Design and realisation of integrated circuit tester
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INTEGRATED CIRCUIT TESTER pdf
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2XVrXfr' To calculate the value for C1 and C2 , we have: C1 = C2 = Normalizing, we chose, C1 = C2 = 1000pF, 35V From the datasheet of the regulators, we see that C3 = 0,33^F, C5 = C7 = 0,1 pF (ceramic) C4 = 0,22^F, C6 = 1pF (electrolytic) Regulating After the filtering, the signal needs to be regulated to fit the various sections to be supplied. The filtration is accompanied by three levels of regulation; firstly by the 7812 which yields an output of 12V. This is used to power the relay. The 12V produced by the 7812 is then fed into another IC regulator 7805. This IC regulator produces an output voltage of 5V which can be used to power LCD and the microcontroller unit. Characteristics for KA7805E For 0°C Vout = +5V, l0 = 500mA at Tj = 25°C Characteristics for KA7812E For 0° C Vout = +12V,l0 = 500mA at Tj = 25°C Characteristics for KA7912E For 0°C Vout = -12V,l0 = 500mA at Tj = 25°C Figure 2. 3: Regulated power supply 2.2.2. The Control Unit This comprises of the microcontroller used, external oscillator including the reset button. > Microcontroller The microcontroller used in this project is the PIC18F4520.This microcontroller offers the following advantages which are, 1,000,000 erase/write cycle Data EEPROM memory typical Flash/Data EEPROM Retention: 100 years typical Self- programmable under software control 100,000 erase/write cycle Enhanced Flash program memory typical Operating Frequency Of 40Mhz 40-pin PDIF RA5№N4/SS/HLVDIMC2OUT RE0/RD/AN5 RE1/WR/AN6 RB7/KB13/PGD RB6/KBJ2/PGC RB57KBI1/PGM RB4/KBI0/AN1t RB3/AN9/CCP2W RB2/IHT2/ANA RB1/IW1/AN10 RBO/!NTO/FLTQ/AN12 Vdd MCLR/VPP/RE3 RAOZAND RA1/AM RA2/AN2MiEF-/CVfceF RA3/AN3A/REF + RM/TDCKt/CtCilJT Figure 2. 4: Pin description of PIC18F4520 The choice characteristics of PIC18F4520 include: 40 pins 5 Ports( A,B,C,D,E) that can be configures as either input or output Program memory(bytes) of 32768 Program memory(instructions) of 16384 Data memory of 1536 bytes Data EEPROM MEMORY PF 256BYTES 13 Input Channels Of Analog-To Digital Module The external oscillator: this is made up of the quartz and two ceramic capacitors of 15pF each. Nl N1 fe- N2 N3 N4 L3 2 3 4 5 6 7 14 13 ui RA0/AN0/C1IN- RA1/AN1/C2IN- RA2/AN2/C2IN+/VREF-/CVRE F RA3/AN3/C1IN+/VRFF+ RA4/T0CKI/C1OUT RA5/AN4/SS/HLVDIN/C2OUT RA6/OSC2/CLKO RA7/OSC1/CLKI RC0/T1OSO/T13CKI RC1/T1OSI/CCP2B RC2/CCP1/P1A RC3/SCK/SCL RC4/SDI/SDA RC5/SDO RC6/TX/CK RC7/RX/DT 15 16 17 18 23 24 25 26 ■> LI > L2 > G1 > G2 Cl C2 C3 C4 D4 < D5 < D6 < D7 < RS < EN 33 34 35 36 37 38 RB0/AN12/FLT0/INT0 RB1/AN10/INT1 RB2/AN8/INT2 RB3/AN9/CCP2A RB4/KBI0/AN11 RB5/KBI1 /PGM RD0/PSP0 RD1/PSP1 RD2/PSP2 RD3/PSP3 RD4/PSP4 RD5/PSP5/P1B 19 20 21 22 27 28 / F Figure 2. 5: The control block Pin 1 is MCLR - Master Clear Reset.is is useful when the user wishes to reinitialize the device to its default states with all registers and ports cleared. The minimum protective resistance is R4min = 25x 1000 = 200R We will chose 220П from E24series, The power is given by: PR4min = 220 x (0.025)2 = 0,1375W Hence we have R4min = 220Q;1/4 The LCD display Unit. Figure 2. 6: Picture of the LCD lcdi This module is made up of two basic components which are: LCD display and a variable resistor. LCD is used in this project to visualize all the event occurring in the system. For example: the display of component reference, the initialization process, etc. A variable resistor is used to calibrate the brightness of LCD. Since we need to test three main types of ICs, we need a display that is able to display all of the options. Hence a 4X20 LCD is best suitable for this purpose. The LCD chosen to be used is the LM020L, and the characteristics are as follows.
