TW201351083A - Current regulation circuit and electronic device thereof - Google Patents

Abstract

A current regulation circuit includes a controlling unit, a current mirror unit, a current-to-voltage unit, and a compensation unit. The controlling unit receives a reference voltage, and outputs a controlling voltage accordingly. The current mirror unit receives the controlling voltage, and outputs a first current and a second current accordingly. The current-to-voltage unit converts the second current to a second feedback voltage, and transmits the first feedback voltage to the controlling unit. The compensation unit receives the second current and transfers the second current to the current-to-voltage unit, wherein the compensation unit compensates the non-ideal characteristics of the current mirror unit, such that the a constant ratio between the first current and the second current is maintained.

Description

Steady current circuit and its electronic device

The invention relates to a current source, and in particular to a steady current circuit for generating a steady current and an electronic device having the same.

Since today's technology products often require a current source to provide a stable current, for example, a flow control oscillating circuit needs to stabilize a current to generate an oscillating signal of a specific frequency, or a battery to be charged needs a stable current to greatly save charging time. In short, it is necessary to provide a stable current source to enable these technology products to operate normally.

In recent years, batteries have been widely used in portable electronic devices, such as laptop computers, mobile phones, personal digital assistants (PDAs), radios, wireless phones, stereo cassette players, and the like. . The battery can be divided into two types: rechargeable and non-rechargeable. The rechargeable battery includes a nickel-cadmium (Ni-Cd) battery, a nickel-hydrogen (Ni-H) battery, a lithium-ion battery, and a nickel metal-hydride (Ni). -MH) batteries, and will have different charging rates under different charging conditions. Under the condition of Constant Voltage (CV), when the battery voltage is close to the final voltage, the charging current is almost zero.

Please refer to FIG. 1. FIG. 1 is a schematic diagram showing a conventional current control circuit. The conventional current control circuit 100 includes a transistor MPP (for example, a P-type transistor) and a control circuit 110, wherein a gate (C terminal) of the transistor MPP is coupled to the control circuit 110. The control circuit 110 is used to adjust the current I flowing through the transistor MPP. If, the current control circuit of Figure 1 is applied to charge the battery In the category of the integrated circuit, the source (A end) of the transistor MPP is coupled to the power adapter 120 (Adapter), and the drain (B end) of the transistor MPP is coupled to the battery 130 to be charged. The circuit 110 can adjust the magnitude of the charging current I flowing through the transistor MPP through the voltage applied to the gate of the transistor MPP.

When the charger 120 starts charging the battery to be charged 130, the rechargeable battery 130 is charged in the constant current mode, and the voltage of the battery to be charged 130 (that is, the voltage at the B terminal) rises rapidly. However, because the voltage at the terminal of the charger 120 (that is, the voltage at the A terminal) is a constant voltage (CV), as the voltage at the B terminal continues to rise, the voltage difference between the A terminal and the B terminal is caused. It will get smaller and smaller. At this time, if the control circuit 110 cannot quickly and quickly adjust the voltage of the gate of the control transistor MPP to adjust the charging current I, this will cause the value of the charging current I to become smaller and smaller, thereby causing the overall charging efficiency to come. The worse.

The embodiment of the invention provides a current stabilizing circuit. The current stabilizing circuit can effectively provide a stable current to the electrically coupled load thereof, and can be used as a charging circuit.

Embodiments of the present invention provide a current stabilizing circuit. The steady current circuit is configured to generate a stable first current, and includes a control unit, a current mirror unit, a current to voltage unit, and a compensation unit. The current mirror unit is electrically coupled to the control unit, and the current-to-voltage unit is electrically coupled between the current mirror unit and the control unit, and the compensation unit is electrically coupled between the current mirror unit and the current-to-voltage circuit. The control unit is configured to receive the reference voltage and the first feedback voltage, and output the control voltage accordingly. The current mirror unit receives the control voltage and outputs the first current and the second current accordingly. A current to voltage unit is used to convert the second current into The first feedback voltage and the first feedback voltage is transmitted to the control unit. The compensation unit is configured to receive the second current and transmit the second current to the current to voltage unit, wherein the compensation unit is configured to compensate for non-ideal characteristics of the current mirror unit such that the first current maintains a fixed proportional relationship with the second current.

The embodiment of the invention further provides an electronic device comprising the above-mentioned current stabilizing circuit and a load. The load is electrically coupled to the current stabilizing circuit and receives the first current generated by the current stabilizing circuit.

In summary, the steady current circuit proposed by the embodiment of the present invention uses the control unit to receive the reference voltage and output the control voltage to the current mirror unit, and receives the current through the current mirror unit and outputs a stable first according to the control voltage. Current and second current. Thereafter, the second current is converted to the first feedback voltage by the current to voltage unit and the first feedback voltage is transmitted to the control unit. Then, the control unit adjusts the control voltage according to the reference voltage and the first feedback voltage to stabilize the first current and the second current, thereby effectively providing a stable first current.

The detailed description of the present invention and the accompanying drawings are to be understood by the claims The scope is subject to any restrictions.

Various illustrative embodiments are described more fully hereinafter with reference to the accompanying drawings. However, the inventive concept may be embodied in many different forms and should not be construed as being limited to the illustrative embodiments set forth herein. Rather, these exemplary embodiments are provided so that this invention will be thorough and complete and will be The scope of the inventive concept is fully conveyed. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Similar numbers always indicate similar components.

