JPH03163613A - Generating method for constant-current pulse - Google Patents

Abstract

PURPOSE:To obtain the pulsative constant-current by a high frequency by allowing a constant current to flow a constant-current source, in all of a period for allowing a constant-current to flow to a load, an opening period and a switching period. CONSTITUTION:A constant-current power source 1 is constituted of resistances 6, 7 and 10, a Zener diode 8, an operational amplifier 9, and a transistor TR 11. When a plus power source and a minus power source are connected to a terminal 4 and a terminal 5, respectively, a constant-current flows to a load 22 through a transistor TR 11. In the switching circuit 2, when switches 18, 19 are turned on to an A side in advance, TRs 12 - 15 are all allowed to conduct and no current flows to the load 22. Also, a clock circuit 3 inputs a signal of a prescribed frequency and a prescribed duty ratio from a terminal 23, and generates a signal required for a switching circuit 2. Subsequently, the circuit 2 switches a connecting state of the current source 1 and the load 2 by a signal from the circuit 2. When a constant-current is allowed to flow to the constant- current source 1 is all of these three periods, a pulsative constant-current can be supplied to the load 22.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of flowing a constant current in a pulsed manner in a constant current source. [Summary of the Invention] The present invention provides the following features: when passing current in pulses from a constant current power source,
A constant current source is characterized by a constant current flowing at all times, and a pulsed current with a desired duty ratio flowing only through the load. C. Prior Art] Generally, a constant current source is constructed using an operational amplifier and a Zener diode. A basic circuit example is shown in Figure 2, and its operation will be explained below. A voltage source is connected to the input terminals 4l and 42, and a load is connected to the output terminals 50 and 51. A constant voltage created by a Zener diode 43, a resistor 44, and a capacitor 45 is applied to one input of the beam amplifier 46, and a resistor 47 is applied to the other input.
The voltage drop is given. This voltage drop is applied to the operational amplifier 4 so that it becomes the same voltage as the Zener diode voltage.
6 and transistor 48. the result,
The load is controlled so that a constant current flows through it. In order to output current in pulses from such a constant current source, it was common practice to turn on a switch in the current supply circuit to the load, as shown in the figure, and thereby intermittent the current. Additionally, electronic switches such as transistors were commonly used as the switch. [Problem to be solved by the invention] When outputting a pulsed constant current using a conventional circuit,
There are methods such as using a human-powered power source or connecting a switch in series with the load circuit to open and close it. The latter method is common for circuit protection and power supply safety.

However, constant current sources usually have a slow response ability to prevent fluctuations in the output current from external noise or fluctuations in the power supply.
In other words, if you increase the switching speed of the switch,
Its frequency response ability is controlled by the response ability of the amplifier, and the limit for -1 is about several tens of KHz. That is, as shown in FIG. 3A, (a) shows the operating state of the switch 49, and (b) shows the current supplied from the terminals 50 and 51. As the switching frequency of the switch is increased, The constant current waterfall output will no longer be able to follow. By the way, in recent years, DC constant current drive, pulse constant current drive, and AC constant current drive devices have become necessary as IC test equipment, and these require high frequency capabilities of about 1 MHz, making it difficult to use conventional constant current sources. Now I can no longer take the test. The present invention solves the above-mentioned problems, and its purpose is to enable pulsed constant current at high frequencies, and furthermore, to enable pulsed constant current with a current value of several hundred mA. The purpose of this is to easily generate a constant current. [Means for Solving the Problem] In a circuit that supplies a constant current pulse to a load, the constant current source is not used during all of the periods in which the constant current is supplied to the load, the period in which the load is released, and the switching period between the two periods. It is characterized by a constant flow of current.