Table 2. 1: Characteristics of LCD The keypad block The keypad is used to input the references of the ICs to be tested. The 4x3 keypad is used. Figure 2. 7: Picture of 4X3 Keypad A keypad is a set of push buttons arranged in a block or “pad” which bear digits, symbols or alphabetical letters. A 3X4 keypad provides a useful human interface component for microcontroller projects. This is the configuration we have used in our project. This configuration is such that we have 12 push buttons and each column is directly connected to a pull down resistor. These pull down resistors ensure that a wire is pulled to a low logical level in the absence of an input signal and it can also protect the push buttons against short circuit when it is pressed. To have a pull down resistor value, we applied the formula: r Output voltage of the microcontroller output current of the microcontroller When a key is pressed, the output voltage +5V is measured across the resistor and a current of about 25mA. => R 5 25* 10-3 = 200П We fixed the calculated value to 220Q found in the market. Sockets: It is the part which contains different sockets based on the ICs to be tested. Different ICs have different number of pins, and so do their corresponding sockets. Based on our study, we shall have 4 sockets: two to test logic gates, one to test NE555, one to test OPAMS. Figure 2. 8: 8 and 14 pins socket THE OPAM Op-amp basically has Voltage Comparator inside, which has two inputs, one is inverting input and second is non-inverting input. When voltage at non-inverting input (+) is higher than the voltage at inverting input (-), then the output of comparator is high. And if the voltage of inverting input (-) is Higher than non-inverting end (+), then output is LOW. Op-amps have large gain and usually used as Voltage Amplifier. Some Op-amps have more than one comparator inside (op-amp LM358 has two, LM324 has four) and some have just one comparator like LM741. IC LM741 is advanced and commonly used Op-amp as voltage amplifier. Pin diagram of LM741 is given below: Figure 2. 9: Opams IC testing circuit The circuit is supplied with +12V and -12V. R15 and R16 are used to limit the inputs, so that the non-inverting input is greater than the inverting. This together with the push button is used when testing the Opam without a microcontroller. The switch connected to the microcontroller is always open, unless the IC is to be tested without a microcontroller. The diode is used to prevent the back flow of signals from the output of the lm741 and that of ne555. R9 = Normalizing we have R9= (1KQ, 1W) R10 = ID 10mA Normalizing we have R10= (1KQ, 1W) THE NE555 Here the NE555 is connected as a monostable. In the stable state, Since pin7 and pin6 are connected to the ground, the capacitor C3 cannot charge, the internal transistor is saturated, thus the output voltage at pin3 is approximately 0V. in the unstable state, a negative trigger though PC817 is applied to pin2, and the output changes to approximately Vcc. Figure 2. 10: NE555 Timer Testing Circuit The delay time is given by tD = RTCTln3 = 1.1RTCT tD = RTCTln3 = 1.1 x 1KQ. x 100pF = 0.11s LOGIC ICs The NOT IC has a different sockets form the other 2-input logic ICs. This is due to the fact the NOT IC has a different pin configuration from the other logic ICs, seeing that it has just one input and one output per gate. Due to the limited number of pins of the microcontroller, just four gates in the NOT IC is tested. (a) (b) Figure 2. 11: (a) XOR IC testing socket (b) NOT IC testing socket The ICs to be tested The particularity of this IC tester is that it can only test a range of circuits mentioned in part one of this work. These are: logic gates (CMOS AND TTL, 40xx and 74xx respectively, and having 4-gates with 2-inputs per gate), NE555, OPAMS. A. Study of logic ICs This IC tester can test both the TTL ICs of the 74XX series and the CMOS ICs of the 40XX series having 4-gates with 2-inputs per gate; NE555 timer and the LM741. Below are the pin description, truth tables of these ICs Download 0.86 Mb. Do'stlaringiz bilan baham: 
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