CN212906040U - A Low Current Wide Range Adjustable Pulse Constant Current Source Circuit - Google Patents
A Low Current Wide Range Adjustable Pulse Constant Current Source Circuit Download PDFInfo
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Abstract
一种低电流宽范围可调脉冲恒流源电路，涉及功率器件静态参数Vgeth测试技术领域，解决现有恒流源不能连续选择输出、无法满足不同型号功率器件Vgeth参数不同而需要的电流值不同、不能覆盖所有功率器件测试的问题，包括数字信号隔离电路、数字电位器输出电路、开关切换电路、电流源电路；数字信号隔离电路与数字电位器输出电路连接，电流源电路通过开关切换电路与数字电位器输出电路连接；数字信号隔离电路将设定的电流信号值发送给数字电位器输出电路，数字电位器输出电路与开关切换电路相互配合输出不同电阻值，选择电流源电路输出回路，从而控制恒流源电路在10uA‑1A持续可调恒定电流输出；电路结构简单、测试速度快，输出低电流10uA‑1A连续可调、精度高。
A low-current wide-range adjustable pulse constant current source circuit relates to the technical field of power device static parameter Vgeth testing, and solves the problem that the existing constant current source cannot continuously select output, cannot meet the different current values required by different Vgeth parameters of different types of power devices, It cannot cover all power device testing problems, including digital signal isolation circuit, digital potentiometer output circuit, switch switching circuit, and current source circuit; the digital signal isolation circuit is connected with the digital potentiometer output circuit, and the current source circuit is connected with the digital signal through the switch switching circuit. The potentiometer output circuit is connected; the digital signal isolation circuit sends the set current signal value to the digital potentiometer output circuit, the digital potentiometer output circuit and the switch switching circuit cooperate with each other to output different resistance values, and the output circuit of the current source circuit is selected to control The constant current source circuit can continuously adjust the constant current output at 10uA‑1A; the circuit structure is simple, the test speed is fast, the output low current is 10uA‑1A continuously adjustable, and the precision is high.
Description
Technical Field
The invention relates to the technical field of power device static parameter Vgeth test, in particular to a low-current wide-range adjustable pulse constant current source circuit.
Background
Nowadays, IGBTs (insulated gate field effect transistors) have become the mainstream of high-power elements and are dominant in the market. Due to the technological progress, the power electronic device is driven by the requirements of lightness, thinness, shortness and high performance and the development of the IGBT, and is particularly applied to the fields of electrical equipment, photoelectricity, aerospace, railways, power conversion and the like, so that semiconductor development technicians are continuously breaking through the development technology of high-power elements under the market demand.
In addition to the good function of the semiconductor device, the quality of the product is difficult to ensure, especially for larger power devices, because of the wearability, the aging and the efficiency reduction, the semiconductor device is burned due to unbalance, and even the semiconductor device may explode in use. It is more important to screen and check the parameters of new products and components in use. For IGBTs, IGBTs are the mainstream semiconductor switching devices widely used in modern medium-high power converters. The IGBT devices are used in a large number of important electrical equipment such as a traction inverter and an auxiliary inverter of the urban rail transit vehicle, and various static parameters of the IGBT devices provide very intuitive reference basis for a user to reliably select the devices, so that the accurate measurement of various static parameters of the IGBT has extremely important practical significance.
The low-current wide-range adjustable pulse constant current source is a key test device specially aiming at parameter measurement of static test Vgeth (grid-emitter threshold voltage) of a power device; as shown in fig. 3, the main function of the constant current source is to output a specified constant current to between G-E after the power device C-G under test is short-circuited, measure Vge, and measure the voltage when Vge is kept constant, i.e., Vgeth.
As shown in fig. 4, in the current national standard test circuit, a power device static test Vgeth parameter is measured by applying a rated voltage between C, E, gradually regulating the voltage by a voltage source, and recording the value of the voltage detection Vge, namely Vgeth, when the value of the current detection Ice reaches a preset current value. In addition, in the current Vgeth test circuit in the market, the applied output current of the constant current source only meets the selectable output of a plurality of fixed values, but cannot meet the requirement of continuous selectable output, cannot meet the requirement of different Vgeth parameters of different types of power devices and different required current values, and cannot cover the test of all power devices.
In the prior art, the design of a novel continuously adjustable pulse current source (Zhou Hai Bing et al, semiconductor institute of Chinese academy of sciences) discloses a novel digitally controlled adjustable pulse current source, the core of which is a precise constant current source circuit and a pulse current mirror circuit. The precise constant current source circuit adopts a depth negative feedback technology based on an operational amplifier, and provides a constant current output with high precision, good stability and continuously adjustable amplitude; the pulse current mirror circuit adopts a high-speed field effect transistor to realize the copy and multiplication of the current of the constant current source, reduces the influence of the output load of the pulse current source on the depth negative feedback part of the front stage, improves the stability of the circuit, and transmits a pulse signal to the pulse current by utilizing the control of the analog multiplexer on the grid electrode of the current mirror, thereby outputting the pulse current.
