CN105278608B - A kind of high accurate overvoltage crowbar - Google Patents
A kind of high accurate overvoltage crowbar Download PDFInfo
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- CN105278608B CN105278608B CN201510712488.5A CN201510712488A CN105278608B CN 105278608 B CN105278608 B CN 105278608B CN 201510712488 A CN201510712488 A CN 201510712488A CN 105278608 B CN105278608 B CN 105278608B
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Abstract
The present invention relates to a kind of high accurate overvoltage crowbars, including high precision reference current generating circuit, high-precision over-voltage time decision generation circuit and overvoltage protection resistance adjustment automatic control circuit, reference voltage is separately connected the positive input terminal of high precision reference current generating circuit and high-precision over-voltage time decision generation circuit, zero temp shift resistance is equipped in high precision reference current generating circuit, the high precision reference current generating circuit is connected by internal regulation resistance control terminal with overvoltage protection resistance adjustment automatic control circuit, overvoltage protection resistance adjustment automatic control circuit is equipped with inside and outside and adjusts resistance switch control unit, the input terminal of reference clock signal connection high-precision over-voltage time decision generation circuit, the output of high-precision over-voltage time decision generation circuit is overvoltage protection output end.This circuit improves the time decision precision of overvoltage protection, also improves the consistency of overvoltage protection, because of energy adjust automatically over-voltage protecting function, improves circuit level.
Description
Technical field
The present invention relates to IC design field, specifically a kind of height applied in LED drive chip is precisely
Overvoltage crowbar.
Background technique
Overvoltage crowbar in existing LED drive chip be by comparing the external inductors erasing time in chip operation with
What the overvoltage protection time of chip interior setting was realized, the mistake in the overvoltage protection time for being less than setting when the inductance erasing time
Voltage protection circuit carries out overvoltage protection, it may be said that the effect of overvoltage crowbar is exactly when generating fixed overvoltage protection reference
Between, to carry out over-voltage judgement to chip system logic control part.
The structural block diagram of overvoltage crowbar in traditional LED drive chip is as shown in Fig. 1, and circuit diagram is for example attached
Shown in Fig. 2.By Fig. 1 and 2 it is found that existing overvoltage crowbar includes that reference current generating circuit and over-voltage time decision generate electricity
Road, circuit structure is fairly simple, but since the overvoltage protection reference time of circuit output is there are biggish error, causes in portion
Occurs the normal work that over-voltage protecting function fails and then influences LED information display system in the application of point LED drive chip.It is tested by analysis
Learn error mainly from following 3 aspects：First, the discreteness of resistance R2 resistance value causes to generate in reference current generating circuit
Reference current there are deviations；Second, the base that the temperature characterisitic of resistance R2 causes the circuit to generate in reference current generating circuit
Deviation brought by temperature change of the quasi- electric current with LED drive chip；Third, defeated used in reference current generating circuit
Phase inverter (OPA) causes its decision threshold to change because of technological fluctuation out, when thus bring capacitor charging to over-voltage is adjudicated
Between output signal OUT flip-flop transition of generation circuit change, i.e. the deviation of overvoltage protection reference time.Therefore, urgent need
A kind of high accurately overvoltage crowbar eliminates error.
Summary of the invention
The present invention is exactly directed to technical problem present in existing overvoltage crowbar, provides a kind of improved accurate mistake of height
Voltage protection circuit substantially increases the precision of overvoltage protection, and real by carrying out structure innovation to existing overvoltage crowbar
Show the outer overvoltage protection of automatic detection LED drive chip and adjusted resistance, carries out the automatic switchover of inside and outside overvoltage protection setting.
To achieve the goals above, the technical solution adopted by the present invention is a kind of high accurate overvoltage crowbar, including height
Precision reference current generating circuit, high-precision over-voltage time decision generation circuit and overvoltage protection resistance adjustment automatically control electricity
Road, reference voltage are separately connected the defeated of the high precision reference current generating circuit and high-precision over-voltage time decision generation circuit
Enter end, zero temp shift resistance is equipped in high precision reference current generating circuit, high precision reference current generating circuit passes through electric current
Mirror image unit exports two-way mirror image high precision reference electric current, wherein mirror image high precision reference electric current I1 connects high-precision over-voltage and sentences all the way
The certainly input terminal of time generation circuit, another way mirror image high precision reference electric current I2 take over pressure protective resistance and adjust automatic control electricity
The input terminal on road, the high precision reference current generating circuit also pass through internal regulation resistance control terminal and overvoltage protection resistance tune
It saves automatic control circuit to be connected, overvoltage protection resistance adjustment automatic control circuit is equipped with inside and outside and adjusts resistance switching control list
Member, reference clock signal connect the input terminal of high-precision over-voltage time decision generation circuit, and high-precision over-voltage time decision generates
The output end of circuit is overvoltage protection output end.
