD exceeds VDDON, the system completes startup and enters normal operating mode. When the output voltage switches from the 5V range to the 20V range, the output voltage of the auxiliary winding La of the transformer TR jumps from less than 40V to 60-100V. Therefore, the conventional switching power supply 10 requires the addition of a 40V clamp 13 to handle the high operating voltage of the auxiliary winding La, which far exceeds 40V. This increases cost and power consumption. Therefore, it is necessary to adopt special technologies to avoid these issues and achieve low-cost user equipment. Summary of the Invention

[0004] Based on this, the object of the present invention is to provide a protection circuit and a switching power supply based on ultra-high voltage polysilicon resistors.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A protection circuit based on an ultra-high voltage polysilicon resistor, the protection circuit based on the ultra-high voltage polysilicon resistor having four ports, namely a VDD terminal, a VLVDD terminal, a VDD1 terminal, and a GND terminal; the protection circuit comprises: a voltage divider and a clamp; the first end of the voltage divider is respectively connected to the VDD terminal and the first end of the clamp, the second end of the voltage divider is connected to the VDD1 terminal, and the third end of the voltage divider is grounded; the second end of the clamp is connected to the VLVDD terminal, and the third end of the clamp is grounded.

[0007] Optionally, the voltage divider includes: a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor; one end of the first resistor is the first end of the voltage divider, one end of the fifth resistor is the second end of the voltage divider, and the other end of the fifth resistor is the third end of the voltage divider;

[0008] One end of the first resistor is connected to the VDD terminal and the first end of the clamp respectively, the other end of the first resistor is connected to one end of the second resistor, the other end of the second resistor is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to one end of the fifth resistor, and one end of the fifth resistor is also connected to the VDD1 terminal; the other end of the fifth resistor is grounded.

[0009] Optionally, the clamp includes: a sixth resistor, a seventh resistor, an eighth resistor, a first clamp tube, a second clamp tube, a third clamp tube, a fourth clamp tube, and a high-voltage tube; one end of the sixth resistor is the first end of the clamp, the source of the high-voltage tube is the second end of the clamp, and the anode of the first clamp tube is the third end of the clamp;

[0010] One end of the sixth resistor is respectively connected to one end of the first resistor and the drain of the high-voltage tube, the other end of the sixth resistor is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the eighth resistor, and the other end of the eighth resistor is respectively connected to the gate of the high-voltage tube, the cathode of the third clamp tube, and the cathode of the fourth clamp tube; the anode of the third clamp tube is connected to the cathode of the second clamp tube, the anode of the second clamp tube is connected to the cathode of the first clamp tube, and the anode of the first clamp tube is grounded; the anode of the fourth clamp tube is connected to the source of the high-voltage tube, and the source of the high-voltage tube is also connected to VLVDD.

[0011] Optionally, the breakdown voltages of the first clamp tube, the second clamp tube, the third clamp tube and the fourth clamp tube are all 5.9-6.67V; and the withstand voltage of the drain to source, gate and substrate of the high-voltage tube is all 100V.

[0012] Optionally, the first resistor, the second resistor, the third resistor, the fourth resistor, the fifth resistor, the sixth resistor, the seventh resistor and the eighth resistor are all polysilicon resistors.

[0013] Optionally, the first resistor and the sixth resistor are located in a first high-voltage N-well, the second resistor and the seventh resistor are located in a second high-voltage N-well, and the third resistor and the eighth resistor are located in a third high-voltage N-well; the first high-voltage N-well, the second high-voltage N-well, and the third high-voltage N-well are electrically connected to the outside world through connection holes and aluminum wires;

[0014] The first high-voltage N-well is connected to the VDD terminal and one end of the first resistor through a connection hole and an aluminum wire, the second high-voltage N-well is connected to one end of the seventh resistor and the other end of the sixth resistor through a connection hole and an aluminum wire, and the third high-voltage N-well is connected to one end of the eighth resistor and the other end of the seventh resistor through a connection hole and an aluminum wire.

[0015] The present invention provides a switching power supply, comprising: a transformer, a switching power supply controller integrated circuit, a power switch tube and a feedback device, wherein the switching power supply controller integrated circuit comprises: the above-mentioned protection circuit based on ultra-high voltage polysilicon resistors, an undervoltage and overvoltage protection circuit, a pulse width modulator and a drive circuit; the VDD terminal of the protection circuit based on ultra-high voltage polysilicon resistors is connected to the power port of the switching power supply controller integrated circuit, the VLVDD terminal of the protection circuit based on ultra-high voltage polysilicon resistors is respectively connected to the first terminal of the undervoltage and overvoltage protection circuit, the fourth terminal of the drive circuit and the third terminal of the pulse width modulator, and the ultra-high voltage polysilicon resistor is connected to the power port of the switching power supply controller integrated circuit. The VDD1 terminal of the silicon resistor protection circuit is connected to the second terminal of the undervoltage and overvoltage protection circuit; the first terminal of the pulse width modulator is connected to the CS terminal of the switching power supply controller integrated circuit, the second terminal of the pulse width modulator is connected to the FB terminal of the switching power supply controller integrated circuit, the fourth terminal of the pulse width modulator is connected to the fourth terminal of the undervoltage and overvoltage protection circuit and the second terminal of the drive circuit; the fifth terminal of the pulse width modulator is connected to the first terminal of the drive circuit; the third terminal of the undervoltage and overvoltage protection circuit is connected to the third terminal of the drive circuit; and the fifth terminal of the drive circuit is connected to the DRV terminal of the switching power supply controller integrated circuit.