[Embodiment of steady current circuit]

Please refer to FIG. 2. FIG. 2 is a schematic structural diagram of a current stabilizing circuit according to an embodiment of the present invention. The steady current circuit 200 includes a control unit 210, a current mirror unit 220, a compensation unit 230, and a current to voltage unit 240. The control unit 210 is electrically coupled to the current mirror unit 220 through the terminal C'. The current mirror unit 220 is electrically coupled to the compensation unit 230 through the terminals T1 and T2, and the current-to-voltage unit 240 is electrically coupled to the control unit. 210 is between the compensation unit 230.

The control unit 210 is configured to receive the reference voltage VREF, and accordingly output the control voltage VC to the current mirror unit 220 through the terminal C', wherein the reference voltage VREF can be appropriately set by the designer according to circuit design requirements. The current mirror unit 220 receives the voltage V2 through the terminal A', and outputs the currents I1 and I2 according to the control voltage VC. The currents I1 and I2 have a proportional relationship with each other, that is, the current I2 is the mapping current of the current I1. . The above proportional relationship can be moderately adjusted by the designer according to the circuit design requirements and process requirements.

In more detail, the current mirror unit 220 can output the current I1 through the terminal T1 to various types of loads electrically coupled to the terminal B' (not shown in FIG. 2), and can output the current I2 to the compensation unit 230 through the terminal T2. Wherein the load may be, for example, a battery to be charged, a discrete electronic component or an electronic wafer, or the like. The terminals T1 and T2 of the current mirror unit 220 are electrically coupled to the compensation unit 230, but the current mirror unit 220 does not substantially output any current to the compensation unit 230 through its terminal T1. Incidentally, when the steady current circuit 200 is to be charged In the charging circuit of the pool, the current I1 can be a charging current, the current I2 can be a mapping current, and the voltage V2 can be a DC voltage provided by a power adapter, wherein the power adapter has a transformer circuit, a rectifier circuit, and a filter circuit. Used to convert household AC power to DC voltage.

The compensation unit 230 is configured to receive the current I2 and transmit the current I2 to the current to voltage unit 240. The compensation unit 230 is used to compensate the non-ideal characteristics of the current mirror unit 220, so that the current mirror unit 220 does not affect the proportional relationship between the currents I1 and I2 because the voltages of the terminals T1 and T2 are different, that is, the compensation unit 230 can make the current I1 and I2 maintain a fixed proportional relationship. In this embodiment, the compensation unit 230 is configured to maintain the voltages of the terminals T1 and T2 substantially at the same voltage level, so that the currents I1 and I2 maintain a fixed proportional relationship. It should be noted that the manner in which the compensation unit 230 maintains the fixed relationship between the currents I1 and I2 is not intended to limit the present invention.

The current-to-voltage unit 240 is configured to convert the current I2 into the feedback voltage VF1 and transmit the feedback voltage VF1 to the control unit 210. Thereafter, the control unit 210 adjusts the control voltage VC according to the received reference voltage VREF and the feedback voltage VF1 to provide stable currents I1 and I2.

In this embodiment, if the reference voltage VREF is less than the feedback voltage VF1, the control unit 210 will lower the control voltage VC. Conversely, if the reference voltage VREF is greater than the feedback voltage VF1, the control unit 210 will increase the control voltage VC. . In another embodiment, if the reference voltage VREF is greater than the feedback voltage VF1, the control unit 210 will lower the control voltage VC. Conversely, if the reference voltage VREF is less than the feedback voltage VF1, the control unit 210 will increase the control voltage. VC is not limited to this embodiment. In summary, the control voltage VC is adjusted to provide stable currents I1 and I2 without departing from the control unit 210 according to the received reference voltage VREF and the first feedback voltage VF1. In the spirit of the present invention, it is within the scope of the technical idea of the present invention. Thereby, the steady current circuit 200 of the present invention can effectively provide the stable current I1 and the current I2 without being affected by the voltage variations of the terminals T1 and T2.

In order to explain the operation flow of the current stabilizing circuit 200 according to the present invention in more detail, the operation of the detailed circuit of the current stabilizing circuit 200 is further taught by another diagram, and if necessary, reference may be made to FIG.

Please refer to FIG. 3. FIG. 3 is a schematic diagram of a detailed circuit of a current stabilizing circuit according to an embodiment of the present invention. The control unit 210 of the current stabilizing circuit 300 includes an amplifier OP1, an N-type transistor MN1, and an impedance element R1 (for example, a resistor). The output of the amplifier OP1 is electrically coupled to the gate of the N-type transistor MN1, and the positive and negative inputs of the amplifier OP1 receive the reference voltage VREF and the feedback voltage VF1, respectively. The source of the N-type transistor MN1 is electrically coupled to the ground voltage GND, and the drain of the N-type transistor MN1 is electrically coupled to one end of the resistor R1 through the terminal C'. The other end of the resistor R1 receives the voltage V2 through the terminal A'.

