JPS63110813A - Driver ic circuit - Google Patents

Abstract

PURPOSE:To obtain a small-sized, low-priced system in which plural IC circuits share a photocoupler for data input and which employs a driver IC circuit by providing the driver IC circuit with a latch circuit and holding input data. CONSTITUTION:The input data from an input terminal 1 is inputted to the terminal D of the latch circuit 7, and a write signal inputted to the terminal T of the circuit 7 from a terminal 3 latches the input data in the circuit 7. If the input data is 'H', a latched output Q in the circuit 7 becomes 'H'. Since the output of a heat blocking and protecting circuit 11 is normally 'H', the output of an AND gate 8 becomes 'H'. The output of a drive circuit 9 with shorting and protecting functions is turned on to drive a load connected to an output terminal 2. If the input data is 'L', the output of the circuit 9 is turned off conversely. Thus the latch circuit is incorporated into the driver IC circuit to eliminate an external latch IC.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a short-circuit protected driver IC circuit used in programmable controllers, NC controllers, and the like.

[Conventional technology]

Control output units of programmable controllers, NC controllers, and the like generally use driver IC circuits with short-circuit protection to prevent damage due to user connection errors, short circuits, and the like.

FIG. 2 shows one of the conventional examples of this driver IC circuit with short circuit protection. In FIG. 2, 1 is a data input terminal, typically 8 or 16 parallel inputs. 2 is the drive output terminal, 5 is the power supply terminal, 6 is the ground terminal, 8 is A
ND gate, 9 is a drive circuit with short circuit protection function,
12 is a circuit for one data, which is a combination of this AND agate and the drive circuit 9. Further, 11 is a heat cutoff protection circuit.

The operation of this conventional circuit will be explained below.

When the data input to the terminal 1 is "H", the output of the thermal shutdown protection circuit 11, which is the other input of the AND gate 8, is "H".
If , the output of the drive circuit 9 having a short-circuit protection function is ONL, and drives the load connected to the output terminal 2. When the data input is “L”, the output of the drive circuit 9 is O.
Do not drive the load in FF state.

If the output terminal 2 is accidentally short-circuited while the output of the drive circuit 9 is in the ON state, the short-circuit protection function of the drive circuit 9 will be activated, and the output transistor of the drive circuit 9 will not be damaged due to excessive current caused by the short circuit. Protect as such. This short-circuit protection function is often a fallback characteristic current limit commonly found in regulator ICs.

During this short circuit, the drive circuit generates heat due to the power consumption determined by the output current and output voltage at the output terminal 2.

In this case, the thermal shutdown protection circuit 11 detects the junction temperature within the IC, and when the temperature exceeds a certain level, sets its output to the "L" state. As a result, the AND gate 9 is closed, the output of the drive circuit 9 is 0FFL, the output current at the output terminal 2 stops flowing, and the rise in junction temperature is stopped. This prevents thermal damage to the drive IC.

Generally, in both the programmable controller and the NC controller, the power for the drive IC is supplied from the outside, so the input of the driver IC is electrically isolated from the inside by a photocoupler.

Both programmable controllers and NC controllers have 24 to 64 or more pieces of data, and typically the data is latched in 8-bit units into eight latch ICs, and the output is input to this driver IC through a photocoupler. Therefore, if the number of data is 64, 64 photocouplers are required. Photocouplers are expensive per bit, each package can accommodate only 2 to 4 bits worth of couplers, and 8 latches are required, making it difficult to use this driver IC. The system has the disadvantage of being expensive and bulky.

[Problem that the invention seeks to solve]

Programmable controllers and NC controllers using conventional driver ICs require a separate launch IC, and the output of the launch IC must be connected to the driver IC with a number of photocouplers equal to the number of data, making the system expensive. It had the disadvantage of being large.

The present invention was made to eliminate the above-mentioned drawbacks, and an object of the present invention is to obtain a driver IC circuit that allows a low-cost and compact system to be obtained by using the circuit according to the present invention.