However, the technical solutions of the above documents do not solve the problems that the applied constant current source cannot meet the requirement of continuously selecting output, cannot meet the requirement of different current values required by different models of power devices Vgeth with different parameters, and cannot cover the test of all power devices.
Disclosure of Invention
The invention aims to solve the technical problems that the conventional constant current source cannot continuously select and output, cannot meet the requirements of different models of power devices on different Vgeth parameters and different required current values, and cannot cover the test of all power devices.
The invention solves the technical problems through the following technical scheme:
a low-current wide-range adjustable pulse constant current source circuit comprises a digital signal isolation circuit, a digital potentiometer output circuit, a switch switching circuit and a current source circuit; the digital signal isolation circuit is connected with the digital potentiometer output circuit, and the current source circuit is connected with the digital potentiometer output circuit through the switch switching circuit; the digital signal isolation circuit sends the set current signal value to the digital potentiometer output circuit, the digital potentiometer output circuit and the switch switching circuit are matched with each other to output different resistance values, and the output loop of the current source circuit is selected, so that the constant current source circuit is controlled to continuously adjust the constant current output at 10 uA-1A.
The constant current source circuit ensures the output of a rapid and high-precision continuous adjustable constant current source by controlling the output adjustable resistance of the high-precision digital potentiometer and combining and selecting high-precision current sources in different ranges; the constant current source is output to the power device of the tested object, so that a stable static parameter Vgeth value of the power device can be directly obtained; in a national standard test circuit, a continuously adjustable voltage source is needed for static test of a power device Vgeth parameter measurement, a real-time detection current value reaches a preset current value, and the applied voltage value is Vgeth.
As a further improvement of the technical scheme of the invention, the digital signal isolation circuit comprises a four-channel digital signal isolator (U1) and a two-channel digital signal isolator (U2); the digital potentiometer output circuit comprises a 100K digital potentiometer (U3), a 10K digital potentiometer (U4) and a 1K digital potentiometer (U5); the 100K digital potentiometer (U3) is connected with a four-channel digital signal isolator (U1); the 10K digital potentiometer (U4) is respectively connected with a four-channel digital signal isolator (U1) and a two-channel digital signal isolator (U2); the 1K digital potentiometer (U5) is respectively connected with the four-channel digital signal isolator (U1) and the two-channel digital signal isolator (U2).
As a further improvement of the technical solution of the present invention, the digital potentiometer output circuit further includes a capacitor C1 and a capacitor C3, wherein one end of the capacitor C1 is connected to pin 7# of the 100K digital potentiometer (U3), and the other end is grounded; one end of the capacitor C3 is connected with the 7# pin of the 10K digital potentiometer (U4), and the other end is grounded.
As a further improvement of the technical solution of the present invention, the switch switching circuit includes a first switch (SW1), a second switch (SW2), a fifth switch (SW5), a sixth switch (SW6), an eighth switch (SW8), and a ninth switch (SW 9); a 1# terminal of the first switch (SW1) is connected to a 4# pin of the 100K digital potentiometer (U3), a 1# terminal of the second switch (SW2) is connected to a 5# pin of the 100K digital potentiometer (U3), a 1# terminal of the fifth switch (SW5) is connected to a 2# pin of the 10K digital potentiometer (U4), a 1# terminal of the sixth switch (SW6) is connected to a 3# pin of the 10K digital potentiometer (U4), a 1# terminal of the eighth switch (SW8) is connected to a 7# pin of the 1K digital potentiometer (U5), and a 1# terminal of the ninth switch (SW9) is connected to a 1# pin of the 1K digital potentiometer (U5); the 2# terminal of the first switch (SW1), the 2# terminal of the fifth switch (SW5) and the 2# terminal of the eighth switch (SW8) are connected together, and the 2# terminal of the second switch (SW2), the 2# terminal of the sixth switch (SW6) and the 2# terminal of the ninth switch (SW9) are connected together.
As a further improvement of the technical solution of the present invention, the switch switching circuit further includes a first selection switch (SW4) and a second selection switch (SW 7); the current source circuit comprises a current source chip (U6), an adjustable low dropout regulator (U7) and a resistor R1; the 2# terminal of the first selection switch (SW4) is connected with the 2# terminal of the first switch (SW1), the 2# terminal of the fifth switch (SW5) and the 2# terminal of the eighth switch (SW8), the 1# terminal of the first selection switch (SW4) is connected with the 1# pin of the current source chip (U6), one end of the resistor R1 is connected with the 2# pin of the adjustable low dropout regulator (U7), and the other end of the resistor R1 is connected with the 3# terminal of the first selection switch (SW 4); the 2# terminal of the second selection switch (SW7) is connected with the 2# terminal of the second switch (SW2), the 2# terminal of the sixth switch (SW6) and the 2# terminal of the ninth switch (SW9), the 1# terminal of the second selection switch (SW7) is connected with the 2# pin of the current source chip (U6), and the 3# terminal of the second selection switch (SW7) is connected with the 1# pin of the adjustable low dropout regulator (U7).