The impedance element R1 may be a metal oxide semiconductor transistor or a resistor biased in a linear region. The amplifier OP1 is used as a comparator, and the amplifier OP1 compares the reference voltage VREF with the feedback voltage VF1 to output a voltage V1 at its output. The gate of the N-type transistor MN1 receives the voltage V1, and the voltage of the N-type transistor MN1 is controlled by the voltage V1. The magnitude of the current flowing through the resistor R1 can be determined to thereby generate the control voltage VC at the terminal C'.

Incidentally, the voltage V2 may be a DC voltage generated by converting, rectifying, and filtering the household AC power through the power adapter, or a system voltage. In summary, the type of voltage V2 is not intended to limit the invention. When the current stabilizing circuit 300 is used as a charging circuit, the terminal A' will receive the voltage, rectification and filtering of the household AC power supply via the power adapter. The DC voltage, and the end point B' will be connected to the battery to be recharged.

The current mirror unit 220 includes P-type transistors MP1 and MP2. The gates of the P-type transistors MP1 and MP2 are electrically coupled to the terminal C', and the sources of the P-type transistors MP1 and MP2 are electrically coupled to the terminal A'. The drains of the P-type transistors MP1 and MP2 are electrically connected to the terminals T1 and T2, respectively, and the terminal T1 is also electrically connected to the terminal B'. The gates of the P-type transistors MP1 and MP2 receive the control voltage VC through the terminal C' to generate currents I1 and I2 at their drains, respectively. The proportional relationship between the currents I1 and I2 respectively generated by the P-type transistors MP1 and MP2 is determined according to the channel aspect ratio transmitted between the P-type transistors MP1 and MP2.

The compensation unit 230 includes an amplifier OP2 and a P-type transistor MP3. The positive and negative input terminals of the amplifier OP2 are electrically coupled to the terminals T1 and T2, respectively, to couple the drains of the P-type transistors MP1 and MP2 through the terminals T1 and T2. The output of the amplifier OP2 is electrically coupled to the gate of the P-type transistor MP3. The source and the drain of the P-type transistor MP3 are electrically coupled to the terminal T2 and the current-to-voltage unit 240, respectively. By connecting the amplifier OP2 and the P-type transistor MP3 to a negative feedback mode, the voltages of the terminals T1 and T2 will be substantially the same, so the proportional relationship between the currents I1 and I2 will remain fixed.

The current to voltage unit 240 includes an N-type transistor MN2. The gate and the drain of the N-type transistor MN2 are electrically coupled to the drain of the P-type transistor MP3, and the source of the N-type transistor MN2 is electrically coupled to the ground voltage GND to convert the current I2 into a feedback Voltage VF1. The gate of the N-type transistor MN2 is also electrically coupled to the control unit 210 to feed back the feedback voltage VF1 to the control unit 210.

Incidentally, as shown in FIG. 3, the current-to-voltage unit 240 may have other implementations. The current to voltage unit 240 can also be An impedance element R2 (for example, a resistor), wherein one end of the impedance element R2 is electrically coupled to the drain of the P-type transistor MP3 and the control unit 210, and the other end of the impedance element R2 is electrically coupled to the ground voltage GND.

The following is to explain the related operation of the current stabilizing circuit 300. Before the following description, it should be noted that the end point B' of the current stabilizing circuit is electrically coupled to the load, and the terminal A' is Receive voltage V2.

When the reference voltage VREF is greater than the feedback voltage VF1, the voltage V1 output by the amplifier OP1 rises. At this time, the N-type transistor MN1 generates a current IC that rises and flows through the impedance element R1. This current IC causes the impedance element R1 to generate a current drop (IR drop) and causes the control voltage VC at the terminal C' to drop. Therefore, the P-type transistors MP1 and MP2 generate currents I1 and I2, respectively, and flow into the load and the P-type transistor MP3.

In order to avoid the channel length modulation effect and cause the magnitudes of the currents I1 and I2 to deviate from the predetermined current value, the current stabilizing circuit 300 locks the terminals T1 and T2 by using the amplifier OP2 and the P-type transistor MP3. The voltage, and further the voltages at the ends T1 and T2 are substantially the same to avoid the effect of the channel length modulation effect. Further, when the voltage of the terminal T2 is greater than the voltage of the terminal T1, the amplifier OP2 outputs a low level voltage, that is, this causes the gate voltage of the P-type transistor MP3 to go to the low-level voltage. The transient phenomenon of the movement, at this time due to the voltage-current relationship, in the case where the current I2 is a fixed constant, this forces the voltage of the terminal T2 to drop until the voltage of the terminal T2 is equal to the voltage of the terminal T1.

On the other hand, when the voltage of the terminal T2 is lower than the voltage of the terminal T1, the amplifier OP2 outputs a high level voltage, that is, this causes the gate voltage of the P-type transistor MP3 to go to the direction of the high level voltage. Moving transient Phenomenon, in the case of a fixed constant of current I2, this forces the voltage at terminal T2 to rise until the voltage at terminal T2 is equal to the voltage at terminal T1.

For example, when the terminal A' is electrically coupled to the charger and the terminal B' is electrically coupled to the battery to be recharged, the voltage of the terminal T1 will be generated and the voltage of the terminal A' will be continuously increased. The phenomenon, at this time due to the action of the amplifier OP2 and the P-type transistor MP3, the voltage of the terminal T2 will continue to rise until the voltage of the terminal T2 is equal to the voltage of the terminal T1.