[Means for solving problems]

The driver IC circuit according to the present invention incorporates a latch circuit.

[Effect]

Since the driver IC circuit of this invention has a built-in latch circuit, data can be latched into the IC circuit without using a separate IC. The number of duplicates can be reduced to approximately the same number as the input data of one driver IC circuit.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a driver IC circuit according to an embodiment of the present invention,
In the figure, 1 is a data input terminal, 2 is a drive output terminal, 3 is a data write input terminal, 4 is a reset input terminal, 5 is a power supply terminal, 6' is a ground terminal, 7 is a latch circuit, and 8
9 is an AND gate, 9 is a drive circuit with short circuit protection, 10 is a latch circuit 7, AND gate 8. This is a circuit for one data consisting of a drive circuit 9. Further, 11 is a heat cutoff protection circuit. Note that the same symbols as in FIG. 3 are the same.

The operation of this embodiment will be explained below.

Data input from the input terminal t-1 is input to the D input of the latch circuit 7, and is latched by the launch circuit 7 by a write signal input from the terminal 3 to the T input of the latch circuit 7. That is, if the input data is "H", the Q output of the latch circuit 7 becomes "H" after latching. Since the output of the thermal shutdown protection circuit 11 is normally 'H', the AND gate 8
The output of a! becomes “H” and short circuit protection a! ! The output of the functional drive circuit 9 is turned ON and drives the load connected to the output terminal 2. Conversely, when the input data is "L", the output of the drive circuit 9 is turned OFF.

The short circuit protection function of the drive circuit 9 and the operation of the heat cutoff protection circuit are the same as in the conventional example.

In this way, in this embodiment, the data latch circuit is built into the driver IC circuit, so there is no need to provide an external latch IC.

In a system using this driver IC, if the number of data is 64 and this IC accommodates eight drive circuits, the system can be configured with eight driver ICs. In this case, if each input of the eight circuits is connected in parallel between eight ICs, eight photocouplers for electrically insulating the system and the external load circuit may be used for data input. In addition, a decoder IC is required to select one of the eight driver ICs and input the write signal, but the photocouplers required for this are three for IC selection and one for the write signal. There is one. Furthermore, one photocoupler is required for reset input, so a total of 13 photocouplers are used.

That is, the number of ICs is reduced by 7 and the number of photocouplers is reduced by 511 compared to the conventional example. As a result, the system
Significantly lower prices and smaller sizes can be achieved.

〔Effect of the invention〕

As described above, according to the present invention, a launch circuit is provided in the driver IC circuit to hold input data, so that an expensive photocoupler for data input can be shared by multiple driver IC circuits. , this driver IC
This has the effect that a system using circuits can be configured in a small size and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a driver IC circuit with short circuit protection according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional driver IC circuit with short circuit protection. In the figure, 1 is a data input terminal, 2 is a drive output terminal, 3 is a data write input terminal, 4 is a reset input terminal, 5 is a power supply terminal, 6 is a ground terminal, 7 is a latch circuit, 8 is an AND gate, and 9 is a A drive circuit with short circuit protection, 10 a circuit for one data, and 11 a heat cutoff protection circuit.

Claims (1)

[Claims] (1) One data portion consisting of a two-input AND gate with one input connected to the data input terminal and a drive circuit with a short-circuit protection function and the output of the AND gate connected to the input and the output to the drive output terminal. The driver IC circuit main body is composed of multiple circuits, and the output is connected to one input of all the AND gates mentioned above.
In a driver IC circuit equipped with a thermal shutdown protection circuit that closes the AND gate when the junction temperature in the C circuit is equal to or higher than a predetermined value, between the data input terminal and the other input of the AND gate,
The same number of latch circuits as the circuits for one data are inserted so that the data input is connected to the data input terminal and the Q output is connected to the other input of the AND gate, and the trigger input of all the latch circuits is connected to the same number of latch circuits as the circuits for one data. A driver IC circuit comprising: a data write terminal; and a reset terminal connected to a reset input of all the latch circuits.