The test circuit of CD4066 four bidirectional analog switch

CD4066 is a four-way two-way analog switch, mainly used for multiplex transmission of analog or digital signals. There are 4 independent analog switches inside each package of CD4066. Each analog switch has input, output, and control terminals. The input and output terminals are interchangeable.
When the control terminal is high, the switch is turned on; when the control terminal is low, the switch is turned off. When the analog switch is turned on, the on-resistance is tens of ohms; when the analog switch is turned off, it presents a very high impedance, which can be regarded as an open circuit. The analog switch can transmit digital and analog signals, and the upper limit frequency of the analog signal that can be transmitted is 40MHz. The crosstalk between the switches is very small, the typical value is -50dB.
The lead-out arrangement of CD4066 is the same as that of CD4016, but it has a relatively low on-resistance. In addition, the on-resistance is basically unchanged in the entire input signal range. CD4066 is made up of four mutually independent two-way switches, each switch has a control signal, the p and n devices in the switch switch simultaneously under the action of the control signal. This structure eliminates the change in the threshold voltage of the switching transistor with the input signal, so the on-resistance is relatively low in the entire operating signal range. Compared with a single-channel switch, it has the advantages that the peak voltage range of the input signal is equal to the power supply voltage and the conduction impedance is relatively stable within the input signal range. But if it is used in sampling circuits, CD4016 is still recommended.
When the power supply voltage of the analog switch adopts dual power supply, for example =﹢5V, =﹣5V (all 0V to ground), then the input voltage is symmetrical to 0V, and both positive and negative signal voltages (﹢5V～﹣5V) can be transmitted . At this time, the control signal C = "1" is +5V, and C = "0" is -5V, otherwise only positive signal voltages can be transmitted.

CD4066 has two-way on-off function. When the control (strobe) terminal adds a high level, the switch turns on; when the control terminal adds a low level, the switch turns off. The analog switch turns on the elbow, the on resistance is generally about tens of ohms, and the resistance is as high as 100MΩ when it is off. Can be seen as an open road. The ratio of turn-off resistance to on-resistance ROFF/RON" 105. It is an ideal switching device. The analog switch mainly plays the role of turning on or turning off signals in electronic equipment, and can transmit digital and analog signals. Because the CMOS analog switch has a wide operating voltage range (4000 series is generally +3V~+18V), micro power consumption (less than IμW), high speed (transmission signal frequency up to tens of MHz), strong anti-interference ability, no mechanical touch Point, small size, long life and small crosstalk between switches, therefore, it has been widely used in automatic control systems and computers. Its pin function is shown in the figure below.

Under amateur conditions, the test of the CD4066 four-way analog switch is mainly to test the control function of each switch and the two-way conduction function. The test circuit is shown in the figure below.
CD4066 four bidirectional analog switch test circuit
In Figure 2, K1 is the control terminal high and low level selection switch, which is a single-pole double-throw switch, used to change the gate state of the analog switch. When the switch is turned to H to turn on the high level, the control terminals of the four switches are at high level, and each switch should be turned on; when the switch is turned to L to low level, the four switches should be turned off. K2 is a two-way conduction selector switch, which is a double-pole double-throw switch. Toggle switch K2. It can control the direction of the two-way flow of the switching signal, and there are two sets of red and green light-emitting diodes to indicate.
When the switch K2-1 is turned to H high level, then K2-2 turns on L low level. At this time, the Kl switch is turned to the high level state, and the switches are in the forward (reverse) conduction state, so the positive electrode of the power supply is limited by the step-down resistor R and added to the parallel light-emitting diodes LED2, LED4, and LED4, which are connected in the forward direction. On LED6 and LED8, four green light-emitting diodes light up.
When the switch K2-1 is turned to L low level, then K2-2 turns on H high level. For example, the Kl switch is turned to the high level state. Then the switches are in the reverse (forward) conduction state, so the anode of the power supply is added to the parallel connected light-emitting diodes LFD1, LED3, IED5, LED7 anode and the step-down resistor R, so the four red light-emitting diodes light up.
When the Kl switch is turned to L low level, each analog switch is in the cut-off state, regardless of whether the K2 two-way selector switch is turned to H or L state. The two sets of red and green LEDs will not light up.
Therefore, when the qualified analog switching element is tested, the switch K1 is turned on and off. Then one group of LEDs will turn on and off alternately; press the two-way selector switch K2. On-off switch Kl. Then the other group of light-emitting diodes will turn on and off alternately.
In the above test, when the switch K1 is turned on and off, if it is found that some or all of the analog switches cannot control the on and off of the two groups of light-emitting diodes, it can be preliminarily determined that the gating function of some or all of the analog switches is invalid and cannot be used. Turn K1 to the strobe state and press the two-way selector switch K2. If it is found that some or all of the switches cannot select the alternate on-off of the two groups of LEDs, it can be preliminarily determined that the two-way conduction of some or all of the analog switches Function failure. At this time, you can record the state of the K2 switch (forward or reverse) when the one-way switch is on. The switch is still flexible. Because in some circuits (such as unidirectional DC circuits), bidirectional on-off functions are not required.
In order to facilitate the replacement of components during testing, the 14-pin dual in-line socket can be welded to the circuit board. Attached are two diagrams of actual production and testing conditions, as shown in the figure below.