The high-precision over-voltage time decision generation circuit is equipped with hysteresis comparator, the charging electricity inputted with reference voltage
Hold, capacitor charging circuit and current source mirror image circuit, reference clock signal connect the first input end of capacitor charging circuit, mirror image
Second input terminal of high precision reference electric current I1 connection capacitor charging circuit, charging capacitor connect the output of capacitor charging circuit
End, charging capacitor are also connected with the negative input end of hysteresis comparator, and reference voltage connects the reference voltage input terminal of hysteresis comparator,
That is the positive input terminal of hysteresis comparator, the hysteresis comparator are using several n type field effect transistors and several p-type fields
Effect transistor is built, including the first n type field effect transistor, the second n type field effect transistor, third N-type field
Effect transistor, the 4th n type field effect transistor, the first p type field effect transistor, the second p type field effect transistor, the 3rd P
The grid of type field effect transistor and the 4th p type field effect transistor, first n type field effect transistor is drawn as sluggish
The negative input end of comparator, the grid of second n type field effect transistor draw the positive input terminal as hysteresis comparator, institute
The source electrode ground connection of third n type field effect transistor is stated, the drain electrode of third n type field effect transistor is drawn as hysteresis comparator
Output end, the drain electrode of drain electrode the first p type field effect transistor of connection of the first n type field effect transistor, the first p-type field-effect are brilliant
Body pipe, the second p type field effect transistor, third p type field effect transistor, the source electrode connection of the 4th p type field effect transistor are electric
Source, the gate interconnection of the first p type field effect transistor and the second p type field effect transistor, the leakage of the second p type field effect transistor
Pole connects the drain electrode of the second n type field effect transistor, and the grid of the second p type field effect transistor is also connected with the first N-type field-effect
The drain electrode of transistor, the grid of third p type field effect transistor connect the grid of the second p type field effect transistor, third p-type field
The drain electrode of drain electrode the 4th n type field effect transistor of connection of effect transistor, the source electrode connection the of the 4th n type field effect transistor
The drain electrode of two n type field effect transistors, the grid of the 4th n type field effect transistor connect the leakage of the 4th p type field effect transistor
Pole, the grid of the 4th p type field effect transistor connect the source electrode of the 4th n type field effect transistor, the 4th p type field effect transistor
Drain electrode connection third n type field effect transistor drain electrode, the current source mirror image circuit use the 5th n type field effect transistor
It connects and builds with the 6th n type field effect transistor common gate, the 5th n type field effect transistor and the 6th N-type field-effect are brilliant
The source electrode of body pipe is grounded, and the drain electrode of the 5th n type field effect transistor connects current source, the drain electrode of the 5th n type field effect transistor
It is also connected with the grid of the 6th n type field effect transistor, drain electrode connection the first N-type field-effect of the 6th n type field effect transistor is brilliant
The grid connection third N-type field-effect of the source electrode of body pipe and the second n type field effect transistor, the 6th n type field effect transistor is brilliant
The grid of body pipe, the output end of hysteresis comparator are overvoltage protection output end.
In addition, the overvoltage protection resistance adjustment automatic control circuit be equipped with it is external adjust resistance detection end, on reply by cable
Position end, charging capacitor, reference current source, phase inverter, d type flip flop and inside and outside adjust resistance switching control end ctrl1 with
Ctrl2, outside adjust the p type field effect transistor and n type field effect transistor that resistance detection end is connected to common gate connection
On grid, the source electrode of p type field effect transistor is the input terminal of mirror image high precision reference electric current I2, n type field effect transistor
Source electrode ground connection, the drain electrode of p type field effect transistor and n type field effect transistor are sequentially connected charging capacitor, with reference to electricity after joining altogether
The input terminal in stream source and phase inverter, the input terminal of the output end connection d type flip flop of phase inverter, p type field effect transistor and N-type field
Effect transistor common gate connection d type flip flop clock pulse terminal, electrification reset end pass sequentially through the first NOT gate and first with
The reset terminal of NOT gate connection d type flip flop；Inside and outside adjusts resistance switching control end ctrl1 and connect adjusting electricity in inside and outside with ctrl2
The input terminal of switch control unit is hindered, the inverse output terminal connection inside and outside of d type flip flop adjusts the defeated of resistance switch control unit
Enter end, the output end that inside and outside adjusts resistance switch control unit connects the input terminal of the first NAND gate, and inside and outside is adjusted
The remaining output end of resistance switch control unit connects internal regulation resistance control terminal.