As a further improvement of the technical scheme of the invention, the current source circuit also comprises an analog selection switch (SW3), a MOSFET power device (Q1), a resistor R2 and a power device control signal generator; a capacitor C2, a capacitor C4; the 2# terminal of the analog selection switch (SW3) is connected with the 1# pin of the current source chip (U6), the 1# terminal of the analog selection switch (SW3) is connected with the drain electrode of the MOSFET power device (Q1), the 3# terminal of the analog selection switch (SW3) is grounded, and the source electrode of the MOSFET power device (Q1) is grounded; one end of the capacitor C2 is connected to the No. 3 pin of the current source chip (U6), and the other end is grounded; one end of the capacitor C4 is connected to the No. 3 pin of the adjustable low dropout regulator (U7), and the other end is grounded; one end of the resistor R1 is connected with the No. 2 pin of the adjustable low dropout regulator (U7), and the other end of the resistor R1 is connected with the drain electrode of the MOSFET power device (Q1); the resistor R2 is connected in parallel between the grid and the source of the MOSFET power device (Q1), and the power device control signal generator is connected in parallel at two ends of the resistor R2.
As a further improvement of the technical scheme of the invention, the constant current source circuit is continuously adjustable at 10uA-1A and is realized by combining 5 sections:
1)10uA-0.06mA continuous adjustable current output
The four-channel digital signal isolator (U1) selects the 100K digital potentiometer (U3), and sets the D value of the 100K digital potentiometer (U3) through formulas (1) and (2), so that the 100K digital potentiometer (U3) outputs a resistance value corresponding to the required current, and the current value is output by the current source chip (U6) selected through the first switch (SW1), the second switch (SW2), the first selection switch (SW4) and the second selection switch (SW7), and the calculation formula is as follows:
Iout＝67.7/RSET(D) (1)
RSET(D)＝D*100K/1024 (2)
wherein Iout is the output current value, RSET (D) is the set resistance value, 67.7 is the rated output value of the current source chip (U6), D is a decimal value, and the value range is 1-69 at the moment;
2)0.06mA-1mA continuous adjustable current output
The four-channel digital signal isolator (U1) and the two-channel digital signal isolator (U2) select the 1K digital potentiometer (U5) and set the D value of the 1K digital potentiometer (U5) through formulas (1) and (3), so that the 1K digital potentiometer (U5) outputs a resistance value corresponding to the required current, and the current value is output through the eighth switch (SW8), the ninth switch (SW9), the first selection switch (SW4) and the second selection switch (SW7) selection current source chip (U6), and the calculation formula is as follows:
Iout＝67.7/RSET(D) (1)
RSET(D)＝D*1K/256 (3)
wherein, the value range of D is 17-256;
3)1mA-10mA continuous adjustable current output
The four-channel digital signal isolator (U1) and the two-channel digital signal isolator (U2) select the 1K digital potentiometer (U5) and set the D value of the 1K digital potentiometer (U5) through formulas (3) and (4), so that the 1K digital potentiometer (U5) outputs a resistance value corresponding to a required current, the eighth switch (SW8), the ninth switch (SW9), the first selection switch (SW4) and the second selection switch (SW7) select the adjustable low-voltage-drop voltage stabilizer (U7) to output a corresponding current value, and the calculation formula is as follows:
RSET(D)＝D*1K/256 (3)
Iout＝RSET(D)*10 (4)
wherein 10 is the rated output value of the adjustable low dropout regulator (U7), and the value range of D is 26-256;
4)10mA-100mA continuous adjustable current output
The four-channel digital signal isolator (U1) and the two-channel digital signal isolator (U2) select the 10K digital potentiometer (U4) and set the D value of the 10K digital potentiometer (U4) through formulas (4) and (5), so that the 10K digital potentiometer (U4) outputs a resistance value corresponding to a required current, and the fifth switch (SW5), the sixth switch (SW6), the first selection switch (SW4) and the second selection switch (SW7) select the adjustable low-voltage-drop voltage stabilizer (U7) to output a corresponding current value, wherein the calculation formula is as follows:
Iout＝RSET(D)*10 (4)
RSET(D)＝D*10K/1024 (5)
wherein, the value range of D is 102-1024;
5)100mA-1A continuous adjustable current output
The four-channel digital signal isolator (U1) selects the 100K digital potentiometer (U3) and sets the D value of the 100K digital potentiometer (U3) through formulas (2) and (4), so that the 100K digital potentiometer (U3) outputs a resistance value corresponding to a required current, the first switch (SW1), the second switch (SW2), the first selection switch (SW4) and the second selection switch (SW7) select the adjustable low-voltage-drop voltage stabilizer (U7) to output a corresponding current value, and the calculation formula is as follows:
RSET(D)＝D*100K/1024 (2)
Iout＝RSET(D)*10 (4)
wherein, the value range of D is 103-1024.
