Integrated switches: parameters, application. Reference data

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Integrated switches: parameters, application. Reference data

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Electronically controlled integrated switches are widely used in modern household equipment for switching video and audio signals. The published article tells about their replacement during the repair of foreign equipment and some interesting examples of the use of such switches.

Of the extensive range of integrated circuits manufactured by foreign companies, switches are one of the most versatile types. You can meet integrated switches (IC) in almost any modern model of a TV, VCR, AF amplifier, video camera, tuner, audio tape recorder, as well as in other household equipment. In communications technology, industrial electronics, and other fields, IR is used no less widely.

A small number of ICs have domestic counterparts, but most of them are produced only by foreign firms. Many ICs have very impressive technical characteristics, often do not require the use of any additional attachments and are "unpretentious" in terms of power supply parameters. In this regard, we will consider aspects of the use of IR in various amateur radio designs, as well as the issues of their identification in equipment and the selection of analogues for repairs.

Problems associated with the identification of microcircuits in general and ICs in particular arise very often in repair practice, especially when microcircuits in miniature surface-mount packages have only digital markings. In such cases, even ordering a microcircuit without having its full name is very difficult.

Since the creation of the first integrated circuits by TEXAS INSTRUMENTS (USA) in 1958, so many types of them have been produced that it is often extremely difficult to obtain reliable technical information about them. The attempts to standardize the designations of microcircuits on an international scale have not been particularly successful, although, for example, European manufacturers are trying to adhere to the principles of coding the names of microcircuits by the international organization PRO ELECTRON (ASSOCIATION INTERNATIONAL PRO ELECTRON) [1]. In practice, most models of video and audio equipment sold by us (and not only) are dominated by microcircuits of Asian, mainly Japanese origin. Moreover, we are talking not only about the actual Japanese equipment, but also about many types of products from European and US companies, in which the share of Japanese microcircuits is very significant.

Unfortunately, the author does not know the principles of chip coding adopted in Japan. They are supposedly defined by the Japanese Industrial Electronics Association EIAJ (ELECTRONIC AND MECHANICAL INDUSTRIAL ASSOCIATION OF JAPAN), but they are not consistent with the European system. Therefore, in the future, the names of microcircuits will be given according to the information obtained by the author from the practice of working with specific equipment (by marking) and from circuit diagrams.

It is noteworthy that at present it is difficult to determine the country of manufacture of microcircuits; their production by leading firms has been established far beyond the borders of their countries. As for the IC, the author came across Japanese microcircuits manufactured in Malaysia, Singapore, the Philippines, Taiwan, Korea and other countries. It can be assumed that the number of countries producing Japanese microcircuits is much larger, since only a few have the corresponding marking. The most widely used ICs for consumer video and audio equipment are manufactured by ROHM, TOSHIBA, SANYO, MATSUSHITA, JRC, MITSUBISHI, NEC (Japan), MOTOROLA (USA), SGS - THOMSON (France) and others. many other firms.

There are quite a few completely or partially interchangeable ICs manufactured by different companies and having different markings on the cases. Information on the selection of analogues for the repair of radio equipment in such cases can be very useful. For example, a rarely sold microcircuit marked 4066 in a surface-mount package (full name - MN4066BS from MATSUSHITA) can be replaced with a functional analogue from a number of other microcircuits: BU4066B, BU4066BC (RHOM), mPD4066BC (NEC), TC4066BP (TOSHIBA), HCF4066BE (SGSTHOMSON), MC14066BCP (MOTOROLA), CD4066BE, LC4066B, etc. in a standard package (14 pins), and in many cases, domestic K561KT3, 564KT3, KR1561KT3. Parameters, pinouts, switching circuits of domestic ICs (multiplexers) are easy to find in the literature [2].

In addition to the four-channel analog switch K561KT3, foreign equipment also uses others that have domestic functional analogues in the K176, K561, 564, KR1561 series. It is much more difficult to find complete analogues made in the same cases and having identical electrical characteristics, since the original reference literature on foreign microcircuits is still difficult to find here. However, from the point of view of repair practice, it does not play a big role, for example, the difference in speed or capacitance values between the terminals and even a different type of package. The specific result is important - the restoration of the equipment's working capacity by available (and inexpensive) means.

Listed below are the functional analogues known to the author of domestic IR series K176, K561, 564, KR1561, corresponding to foreign ones: TS4016B, TS4016BP, CD4016BE, CD4016BF - K176KT1; MN4051B, CD4051BF, MC14051BF, HD14051BP, HEF14051BP, SCL4051BE - K561KP2, 564KP2, KR1561KP2; M4052BP, MC14052BCP, TC4052BP, CD4052BE, HCF4052BE - K561KP1, 564KP1, KR1561KP1; MC14512AP, CD4512BE - KR1561KP3; MC14519BF, MC14519BP, CD4519BE - KR1561KP4.