It as an improvement of the present invention, further include current source, multistage fortune in the high precision reference current generating circuit
Amplifier and reference voltage mirror image unit, the input termination power of the current source are calculated, output terminates multi-stage operational amplifier
First input end, reference voltage mirror image unit connect the second input terminal of multi-stage operational amplifier, and reference voltage connects reference voltage mirror
As the input terminal of unit, the input terminal of current mirror unit is connected with the output end of multi-stage operational amplifier, internal regulation resistance
Control terminal is connected on zero temp shift resistance by n type field effect transistor.The multi-stage operational amplifier is using several N-types
Field effect transistor and several p type field effect transistors are built with cascode structure (casecode structure), not only
Output impedance is big, reduces channel current mudulation effect, and substantially increases the precision of current mirror, and then improve height
The precision of reference current caused by precision reference current generating circuit.The reference voltage mirror image unit is two p-type field effects
Transistor is answered to connect composition by the way of common source connection, reference voltage is connected to the grid of a p type field effect transistor,
Zero temp shift resistance is connected to the grid of another p type field effect transistor, so that the end voltage Vr of zero temp shift resistance is equal to
Reference voltage.The current mirror unit is that three p type field effect transistors connect composition by the way of cascade connection,
Zero temp shift resistance is connected to the drain electrode of a p type field effect transistor, and mirror image high precision reference electric current I1 is resulted from another all the way
The drain electrode of a p type field effect transistor, another way mirror image high precision reference electric current I2, which is resulted from, remains next p-type field effect transistor
The drain electrode of pipe, zero temp shift is ohmically, and to be mirrored electric current equal with two-way mirror image high precision reference electric current.
As an improvement of the present invention, the zero temp shift resistance be by positive temperature coefficient resistance and negative temperature coefficient resistance by
Ratio series connection is formed by equivalent resistance, and the temperature coefficient of the equivalent resistance is zero, and its resistance value does not work with LED drive chip
The variation of temperature and change, overcoming the resistance-temperature characteristic in the presence of traditional circuit influences the defect of reference current.
As an improvement of the present invention, it includes the second NOT gate, third that the inside and outside, which adjusts resistance switch control unit,
NOT gate, the second NAND gate, third NAND gate, the 4th NAND gate and the 5th NAND gate, first NAND gate and the second NAND gate
For two input nand gates, third and fourth, five NAND gates be three input nand gates；The inside and outside adjusts resistance switching control end
Ctrl1 connect the input terminal of the second NAND gate with ctrl2, and the inside and outside adjusts resistance switching control end ctrl1 connection third
The input terminal of NAND gate, the inside and outside adjust resistance switching control end ctrl2 by the second NOT gate connect third NAND gate and
The input terminal of 4th NAND gate, the inside and outside adjust resistance switching control end ctrl1 by third NOT gate connection the 4th with it is non-
The inverse output terminal of the input terminal of door and the 5th NAND gate, d type flip flop connects the third NAND gate, the 4th NAND gate and the 5th
The input terminal of NAND gate, the inside and outside adjust the input terminal of the 5th NAND gate of resistance switching control end ctrl2 connection, and described the
Three NAND gates, the 4th NAND gate connect internal regulation resistance control terminal with the output end of the 5th NAND gate.
Precisely overvoltage crowbar selects to adjust resistance string in zero temp shift resistance by internal regulation resistance control terminal this height
Join number, so that high precision reference current generating circuit generates high precision reference electric current (i.e. mirror image high precision reference electric current), and
High precision reference electric current is charged to the charging capacitor in high-precision over-voltage time decision generation circuit, when realizing stable charging
Between, which is the over-voltage time decision of circuit.Meanwhile it being powered on by overvoltage protection resistance adjustment automatic control circuit
Whether detection outside has external adjusting resistance, and adjusts resistance to inside and outside and automatically select, when in the presence of external adjusting
When resistance, then the zero temp shift resistance of inner setting is automatically switched into external adjust on resistance.Further, it is also possible to be protected by over-voltage
The internal regulation resistance control terminal protected in resistance adjustment automatic control circuit closes over-voltage protecting function, realizes under big voltage
Using.
Compared with the existing technology, advantages of the present invention is as follows, and 1) by introducing zero temp shift resistance and there is casecode knot
The operational amplifier of structure guarantees that high precision reference current generating circuit exports high-precision reference current, to improve over-voltage
The precision of the time decision of protection, and improve the consistency of overvoltage protection；2) by introducing overvoltage protection resistance in circuit
Adjusting automatic control circuit realizes the overvoltage protection adjusting resistance of automatic detection LED drive chip inside and outside, and passes through circuit
The inside and outside being equipped with adjusts resistance switch control unit and carries out the automatic switchover that inside and outside overvoltage protection adjusts resistance, reduces more
The investment of a series of products substantially increases the integrated level and versatility of overvoltage crowbar；3) it is detected in part without over-voltage
Applicable cases under, which also has in by being arranged in overvoltage protection resistance adjustment automatic control circuit
Portion adjusts resistance control terminal and closes over-voltage protecting function, suitable for the application under big voltage；It 4) can be by high-precision
The internal regulation resistance control terminal being arranged in reference current generating circuit adjusts resistance (i.e. zero temp shift to adjust internal over pressure protection
Resistance) on positive temperature coefficient resistance and negative temperature coefficient resistance series connection number, come reduce this overvoltage crowbar be applied to difference
Resistance difference between LED drive chip, improves the scope of application of this overvoltage crowbar；5) by this height, precisely over-voltage is protected
Protection circuit is applied to not only can solve existing high temperature flicker problem when LED operation in LED drive chip, but also can solve LED and disliking
Lamp problem is fried under bad working environment, substantially increases the quality of LED product.