[0016] The present invention provides a switching power supply, comprising: a transformer, a switching power supply controller integrated circuit, a power switch tube and a feedback device, wherein the switching power supply controller integrated circuit comprises: the above-mentioned protection circuit based on ultra-high voltage polysilicon resistors, an undervoltage and overvoltage protection circuit, a pulse width modulator, a drive circuit and a high-voltage startup circuit; the VDD end of the protection circuit based on ultra-high voltage polysilicon resistors is respectively connected to the power port of the switching power supply controller integrated circuit and the second end of the high-voltage startup circuit, the VLVDD end of the protection circuit based on ultra-high voltage polysilicon resistors is respectively connected to the first end of the undervoltage and overvoltage protection circuit, the fourth end of the drive circuit and the third end of the pulse width modulator, and the VDD end of the protection circuit based on ultra-high voltage polysilicon resistors is respectively connected to the first end of the undervoltage and overvoltage protection circuit, the fourth end of the drive circuit and the third end of the pulse width modulator. 1 end is connected to the second end of the undervoltage and overvoltage protection circuit; the first end of the pulse width modulator is connected to the CS end of the switching power supply controller integrated circuit, the second end of the pulse width modulator is connected to the FB end of the switching power supply controller integrated circuit, the fourth end of the pulse width modulator is connected to the fourth end of the undervoltage and overvoltage protection circuit, the third end of the high-voltage startup circuit and the second end of the drive circuit; the fifth end of the pulse width modulator is connected to the first end of the drive circuit; the third end of the undervoltage and overvoltage protection circuit is connected to the third end of the drive circuit; the fifth end of the drive circuit is connected to the DRV end of the switching power supply controller integrated circuit; the first end of the high-voltage startup circuit is connected to the HV end of the switching power supply controller integrated circuit.

[0017] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0018] (1) By using a protection circuit based on ultra-high voltage polysilicon resistors to provide low-voltage power to other modules in the switching power supply controller integrated circuit and to monitor the VDD pin voltage, the switching power supply provided by the present invention can have lower cost and higher safety.

[0019] (2) The switching power supply provided by the present invention can realize the low-voltage power supply function of the VDD pin of the traditional switching power supply to other functional block circuits in the chip and the VDD pin voltage monitoring function without the help of an external 40V clamp. In other words, the external 40V clamp in the traditional switching power supply system is built into the switching power supply controller integrated circuit, thereby greatly reducing the customer's cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a circuit diagram of a traditional switching power supply;

[0022] Figure 2 A circuit diagram of the switching power supply provided by the present invention;

[0023] Figure 3 A schematic diagram of the electrical connections of the protection circuit based on the ultra-high voltage polysilicon resistor provided by the present invention;

[0024] Figure 4 A schematic diagram of the key device structure layout design of the protection circuit based on ultra-high voltage polysilicon resistors provided by the present invention;

[0025] Figure 5 This is the timing waveform of the normal power-on operation and overvoltage protection operation of the traditional switching power supply VDD

[0026] Figure 6 This is the timing waveform of the switching power supply VDD working normally and overvoltage protection working

[0027] The symbols in the figure are explained as follows:

[0028] 10: Traditional switching power supply, used in PD3.0 fast charging charger

[0029] 10A: The switching power supply of the present invention is used in PD3.0 fast charging chargers

[0030] 11: Traditional switching power supply controller integrated circuit

[0031] 11A: Switching power supply controller integrated circuit of the present invention

[0032] 12: Feedback

[0033] 13: 40V clamp

[0034] 20: High voltage startup circuit, namely HVStartup

[0035] 30: Pulse Width Modulator, or PWM

[0036] 40: Drive circuit, DRIVER

[0037] 50: Undervoltage and overvoltage protection circuit, namely UVLOVP

[0038] 60: Protection circuit based on ultra-high voltage polysilicon resistor inside the switching power supply controller integrated circuit 11A, namely LDO

[0039] (D): Well connection hole of the first high-voltage N-well (A)

[0040] (E) Well connection hole of the second high-voltage N-well (B)

[0041] (F): Well connection hole of the third high-voltage N well (C)