Incidentally, it can be known from the above description that the voltage of the terminal T1 will continuously rise. Therefore, the transistor selected by the compensation unit 230 in the present invention is a P-type transistor MP3, which can be compared with a general N-type transistor. It can withstand a large cross-over voltage, thus helping to protect the N-type transistor MN2, and avoiding the excessive voltage and damage of both ends (source and drain) of the N-type transistor MN2.

Next, the current-to-voltage unit 240 receives the current I2 output by the P-type transistor MP3, and converts the current I2 into the feedback voltage VF1, and transmits the feedback voltage VF1 to the amplifier OP1. When the current I2 is larger, the feedback voltage VF1 output by the current-to-voltage unit 240 is larger. When the reference voltage VREF is less than the feedback voltage VF1, the amplifier OP1 outputs a voltage V1 of a low voltage level to the gate of the N-type transistor MN1. At this time, the N-type transistor MN1 generates a current IC which becomes small, causing the control voltage VC to rise, and further causes the P-type transistors MP1 and MP2 to generate currents I1 and I2, respectively, to be temporarily lowered. Then, the current I2 is lowered, and the feedback voltage VF1 is also lowered. Therefore, the steady current circuit 300 can provide a stable current I1 through the negative feedback mechanism described above.

In the following various embodiments, portions different from the above-described embodiments will be described, and the remaining omitted portions are the same as those of the above-described embodiments. In addition For the sake of convenience, like reference numerals or numerals indicate similar elements.

[Another embodiment of the steady current circuit]

Please refer to FIG. 4. FIG. 4 is a schematic diagram of a steady current circuit capable of adjusting a reference voltage according to an embodiment of the invention. In contrast to the embodiment of FIG. 2, the current stabilizing circuit 400 of FIG. 4 includes a programmable control reference voltage unit 410. The programmable control reference voltage unit 410 is electrically coupled to the control unit 210. In this embodiment, the programmable control reference voltage unit 410 can receive and determine the magnitude of the reference voltage VREF according to the voltage V3 and the plurality of digital signals DS1 DSDSX, and transmit the reference voltage VREF to the control unit 210.

Next, the implementation of the programmable control reference voltage circuit 410 in the current stabilizing circuit 400 and the related operation of how the programmable reference voltage circuit 410 adjusts the reference voltage VREF can be described in another diagram.

Please refer to FIG. 5. FIG. 5 is a schematic diagram of a detailed circuit of a steady current circuit capable of adjusting a reference voltage according to an embodiment of the invention. In this embodiment, the programmable control reference voltage unit 410 includes an amplifier OP3, a P-type transistor MP4, MP[1]~MP[X], an impedance element R3 (eg, a resistor), and a plurality of switches SW1 SWSWX and N. Type transistor MN3. The negative input terminal of the amplifier OP3 receives the voltage V3, and the positive input terminal of the amplifier OP3 is electrically coupled to one end of the impedance element R3 and the drain of the P-type transistor MP4. The other end of the impedance element R3 is electrically coupled to the ground voltage GND. The output end of the amplifier OP3 is electrically coupled to the gate of the P-type transistor MP4, and is electrically coupled to the gates of the P-type transistors MP[1]~MP[X] through the switches SW1~SWX. The source of the P-type transistor MP4, MP[1]~MP[X] receives the voltage VDD, and the gate of the P-type transistor MP[1]~MP[X] is electrically coupled to the gate of the N-type transistor MN3. Extreme and bungee jumping. N The source of the NMOS transistor MN3 is electrically coupled to the ground voltage GND, and the gate and the drain of the N-type transistor MN3 are electrically coupled to the control unit 210.

The amplifier OP3 is used to compare the voltage V3 with the feedback voltage VF2 to output the voltage V4. The amplifier OP3 and the P-type transistor MP4 form a negative feedback circuit to pass the negative feedback mechanism such that the voltage V3 is substantially equal to the feedback voltage VF2. The switches SW1 to SWX are controlled to be turned on and off by being controlled by a plurality of digital signals DS1 to DSX, respectively. In addition, X is a positive integer greater than 1, and its value can be determined by the designer according to actual design needs.

The detailed action in the programmable control reference voltage unit 410 in the steady current circuit 400 will be further taught below. When the voltage V3 is greater than the feedback voltage VF2, the output of the amplifier OP3 outputs a voltage V4 of a low level voltage, thereby turning on the P-type transistor MP4, and then generating a stable current by the source-drain voltage across the gate. It flows through the impedance element R3. Then, the digital signals DS1 to DSX are controlled to turn on and off the switches SW1 to SWX, and the on and off of the P-type transistors MP[1] to MP[X] are also controlled together, so that the generated current will be determined. The size of I[1]~I[X]. The N-type transistor MN3 is used to convert the sum of the received currents I[1]~I[X] into a corresponding reference voltage VREF. Accordingly, the user can determine the reference voltage VREF received by the control unit 210 by generating the digital signals DS1 to DSX.