Detailed description of the invention
Fig. 1 is the overvoltage crowbar structural block diagram in existing LED drive chip.
Fig. 2 is the overvoltage crowbar schematic diagram in existing LED drive chip.
Fig. 3 is the accurate overvoltage crowbar of height proposed by the invention.
Fig. 4 is the circuit diagram of high precision reference current generating circuit in the present invention.
Fig. 5 is the circuit diagram of overvoltage protection resistance adjustment automatic control circuit in the present invention.
Fig. 6 is the circuit diagram of high-precision over-voltage time decision generation circuit in the present invention.
Specific embodiment
In order to deepen the understanding of the present invention and recognize, the invention will be further described below in conjunction with the accompanying drawings and introduces.
Embodiment 1：As seen in figures 3-6, a kind of high accurate overvoltage crowbar, including high precision reference electric current generate electricity
Road, high-precision over-voltage time decision generation circuit and overvoltage protection resistance adjustment automatic control circuit, reference voltage Vref difference
The input terminal for connecting the high precision reference current generating circuit and high-precision over-voltage time decision generation circuit, in high-precision base
Zero temp shift resistance R0 is equipped in quasi- current generating circuit, high precision reference current generating circuit passes through current mirror unit output two
Road mirror image high precision reference electric current, wherein mirror image high precision reference electric current I1 connects high-precision over-voltage time decision generation circuit all the way
Input terminal, another way mirror image high precision reference electric current I2 take over pressure protective resistance adjust automatic control circuit input terminal, institute
It states high precision reference current generating circuit and also passes through internal regulation resistance control terminal con1, con2 and con3 and overvoltage protection resistance
It adjusts automatic control circuit to be connected, overvoltage protection resistance adjustment automatic control circuit is equipped with inside and outside and adjusts resistance switching control
Unit, the input terminal of reference clock signal Tin connection high-precision over-voltage time decision generation circuit, high-precision over-voltage time decision
The output end of generation circuit is overvoltage protection output end OVP.
Specifically, as shown in fig. 6, the high-precision over-voltage time decision generation circuit is equipped with inputs with reference voltage
Hysteresis comparator, charging capacitor, capacitor charging circuit and current source mirror image circuit, reference clock signal Tin connection capacitor charging
The first input end of circuit, the second input terminal of mirror image high precision reference electric current I1 connection capacitor charging circuit, charging capacitor connect
The output end of capacitor charging circuit is connect, charging capacitor is also connected with the negative input end of hysteresis comparator, and reference voltage Vref connection is slow
The reference voltage input terminal of stagnant comparator, the i.e. positive input terminal of hysteresis comparator, the hysteresis comparator are using several N-types
Field effect transistor and several p type field effect transistors are built, including the first n type field effect transistor, the 2nd N
Type field effect transistor, third n type field effect transistor, the 4th n type field effect transistor, the first p type field effect transistor,
Two p type field effect transistors, third p type field effect transistor and the 4th p type field effect transistor, the first N-type field-effect
The grid of transistor draws the negative input end as hysteresis comparator, and the grid of second n type field effect transistor, which is drawn, to be made
Source electrode for the positive input terminal of hysteresis comparator, the third n type field effect transistor is grounded, third n type field effect transistor
Drain electrode draw output end as hysteresis comparator, drain electrode connection the first p-type field-effect crystalline substance of the first n type field effect transistor
The drain electrode of body pipe, the first p type field effect transistor, the second p type field effect transistor, third p type field effect transistor, the 4th P
The grid of the source electrode connection power supply of type field effect transistor, the first p type field effect transistor and the second p type field effect transistor is mutual
Even, the drain electrode of drain electrode the second n type field effect transistor of connection of the second p type field effect transistor, the second p type field effect transistor
Grid be also connected with the drain electrode of the first n type field effect transistor, the grid of third p type field effect transistor connects the second p-type field
The grid of effect transistor, the drain electrode of drain electrode the 4th n type field effect transistor of connection of third p type field effect transistor, the 4th N
The source electrode of type field effect transistor connects the drain electrode of the second n type field effect transistor, and the grid of the 4th n type field effect transistor connects
The drain electrode of the 4th p type field effect transistor is connect, the grid of the 4th p type field effect transistor connects the 4th n type field effect transistor
Source electrode, the 4th p type field effect transistor drain electrode connection third n type field effect transistor drain electrode, the current source mirror image
Circuit is built using the 5th n type field effect transistor and the connection of the 6th n type field effect transistor common gate, the 5th N-type field
The drain electrode of the source electrode of effect transistor and the 6th n type field effect transistor ground connection, the 5th n type field effect transistor connects electric current
Source, the drain electrode of the 5th n type field effect transistor are also connected with the grid of the 6th n type field effect transistor, the 6th N-type field effect transistor
The source electrode of drain electrode connection the first n type field effect transistor and the second n type field effect transistor of pipe, the 6th N-type field effect transistor
The grid of the grid connection third n type field effect transistor of pipe, the output end of hysteresis comparator is overvoltage protection output end
OVP。
Working principle：When reference clock signal Tin failing edge arrives, generated by high precision reference current generating circuit
High-precision current I1 charges to charging capacitor, when charging capacitor, which powers on, to be pressed onto up to Vref, hysteresis comparator output over-voltage protection
Signal OVP, the delay that accurate OVP signal overturning overturns Tin signal is over-voltage time decision.