[0042] M1: external power switch tube

[0043] M51: High pressure pipe

[0044] TR: Transformer

[0045] Lp: TR primary coil

[0046] Ls: secondary coil of TR

[0047] La: TR's auxiliary coil, responsible for supplying the capacitor C of the VDD port VDD powered by

[0048] VDD: power supply port

[0049] FB: Feedback port

[0050] CS: Current monitoring port

[0051] DRV: driver output port

[0052] GND: Ground port

[0053] VAC: AC input voltage

[0054] Vo: DC output voltage of switching power supply 10

[0055] Ip: Current in the primary coil Lp of the transformer TR

[0056] D1: Full-wave rectifier diode for AC input

[0057] D2, D3: diodes

[0058] Rst: Starting resistance of the switching power supply system 10, 10A

[0059] R1, Rx, Rcs: resistors

[0060] R51, R52, R53, R54, R55, R56, R57, R58: the first to eighth resistors respectively

[0061] C1, Cx, C VDD , C2: capacitor

[0062] Z1, Z2, Z3, Z4: zero-drift clamping diodes with clamping voltage VZ

[0063] 51: Voltage divider, which accurately divides the ultra-high voltage VDD and inputs it to other modules for VDD voltage monitoring

[0064] 52: Clamp, clamps and reduces the voltage of ultra-high voltage VDD, making it more suitable for use in IC devices

[0065] Vsw: switching signal, that is, the pulse width voltage signal that drives the gate of power tube M1

[0066] V FB : Feedback voltage

[0067] V CS :The current limiting voltage of the CS port, the source voltage of M1, is equal to the product of the current Ip in Lp and Rcs, and has the same frequency as Vsw

[0068] V DD : Power supply VDD port voltage

[0069] V DD2 : Voltage at the common end of resistors R54 and R55

[0070] V PWM : PWM output logic signal, used to modulate the pulse width of Vsw

[0071] EN: Undervoltage and overvoltage protection circuit 50 power-on and power-off enable logic signal

[0072] OVP: Overvoltage protection logic control signal output by undervoltage and overvoltage protection circuit 50

[0073] V DD1 : VDD proportional voltage, 11A UVLOVP uses this signal to monitor VDD voltage

[0074] VDD OFF : VDD voltage power-down threshold

[0075] VDD ON : VDD voltage power-on threshold

[0076] V FB_OPEN : FB port open circuit voltage

[0077] VB1: The grid voltage of the high-voltage tube M51, which is also connected to the other end of the resistor R57 and the cathode of the clamp tube Z4

[0078] V LVDD : The source voltage of the high-voltage tube M51 is also connected to the anode of the clamp tube Z4

[0079] V THN : Gate turn-on threshold voltage of M51

[0080] V GS51 : During normal operation, the voltage difference between the gate and source of M51 is

[0081] V POLY56_58 : The voltage difference between each of the resistors R56 / R57 / R58

[0082] V POLY51_53 : The voltage difference between each of the resistors R51 / R52 / R53

[0083] "1": Logic high

[0084] “0”: logic low. DETAILED DESCRIPTION

[0085] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0086] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0087] like Figure 2 As shown, the protection circuit 60 based on ultra-high voltage polysilicon resistor provided by the present invention has four ports, namely VDD terminal, V LVDD Terminal, V DD1 The VDD terminal of the protection circuit 60 based on the ultra-high voltage polysilicon resistor is at its V LVDD The lower voltage supply voltage source V LVDD , for use by other circuit devices in the switching power supply controller integrated circuit 11A to reduce area and cost; the VDD terminal of the protection circuit 60 based on the ultra-high voltage polysilicon resistor is at V DD1 The terminal generates a voltage-divided signal for use by other functional blocks in the switching power supply controller integrated circuit 11A to facilitate monitoring of the VDD terminal voltage; the VDD terminal voltage of the protection circuit 60 based on the ultra-high voltage polysilicon resistor can reach 100V, and the upper limit of the operating voltage range can reach between 80 and 100V.

[0088] The protection circuit 60 based on ultra-high voltage polysilicon resistors includes a voltage divider 51 and a clamp 52 .

[0089] The first end of the voltage divider 51 is connected to the VDD end and the first end of the clamp 52 respectively, and the second end of the voltage divider 51 is connected to the V DD1 The third end of the voltage divider 51 is grounded; the second end of the clamp 52 is connected to V LVDD The third terminal of the clamper 52 is connected to the ground.

[0090] like Figure 3 As shown, the voltage divider 51 includes: a first resistor R51, a second resistor R52, a third resistor R53, a fourth resistor R54 and a fifth resistor R55; one end of the first resistor R51 is the first end of the voltage divider 51, one end of the fifth resistor R55 is the second end of the voltage divider 51, and the other end of the fifth resistor R55 is the third end of the voltage divider 51.