Very widely used in consumer video and audio equipment is a built-in two-channel IR with separate control, which has no domestic analogues, with different markings, depending on the manufacturer: BU4053, TC4053BP, CD4053AE, CD4053BF, HEF4053BP, HD14053BP, MC14053BCP, MC14053BE, 4053BCN, SCL4053 1BE etc. Using it, it is convenient, for example, to organize the connection of two stereo sound video recorders to the UMZCH and a TV (left and right channel inputs and video inputs). The pinout and block diagram of such a switch are shown in fig. 1 (pin designations correspond to those adopted by MITSUBISHI). The keys A, B, C are controlled independently by the inputs SA, SB, SC. Position H of the keys corresponds to level 0 at the control input, position L - level 1. Level 70 voltage at the control inputs must be at least 0% of the supply voltage VDD, and level 30 - no more than 1%. When level XNUMX is applied to the control input E, all switches are open, regardless of the voltage value at the inputs SA, SB, SC. With a single supply, the VEE pin is connected to the VCS common wire.

Integrated switches: parameters, application

The supply voltage VDD of the switch can be in the range of 3 ... 15 V. The public key resistance, speed, input and output capacitances depend on its value. The higher this voltage, the better the parameters of the keys. The resistance of a public key from a value of 500 ohms or more at a supply voltage of 5 V decreases to 100 ohms or less at 15 V. The speed of the keys increases almost in proportion to the supply voltage, depends on the parameters (resistance and capacitance) of the load and is approximately equal to 50 ns at a supply voltage of 15 B (speed is understood as the delay time of turning on / off the key from the moment the control signal is given). The values of input and output capacitances are also minimal at a supply voltage of 15 V and equal to 15...30 pF.

The specific values of the IC parameters are also determined by the versions (they have different letter indices: AE, BE, BF, BP, BCP, BCN, etc.) from different manufacturers.

If it is necessary to switch bipolar signals, the VEE pin is supplied with a supply voltage in the range of 0 ... -12 V. It is only necessary to remember that the maximum voltage between the VDD and VEE pins should not exceed 15 V (total in absolute value). The maximum range of the transmitted signals also depends on the values of the supply voltages, which should not “approach” by more than 0,2 V to the voltages at the VDD and VEE pins.

We will consider the features of the use of IR using the example of a common TV FUNAI-TV-2100AMK10HYPER, a fragment of the circuit diagram of which is shown in fig. 2. This model has a stereo sound mode when working through external inputs located on both the front and rear panels. The 100 kΩ input resistances are determined by resistors R729, R730. The sound signals of the left and right channels through the capacitors C703, C704 are sent to pins 5 and 2 of the IC701 chip. Since a unipolar power supply of the microcircuit with a voltage of +8 V is used, the presence of some constant voltage at the inputs should be indicated as a prerequisite for undistorted transmission of audio signals. In our case, +710 V is applied to the inputs of the microcircuit from the dividers R711R713 and R714R4. Zener diodes D704, D706 for a voltage of 8,2 V are installed to protect the inputs from overvoltage.

(click to enlarge)

In the case of receiving on-air TV broadcasts, an audio signal from the MITSUBISHI M52340S radio channel chip (IC301, there is a voltage of +46 V at its pin 2,6) arrives simultaneously at pins 1 and 3 of the IC701 chip.

The output signals from pins 15 and 4 of the switch pass through the electronic volume control on the IC801 chip (UPC1406HA) to the integrated stereo amplifier AF LA4261.

The nodes of the video signal passage are made a little unusual. From the external video inputs, through the L702C713 anti-noise filter, it enters the emitter follower on the Q701 transistor with a high input resistance. In this case, the range of the PCTV at the input, instead of the standard value of 1 V, turns out to be 1,8 ... repeater on transistors Q2, Q12. As a result, the signal amplitude at the video output when it is loaded at the video input with a resistance of 701 ohms turns out to be equal to the standard value of 14 V. clarity and even color saturation in the PAL system.

In the TV viewing mode (another key position A), the signal from the video detector of the radio channel block (pin 52 of the IC301 chip) through the notch filters CF31, CF32, the divider R722R723 comes to pin 13 of the IC701 chip. Further, the video signal through the emitter follower on the Q703 transistor branches into two directions: to the video output, as described, and through the R732R705 divider to the input of the brightness and color channels of the IC301 chip (pin 36).

All switches of the IC701 switch are simultaneously controlled by applying level 0 or 1 (+8 V) from the inverter on the transistor Q706, which is switched by the microprocessor IC101 (M37220M). At its pin 5, level 1 (+5 V) corresponds to the video input mode, and level 0 corresponds to the TV viewing mode.