As a further improvement of the technical solution of the present invention, the model of the four-channel digital signal isolator (U1) is ADUM141E, and the model of the two-channel digital signal isolator (U2) is ADUM 1200.
As a further improvement of the technical scheme of the invention, the model of the 100K digital potentiometer (U3) is AD5293, the model of the 10K digital potentiometer (U4) is AD5174, and the model of the 1K digital potentiometer (U5) is AD 8400.
As a further improvement of the technical scheme of the invention, the model of the current source chip (U6) is LM 334; the adjustable low dropout regulator (U7) is LT3080 in model number; the model of the analog selection switch (SW3) is ADG 5419; the model of the MOSFET power device (Q1) is FQP50N 06.
The invention has the advantages that:
(1) the constant current source circuit ensures the output of a rapid and high-precision continuous adjustable constant current source by controlling the output adjustable resistance of the high-precision digital potentiometer and combining and selecting high-precision current sources in different ranges; the constant current source is output to the power device of the tested object, so that a stable static parameter Vgeth value of the power device can be directly obtained; in a national standard test circuit, a continuously adjustable voltage source is needed for static test of a power device Vgeth parameter measurement, a real-time detection current value reaches a preset current value, and the applied voltage value is Vgeth.
(2) The constant current source outputs low current 10uA-1A which is continuously adjustable and has high output precision. The constant current source output is mostly single non-adjustable or multi-step adjustable. The continuous adjustable resistance value is output by programming control of three high-precision digital potentiometers of 1K, 10K and 100K, and the constant current source output with wide range, low current, continuous adjustability and high precision is output by combining different combination modes of power chips with high current and low current ranges.
Drawings
Fig. 1 is a digital signal isolation circuit diagram of a low-current wide-range adjustable pulse constant current source circuit according to an embodiment of the present invention;
FIG. 2 is a main circuit diagram of a low-current wide-range adjustable pulse constant current source circuit according to an embodiment of the present invention;
FIG. 3 is a schematic circuit diagram of a national standard Vgeth parameter testing method;
fig. 4 is a circuit schematic diagram of a parameter testing method using a wide-range adjustable constant current source Vgeth.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The technical scheme of the invention is further described by combining the drawings and the specific embodiments in the specification:
example one
As shown in fig. 1 and fig. 2, a low-current wide-range adjustable pulse constant current source circuit includes a digital signal isolation circuit, a digital potentiometer output circuit, a switch switching circuit, and a current source circuit; the digital signal isolation circuit is connected with the digital potentiometer output circuit, and the current source circuit is connected with the digital potentiometer output circuit through the switch switching circuit; the tested IGBT power device DUT1 is connected with the current source circuit through the analog selection switch SW3 or the MOSFET power device Q1.
As shown in fig. 1, the digital signal isolation circuit includes a four-channel digital signal isolator U1, a two-channel digital signal isolator U2; the model of the four-channel digital signal isolator U1 is ADUM141E, and the model of the two-channel digital signal isolator U2 is ADUM 1200; four-channel digital signal isolator U1, two-channel digital signal isolator U2's signal input part be connected with the DSP controller through SPI communication respectively, four-channel digital signal isolator U1, two-channel digital signal isolator U2's signal output part be connected with 100K digital potentiometer U3, 10K digital potentiometer U4 and 1K digital potentiometer U5 respectively.
As shown in fig. 2, the digital potentiometer output circuit includes a 100K digital potentiometer U3, an external capacitor C1, a 10K digital potentiometer U4, an external capacitor C3, a 1K digital potentiometer U5; the model of the 100K digital potentiometer U3 is AD5293, the model of the 10K digital potentiometer U4 is AD5174, and the model of the 1K digital potentiometer U5 is AD 8400.
The switch switching circuit comprises a first switch SW1, a second switch SW2, a fifth switch SW5, a sixth switch SW6, an eighth switch SW8, a ninth switch SW9, a first selection switch SW4 and a second selection switch SW7, and different resistance values and selection current source circuits are switched and matched through switch combination.