Incidentally, the feedback voltage VF2 is the voltage of one end of the impedance element R3, so the voltage V3 selected by the designer can drive the programmable control reference as long as it is between the system voltage VDD and the ground voltage GND. Voltage unit 410. In another embodiment, an impedance providing component (not shown in FIG. 5) may be added between the drain of the P-type transistor MP4 and one end of the impedance providing component R3. Those skilled in the art will appreciate that circuits capable of producing a stable voltage V4 (e.g., bandgap circuits or others) The bias circuit can replace the circuit function of this part.

It is worth mentioning that all the switches SW1~SWX are connected to the voltage V4, and then connected to the gates of MP[1]~MP[X] respectively, wherein the channel lengths of MP[1]~MP[X] When L[1]~L[X] are equal (L[1]=L[2]=L[3]=...=L[X]), the channel width W[1]~W[X] can be It is a 2x proportional increase (W[X]=2 ¹ ×W[X-1]=2 ² ×W[X-2]=...=2 ^(x-1) ×W[1]), so that The current I[1]~I[X] generated by MP[1]~MP[X] will have I[X]=2 ¹ ×I[X-1]=2 ² ×I[X-2]= ...=2 ^(x-1) ×I[1] proportional relationship.

Here, X is equal to 6 as an example for explanation. To increase the reference voltage VREF, the user or designer can transmit the digital signals DS6~DS1, for example, 000111 to the switches SW6~SW1. When the switches SW6~SW1 receive their corresponding digital signals DS6~DS1(000111), the switches SW1~SW3 will be turned on, and the other switches SW4~SW6 will be turned off. As a result, the voltage V4 will simultaneously turn on the P-type transistor MP4. And M[1]~M[3] to generate currents I1~I3. Therefore, the sum of the currents flowing through the N-type transistor MN3 is I1+I2+I3=I1+2 ¹ ×I1+2 ² ×I1=7×I1, and then the drain voltage of the N-type transistor MN3 rises, so In one case, the reference voltage VREF can be raised to allow the user or the designer to flexibly adjust the reference voltage VREF in the steady current circuit 500.

[Another embodiment of the steady current circuit]

Please refer to FIG. 6. FIG. 6 is a schematic diagram of a current stabilizing circuit of a pre-chargeable flow according to an embodiment of the invention. Compared with the embodiment of FIG. 4, the current stabilizing circuit 600 of FIG. 6 further includes a pre-charging unit 610, a pre-charging unit switch SWP, and a control unit switch SWC, and the control unit 210' additionally has an N-type transistor to enhance the Pressure resistance. The pre-charging unit 610 is electrically coupled to the pre-charging unit. The SWP is electrically coupled between the SWP and the terminal T1, and the control unit switch SWC is electrically coupled between the programmable reference voltage unit 410 and the control unit 210'. The precharge unit switch SWP is electrically coupled between the programmable control reference voltage unit 410 and the precharge unit 610.

When the load is electrically coupled to the terminal B', the pre-charge unit switch SWP is first turned on (transmitted through the control signal SC1), the control unit switch SWC is first turned off (transmitted through the control signal SC2), and the pre-charge unit 610 Used to provide a precharge stream IP to the load. Then, when the voltage V5 of the terminal B' rises to a certain extent, the pre-charge unit switch SWP is turned off, the control unit switch SWC is turned on, and then the control unit VC' generates the control voltage VC to cause the current mirror unit 220. A stable current I1 is generated to the load.

Next, the operation of the current stabilizing circuit that can provide the precharge current will be more clearly described in another figure.

Please refer to FIG. 7. FIG. 7 is a schematic diagram showing a detailed circuit of a current stabilizing circuit for providing a precharge current according to still another embodiment of the present invention. In contrast to the aforementioned control unit 210, the control unit 210' in the current stabilizing circuit 700 further includes an N-type transistor MN4 electrically coupled to the terminal C' and the drain of the N-type transistor MN1. The gate of the N-type transistor MN4 receives a bias voltage VB1 for turning on the N-type transistor MN4. In the present embodiment, the presence of the N-type transistor MN4 helps to avoid damaging the N-type transistor MN1 by an excessive voltage difference. It should be noted that the implementation of the control units 210 and 210' is not intended to limit the present invention. In other words, the control unit 210' of FIGS. 6 and 7 may be replaced with the control unit 210, and the control unit 210 of FIGS. 2 to 5. It is also possible to use the control unit 210' instead.

The precharge unit 610 includes P-type transistors MP5 to MP7 and N-type transistors MN5 to MN6. Source coupling of P-type transistor MP5 and MP6 Connected to the terminal A', the gate of the P-type transistor MP6 is electrically coupled to the gate and the drain of the P-type transistor MP5. The gate of the N-type transistor MN5 is electrically coupled to the system voltage VDD, and the drain of the N-type transistor MN5 is electrically coupled to the drain of the P-type transistor MP5. The gate of the P-type transistor MP7 is electrically coupled to the source of the N-type transistor MN5, the source of the P-type transistor MP7 is electrically coupled to the drain of the P-type transistor MP6, and the drain of the P-type transistor MP7 Electrically coupled to the drain of the P-type transistor MP1. The gate of the N-type transistor MN6 is electrically coupled to the programmable reference voltage unit 410 through the pre-charge unit switch SWP. The drain of the N-type transistor MN6 is electrically coupled to the source of the N-type transistor MN5, N-type. The source of the transistor MN6 is electrically coupled to the ground voltage GND.

