Linear current regulator
The present invention relates to a kind of current regulator, and particularly to a kind of linear current regulator.
Due to the demand of energy saving, LED is at present to be widely used in various field, all
It is that electronic product, household appliances, automobile, traffic sign, billboard etc. need point source or face light
The occasion in source, has become the application market of LED the most.No matter LED be via boosting, blood pressure lowering,
Step-up/down or linear voltage regulator drive, and connect that each drive circuit is modal to be needed exactly
Control the output brightness of light.At present, for the control method of LED luminance, predominantly numeral is adjusted
Light and simulation light modulation two kinds.
Digital dimming i.e. allows driving electric current toggle from the zero between target current value, modal
Method is to utilize pulse width modulation (PWM) to set to circulate and the working cycle, but often
Can produce along with the problem of Electro Magnetic Compatibility with electromagnetic interference, the problem causing potential frequency.
In contrast, according to the relation that the output curent change of LED driver is proportional to brightness,
With the simulation dimming mode of linear regulation LED, it is easier to carry out.Therefore, searching one is high
The current regulator of the linearity is with the brightness of stability contorting LED, it has also become the art one
Summary of the invention
In view of this, the present invention provides a kind of linear current regulator, by adjusting reference current
The reference current in source, to set the magnitude of voltage of a wherein input of the first amplifier, and by means of
Current conversion unit, changes into adjustment electric current output by this magnitude of voltage, to realize the function that electric current adjusts,
And apply function that this electric current adjusts in the control of LED luminance.
Additionally, the present invention can go to adjust reference current source by having variable-resistance adjustment unit
Current value, and when the parameter of current regulator is setting value, variable-resistance resistance value is with upper
State magnitude of voltage the most linear, and can directly adjust its resistance value and linearly set adjustment electric current,
This adjust electric current in addition to can be applicable to LED luminance, the charged electrical being equally applicable in charger
Stream, finely tunes charging current by adjusting variable-resistance resistance value, and saves replacing charger
The inconvenience of hardware is with time-consuming.
According to the linear current regulator of one embodiment of the invention, comprise:
One first amplifier, a current conversion unit, one first resistance, a reference current source,
One adjustment unit and a reference voltage circuit；Above-mentioned first amplifier has reverse input end, non-
Reverse input end and outfan.Current conversion unit, by the non-inverting input of the first amplifier
Magnitude of voltage, be converted into adjustment electric current output；First resistance, this coupling the first amplifier is reverse
Input and outfan；Reference current source, couples reverse input end and a resistance of the first amplifier；
Adjustment unit, couples reference current source, and exports a current signal in order to adjust reference current source
One reference current；And a reference voltage circuit, there are two inputs, wherein this input is defeated
Enter a reference voltage, another this input, it is coupled to the outfan of the first amplifier.
Above-mentioned reference voltage circuit is an error amplifier or a comparator, and this reference voltage
Circuit also includes an outfan, and this outfan exports a voltage signal to a power stage circuit.
According to another embodiment of the present invention, above-mentioned reference current source produces ginseng according to reference voltage
Examine electric current.
According to another embodiment of the present invention, above-mentioned adjustment unit has a variable resistance, in order to
Adjust reference current.
According to another embodiment of the present invention, above-mentioned adjustment unit also comprise one second amplifier,
One fixed current source, one first switch element and one first mirror current source.And second amplifier,
There is reverse input end, non-inverting input and outfan；Fixed current source, couples variable resistance
With this non-inverting input of the second amplifier, and export a fixed current；First switch element,
Having the first end, the second end and the 3rd end, the second end of the first switch element couples the second amplifier
Outfan, the 3rd end couples reverse input end and one second resistance of the second amplifier；And the
One mirror current source, couples the first end of the first switch element, and exports this current signal, wherein,
This current signal is directly proportional to this fixed current.
Foundation another embodiment of the present invention, above-mentioned current regulator, wherein, fixed current source
It is positioned at the inside of integrated circuit (IC), and this variable resistance is positioned at the outside of integrated circuit.
According to another embodiment of the present invention, above-mentioned reference current source comprise one the 3rd amplifier,
One second switch element and one second mirror current source.3rd amplifier, have reverse input end,
Non-inverting input and outfan, wherein the reverse input end input reference voltage of the 3rd amplifier；
Second switch element, has the first end, the second end and the 3rd end, the second end of second switch element
Coupling the outfan of the 3rd amplifier, the first end couples the non-inverting input and of the 3rd amplifier
3rd resistance；And second mirror current source, couple the 3rd end of second switch element, and export
Reference current, wherein, reference current is directly proportional to reference voltage.
According to another embodiment of the present invention, above-mentioned current regulator, the second resistance therein etc.
In the 3rd resistance.
According to another embodiment of the present invention, the electricity of the non-inverting input of the first above-mentioned amplifier
Pressure value is directly proportional to variable-resistance resistance value.
According to another embodiment of the present invention, the non-inverting input of this above-mentioned the first amplifier
Magnitude of voltage is equal to the product of variable-resistance resistance value with the current value of fixed current.