[0091] One end of the first resistor R51 is connected to the VDD terminal and the first end of the clamp 52 respectively, the other end of the first resistor R51 is connected to one end of the second resistor R52, the other end of the second resistor R52 is connected to one end of the third resistor R53, the other end of the third resistor R53 is connected to one end of the fourth resistor R54, the other end of the fourth resistor R54 is connected to one end of the fifth resistor R55, and one end of the fifth resistor R55 is also connected to VDD. DD1 The other end of the fifth resistor R55 is grounded.

[0092] The first terminal VDD of the voltage divider 51 is connected to the second terminal V DD1 Generates a proportional divided voltage V DD1 , the undervoltage and overvoltage protection circuit 50 in the switching power supply controller integrated circuit 11A passes the voltage V DD1 Monitor the VDD voltage for 11A operation.

[0093] like Figure 3 As shown, the clamper 52 includes: a sixth resistor R56, a seventh resistor R57, an eighth resistor R58, a first clamping tube Z1, a second clamping tube Z2, a third clamping tube Z3, a fourth clamping tube Z4 and a high-voltage tube M51; one end of the sixth resistor R56 is the first end of the clamper 52, the source of the high-voltage tube M51 is the second end of the clamper 52, and the anode of the first clamping tube Z1 is the third end of the clamper 52.

[0094] One end of the sixth resistor R56 is connected to one end of the first resistor R51 and the drain of the high-voltage tube M51, respectively. The other end of the sixth resistor R56 is connected to one end of the seventh resistor R57, the other end of the seventh resistor R57 is connected to one end of the eighth resistor R58, and the other end of the eighth resistor R58 is connected to the gate of the high-voltage tube M51, the cathode of the third clamping tube Z3, and the cathode of the fourth clamping tube Z4, respectively. The anode of the third clamping tube Z3 is connected to the cathode of the second clamping tube Z2, the anode of the second clamping tube Z2 is connected to the cathode of the first clamping tube Z1, and the anode of the first clamping tube Z1 is grounded. The anode of the fourth clamping tube Z4 is connected to the source of the high-voltage tube M51, and the source of the high-voltage tube M51 is also connected to V LVDD End connection.

[0095] The first terminal VDD of the clamp 52 is connected to the second terminal V LVDD Output lower supply voltage source V LVDD It can be used by other circuit devices to reduce area and cost; the fourth clamping tube Z4 can prevent the gate-source breakdown of the high-voltage tube M51.

[0096] Specifically, the breakdown voltages of the first clamping transistor Z1, the second clamping transistor Z2, the third clamping transistor Z3, and the fourth clamping transistor Z4 are all 5.9-6.67V; the withstand voltage of the drain to source, gate, and substrate of the high-voltage transistor M1 is all 100V; and the withstand voltage between the metal layer and the adjacent material layer is greater than 100V.

[0097] Resistors R51 to R58 are all polysilicon resistors, and the withstand voltage between the two ends of each polysilicon resistor is 30V. The withstand voltage between each polysilicon resistor and the adjacent non-metallic material layer is 30V. The metal layer used for electrical connection has a withstand voltage of far more than 100V to other adjacent material layers. The resistance values ​​of R51, R52, and R53 are equal, the resistance values ​​of R56, R57, and R58 are equal, and the resistance value of R54 is 2.333 times that of R55.

[0098] The layout structure design of resistors R51~R53 and R56~R58 is as follows Figure 4 As shown, the first resistor R51 and the sixth resistor R56 are located in the first high-voltage N-well (A), the second resistor R52 and the seventh resistor R57 are located in the second high-voltage N-well (B), and the third resistor R53 and the eighth resistor R58 are located in the third high-voltage N-well (C). The high-voltage N-well is electrically connected to the outside world through connection holes and aluminum wires. The polysilicon resistor is also electrically connected to the outside world through connection holes and aluminum wires. The first high-voltage N-well (A), the second high-voltage N-well (B), and the third high-voltage N-well (C) all have a withstand voltage of 100V to ground and the substrate layer.

[0099] The first high-voltage N-well (A) is connected to the VDD terminal and one end of the first resistor R51 through the connection hole (D) and the aluminum wire therein; the second high-voltage N-well (B) is connected to one end of the seventh resistor R57 and the other end of the sixth resistor R56 through the connection hole (E) therein; the third high-voltage N-well (C) is connected to one end of the eighth resistor R58 and the other end of the seventh resistor R57 through the connection hole (F) therein.

[0100] In the physical structure of resistors R51~R53, R56~R58, a high-voltage N-well is placed underneath them to isolate the polysilicon resistors operating above 30V from the grounded substrate layer. This can prevent the polysilicon resistors operating at high voltage from leaking electricity to the substrate layer and causing the polysilicon resistors to fail.