[Function 1] According to the method of the present invention, during the period when the pulse current is not flowing through the load, both ends of the load are short-circuited by the switching circuit, and a constant current continues to flow at all times. . Therefore, the constant current source can generate a stable constant current, and the frequency response of the switching circuit allows the pulse current to be generated at a high frequency. C
Example 3 An example of the present invention will be described with reference to FIG. In the figure, 1 is a constant current source, 2 is a switching circuit, and 3 is a clock circuit. The constant current source is the same as the conventional example, and includes resistors 6, 7, 10, Zener die 8, operational amplifier 9, 1, and transistor 1.
If a positive power source is connected to terminal 4 and a negative power source is connected to terminal 5, a constant current will flow through the output of transistor 11. The switching circuit 2 is composed of transistors 12, 13, 14, 15, an inverter i6, a switch 7, and changeover switches 18, 19, and switches the connection state between the constant current source 1 and the load 22 by a signal from a clock circuit. The clock circuit includes inverters 25, 28, 29 . NAN
Consists of D circuits 26, 27, NOR circuits 30, 31,
By manually inputting a signal with a predetermined frequency and duty ratio from the terminal 23, the signal necessary for the above-mentioned switching circuit is created.

Next, we will discuss the operation of the circuit. Terminal 24 is used to start operation, and should be given a low level to keep the circuit in operation. When a reference clock as shown in FIG. 3B (C) is inputted from the terminal 23, the NOR circuit 30 receives (d). N
A waveform as shown in (e) is obtained in the OR circuit 3I. Here, at the rising and falling points of the clock, there are high-level intervals t+j3 and t3 between both signals, and this period is shown enlarged in the figure. The switching circuit 2 is controlled by these signals, but first we will discuss the case where the switches 18 and 19 are turned on the A side. 6 During period t in FIG. 3B, the transistor 1 is turned on.
2.13, 14, and l5 are all in a conductive state, but the constant current flows through the paths of switch tS-transistor l4 and transistor 15-switch l9, and is not supplied to load 22. During period t2, transistors 14 and 15
is in a conductive state, a constant current flows through the paths from switch l8 to transistor 14 and from transistor 15 to switch l9. t. The period is the same as tl. During the t4 period, the transistors 12 and 13 are in a conductive state, so a constant current is supplied to the load 22. The above is one cycle of operation, and the same process is repeated thereafter. Therefore, the current flowing through the load 22 becomes a pulsed constant current as shown in (f). The output current from the constant current source l remains constant as shown in (g).Next, we will discuss the case in which switches l8 and l9 are turned to the B side in Fig. 1. During the tI period, transistors l2, l3, and 14.15 become conductive, but a constant current flows through the paths from switch 18 to transistor l4 and from transistor l5 to switch 19, and is not supplied to load 22. During period t2, transistors 14 and 15 are conductive, so a constant current flows through the path of transistor l5 -> switch l9 -> load 22 -> switch 18 -> transistor 14. The ts period is similar to the t1 period++t
Since the transistors 12 and 13 are in a conductive state during the fourth period, a constant current flows through the path from the transistor 12 to the load 22-4 to the transistor 13. Therefore, the current flowing through the load 22 becomes a constant current in the form of an alternating pulse, as shown in (h).
The current from the constant current source 1 is constant as shown in (i). The above is one cycle of operation, and the same process is repeated thereafter. As described above, it can be seen that the frequency response of the constant current pulse supplied to the load is not affected by the response of the original constant current source, but is determined by the response speed of the elements of the switching circuit.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to supply a pulsed constant current to a load, and furthermore, it has become possible to supply a positive/negative alternating pulsed constant current to the load.

Furthermore, since the output frequency capability of the constant current pulse is determined by the switching element, the original constant current source has the advantage that it can be easily created without any special configuration. Furthermore, since the constant current source can be designed separately from the switching circuit for pulsing, it is easy to ensure stable operation of the circuit. Furthermore, when creating a switching circuit, there is an advantage that it can be designed without regard to interference with a constant current source, synchronization, etc.

Conventionally, it was only possible to output pulses equivalent to F[10 KHz, but by using the method of the present invention, it has become possible to output constant current pulses equivalent to several MHz.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a constant current pulse drive using the method of the present invention. Figure 2 is a circuit diagram of a general constant current source. Figure 3A is a timing diagram when a pulse current is output from a conventional constant current source. FIG. 3B is a timing diagram of constant current output according to the method of the present invention. Figure 2

Claims (1)

[Claims] In a circuit that supplies a constant current pulse to a load, a constant current flows through the constant current source during all of the periods in which the constant current is supplied to the load, the period in which the load is released, and the switching period between the two periods. How to generate constant current pulses.