In sum, the having the advantage that of the present invention
1, the linear current regulator of the present invention, is applicable to the electricity needing electric current to adjust application
On sub-commodity, such as: LED and charger；
2, by means of adjusting reference current source, to realize the function that electric current adjusts；And
3, by means of adjusting variable resistance, with direct Serial regulation electric current, and replacing can be saved
The inconvenience of charger hardware is with time-consuming.
With embodiment, above-mentioned explanation will be explained in detail below, and the skill to the present invention
Art scheme provides and further explains.
Accompanying drawing explanation
For the above and other purpose of the present invention, feature, advantage and embodiment can be become apparent from easily
Understanding, appended accompanying drawing is described as follows:
Fig. 1 is the circuit diagram of an embodiment of the linear current regulator of the present invention；
Fig. 2 is that the circuit of an embodiment of the adjustment unit of the linear current regulator of the present invention shows
It is intended to；
Fig. 3 is the circuit of an embodiment of the reference current source of the linear current regulator of the present invention
Fig. 4 is the high linearity Voltage Cortrol of an embodiment of the linear current regulator of the present invention
[main element description of reference numerals]
First amplifier 110
Current conversion unit 120
First resistance R1
Reference current source 130
Adjustment unit 140
Reference voltage circuit 150
Output electric current Io
The magnitude of voltage V1 of the non-inverting input of the first amplifier
Adjust electric current Ia
Current signal Im
Reference current Iref
Reference voltage Vref
Running voltage VDD
Fixed current Id
Second amplifier 141
Fixed current source 142
Variable resistance Rj
Second resistance R2
First switch element M1
First mirror current source 143
3rd amplifier 131
Second switch element M2
Second mirror current source 132
3rd mirror current source 133
3rd resistance R3
Detailed description of the invention
In order to the narration making the present invention is more detailed with complete, can refer to appended accompanying drawing and following
Described various embodiment, number identical in accompanying drawing represents same or analogous element.On the other hand,
Well-known element and step are not described in embodiment, so that avoid causing the present invention need not
The restriction wanted.
In " detailed description of the invention " with " claims ", unless literary composition has for article
Being particularly limited to, otherwise " one " can refer to one or more with " being somebody's turn to do ".
Fig. 1 is the circuit diagram of an embodiment of the linear current regulator of the present invention.This line
Property current regulator comprise one first amplifier 110, current conversion unit 120,1 first electricity
Resistance R1, reference current source 130, adjustment unit 140 and a reference voltage circuit 150.
Above-mentioned first amplifier 110 has a reverse input end, a non-inverting input and an output
End.Current conversion unit 120, by the magnitude of voltage of the non-inverting input of the first amplifier 110
V1, is converted into an adjustment electric current Ia output.First resistance R1 is coupled to the first amplifier 110
Reverse input end and outfan.Reference current source 130, is coupled to the anti-of the first amplifier 110
To input and the first resistance R1.Adjustment unit 140, is coupled to reference current source 130, and defeated
Go out a current signal Im in order to adjust a reference current Iref of reference current source 130.
Reference voltage circuit 150 has two inputs, and wherein this input input one is with reference to electricity
Pressure Vref, another input is coupled to the outfan of the first amplifier 110.In the present embodiment, ginseng
Examine potential circuit 150 as a example by error amplifier, but the present invention is not limited, reference voltage electricity
Road also can be selected for comparator or similar circuit.Reference circuit 150 is in order to (to be coupled to its one end
This end of first amplifier 110) current potential, be equivalent to the current potential of the other end of reference circuit 150,
The i.e. current potential of reference voltage Vref, and exported a voltage signal by the outfan of reference circuit 150
To a power stage circuit (not shown).
According to above-mentioned current regulator, the non-inverting input of the first amplifier 110 can be obtained
Magnitude of voltage V1, equation below (1) calculates:
V1=(Im-Iref) × R1+Vref ... (1)
Wherein, V1 refers to the magnitude of voltage of the non-inverting input of the first amplifier 110, and Im refers to electric current
Signal, Iref refers to the reference current of current source 130, and R1 refers to the first resistance, and Vref refers to reference to electricity
Pressure.Can obtain via formula (1), magnitude of voltage V1 linearly changes along with current signal Im, electricity
Stream signal Im is used for adjusting the reference current Iref of reference current source 130, via adjusting with reference to electricity
Stream Iref, to set the magnitude of voltage V1 of the non-inverting input of the first amplifier 110, then by electricity
Magnitude of voltage V1, via current conversion unit 120, is changed into adjustment electric current Ia output by pressure value V1,
This adjusts electric current Ia and can be used to adjust the output electric current Io of electronic component, with LED with charger is
Example, i.e. can be used to adjust the electric current flowing through LED, and then the brightness of control LED, also may utilize
This adjusts electric current and is finely adjusted the electric current of charger, to control the charging interval of charger.Wherein,
Above-mentioned current conversion unit 120 utilizes a resistance circuit to realize.