[0101] Option A of the embodiment of the present invention provides a switching power supply, including: a transformer TR, a switching power supply controller integrated circuit 11A, a power switch tube M1, and a feedback device 12. The switching power supply controller integrated circuit 11A includes: the above-mentioned ultra-high voltage polysilicon resistor-based protection circuit 60, the undervoltage and overvoltage protection circuit 50, the pulse width modulator 30, and the drive circuit 40. The VDD terminal of the ultra-high voltage polysilicon resistor-based protection circuit 60 is connected to the power port of the switching power supply controller integrated circuit 11A. LVDD The terminals are respectively connected to the first terminal of the undervoltage and overvoltage protection circuit 50, the fourth terminal of the driving circuit 40 and the third terminal of the pulse width modulator 30, and the V of the protection circuit 60 based on the ultra-high voltage polysilicon resistor is DD1 The first end of the pulse width modulator 30 is connected to the CS end of the switching power supply controller integrated circuit 11A, the second end of the pulse width modulator 30 is connected to the FB end of the switching power supply controller integrated circuit 11A, the fourth end of the pulse width modulator 30 is connected to the fourth end of the undervoltage and overvoltage protection circuit 50 and the second end of the drive circuit 40; the fifth end of the pulse width modulator 30 is connected to the first end of the drive circuit 40; the third end of the undervoltage and overvoltage protection circuit 50 is connected to the third end of the drive circuit 40; the fifth end of the drive circuit 40 is connected to the DRV end of the switching power supply controller integrated circuit 11A.

[0102] like Figure 2 As shown, Option B of the embodiment of the present invention provides a switching power supply, including: a transformer TR, a switching power supply controller integrated circuit 11A, a power switch tube M1 and a feedback device 12. The switching power supply controller integrated circuit 11A includes: the above-mentioned ultra-high voltage polysilicon resistor-based protection circuit 60, the undervoltage and overvoltage protection circuit 50, the pulse width modulator 30, the drive circuit 40 and the high-voltage startup circuit; the VDD terminal of the ultra-high voltage polysilicon resistor-based protection circuit 60 is respectively connected to the power port of the switching power supply controller integrated circuit 11A and the second terminal of the high-voltage startup circuit 20, and the VDD terminal of the ultra-high voltage polysilicon resistor-based protection circuit 60 is respectively connected to the power port of the switching power supply controller integrated circuit 11A and the second terminal of the high-voltage startup circuit 20. LVDD The terminals are respectively connected to the first terminal of the undervoltage and overvoltage protection circuit 50, the fourth terminal of the driving circuit 40 and the third terminal of the pulse width modulator 30, and the V of the protection circuit 60 based on the ultra-high voltage polysilicon resistor is DD1The first end of the pulse width modulator 30 is connected to the CS end of the switching power supply controller integrated circuit 11A, the second end of the pulse width modulator 30 is connected to the FB end of the switching power supply controller integrated circuit 11A, the fourth end of the pulse width modulator 30 is connected to the fourth end of the undervoltage and overvoltage protection circuit 50, the third end of the high-voltage startup circuit 20 and the second end of the drive circuit 40; the fifth end of the pulse width modulator 30 is connected to the first end of the drive circuit 40; the third end of the undervoltage and overvoltage protection circuit 50 is connected to the third end of the drive circuit 40; the fifth end of the drive circuit 40 is connected to the DRV end of the switching power supply controller integrated circuit 11A; the first end of the high-voltage startup circuit 20 is connected to the HV end of the switching power supply controller integrated circuit 11A.

[0103] The CS terminal of the switching power supply controller integrated circuit 11A is connected to the first end of the sampling resistor Rcs and the source of the power transistor M1, its FB terminal is connected to the output end of the feedback device 12, its DRV terminal is externally connected to the gate of the power transistor M1, and its VDD terminal is connected to Rst (Option A in the example), R1 and C VDD The common terminal, in Option B, has the HV terminal connected to the common terminal of C1, D1, and TR, and its GND terminal is grounded; the second terminal of the sampling resistor Rcs is grounded; and the drain of the power tube M1 is connected to the primary winding Lp of the transformer.

[0104] The switching power supply controller integrated circuit 11A of the present invention has two optional startup modes at the VDD end. In embodiment Option A, the VDD is connected to the high voltage input end by an external startup resistor Rst. In embodiment Option B, the VDD is connected to the high voltage input end by an external startup resistor Rst. Figure 2 The dotted line in the middle shows that the port HV is connected to the common terminal of D1, C1, and TR. The HV is connected to the HVStartup module to charge VDD. When VDD exceeds VDD ON Then close HVStartup.