Please refer to FIG. 7 and FIG. 8 simultaneously. FIG. 8 is a schematic diagram of a detection circuit for detecting a steady current circuit according to an embodiment of the invention. Before the following description is made, it should be noted that the current stabilizing circuit 700 in this embodiment further includes the detecting circuit 810. The detecting circuit 810 is configured to receive the voltages V2 and V5, and output the control signal SC1 and the control signal SC2 accordingly to turn on or off the pre-charge unit switch SWP and the control unit switch SWC.

In more detail, the detecting circuit 810 can detect whether the voltage difference between the voltages V2 and V5 is higher than a preset voltage value to determine the voltage levels of the output control signals SC1 and SC2, thereby controlling pre-charging. The switch SWP and the control unit switch SWC are turned on (opened) or turned off (off).

For example, when the end point B' of the current mirror unit 220 is coupled to the load, the detecting circuit 810 starts detecting the voltages V2 and V5, if the voltage difference between the voltages V2 and V5 is greater than the preset voltage. The detection circuit 810 outputs a high voltage level control signal SC1 and a low voltage level control signal SC2 to the corresponding precharge unit switch SWP and the control unit switch SWC, and the current stabilization circuit 700 Enter the pre-charge phase, which can Avoid excessive voltage differences and damage the current draw unit.

Then, the pre-charge unit switch SWP is turned on and the control unit switch SWC is turned off, and the N-type transistor MN6 is biased by the reference voltage VREF generated by the programmable control reference voltage unit 410. Of course, from the above description of the embodiment of FIG. 4 and FIG. 5, the designer can determine the required reference voltage VREF by transmitting the digital signals DS1 to DSX, and further determine the gate voltage of the N-type transistor MN6. At this time, those having ordinary knowledge in the art should understand that the tandem current mirror unit as the pre-charging unit 610 generates current in its P-type transistors MP6 and MP7 as the pre-charge stream IP in this embodiment, and This pre-charged stream IP is supplied to the load, which in turn increases the voltage V5 of the terminal B'.

When the detecting circuit 810 detects that the voltage V5 of the terminal B' rises to a predetermined value (for example, the voltage VP), the voltage levels of the control signals SC1 and SC2 are switched such that the control signal SC1 is at a low voltage level, and The control signal SC2 is at a high voltage level, thereby causing the precharge unit switch SWP to be turned off and the control unit switch SWC to be turned on. In this way, the steady current circuit 700 enters the actuation mechanism in the above embodiment of FIG. 5, and can continuously provide a steady current to the current extraction unit until the voltage V5 of the terminal B' rises to the voltage V2 or rises to the Set voltage VQ (less than but close to voltage V2). Then, the detection circuit 810 automatically transmits the low voltage level control signals SC1 and SC2 to its corresponding pre-charge unit switch SWP and control unit switch SWC, thereby cutting off its current path to avoid excessive damage to the load (eg , damage to the battery to be recharged).

[Embodiment of Electronic Apparatus]

Please refer to FIG. 9. FIG. 9 is a schematic diagram of an electronic device with a current stabilizing circuit according to an embodiment of the present invention. The electronic device 900 includes a load 910 and is electrically coupled A steady current circuit 920 of the load, wherein the steady current circuit 920 receives the voltage V2. The voltage V2 may be a DC voltage or a system voltage generated by the power adapter to receive the household AC power. The current stabilizing circuit 920 may be one of the current stabilizing circuits 200, 300, 400, 500, and 600 in the above embodiments, and is configured to provide a stable current I1 to the load. The electronic device 900 can be various types of electronic devices, such as handheld devices or mobile devices.

[Possible effects of the examples]

In summary, the current stabilization circuit provided by the embodiment of the present invention uses the control unit to receive the reference voltage and output the control voltage to the current mirror unit, and receives the current through the current mirror unit and outputs a stable first according to the control voltage. Current and second current. Thereafter, the second current is converted to the first feedback voltage by the current to voltage unit and the first feedback voltage is transmitted to the control unit. Then, the control unit adjusts the control voltage according to the reference voltage and the first feedback voltage to stabilize the first current and the second current, thereby effectively providing a stable first current.

Furthermore, another embodiment of the present invention further utilizes a programmable control reference voltage unit to enable a designer or user to flexibly adjust or change the magnitude of the reference voltage in accordance with circuit design requirements or usage requirements.

Finally, still another embodiment of the present invention further utilizes a precharge unit to provide a precharge stream to the load, whereby the mechanism of the precharge stream can avoid excessive voltage differences from damaging the load.

The above description is only an embodiment of the present invention, and is not intended to limit the scope of the invention.