Integrated switches (IC) are currently not in short supply, and their prices are quite affordable. Therefore, the difficulties of their application mainly arise only when it is necessary to replace microcircuits in miniature surface-mount packages. They are widely used in camcorders and modern models of VCRs from various companies. For these cases, domestic microcircuits of the 564 series in packages with planar leads are more suitable. The built-in switches TC4053 and others, although they do not have full domestic analogues, can be completely replaced, for example, by two KR590KN4 microcircuits, each of which contains dual keys with independent control.

On IR, you can assemble a variety of amateur radio devices. For example, in [3] their use is described in a linearly varying voltage generator and in a sample-and-hold device for a line-number converter of video recorder auto-adjustment systems.

As another example, consider the use of IR in a device for restoring the DC component of a television signal.

It is known that the video signal contains a constant component, the value of which depends on the content of the image and changes with a frequency of 0...3 Hz. Due to the presence of coupling capacitors in video signal conditioning equipment, it is usually lost. At the right points of the tract, it is artificially restored. One of these points should be called the input of a television modulator that transfers the PDTV to the high frequency region. How the direct component of the television video signal affects the quality of the modulation is sketched in Fig. 3.

Integrated switches: parameters, application

Modulators for low-power television radio signal conditioners are often devices whose resistance to high-frequency currents depends on the voltage value at the control input. A typical modulation response of such a device is shown in fig. 3a. For undistorted transmission of image signals, the modulating voltage should not go beyond the linear section of the characteristic. In this case, the envelope of the radio signal (HF filling is not drawn) will have the form shown in Fig. 3b. According to GOST 18471-83, GOST 21879-76, which determine the parameters of the paths and signals of broadcast television, the image radio signal levels should be as follows:

1) corresponding to sync pulses (maximum carrier level) - 100%;

2) corresponding to the level of extinction - 75 + 2,5%;

3) corresponding to the level of white - 155 + 2%;

4) minimum (residual unmodulated carrier) - 75 + 2%.

These requirements are rather strict, and it is not easy to meet them during long-term operation of the equipment in various external conditions. The acuteness of the problem is evidenced by the experience of many low-budget regional and local television companies, whose signal quality does not always meet the requirements of standards (when there is no money for control and measuring equipment, it is difficult to talk about the quality of broadcasting).

The level of the constant component of the real image signal varies over a fairly wide range. Without a constant component, it will be reproduced on the kinescope screen with distortions in the background brightness and brightness differences between large details (instead of white details there will be gray ones, etc.). To eliminate them, special devices are used to restore the constant component (VPS) or, in other words, level clamps (CLAMPING).

There are two types of EPSs - uncontrolled (using a peak diode detector) and controlled (using a clamp pulse generator). Uncontrolled level clamps have a lower accuracy of restoration of the constant component and, most importantly, low temperature and long-term stability, i.e., with temperature changes and aging, the operating point (in our case, the modulator) moves along the modulation characteristic (Fig. 3, a). When the operating point drifts to the right, the television signal sync pulses fall on the upper non-linear section of the characteristic. As a result, the sync pulses are "flattened" in the radio signal, which leads to a breakdown in the receiver, especially frame synchronization (vertical image twitching). If the operating point drifts to the left, the white level in the signal is in the lower non-linear section of the characteristic, and a "negative" and colored halos around objects appear on the image. In both cases, the level of out-of-band emissions and combination noise also increases sharply.

Managed IPUs do not have these shortcomings, but they are much more complicated. Areas of application of controlled TPSs: multichannel television signal generators, high-precision test signal generators, standard television signal formers operating at large changes in ambient temperature, etc. In general, if it is necessary to obtain a high-quality stable image when docking video equipment, the use of controlled TPSs is very helpful.

The level fixer developed by the author does not contain deficient elements and can be repeated by radio amateurs of average qualification. Its schematic diagram is shown in Fig. 4, and oscillograms at characteristic points - in fig. 5. The basis of the EPS is an integrated switch DA2, controlled by a fixation pulse generator on DA3, DD1 microcircuits.

(click to enlarge)

The PCTV coming to the video input enters through the capacitor C6 to the horizontal synchronizing pulse generator on the DA3 chip, which is a simplified version of the 3USCT TV synchronization submodule. Positive pulses (Fig. 5, oscillator 2) from pin 3 of this microcircuit act on the time delay single vibrator on the DD1.1 trigger, triggered by the edge of each pulse. On the trigger DD1.2, the actual clamping pulse generator is assembled, triggered by the decays of the delay generator pulses (Fig. 5, oscillators 3 and 4). The fixation pulses (Fig. 5, oscillator 4) are located in time on the rear area of the horizontal quenching pulses.