The current source circuit comprises a current source chip U6, an adjustable low-voltage-drop voltage stabilizer U7, a capacitor C2, a capacitor C4, an analog selection switch SW3, a MOSFET power device Q1, a resistor R1, a resistor R2 and a power device control signal generator; the current source chip U6 is LM 334; the adjustable low dropout regulator U7 is LT 3080; the model of the analog selection switch SW3 for controlling the on-off of the output current of the current source chip U6 is ADG 5419; the MOSFET power device Q1 for controlling the on-off of the output current of the adjustable low dropout voltage regulator U7 has the model number of FQP50N 06.
The 100K digital potentiometer U3 is connected with a four-channel digital signal isolator U1; the 10K digital potentiometer U4 is respectively connected with a four-channel digital signal isolator U1 and a two-channel digital signal isolator U2; the 1K digital potentiometer U5 is respectively connected with a four-channel digital signal isolator U1 and a two-channel digital signal isolator U2; one end of the capacitor C1 is connected to the 7# pin of the 100K digital potentiometer U3, and the other end of the capacitor C1 is grounded; one end of the capacitor C3 is connected to the No. 7 pin of the 10K digital potentiometer U4, and the other end is grounded.
A 1# terminal of the first switch SW1 is connected to a 4# pin of the 100K digital potentiometer U3, a 1# terminal of the second switch SW2 is connected to a 5# pin of the 100K digital potentiometer U3, a 1# terminal of the fifth switch SW5 is connected to a 2# pin of the 10K digital potentiometer U4, a 1# terminal of the sixth switch SW6 is connected to a 3# pin of the 10K digital potentiometer U4, a 1# terminal of the eighth switch SW8 is connected to a 7# pin of the 1K digital potentiometer U5, and a 1# terminal of the ninth switch SW9 is connected to a 1# pin of the 1K digital potentiometer U5; the 2# terminal of the first switch SW1, the 2# terminal of the fifth switch SW5 and the 2# terminal of the eighth switch SW8 are connected together, and the 2# terminal of the second switch SW2, the 2# terminal of the sixth switch SW6 and the 2# terminal of the ninth switch SW9 are connected together.
The 2# terminal of the first selection switch SW4 is connected with the 2# terminal of the first switch SW1, the 2# terminal of the fifth switch SW5 and the 2# terminal of the eighth switch SW8, the 1# terminal of the first selection switch SW4 is connected with the 1# pin of the current source chip U6, and the 3# terminal of the first selection switch SW4 is connected with the drain of the MOSFET power device Q1.
The 2# terminal of the second selection switch SW7 is connected with the 2# terminal of the second switch SW2, the 2# terminal of the sixth switch SW6 and the 2# terminal of the ninth switch SW9, the 1# terminal of the second selection switch SW7 is connected with the 2# pin of the current source chip U6, and the 3# terminal of the second selection switch SW7 is connected with the 1# pin of the adjustable low dropout regulator U7.
One end of the capacitor C2 is connected to the No. 3 pin of the current source chip U6, and the other end is grounded; one end of the capacitor C4 is connected to the 3# pin of the adjustable low dropout regulator U7, and the other end is grounded; one end of the resistor R1 is connected with the No. 2 pin of the adjustable low dropout regulator U7, and the other end of the resistor R1 is connected with the drain electrode of the MOSFET power device Q1; the resistor R2 is connected in parallel between the grid and the source of the MOSFET power device Q1, the power device control signal generator is connected in parallel at two ends of the resistor R2, and the source of the MOSFET power device Q1 is grounded; the 2# terminal of the analog selection switch SW3 is connected with the 1# pin of the current source chip U6, the 1# terminal of the analog selection switch SW3 is connected with the drain of the MOSFET power device Q1, and the 3# terminal of the analog selection switch SW3 is grounded.
The upper computer sends the set current signal value to the DSP controller, the DSP controller sends the current signal value to the digital signal isolation circuit in an SPI communication mode, the digital signal isolation circuit sends the current signal value to the digital potentiometer output circuit, the digital potentiometer output circuit outputs the resistance value corresponding to the current signal value by selecting a 100K digital potentiometer U3, a 10K digital potentiometer U4 or a 1K digital potentiometer U5, and the switch switching circuit selects the current source chip U6 or the adjustable low-voltage-drop voltage stabilizer U7 to realize 10uA-1A continuous adjustable constant current output.
In the embodiment of the invention, the output of a 10uA-1A continuous adjustable constant current source is realized by a way of combining 5 sections, which respectively are as follows:
(1)10uA-0.06mA continuous adjustable current output
The DSP selects the 100K digital potentiometer U3 through the four-channel digital signal isolator U1, and sets the D value of the 100K digital potentiometer U3 through formulas (1) and (2), so that the 100K digital potentiometer U3 outputs a resistance value corresponding to the required current, and the current source chip U6 is selected to output a corresponding current value through the first switch SW1, the second switch SW2, the first selection switch SW4 and the second selection switch SW7, and the calculation formula is as follows:
Iout＝67.7/RSET(D) (1)
RSET(D)＝D*100K/1024 (2)
iout is the output current value, RSET (D) is the set resistance value, 67.7 is the rated output value of the current source chip U6, and D is a decimal value, and the value range is 1-69 at this time.