100‧‧‧ Current Control Circuit

110‧‧‧Control circuit

120‧‧‧Power adapter

130‧‧‧ Rechargeable battery

200, 300, 400, 500, 600, 700‧‧‧ steady current circuit

210, 210’‧‧‧Control unit

220‧‧‧current mirror unit

230‧‧‧Compensation unit

240‧‧‧current to voltage unit

410‧‧‧Programmable control reference voltage unit

610‧‧‧Precharge unit

810‧‧‧Detection circuit

900‧‧‧Electronic devices

910‧‧‧load

920‧‧‧ steady current circuit

A, B, C, T1, T2, A', B', C'‧‧‧ endpoints

DS1~DSX‧‧‧ digital signal

GND‧‧‧ Grounding voltage

I‧‧‧Charging current

I1, I2, IC, I[1]~I[X]‧‧‧ current

IP‧‧‧Precharge current

MPP, M[1]~M[X], MP1, MP2, MP3, MP4, MP5, MP6, MP7‧‧‧P type transistor

MN1, MN2, MN3, MN4, MN5, MN6‧‧‧N type transistor

OP1, OP2, OP3‧‧‧ amplifier

R1, R2, R3‧‧‧ impedance components

SC1, SC2‧‧‧ control signals

SW1~SWX‧‧‧ switch

SWP‧‧‧Precharge unit switch

SWC‧‧‧Control unit switch

V1~V5, VP, VQ‧‧‧ voltage

VB1‧‧‧ bias

VC‧‧‧ control voltage

VDD‧‧‧ system voltage

VF1, VF2‧‧‧ feedback voltage

VREF‧‧‧reference voltage

FIG. 1 is a schematic diagram showing a conventional current control circuit.

2 is a schematic block diagram of a current stabilizing circuit according to an embodiment of the invention.

3 is a schematic diagram of a detailed circuit of a current stabilizing circuit in accordance with an embodiment of the present invention.

4 is a schematic diagram of a current stabilizing circuit capable of adjusting a reference voltage according to another embodiment of the present invention.

FIG. 5 is a detailed circuit diagram of a steady current circuit capable of adjusting a reference voltage according to another embodiment of the present invention.

6 is a schematic diagram of a current stabilizing circuit of a prechargeable current according to still another embodiment of the present invention.

FIG. 7 is a detailed circuit diagram of a current stabilizing circuit for providing a precharge current according to still another embodiment of the present invention.

FIG. 8 is a schematic diagram of a detection circuit for detecting a steady current circuit according to an embodiment of the invention.

9 is a schematic diagram of an electronic device having a current stabilizing circuit according to an embodiment of the present invention.

200‧‧‧ steady current circuit

210‧‧‧Control unit

220‧‧‧current mirror unit

230‧‧‧Compensation unit

240‧‧‧current to voltage unit

VREF‧‧‧reference voltage

VC‧‧‧ control voltage

VF1‧‧‧ feedback voltage

I1, I2‧‧‧ current

A', B', C', T1, T2‧‧‧ endpoints

Claims (16)