As shown in figure 5, the overvoltage protection resistance adjustment automatic control circuit is equipped with external adjusting resistance detection end
Test, electrification reset end reset, charging capacitor, reference current source, phase inverter inv1, d type flip flop and inside and outside adjust resistance and cut
Control terminal ctrl1 and ctrl2 are changed, outside adjusts the p type field effect transistor that resistance detection end test is connected to common gate connection
On the grid of n type field effect transistor, the source electrode of p type field effect transistor is the input of mirror image high precision reference electric current I2
End, n type field effect transistor source electrode ground connection, the drain electrode of p type field effect transistor and n type field effect transistor join altogether after successively
The input terminal of charging capacitor, reference current source and phase inverter inv1 is connected, the output end of phase inverter inv1 connects the defeated of d type flip flop
Enter and hold D, p type field effect transistor connects the clock pulse terminal CLK of d type flip flop with the common gate of n type field effect transistor, powers on
Reset terminal reset passes sequentially through the reset terminal R of the first NOT gate inv2 and the first NAND gate connection d type flip flop；Inside and outside adjusts electricity
Resistance switching control end ctrl1 connect with ctrl2 inside and outside adjusting resistance switch control unit input terminal, d type flip flop it is reversed
Output endThe input terminal that inside and outside adjusts resistance switch control unit is connected, inside and outside adjusts resistance switch control unit
One output end connects the input terminal of the first NAND gate, and inside and outside is adjusted in the remaining output end connection of resistance switch control unit
Portion adjusts resistance control terminal con1, con2 and con3.Pass through zero temperature of internal regulation resistance control terminal con1, con2 and con3 adjustment
The resistance value for floating resistance R0, to reduce the resistance difference of different chip chambers.
Working principle：When reset signal rising edge arrives, d type flip flop reset signal R becomes 1, the normal work of trigger
Make.Start to detect whether I2 has electric current when test failing edge, by I2 compared with reference current source, if I2 is greater than reference current source
It charges to charging capacitor, phase inverter inv1 overturning illustrates that there is adjusting resistance in outside, so that con1, con2, con3 output are 0, closes
It closes internal over pressure protection and adjusts resistance (zero temp shift resistance R0)；Voltage is always on charging capacitor if I2 is less than reference current source
0, phase inverter inv1 output are constant, illustrate that outside without resistance is adjusted, is controlled according to the selection of ctrl1 and ctrl2, so that con1,
Some output is 1 in con2, con3, opens internal over pressure protection and adjusts resistance (zero temp shift resistance R0).Over-voltage is not necessarily in part
Under the applicable cases of detection, ctrl1=ctrl2=0 is controlled, over-voltage protecting function is closed.
Precisely overvoltage crowbar passes through internal regulation resistance control terminal con1, con2 and con3 selection zero temp shift electricity to this height
It hinders and adjusts resistance series connection number in R0, (i.e. mirror image is high so that high precision reference current generating circuit generates high precision reference electric current
Precision reference electric current), and high precision reference electric current is charged to the charging capacitor in high-precision over-voltage time decision generation circuit,
Realize the stable charging time, which is the over-voltage time decision of circuit.Meanwhile passing through overvoltage protection resistance adjustment
Whether there is external adjusting resistance on automatic control circuit outside electro-detection, and resistance adjusted to inside and outside and is automatically selected,
When there is external adjusting resistance, then the zero temp shift resistance R0 of inner setting is automatically switched into external adjust on resistance.This
Outside, can also by internal regulation resistance control terminal con1, con2 in overvoltage protection resistance adjustment automatic control circuit and
Con3 closes over-voltage protecting function, realizes the application under big voltage.