(2)0.06mA-1mA continuous adjustable current output
The DSP selects the 1K digital potentiometer U5 through the four-channel digital signal isolator U1 and the two-channel digital signal isolator U2 and sets the D value of the 1K digital potentiometer U5 through formulas (1) and (3), so that the 1K digital potentiometer U5 outputs a resistance value corresponding to the required current, and selects the current source chip U6 to output a corresponding current value through the eighth switch SW8, the ninth switch SW9, the first selection switch SW4 and the second selection switch SW7, and the calculation formula is as follows:
Iout＝67.7/RSET(D) (1)
RSET(D)＝D*1K/256 (3)
wherein, the value range of D is 17-256.
(3)1mA-10mA continuous adjustable current output
The DSP selects the 1K digital potentiometer U5 through the four-channel digital signal isolator U1 and the two-channel digital signal isolator U2 and sets the D value of the 1K digital potentiometer U5 through formulas (3) and (4), so that the 1K digital potentiometer U5 outputs a resistance value corresponding to the required current, the adjustable low-voltage-drop voltage stabilizer U7 is selected through the eighth switch SW8, the ninth switch SW9, the first selection switch SW4 and the second selection switch SW7 to output a corresponding current value, and the calculation formula is as follows:
RSET(D)＝D*1K/256 (3)
Iout＝RSET(D)*10 (4)
wherein 10 is the rated output value of the adjustable low dropout regulator U7, and the value range of D is 26-256.
(4)10mA-100mA continuous adjustable current output
The DSP selects the 10K digital potentiometer U4 through the four-channel digital signal isolator U1 and the two-channel digital signal isolator U2 and sets the D value of the 10K digital potentiometer U4 through formulas (4) and (5), so that the 10K digital potentiometer U4 outputs a resistance value corresponding to the required current, the adjustable low-voltage-drop voltage stabilizer U7 is selected to output a corresponding current value through the fifth switch SW5, the sixth switch SW6, the first selection switch SW4 and the second selection switch SW7, and the calculation formula is as follows:
Iout＝RSET(D)*10 (4)
RSET(D)＝D*10K/1024 (5)
wherein, the value range of D is 102-1024.
(5)100mA-1A continuous adjustable current output
The DSP selects the 100K digital potentiometer U3 through the four-channel digital signal isolator U1 and sets the D value of the 100K digital potentiometer U3 through formulas (2) and (4), so that the 100K digital potentiometer U3 outputs a resistance value corresponding to the required current, the adjustable low-voltage-drop voltage stabilizer U7 is selected to output a corresponding current value through the first switch SW1, the second switch SW2, the first selection switch SW4 and the second selection switch SW7, and the calculation formula is as follows:
RSET(D)＝D*100K/1024 (2)
Iout＝RSET(D)*10 (4)
wherein, the value range of D is 103-1024.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A low-current wide-range adjustable pulse constant current source circuit is characterized by comprising a digital signal isolation circuit, a digital potentiometer output circuit, a switch switching circuit and a current source circuit; the digital signal isolation circuit is connected with the digital potentiometer output circuit, and the current source circuit is connected with the digital potentiometer output circuit through the switch switching circuit; the digital signal isolation circuit sends the set current signal value to the digital potentiometer output circuit, the digital potentiometer output circuit and the switch switching circuit are matched with each other to output different resistance values, and the output loop of the current source circuit is selected, so that the constant current source circuit is controlled to continuously adjust the constant current output at 10 uA-1A.
2. A low current wide range adjustable pulse constant current source circuit as claimed in claim 1, wherein said digital signal isolation circuit comprises a four channel digital signal isolator (U1), a two channel digital signal isolator (U2); the digital potentiometer output circuit comprises a 100K digital potentiometer (U3), a 10K digital potentiometer (U4) and a 1K digital potentiometer (U5); the 100K digital potentiometer (U3) is connected with a four-channel digital signal isolator (U1); the 10K digital potentiometer (U4) is respectively connected with a four-channel digital signal isolator (U1) and a two-channel digital signal isolator (U2); the 1K digital potentiometer (U5) is respectively connected with the four-channel digital signal isolator (U1) and the two-channel digital signal isolator (U2).
3. The circuit as claimed in claim 2, wherein the digital potentiometer output circuit further comprises a capacitor C1 and a capacitor C3, wherein one end of the capacitor C1 is connected to pin 7# of the 100K digital potentiometer (U3), and the other end is grounded; one end of the capacitor C3 is connected with the 7# pin of the 10K digital potentiometer (U4), and the other end is grounded.