Integrated switches: parameters, application

At the same time, the PCTV through the low-pass filter R2C1L1C2R3, which serves to limit the spectrum of the signal received at the output of the RF modulator, through the emitter follower on the transistor VT1, the memory capacitor C5 and the op-amp DA1 passes to the output of the VPS for further supply to the modulator or other necessary devices. The clamping voltage (Fig. 5, osc. 5) depends on the position of the trimmer R15 slider.

At the moments of the appearance of fixing pulses, the switch on the DA2 chip opens and the storage capacitor C5 is quickly charged to a voltage approximately equal to the voltage on the resistor R15 engine. After the end of the fixing pulse, i.e., during the active part of each row, the constant voltage on the right (according to the scheme) plate of the capacitor C5 remains practically unchanged, since the input resistance of the op-amp DA1 and the output resistance of the private key of the switch DA2 are very large (a few megaohms) . Consequently, the clamping voltage turns out to be independent of the image content of the transmitted signal and highly stable (determined by the parameters of the Zener diode VD2). It can be changed within a fairly wide range with a tuning resistor R15, i.e., to ensure that the modulator can operate only in the linear section of the modulation characteristic.

In the level fixer, oxide capacitors are K50-35, etc., the rest are ceramic of any type, variable resistors are SP4-1a, etc., sealed, constant ones are OMLT-0,125, chokes are DM-0,1. The device must be powered from a highly stable source with low ripple. The printed circuit board of the device is placed in a shielding case and separated from the RF modulator nodes by shielding partitions.

The R10C21R11 circuit is used to eliminate the influence of the output impedance of the public key of the DA2 switch on the level of the chrominance subcarrier transmitted during the rear pads of horizontal quenching pulses when operating in the SECAM system, as well as to limit the spectrum of the radio signal of the modulator. Resistor R7 is included to eliminate the possible self-excitation of the op-amp DA1. The divider R12R13 (it may be absent) is necessary for modulators with a low clamping voltage required (below 2 V). The approximate resistance of the resistor R12 is 1 ... 2 kOhm. Resistor R13 is selected for a specific version of the device on which the latch is loaded. As for the construction of the modulator itself, it is possible to use, for example, a modified version used in the transceiver device of the "Electronics-VM12" video recorder described in [4]. The revision comes down to removing the diode VD3 and closing the capacitor C24 (Fig. 3,b in [4]).

To set up the EPS, you need a universal oscilloscope with external synchronization mode and a television test signal generator. The form of high-frequency radio signals is controlled either by a broadband oscilloscope (С1-75, С1-108), or, using the control TV radio channel unit, tuned to the required frequency, by a universal oscilloscope, which is connected to the TV video detector output.

First of all, the pulse repetition period at pin 3 of the DA3 chip (see Fig. 4) is set to 64 + 0,5 μs. In this case, no entry signal is given. Then, having applied to the input of the PCTV, the duration of the pulses is measured at pins 1 and 13 of the DD1 microcircuit. With deviations from the values shown in fig. 5, select resistors R20 and R21. Further, having connected a control TV or a broadband oscilloscope to the output of the RF modulator, adjust the resistors R15 and R3 so that the ratio of the levels of the modulated radio signal corresponds to the gradations of the brightness signal of the input PCTV (it is more convenient to do this with the "Grayscale" signal, without color signals), focusing on Fig. . 3

No less widely foreign firms use IR with built-in amplifiers. They are characterized by the use of a unipolar power supply, direct control of TTL or CMOS levels and a small number of add-on elements. As an example, microcircuits can be listed: LA7026 (SANYO) - dual audio-video IR, LA7016 (SANYO) - video IR, NJM2234L (JRC) - two-channel audio-IR, BA7604N (ROHM) - two-channel universal, М52065FP (MITSUBISHI ) - built-in two-channel broadband, etc.

Literature

Nefedov A. V., Savchenko A. M., Feoktistov Yu. F. Foreign integrated circuits for industrial electronic equipment. Handbook, ed. Yu. F. Shirokova. - M.: Energoatomizdat, 1989, p. 1-30.
Bogdanovich M. I., Grel I. N., Dubina S. A., Prokhorenko V. A., Shalimo V. V. Digital integrated circuits. - Minsk: Polymya, 1996, pp. 312-318.
Petropavlovsky Yu. VHS format video equipment. Converters of the number of lines 525/625 to ATS of video recorders. - Radio, 1993, No. 7, p. 5-7.
Bondarenko A., Krylov A. Cassette video recorder "Electronics-VM-12. Transceiver device.

Author: Yu.Petropavlovsky, Taganrog

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