A current stabilizing circuit for generating a stable first current, the steady current circuit comprising: a control unit for receiving a reference voltage and a first feedback voltage, and outputting a control voltage according thereto; a current mirror The unit is electrically coupled to the control unit, receives the control voltage, and outputs the first current and a second current according to the current; a current-to-voltage unit is electrically coupled between the current mirror unit and the control unit The second current is converted into the first feedback voltage, and the first feedback voltage is transmitted to the control unit; and a compensation unit electrically coupled to the current mirror unit and the current-to-voltage circuit And receiving the second current, and transmitting the second current to the current-to-voltage unit, wherein the compensation unit is configured to compensate for a non-ideal characteristic of the current mirror unit, so that the first current and the first The two currents maintain a fixed proportional relationship. The steady current circuit of claim 1, wherein the compensation unit causes the current mirror unit to output the first current and the voltage at the two ends of the second current to be substantially equal. The steady current circuit of claim 1, wherein the control unit comprises: a first amplifier, the positive input terminal receives the reference voltage, the negative input terminal receives the first feedback voltage, and the output terminal outputs a first voltage; a first N-type transistor, the gate receiving the first voltage, the source electrically coupled to a ground voltage, the drain outputting the control voltage; and a first impedance component, the first One end is electrically coupled to a second voltage, and the second end is electrically coupled to the drain of the first N-type transistor. The steady current circuit of claim 3, wherein the control unit further comprises: a second N-type transistor, the gate is electrically coupled to a bias, and the source is electrically coupled to the first The drain of the N-type transistor is electrically coupled to the second end of the first impedance element. The steady current circuit of claim 1, wherein the current mirror unit comprises: a first P-type transistor, wherein the gate receives the control voltage, and the source is electrically coupled to a second voltage, The drain generates the first current; and a second P-type transistor, the gate of which is electrically coupled to the gate of the first P-type transistor, the source of which is electrically coupled to the second voltage, and the drain The second current is output, wherein a proportional relationship between the first current and the second current is determined by a channel aspect ratio of the first P-type transistor and the second P-type transistor. The current-stabilizing circuit of claim 5, wherein the compensation unit comprises: a second amplifier, the positive input end of which is electrically coupled to the drain of the first P-type transistor, and the negative input terminal is electrically The first P-type transistor is coupled to the drain of the second P-type transistor; and the third P-type transistor is electrically coupled to the output end of the second amplifier, and the source is electrically coupled to the second P-type The drain of the crystal receives the second current, and the drain outputs the second current to the current-to-voltage unit, wherein the voltages of the positive input and the negative input of the second amplifier are substantially the same. The steady current circuit as described in claim 6 wherein the current to voltage The circuit is a third N-type transistor, the gate and the drain are electrically coupled to the drain of the third P-type transistor, and the source is electrically coupled to the ground voltage, wherein the third N-type transistor The drain outputs the first feedback voltage to the control unit. The current-stabilizing circuit of claim 6, wherein the current-to-voltage circuit is a second impedance component, the first end of which is electrically coupled to the drain of the third P-type transistor, and the second end thereof Electrically coupling the ground voltage, wherein the second current flows through the second impedance element, generates the first feedback voltage at a second end thereof, and transmits the first feedback voltage to the control unit. The steady current circuit of claim 1, further comprising: a programmable control reference voltage circuit electrically coupled to the control unit, the programmable control reference voltage unit for receiving and according to a third The voltage and the plurality of digit signals determine the magnitude of the reference voltage and the reference voltage is transmitted to the control unit. The steady current circuit of claim 9, wherein the programmable control reference voltage circuit comprises: a third amplifier, the negative input terminal receives the third voltage, and the output terminal outputs a fourth voltage; The fourth P-type transistor has a gate receiving the fourth voltage, a source electrically coupled to a system voltage, and a drain electrically coupled to the positive input terminal of the third amplifier; a third impedance component, the first One end is electrically coupled to the positive input terminal of the third amplifier to provide a second feedback voltage to the positive input end of the third amplifier, and the second end is electrically coupled to the ground voltage; And a plurality of fifth P-type transistors, wherein the sources of the fifth P-type transistors are electrically coupled to the system voltage, and the gates of the fifth P-type transistors pass through the gates The switch is electrically coupled to the output end of the third amplifier; and a fourth N-type transistor, the gate and the drain are electrically coupled to the positive input end of the first amplifier and the fifth P-type transistor a pole for providing the reference voltage to the control unit, and a source electrically coupled to the ground voltage. The current-stabilizing circuit of claim 9, further comprising: a pre-charging unit electrically coupled to the programmable control reference voltage unit for providing a pre-charge flow to a load; a pre-charge unit The first end of the switch is electrically coupled to the programmable control reference voltage circuit, and the second end is electrically coupled to the precharge unit, and the precharge unit switch is configured to receive a first control signal to determine its conduction. Or a disconnected state; and a control unit switch, the first end of which is electrically coupled to the programmable control reference voltage unit, the second end of which is electrically coupled to the control unit, and the control unit switch is configured to receive a second The control signal determines its on or off state, wherein the on or off state of the precharge unit switch is opposite to the on or off state of the control unit switch. The current-stabilizing circuit of claim 11, wherein the pre-charging unit comprises: a sixth P-type transistor, the source of which is electrically coupled to the second voltage; and a seventh P-type transistor, The source is electrically coupled to the second voltage, the gate is electrically coupled to the gate and the drain of the sixth P-type transistor; and the fifth N-type transistor is electrically coupled to the system voltage The anode is electrically coupled to the drain of the sixth P-type transistor; an eighth P-type transistor has an electrical gate coupled to the fifth N-type transistor a source, the source is electrically coupled to the drain of the seventh P-type transistor, the drain is electrically coupled to the drain of the first P-type transistor to provide the precharge current; and a sixth The N-type transistor has a gate electrically coupled to the second end of the pre-charged unit switch, and a gate electrically coupled to the source of the fifth N-type transistor, the source of which is electrically coupled to the ground voltage . The steady current circuit of claim 11, further comprising: a detecting circuit, configured to receive the second voltage and a fifth voltage, and output the first control signal and the second control signal accordingly And determining an on or off state of the precharge unit switch and the control unit switch, wherein the fifth voltage is a voltage of the load. An electronic device includes: a steady current circuit for generating a stable first current; and a load electrically coupled to the current stabilizing circuit for receiving the first current, wherein the current stabilizing circuit comprises: The control unit is configured to receive a reference voltage and a first feedback voltage, and output a control voltage according to the control unit; a current mirror unit electrically coupled to the control unit, the current mirror unit receives and outputs according to the control voltage The first current and a second current; a current-to-voltage unit electrically coupled between the current mirror unit and the control unit for converting the first current into the first feedback voltage and transmitting The first feedback voltage is applied to the control unit; and a compensation unit electrically coupled between the current mirror unit and the current-to-voltage circuit for receiving the second current, and the second Current is delivered to the current to voltage unit, wherein the complement The compensation unit is configured to compensate for non-ideal characteristics of the current mirror unit such that the first current maintains a fixed proportional relationship with the second current. The electronic device of claim 14, wherein the current stabilizing circuit further comprises: a programmable control reference voltage circuit electrically coupled to the control unit, the programmable control reference voltage unit for receiving The magnitude of the reference voltage is determined according to a third voltage and a plurality of digital signals, and the reference voltage is transmitted to the control unit. The electronic device of claim 15 , wherein the current stabilizing circuit further comprises: a pre-charging unit electrically coupled to the programmable control reference voltage unit for providing a pre-charge current to a load; a pre-charging unit switch electrically coupled to the programmable control reference voltage circuit, the second end of which is electrically coupled to the pre-charging unit, the pre-charging unit switch is configured to receive a first control signal The control unit is electrically coupled to the programmable control reference voltage unit, and the second end is electrically coupled to the control unit, and the control unit switch is used to control the on or off state. A second control signal is received to determine its on or off state, wherein the on or off state of the precharge unit switch is opposite to the on or off state of the control unit switch.