Fig. 2 is the electricity of an embodiment of the adjustment unit 140 of the linear current regulator of the present invention
Road schematic diagram.Fix as in figure 2 it is shown, adjustment unit 140 comprises one second amplifier 141,
Current source 142, one variable resistance Rj, one first switch element M1 and one first mirror current source
Above-mentioned second amplifier 141, has a reverse input end, a non-inverting input and one defeated
Go out end.Fixed current source 142, couples the non-inverting input of the second amplifier 141, and exports
One fixed current Id.Variable resistance Rj couples this fixed current source 142.First switch element M1
Having one first end, one second end and one the 3rd end, second end of the first switch element M1 couples
This outfan of second amplifier 141, the 3rd end couples the reverse input end of the second amplifier 141
With one second resistance R2.First mirror current source 143, has current amplification factor α and couples
This first end of first switch element M1, and output current signal Im.
According to above-mentioned adjustment unit 140, can obtain current signal Im, equation below (2) is counted
Im=α × Id × Rj/R2 ... (2)
Wherein, Im refers to the output current signal of the first mirror current source 143, and α refers to the first mirror image
The current amplification factor of current source 143, Id refers to the output fixed current in fixed current source 142,
Rj refers to that variable resistance, R2 refer to the second resistance.Can obtain via formula (2), current signal Im with
The output fixed current Id in fixed current source 142 is directly proportional, and via changing variable resistance Rj's
Resistance value, can change output current signal Im, and then adjust the reference of reference current source 130
Electric current Iref(refer to Fig. 1).
Above-mentioned fixed current source 142 can be the fixed current source that integrated circuit (IC) is internal, and
Variable resistance Rj is positioned at integrated circuit external, adjusts the resistance value of variable resistance Rj by means of outside,
The current value of IC interior can be controlled, so, the inconvenience changing hardware can be saved with time-consuming.
Fig. 3 is an embodiment of the reference current source 130 of the property degree current regulator of the present invention
Circuit diagram.As it is shown on figure 3, reference current source comprises one the 3rd amplifier 131,1 second
Switch element M2, one second mirror current source 132 and one the 3rd mirror current source 133.On
State the 3rd amplifier 131 and there is a reverse input end, a non-inverting input and an outfan, its
In the non-inverting input input reference voltage Vref of the 3rd amplifier 131.Second switch element
M2 has one first end, one second end and one the 3rd end, second end of second switch element M2
Coupling the outfan of the 3rd amplifier 131, the first end couples one end of the 3rd mirror current source 133,
3rd end couples reverse input end and one the 3rd resistance R3 of the 3rd amplifier 131.Second mirror image
Current source 132, has currentamplificationfactorβ and couples the other end of the 3rd mirror current source 133
3rd end of second switch element M2, and output reference current Iref.
According to above-mentioned reference current source 130, reference current Iref, equation below (3) can be obtained
Iref=β × Vref/R3 ... (3)
Wherein, Iref refers to that reference current Iref, β that reference current source 130 exports refer to the second mirror image
The currentamplificationfactorβ of current source 132, Vref refers to that reference voltage, R3 refer to the 3rd resistance.By
Formula (3) can be learnt, reference current source 130 produces reference current Iref according to reference voltage Vref,
When required reference current Iref is the biggest, the biggest optional reference voltage Vref, i.e. reference
Electric current Iref and reference voltage Vref direct ratio.
According to formula (1)～formula (3), as R2=R3 and α=β, following equation can be obtained
V1=(IdRj-Vref) R1 α/R2+Vref ... (4)
When R1 × α=R2 or R1=R2 and α=1, following equation (5) can be obtained:
V1=IdRj ... (5)
Wherein, V1 refers to the magnitude of voltage of the non-inverting input of the first amplifier 110, and Id refers to fix
The output fixed current of current source 142, Rj refers to that variable resistance, Vref refer to that reference voltage, β refer to
The current amplification factor of two mirror current sources 132, β, α refer to the electricity of the first mirror current source 143
Stream amplification coefficient, R1 refers to the first resistance, and R2 refers to the second resistance, and R3 refers to the 3rd resistance.
According to formula (5), the magnitude of voltage of the non-inverting input of the first amplifier 110 can be learnt
V1 is directly proportional to variable resistance Rj, and as shown in Figure 4, Fig. 4 is that the linear current of the present invention adjusts
The high linearity Voltage Cortrol schematic diagram of one embodiment of device.By means of adjusting variable resistance Rj's
Resistance value, can obtain the magnitude of voltage V1 of the non-inverting input of high linearity, then by non-return defeated
Enter end magnitude of voltage V1 via current conversion unit 120, change into adjustment electric current Ia output,
Obtaining the adjustment electric current Ia with high linearity, this adjusts electric current Ia and can be used to control the bright of LED
Spend or the electric current of charger is adjusted.
Although the disclosed mode performed as described above of the present invention, but the present invention of being not limited to, appoint
What those of ordinary skill in the art, without departing from the spirit and scope of the present invention, it is possible to can make each
Kind change and modification, therefore protection scope of the present invention with claim defined in the range of