Embodiment 2：As shown in figure 4, as an improvement of the present invention, in the high precision reference current generating circuit also
Including current source, multi-stage operational amplifier and reference voltage mirror image unit, the input termination power of the current source, output termination
The first input end of multi-stage operational amplifier, reference voltage mirror image unit connect the second input terminal of multi-stage operational amplifier, benchmark
Voltage Vref connects the input terminal of reference voltage mirror image unit, the output of the input terminal and multi-stage operational amplifier of current mirror unit
End is connected, and internal regulation resistance control terminal con1, con2 and con3 is connected to zero temp shift resistance R0 by n type field effect transistor
On.The multi-stage operational amplifier is to use several n type field effect transistors and several p type field effect transistors with common source
Common gate structure (casecode structure) is built, and not only output impedance is big, reduces channel current mudulation effect, Er Qie great
The precision of current mirror is improved greatly, and then improves the essence of reference current caused by high precision reference current generating circuit
Degree.The reference voltage mirror image unit is that two p type field effect transistors connect composition, benchmark by the way of common source connection
Voltage Vref is connected to the grid of a p type field effect transistor, and zero temp shift resistance R0 is connected to another p-type field effect transistor
The grid of pipe, so that the end voltage Vr of zero temp shift resistance R0 is equal to reference voltage Vref.The current mirror unit is three
A p type field effect transistor connects composition by the way of cascade connection, and mirror image high precision reference electric current I1 is generated all the way
In the drain electrode of another p type field effect transistor, another way mirror image high precision reference electric current I2, which is resulted from, remains next p-type field effect
Answer the drain electrode of transistor, on zero temp shift resistance R0 to be mirrored electric current equal with two-way mirror image high precision reference electric current (I1/I2).
Remaining structure and advantage are identical with embodiment 1.
Embodiment 3：As shown in figure 4, as an improvement of the present invention, the zero temp shift resistance R0 is to pass through positive temperature coefficient
Resistance and negative temperature coefficient resistance press 1:The series connection of 1 ratio is formed by equivalent resistance, and the temperature coefficient of the equivalent resistance is zero, and its
Resistance value does not change with the variation of LED drive chip operating temperature, overcomes the resistance-temperature characteristic in the presence of traditional circuit
Influence the defect of reference current.Zero temp shift resistance R0 forms the zero-temperature coefficient electricity not varied with temperature between the end Vr and ground
Resistance is mirrored electric current I0=Vref/R0 so as to generate high-precision.Remaining structure and advantage are identical with embodiment 2.
Embodiment 4：As shown in figure 5, as an improvement of the present invention, the inside and outside adjusts resistance switch control unit
Including the second NOT gate, third NOT gate, the second NAND gate, third NAND gate, the 4th NAND gate and the 5th NAND gate, described first with
NOT gate and the second NAND gate are two input nand gates, third and fourth, five NAND gates be three input nand gates；The inside and outside is adjusted
Resistance switching control end ctrl1 connect the input terminal of the second NAND gate with ctrl2, and the inside and outside adjusts resistance switching control end
The input terminal of ctrl1 connection third NAND gate, the inside and outside adjust resistance switching control end ctrl2 and are connected by the second NOT gate
The input terminal of third NAND gate and the 4th NAND gate, the inside and outside adjust resistance switching control end ctrl1 and pass through third NOT gate
Connect the input terminal of the 4th NAND gate and the 5th NAND gate, the inverse output terminal of d type flip flopConnect the third NAND gate,
The input terminal of 4th NAND gate and the 5th NAND gate, the inside and outside adjust resistance switching control end ctrl2 connection the 5th with it is non-
The input terminal of door, the third NAND gate, the 4th NAND gate connect the control of internal regulation resistance with the output end of the 5th NAND gate
Hold con1, con2 and con3.Remaining structure and advantage are identical with embodiment 2.
The present invention can also be formed in combination with example 1 at least one of described technical characteristic of embodiment 2,3,4 newly
Embodiment.
It should be noted that above-described embodiment, is not intended to limit the scope of protection of the present invention, in above-mentioned technical proposal
On the basis of made equivalents or substitution each fall within the range that the claims in the present invention are protected.In the claims, single
Word "comprising" does not exclude the presence of element or step not listed in the claims.The use of word first, second and third etc.
Any sequence is not indicated, these words can be construed to title.