4. A low current wide range adjustable pulse constant current source circuit as claimed in claim 2, wherein said switch switching circuit comprises a first switch (SW1), a second switch (SW2), a fifth switch (SW5), a sixth switch (SW6), an eighth switch (SW8), a ninth switch (SW 9); a 1# terminal of the first switch (SW1) is connected to a 4# pin of the 100K digital potentiometer (U3), a 1# terminal of the second switch (SW2) is connected to a 5# pin of the 100K digital potentiometer (U3), a 1# terminal of the fifth switch (SW5) is connected to a 2# pin of the 10K digital potentiometer (U4), a 1# terminal of the sixth switch (SW6) is connected to a 3# pin of the 10K digital potentiometer (U4), a 1# terminal of the eighth switch (SW8) is connected to a 7# pin of the 1K digital potentiometer (U5), and a 1# terminal of the ninth switch (SW9) is connected to a 1# pin of the 1K digital potentiometer (U5); the 2# terminal of the first switch (SW1), the 2# terminal of the fifth switch (SW5) and the 2# terminal of the eighth switch (SW8) are connected together, and the 2# terminal of the second switch (SW2), the 2# terminal of the sixth switch (SW6) and the 2# terminal of the ninth switch (SW9) are connected together.
5. A low current wide range adjustable pulse constant current source circuit as claimed in claim 4, wherein said switch switching circuit further comprises a first selection switch (SW4), a second selection switch (SW 7); the current source circuit comprises a current source chip (U6), an adjustable low dropout regulator (U7) and a resistor R1; the 2# terminal of the first selection switch (SW4) is connected with the 2# terminal of the first switch (SW1), the 2# terminal of the fifth switch (SW5) and the 2# terminal of the eighth switch (SW8), the 1# terminal of the first selection switch (SW4) is connected with the 1# pin of the current source chip (U6), one end of the resistor R1 is connected with the 2# pin of the adjustable low dropout regulator (U7), and the other end of the resistor R1 is connected with the 3# terminal of the first selection switch (SW 4); the 2# terminal of the second selection switch (SW7) is connected with the 2# terminal of the second switch (SW2), the 2# terminal of the sixth switch (SW6) and the 2# terminal of the ninth switch (SW9), the 1# terminal of the second selection switch (SW7) is connected with the 2# pin of the current source chip (U6), and the 3# terminal of the second selection switch (SW7) is connected with the 1# pin of the adjustable low dropout regulator (U7).
6. A low current wide range adjustable pulse constant current source circuit as claimed in claim 5, wherein said current source circuit further comprises analog selection switch (SW3), MOSFET power device (Q1), resistor R2, power device control signal generator; a capacitor C2, a capacitor C4; the 2# terminal of the analog selection switch (SW3) is connected with the 1# pin of the current source chip (U6), the 1# terminal of the analog selection switch (SW3) is connected with the drain electrode of the MOSFET power device (Q1), the 3# terminal of the analog selection switch (SW3) is grounded, and the source electrode of the MOSFET power device (Q1) is grounded; one end of the capacitor C2 is connected to the No. 3 pin of the current source chip (U6), and the other end is grounded; one end of the capacitor C4 is connected to the No. 3 pin of the adjustable low dropout regulator (U7), and the other end is grounded; one end of the resistor R1 is connected with the No. 2 pin of the adjustable low dropout regulator (U7), and the other end of the resistor R1 is connected with the drain electrode of the MOSFET power device (Q1); the resistor R2 is connected in parallel between the grid and the source of the MOSFET power device (Q1), and the power device control signal generator is connected in parallel at two ends of the resistor R2.