[0105] The voltage dividing function principle of the voltage divider 51 in the protection circuit 60 based on ultra-high voltage polysilicon resistor is as follows:

[0106] The resistance values ​​of resistors R51, R52, and R53 are equal. The resistance values ​​of resistors R56, R57, and R58 are equal. The resistance value of R54 is 2.33 times that of R55. R51 / (R51+R52+R53+R54+R55)=α, 0<<<1. The common terminal voltage of R53 and R54 is V DD2 , the VDD terminal voltage is V DD , VDD ON is the power-on threshold, VDD OFF is the power-off threshold, then:

[0107] V DD1 =αV DD <6V, 0≤VDD ≤100V (1)

[0108] During the normal operation of VDD powered on from 0 and when an overvoltage abnormality occurs during normal operation, the voltage divider output V DD1 is proportional to VDD, and V DD1 The voltage is low enough to be provided to the low voltage circuit function block in the switching power supply controller 11A: the undervoltage and overvoltage protection circuit 50, which detects V DD1 The voltage value of VDD can be determined to complete undervoltage lockout and overvoltage protection control.

[0109] In addition, R51 to R58 are all resistors made of polysilicon, also known as polysilicon resistors. The withstand voltage between the two ends of a polysilicon resistor is generally 30V, and the withstand voltage between the polysilicon resistor body and the adjacent non-metallic material layer is generally 30V. Therefore, without special technical processing, polysilicon resistors cannot operate within the voltage range of 30-100V.

[0110] The new technical means used in the present invention is to place a layer of high-voltage N-well material that can withstand a voltage of 100V against the substrate material under the polysilicon resistor to isolate the polysilicon resistor from the substrate material layer (the substrate layer is generally grounded), and at the same time connect the high-voltage N-well to the high-voltage end of the resistor body. In this way, even if the polysilicon resistor is exposed to a potential of 30 to 100V relative to the ground, the voltage difference between the two ends of the resistor and between the resistor and the adjacent high-voltage N-well layer can be controlled within a safe zone below 30V.

[0111] like Figure 4 As shown, R51 and R56 are located below the first high-voltage N-well (A), R52 and R57 are located below the second high-voltage N-well (B), and R53 and R58 are located below the third high-voltage N-well (C). R54 is placed directly on the substrate, which is grounded. (D), (E), and (F) are the connection holes for the high-voltage N-wells (A), (B), and (C), respectively. A metal aluminum wire layer is used for electrical connections. The first high-voltage N-well (A) is connected to VDD and the common terminal of R51 and R56 via (D) and the aluminum wire layer. The high-voltage N-well (B) is connected to the common terminal of R56 and R57 via (E) and the aluminum wire layer. The high-voltage N-well (C) is connected to the common terminal of R57 and R58 via (F) and the aluminum wire layer. The other end of R58 is connected to VB1, the gate of high-voltage transistor M51, and the cathode of clamp transistor Z4, via a connection hole and the aluminum wire layer. The other end of R51 is connected to one end of R52, the other end of R52 is connected to one end of R53, and the other end of R53 is connected to the voltage V DD2 The withstand voltage of the metal aluminum wire layer used for electrical connection and its adjacent material layer exceeds 100V.

[0112] V DD2 =V DD1(R54 / R55+1)=3.33V DD1 <20V, 0≤V DD ≤100V (2)

[0113] Among them, V DD2 The voltage of the common terminal of R53 and R54. The maximum value of the voltage VB1 of the other end of R58 to the ground is VB1. MAX for:

[0114] VB1 MAX =3V Z ≤20V, 100V≥V DD ≥3V Z (3)

[0115] Therefore, for resistors R56, R57, and R58 of equal resistance, the voltage difference between the two ends of each resistor is V POLY56_58 , then:

[0116] V POLY56_58 ≤(100-3V Z ) / 3≤26.67V<30V,100V≥V DD ≥3V Z (4)

[0117] For resistors R51, R52, and R53 of equal resistance, the voltage difference between the two ends of each resistor is V POLY51_53 , then:

[0118] V POLY51_53 ≤(100-V DD2 ) / 3≤26.67V<30V,100V≥V DD ≥3V Z (5)

[0119] As can be seen from the circuit diagram, the potentials of R51 and R56 are close, so they are arranged on the first high-voltage N-well (A); the potentials of R52 and R57 are close, so they are arranged on the second high-voltage N-well (B); the potentials of R53 and R58 are close, so they are arranged on the third high-voltage N-well (C).

[0120] From equations (4) and (5), we can see that the voltage difference across each resistor in R51-R53 and R56-R58 is much less than 30V. The adjacent material layer of these resistors is a high-voltage N-well, and the potential of the high-voltage N-well is connected to the high-potential terminal of the internal resistor. Therefore, the voltage difference between each resistor and the high-voltage N-well of its adjacent material layer is also much less than 30V. In this way, each resistor, whether between its two ends or between the resistor and the adjacent material layer, operates within the safe working area with a voltage difference of less than 30V.