Claims (4)
1. a kind of high accurate overvoltage crowbar, it is characterised in that：Including high precision reference current generating circuit, high-precision over-voltage
Time decision generation circuit and overvoltage protection resistance adjustment automatic control circuit, reference voltage are separately connected the high precision reference
The input terminal of current generating circuit and high-precision over-voltage time decision generation circuit, sets in high precision reference current generating circuit
There is zero temp shift resistance, high precision reference current generating circuit exports two-way mirror image high precision reference electricity by current mirror unit
Stream, wherein mirror image high precision reference electric current I1 connects the input terminal of high-precision over-voltage time decision generation circuit, another way mirror all the way
Image height precision reference electric current I2 takes over the input terminal that pressure protective resistance adjusts automatic control circuit, and the high precision reference electric current produces
Raw circuit also passes through internal regulation resistance control terminal and is connected with overvoltage protection resistance adjustment automatic control circuit, reference clock signal
The input terminal of high-precision over-voltage time decision generation circuit is connected, the output end of high-precision over-voltage time decision generation circuit is
Overvoltage protection output end；
The high-precision over-voltage time decision generation circuit be equipped with the hysteresis comparator inputted with reference voltage, charging capacitor,
Capacitor charging circuit and current source mirror image circuit, reference clock signal connect the first input end of capacitor charging circuit, and mirror image is high
Second input terminal of precision reference electric current I1 connection capacitor charging circuit, charging capacitor connect the output end of capacitor charging circuit,
Charging capacitor is also connected with the negative input end of hysteresis comparator, and reference voltage connects the reference voltage input terminal of hysteresis comparator, i.e.,
The positive input terminal of hysteresis comparator, the hysteresis comparator are using several n type field effect transistors and several p-type fields effect
It answers transistor to build, is imitated including the first n type field effect transistor, the second n type field effect transistor, third N-type field
Answer transistor, the 4th n type field effect transistor, the first p type field effect transistor, the second p type field effect transistor, third p-type
Field effect transistor and the 4th p type field effect transistor, the grid of first n type field effect transistor are drawn as sluggish ratio
Compared with the negative input end of device, the grid of second n type field effect transistor draws the positive input terminal as hysteresis comparator, described
The source electrode of third n type field effect transistor is grounded, and the drain electrode of third n type field effect transistor is drawn as the defeated of hysteresis comparator
Outlet, the drain electrode of drain electrode the first p type field effect transistor of connection of the first n type field effect transistor, the first p-type field effect transistor
The source electrode connection power supply of pipe, the second p type field effect transistor, third p type field effect transistor, the 4th p type field effect transistor,
The gate interconnection of first p type field effect transistor and the second p type field effect transistor, the drain electrode of the second p type field effect transistor
The drain electrode of the second n type field effect transistor is connected, it is brilliant that the grid of the second p type field effect transistor is also connected with the first N-type field-effect
The drain electrode of body pipe, the grid of third p type field effect transistor connect the grid of the second p type field effect transistor, third p-type field effect
Answer the drain electrode of drain electrode the 4th n type field effect transistor of connection of transistor, the source electrode connection second of the 4th n type field effect transistor
The drain electrode of n type field effect transistor, the grid of the 4th n type field effect transistor connect the drain electrode of the 4th p type field effect transistor,
The grid of 4th p type field effect transistor connects the source electrode of the 4th n type field effect transistor, the 4th p type field effect transistor
The drain electrode of drain electrode connection third n type field effect transistor, the current source mirror image circuit using the 5th n type field effect transistor and
The connection of 6th n type field effect transistor common gate is built, the 5th n type field effect transistor and the 6th N-type field effect transistor
The source electrode of pipe is grounded, and the drain electrode of the 5th n type field effect transistor connects current source, and the drain electrode of the 5th n type field effect transistor is also
The grid of the 6th n type field effect transistor is connected, the drain electrode of the 6th n type field effect transistor connects the first N-type field effect transistor
The grid of the source electrode of pipe and the second n type field effect transistor, the 6th n type field effect transistor connects third N-type field effect transistor
The grid of pipe, the output end of hysteresis comparator are overvoltage protection output end；
Overvoltage protection resistance adjustment automatic control circuit is equipped with inside and outside and adjusts resistance switch control unit, and overvoltage protection
External adjusting resistance detection end, electrification reset end, charging capacitor, reference current are additionally provided on resistance adjustment automatic control circuit
Source, phase inverter, d type flip flop and inside and outside adjust resistance switching control end ctrl1 and ctrl2, and outside adjusts resistance detection end and connects
It connects on the p type field effect transistor of common gate connection and the grid of n type field effect transistor, the source of p type field effect transistor
The extremely input terminal of mirror image high precision reference electric current I2, the source electrode ground connection of n type field effect transistor, p type field effect transistor and N
The drain electrode of type field effect transistor is sequentially connected the input terminal of charging capacitor, reference current source and phase inverter, phase inverter after joining altogether
Output end connection d type flip flop input terminal, p type field effect transistor connect with the common gate of n type field effect transistor D trigger
The clock pulse terminal of device, electrification reset end pass sequentially through the reset terminal of the first NOT gate and the first NAND gate connection d type flip flop；It is inside and outside
Portion adjusts resistance switching control end ctrl1 and connect the input terminal that inside and outside adjusts resistance switch control unit, D triggering with ctrl2
The inverse output terminal connection inside and outside of device adjusts the input terminal of resistance switch control unit, and inside and outside adjusts resistance switching control list
One output end of member connects the input terminal of the first NAND gate, and the remaining output end that inside and outside adjusts resistance switch control unit connects
Connect internal regulation resistance control terminal.