7. The low-current wide-range adjustable pulse constant current source circuit as claimed in claim 5, wherein the constant current source circuit is implemented by combining 5 segments at a constant adjustable current output of 10 uA-1A:
1)10uA-0.06mA continuous adjustable current output
The four-channel digital signal isolator (U1) selects the 100K digital potentiometer (U3), and sets the D value of the 100K digital potentiometer (U3) through formulas (1) and (2), so that the 100K digital potentiometer (U3) outputs a resistance value corresponding to the required current, and the current value is output by the current source chip (U6) selected through the first switch (SW1), the second switch (SW2), the first selection switch (SW4) and the second selection switch (SW7), and the calculation formula is as follows:
Iout＝67.7/RSET(D) (1)
RSET(D)＝D*100K/1024 (2)
wherein Iout is the output current value, RSET (D) is the set resistance value, 67.7 is the rated output value of the current source chip (U6), D is a decimal value, and the value range is 1-69 at the moment;
2)0.06mA-1mA continuous adjustable current output
The four-channel digital signal isolator (U1) and the two-channel digital signal isolator (U2) select the 1K digital potentiometer (U5) and set the D value of the 1K digital potentiometer (U5) through formulas (1) and (3), so that the 1K digital potentiometer (U5) outputs a resistance value corresponding to the required current, and the current value is output through the eighth switch (SW8), the ninth switch (SW9), the first selection switch (SW4) and the second selection switch (SW7) selection current source chip (U6), and the calculation formula is as follows:
Iout＝67.7/RSET(D) (1)
RSET(D)＝D*1K/256 (3)
wherein, the value range of D is 17-256;
3)1mA-10mA continuous adjustable current output
The four-channel digital signal isolator (U1) and the two-channel digital signal isolator (U2) select the 1K digital potentiometer (U5) and set the D value of the 1K digital potentiometer (U5) through formulas (3) and (4), so that the 1K digital potentiometer (U5) outputs a resistance value corresponding to a required current, the eighth switch (SW8), the ninth switch (SW9), the first selection switch (SW4) and the second selection switch (SW7) select the adjustable low-voltage-drop voltage stabilizer (U7) to output a corresponding current value, and the calculation formula is as follows:
RSET(D)＝D*1K/256 (3)
Iout＝RSET(D)*10 (4)
wherein 10 is the rated output value of the adjustable low dropout regulator (U7), and the value range of D is 26-256;
4)10mA-100mA continuous adjustable current output
The four-channel digital signal isolator (U1) and the two-channel digital signal isolator (U2) select the 10K digital potentiometer (U4) and set the D value of the 10K digital potentiometer (U4) through formulas (4) and (5), so that the 10K digital potentiometer (U4) outputs a resistance value corresponding to a required current, and the fifth switch (SW5), the sixth switch (SW6), the first selection switch (SW4) and the second selection switch (SW7) select the adjustable low-voltage-drop voltage stabilizer (U7) to output a corresponding current value, wherein the calculation formula is as follows:
Iout＝RSET(D)*10 (4)
RSET(D)＝D*10K/1024 (5)
wherein, the value range of D is 102-1024;
5)100mA-1A continuous adjustable current output
The four-channel digital signal isolator (U1) selects the 100K digital potentiometer (U3) and sets the D value of the 100K digital potentiometer (U3) through formulas (2) and (4), so that the 100K digital potentiometer (U3) outputs a resistance value corresponding to a required current, the first switch (SW1), the second switch (SW2), the first selection switch (SW4) and the second selection switch (SW7) select the adjustable low-voltage-drop voltage stabilizer (U7) to output a corresponding current value, and the calculation formula is as follows:
RSET(D)＝D*100K/1024 (2)
Iout＝RSET(D)*10 (4)
wherein, the value range of D is 103-1024.
8. A low current wide range adjustable pulse constant current source circuit as claimed in claim 2, wherein said four channel digital signal isolator (U1) is type ADUM141E and said two channel digital signal isolator (U2) is type ADUM 1200.
9. The circuit of claim 2, wherein the 100K digital potentiometer (U3) is AD5293, the 10K digital potentiometer (U4) is AD5174, and the 1K digital potentiometer (U5) is AD 8400.
10. The circuit of claim 6, wherein the current source chip (U6) is LM 334; the adjustable low dropout regulator (U7) is LT3080 in model number; the model of the analog selection switch (SW3) is ADG 5419; the model number of the MOSFET power device (Q1) is FQP50N 06.
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| CN202022417751.7U CN212906040U (en) | 2020-10-27 | 2020-10-27 | A Low Current Wide Range Adjustable Pulse Constant Current Source Circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112256080A (en) * | 2020-10-27 | 2021-01-22 | 合肥科威尔电源系统股份有限公司 | A Low Current Wide Range Adjustable Pulse Constant Current Source Circuit |
| CN115826467A (en) * | 2022-12-07 | 2023-03-21 | 深圳市度信科技有限公司 | System and method for repairing conduction resistance of conductive silver adhesive |
-
2020
- 2020-10-27 CN CN202022417751.7U patent/CN212906040U/en not_active Withdrawn - After Issue
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112256080A (en) * | 2020-10-27 | 2021-01-22 | 合肥科威尔电源系统股份有限公司 | A Low Current Wide Range Adjustable Pulse Constant Current Source Circuit |
| WO2022088403A1 (en) * | 2020-10-27 | 2022-05-05 | 合肥科威尔电源系统股份有限公司 | Low-current wide-range adjustable pulse constant current source circuit |
| CN112256080B (en) * | 2020-10-27 | 2025-03-04 | 科威尔技术股份有限公司 | A low current wide range adjustable pulse constant current source circuit |
| CN115826467A (en) * | 2022-12-07 | 2023-03-21 | 深圳市度信科技有限公司 | System and method for repairing conduction resistance of conductive silver adhesive |
| CN115826467B (en) * | 2022-12-07 | 2023-06-23 | 深圳市度信科技有限公司 | System and method for repairing conductive silver adhesive conduction resistance |
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