[0121] The principle of the clamp 52 in the protection circuit 60 based on ultra-high voltage polysilicon resistors is as follows:

[0122] The drain of the high-voltage tube M51 is connected to VDD, and the voltage clamping resistors, namely the sixth resistor R56, the seventh resistor R57 and the eighth resistor R58, are connected between the gate and the drain to reduce the VDD voltage. The source outputs a lower supply voltage V to the internal circuit. LVDD , in order to reduce the contact voltage of internal circuit devices, reduce the device layout area and thus greatly reduce chip costs. Low voltage supply voltage V LVDD It provides power to other module circuits in the switching power supply controller 11A. Clamping transistors Z1-Z3 are connected in series between ground and the gate of the high-voltage transistor M51, clamping the gate voltage of the high-voltage transistor M51 to a lower voltage. The fourth clamping transistor Z4 is used to clamp the gate-source voltage of the high-voltage transistor M51 to prevent the gate oxide layer of the high-voltage transistor M51 from breaking down. The reverse breakdown voltage threshold of the Zener transistor V 齐纳击穿 5.3V~5.97V, forward conduction voltage V be =0.6~0.7V, each clamping tube is a pair of Zener tubes connected in series, so the clamping voltage threshold of the clamping tube is V Z =V 齐纳击穿 +V be =5.9~6.67V is close to zero temperature drift.

[0123] VB1=V DD , V DD <3V Z (6)

[0124] VB1=3V Z =20V, 100V≥V DD ≥3V Z (7)

[0125] V LVDD =VB1-V GS51 <19.3V (8)

[0126] Here, 0.7V <V GS51 <2V is the gate-source voltage difference of the high-voltage tube M51. Figure 3 Three clamping tubes are used in the embodiment, but the VDD voltage clamping function of the present invention is not limited to three clamping tubes, and can also be implemented with two or one clamping tube. From formula (8), it can be seen that the power supply V of other circuits in the switching power supply controller integrated circuit 11A is LVDD It is a low-voltage power supply, which is much lower than the maximum voltage of 100V of the VDD pin. Therefore, the area of ​​other circuit devices inside the switching power supply controller integrated circuit 11A is reduced to the maximum extent, further reducing the total chip area and cost.

[0127] The protection circuit 60 based on ultra-high voltage polysilicon resistors provided by the present invention can realize the operation of the VDD port in an ultra-wide voltage range of 0 to 100V, so that it can not only monitor the voltage of the VDD port and protect the switching power supply system when the voltage is abnormal, but also provide low-voltage power V to other circuits inside the switching power supply controller integrated circuit 11A. LVDD It is convenient to use low voltage devices to construct the circuit, thus saving chip area and cost, and also eliminating Figure 1 The 40V clamp 13 in the traditional switching power supply 10 is removed. Therefore, the switching power supply system 10A of the present invention saves customer costs to the greatest extent and reduces the chip area and cost of the switching power supply controller integrated circuit 11A.

[0128] Figure 5 and Figure 6 The following diagram compares the normal power-on operating waveforms and overvoltage protection waveforms of the VDD pin of a conventional switching power supply 10 and a switching power supply 10A according to the present invention. The switching power supply 10A according to the present invention achieves the VDD pin undervoltage lockout and overvoltage protection functions of the conventional switching power supply 10, while also providing power to other modules within chip 11A, without the need for an external 40V clamp 13. This significantly reduces both customer costs and the cost of chip 11A.

[0129] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0130] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A protection circuit based on ultra-high voltage polysilicon resistor, characterized in that: The protection circuit based on ultra-high voltage polysilicon resistor has four ports, namely VDD terminal, V LVDD Terminal, V DD1 The protection circuit includes: a voltage divider and a clamp; the first end of the voltage divider is connected to the VDD end and the first end of the clamp respectively, and the second end of the voltage divider is connected to the V DD1 The third end of the voltage divider is grounded; the second end of the clamp is connected to the V LVDD The third terminal of the clamp is connected to the ground; The voltage divider includes: a first resistor, a second resistor, a third resistor, a fourth resistor, and a fifth resistor; one end of the first resistor is the first end of the voltage divider, one end of the fifth resistor is the second end of the voltage divider, and the other end of the fifth resistor is the third end of the voltage divider; One end of the first resistor is connected to the VDD terminal and the first end of the clamp respectively, the other end of the first resistor is connected to one end of the second resistor, the other end of the second resistor is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the fourth resistor, the other end of the fourth resistor is connected to one end of the fifth resistor, and one end of the fifth resistor is also connected to the VDD terminal. DD1 The other end of the fifth resistor is grounded; The clamp includes: a sixth resistor, a seventh resistor, an eighth resistor, a first clamp tube, a second clamp tube, a third clamp tube, a fourth clamp tube, and a high-voltage tube; one end of the sixth resistor is the first end of the clamp, the source of the high-voltage tube is the second end of the clamp, and the anode of the first clamp tube is the third end of the clamp; One end of the sixth resistor is connected to one end of the first resistor and the drain of the high-voltage tube, respectively; the other end of the sixth resistor is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the eighth resistor, and the other end of the eighth resistor is connected to the gate of the high-voltage tube, the cathode of the third clamp tube, and the cathode of the fourth clamp tube, respectively; the anode of the third clamp tube is connected to the cathode of the second clamp tube, the anode of the second clamp tube is connected to the cathode of the first clamp tube, and the anode of the first clamp tube is grounded; the anode of the fourth clamp tube is connected to the source of the high-voltage tube, and the source of the high-voltage tube is also connected to the V LVDD connect; The first resistor and the sixth resistor are located in a first high-voltage N-well, the second resistor and the seventh resistor are located in a second high-voltage N-well, and the third resistor and the eighth resistor are located in a third high-voltage N-well; the first high-voltage N-well, the second high-voltage N-well, and the third high-voltage N-well are electrically connected to the outside world through connection holes and aluminum wires; The first high-voltage N-well is connected to the VDD terminal and one end of the first resistor through a connection hole and an aluminum wire, the second high-voltage N-well is connected to one end of the seventh resistor and the other end of the sixth resistor through a connection hole and an aluminum wire, and the third high-voltage N-well is connected to one end of the eighth resistor and the other end of the seventh resistor through a connection hole and an aluminum wire.