2. a kind of high accurate overvoltage crowbar as described in claim 1, which is characterized in that the high precision reference electric current produces
It further include current source, multi-stage operational amplifier and reference voltage mirror image unit in raw circuit, the input of the current source terminates electricity
Source, the first input end of output termination multi-stage operational amplifier, reference voltage mirror image unit connect the second of multi-stage operational amplifier
Input terminal, reference voltage connect the input terminal of reference voltage mirror image unit, and the input terminal and multistage operations of current mirror unit amplify
The output end of device is connected, and internal regulation resistance control terminal is connected on zero temp shift resistance by n type field effect transistor；It is described more
Grade operational amplifier is to use several n type field effect transistors and several p type field effect transistors with cascode structure
It builds, the reference voltage mirror image unit is two p type field effect transistors connection group by the way of common source connection
At reference voltage is connected to the grid of a p type field effect transistor, and it is brilliant that zero temp shift resistance is connected to another p-type field-effect
The grid of body pipe, the current mirror unit are three p type field effect transistors connection groups by the way of cascade connection
At zero temp shift resistance is connected to the drain electrode of a p type field effect transistor, and mirror image high precision reference electric current I1 is resulted from separately all the way
The drain electrode of one p type field effect transistor, another way mirror image high precision reference electric current I2, which is resulted from, remains next p-type field-effect crystalline substance
The drain electrode of body pipe.
3. a kind of high accurate overvoltage crowbar as described in claim 1, which is characterized in that the zero temp shift resistance is to pass through
Positive temperature coefficient resistance and negative temperature coefficient resistance are connected in proportion is formed by equivalent resistance.
4. a kind of high accurate overvoltage crowbar as described in claim 1, which is characterized in that the inside and outside adjusts resistance and cuts
It changes control unit and includes the second NOT gate, third NOT gate, the second NAND gate, third NAND gate, the 4th NAND gate and the 5th NAND gate,
First NAND gate and the second NAND gate are two input nand gates, third and fourth, five NAND gates be three input nand gates；It is described
Inside and outside adjusts the input terminal that resistance switching control end ctrl1 connect the second NAND gate with ctrl2, and the inside and outside adjusts resistance
The input terminal of switching control end ctrl1 connection third NAND gate, the inside and outside adjust resistance switching control end ctrl2 by the
Two NOT gates connect the input terminal of third NAND gate and the 4th NAND gate, and it is logical that the inside and outside adjusts resistance switching control end ctrl1
The input terminal that third NOT gate connects the 4th NAND gate and the 5th NAND gate is crossed, the inverse output terminal of d type flip flop connects the third
The input terminal of NAND gate, the 4th NAND gate and the 5th NAND gate, the inside and outside adjust resistance switching control end ctrl2 connection the
The input terminal of five NAND gates, the third NAND gate, the 4th NAND gate connect internal regulation electricity with the output end of the 5th NAND gate
Hinder control terminal.
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| CN201510712488.5A CN105278608B (en) | 2015-10-28 | 2015-10-28 | A kind of high accurate overvoltage crowbar |
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| CN201510712488.5A CN105278608B (en) | 2015-10-28 | 2015-10-28 | A kind of high accurate overvoltage crowbar |
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| US8649144B2 (en) * | 2007-02-05 | 2014-02-11 | Semiconductor Components Industries, Llc | Method of forming an over-voltage protection circuit and structure therefor |
| CN103699168A (en) * | 2013-12-10 | 2014-04-02 | 北京中电华大电子设计有限责任公司 | Voltage overshoot protection circuit of zero power consumption voltage regulator |
| CN205210748U (en) * | 2015-10-28 | 2016-05-04 | 苏州锴威特半导体有限公司 | High accurate overvoltage crowbar |
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Address after: 215600 Shazhou Lake Science Park Building A1, 9 Floors, Yangshe Town, Zhangjiagang City, Suzhou City, Jiangsu Province Patentee after: Suzhou Covette Semiconductor Co., Ltd. Address before: 511, building 1, building B, science and Technology Pioneer Park, 215600 Cathay Pacific Road, Zhangjiagang economic and Technological Development Zone, Suzhou, Jiangsu, China Patentee before: Iron of fine quality Witter, Suzhou Semiconductor Co., Ltd |
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