2. The protection circuit based on ultra-high voltage polysilicon resistor according to claim 1, characterized in that: The breakdown voltages of the first clamp tube, the second clamp tube, the third clamp tube and the fourth clamp tube are all 5.9-6.67V; the withstand voltage of the drain to source, gate and substrate of the high-voltage tube is all 100V.

3. The protection circuit based on ultra-high voltage polysilicon resistor according to claim 1, characterized in that: The first resistor, the second resistor, the third resistor, the fourth resistor, the fifth resistor, the sixth resistor, the seventh resistor, and the eighth resistor are all polysilicon resistors.

4. A switching power supply, characterized in that: include: A transformer, a switching power supply controller integrated circuit, a power switch tube and a feedback device, wherein the switching power supply controller integrated circuit includes: a protection circuit based on an ultra-high voltage polysilicon resistor, an undervoltage and overvoltage protection circuit, a pulse width modulator and a drive circuit according to any one of claims 1 to 3; The VDD end of the protection circuit based on the ultra-high voltage polysilicon resistor is connected to the power port of the switching power supply controller integrated circuit, and the V LVDD The first and second terminals of the undervoltage and overvoltage protection circuit, the fourth terminal of the driving circuit and the third terminal of the pulse width modulator are connected respectively. The V DD1 The first end of the pulse width modulator is connected to the CS end of the switching power supply controller integrated circuit, the second end of the pulse width modulator is connected to the FB end of the switching power supply controller integrated circuit, the fourth end of the pulse width modulator is connected to the fourth end of the undervoltage and overvoltage protection circuit and the second end of the drive circuit; the fifth end of the pulse width modulator is connected to the first end of the drive circuit; the third end of the undervoltage and overvoltage protection circuit is connected to the third end of the drive circuit; and the fifth end of the drive circuit is connected to the DRV end of the switching power supply controller integrated circuit.

5. A switching power supply, characterized in that: include: A transformer, a switching power supply controller integrated circuit, a power switch tube and a feedback device, wherein the switching power supply controller integrated circuit includes: a protection circuit based on an ultra-high voltage polysilicon resistor, an undervoltage and overvoltage protection circuit, a pulse width modulator, a drive circuit and a high-voltage startup circuit as described in any one of claims 1 to 3; the VDD end of the protection circuit based on the ultra-high voltage polysilicon resistor is respectively connected to the power port of the switching power supply controller integrated circuit and the second end of the high-voltage startup circuit, the VLVDD end of the protection circuit based on the ultra-high voltage polysilicon resistor is respectively connected to the first end of the undervoltage and overvoltage protection circuit, the fourth end of the drive circuit and the third end of the pulse width modulator, and the VDD1 end of the protection circuit based on the ultra-high voltage polysilicon resistor is respectively connected to the power port of the switching power supply controller integrated circuit and the second end of the high-voltage startup circuit. The second end of the undervoltage and overvoltage protection circuit is connected; the first end of the pulse width modulator is connected to the CS end of the switching power supply controller integrated circuit, the second end of the pulse width modulator is connected to the FB end of the switching power supply controller integrated circuit, the fourth end of the pulse width modulator is connected to the fourth end of the undervoltage and overvoltage protection circuit, the third end of the high-voltage startup circuit and the second end of the drive circuit; the fifth end of the pulse width modulator is connected to the first end of the drive circuit; the third end of the undervoltage and overvoltage protection circuit is connected to the third end of the drive circuit; the fifth end of the drive circuit is connected to the DRV end of the switching power supply controller integrated circuit; the first end of the high-voltage startup circuit is connected to the HV end of the switching power supply controller integrated circuit.

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