Review: Basic ICs commonly used in System Design_

The Basic ICs commonly used in any system design are: 555 Timer IC, Op-amp IC, H-Bridge IC, Regulator IC, 8051, MAX232 etc. A small description about all these is presented here for reader perusal.

555 Timer IC
3 operating modes & uses of Timer IC 555

The 555 is the most popular integrated circuit ever manufactured and is popularly known as Timer IC. The 555 IC is used as flip-flop or an oscillator or timer or simple ADC along with microcontroller chip and contains single timer in one IC package. Derivatives: low-power version 7555 and CMOS TLC555, NE555V [commercial- temperature range, 0 °C to +70 °C & inexpensive epoxy plastic (V package) package], and SE555T [military- temperature range, −55 °C to +125 °C & high-reliability metal can (T package)], and dual version 556 [two complete 555s in a 14 pin DIL package].

3 operating modes	uses of Timer IC 555
Bistable mode or Schmitt trigger (555 operate as flip-flop)	bounce-free latched switches
Monostable mode ("one-shot" pulse generator)	timers, missing pulse detection, bounce-free switches, touch switches, frequency divider, capacitance measurement, pulse-width modulation (PWM)
Astable (free-running) mode (electronic oscillator)	LED and lamp flashers, pulse generation, logic clocks, tone generation, security alarms, pulse position modulation

Op-amp IC

Next to Timer IC, Op-amps or Operational Amplifier are among the most widely used electronic devices today, being used in a vast array of consumer, industrial, and scientific devices. The op-amp is one type of differential amplifier and is constructed in three ways: using discrete components, using IC chip or both. The characteristics of Op-amps are such as gain, feedback, input or output impedance, bandwidth, temperature coefficients specified by external components.

Due to single-ended output, usually and with DC-coupled high-gain differential input

Op-amp produces an output potential (relative to circuit ground) that is typically hundreds of thousands of times larger than the potential difference between its input terminals.

Op-amps applications

¾    filters, ADC or DAC, analog calculators, Voltage clamping

¾    audio- and video-frequency pre-amplifiers and buffers

¾    differential amplifiers, differentiators and integrators

¾    precision rectifiers, precision peak detectors

¾    oscillators and waveform generators

¾    voltage and current regulators

H Bridge

Usually in robotics it is mandatory to make vehicle run forwards or backwards using DC motors. This can be done using discrete components arranging in H shape configuration [usually with relays]. Such an H bridge is an electronic circuit that enables a voltage to be applied across a load in either direction. There are many commercially available inexpensive single and dual H-bridge packages, of which the L293x series includes the most common ones. Few packages, like L9110, have built-in flyback diodes for back EMF protection.

Voltage Regulators

The 78xx is a family of self-contained fixed linear voltage regulator integrated circuits. They are popular because they do not require additional components to provide a constant and regulated source of power to load. They are compact in size, three legs, have built-in protection for over current draw, overheating and short-circuits making them quite robust in most applications.

The 78xx family is commonly used in electronic circuits requiring a regulated power supply due to their ease-of-use and low cost. For ICs within the family, the xx is replaced with two digits, indicating the output voltage (for example, the 7805 has a 5-volt output, while the 7812 produces 12 volts). The 78xx line are positive voltage regulators: they produce a voltage that is positive relative to a common ground. There is a related line of 79xx devices which are complementary negative voltage regulators. 78xx and 79xx ICs can be used in combination to provide positive and negative supply voltages in the same circuit.

The 7805 is the most common, as its regulated 5-volt supply provides a convenient power source for most TTL components. The input voltage must be 2.5 Volts over rated value and provide 1 or 1.5 amperes of current to load.

Serial Port Line Converter

The MAX232 is an integrated circuit first created in 1987 by Maxim Integrated Products that converts signals from a TIA-232 (RS-232) serial port to signals suitable for use in TTL-compatible digital logic circuits. The MAX232 is a dual transmitter / dual receiver that typically is used to convert the RX, TX, CTS, RTS signals.

8051 Microcontroller IC ^[Wikipedia]

The Intel MCS-51 (commonly termed 8051) is an internally Harvard architecture, complex instruction set computing (CISC) instruction set, single chip microcontroller (µC) series developed by Intel in 1980 for use in embedded systems.[1] Intel's original versions were popular in the 1980s and early 1990s and enhanced binary compatible derivatives remain popular today.

Intel's original MCS-51 family was developed using N-type metal-oxide-semiconductor (NMOS) technology like its predecessor Intel MCS-48, but later versions, identified by a letter C in their name (e.g., 80C51) used complementary metal–oxide–semiconductor (CMOS) technology and consume less power than their NMOS predecessors. This made them more suitable for battery-powered devices.

The 8051 architecture provides many functions (central processing unit (CPU), random access memory (RAM), read-only memory (ROM), input/output (I/O), interrupt logic, timer, etc.) in one package:

8051 variants may include built-in reset timers with brown-out detection, on-chip oscillators, self-programmable Flash ROM program memory, built-in external RAM, extra internal program storage, bootloader code in ROM, EEPROM non-volatile data storage, I²C, SPI, and USB host interfaces, CAN or LIN bus, ZigBee or Bluetooth radio modules, PWM generators, analog comparators, A/D and D/A converters, RTCs, extra counters and timers, in-circuit debugging facilities, more interrupt sources, extra power saving modes, more/less parallel ports etc.

The MCS-51 has four distinct types of memory – internal RAM, special function registers, program memory, and external data memory.

The 8051 is designed as a strict Harvard architecture; it can only execute code fetched from program memory, and has no instructions to write to program memory.

Designers use 8051 silicon IP cores, because of the smaller size, and lower power, compared to 32 bit processors like ARM Cortex-M series, MIPS and BA22.

Title: Basic ICs commonly used in System Design

External Links: 555 Timer , Wikipedia,

Keywords: Timer, 555, Op-amp, Operational Amplifier, MAX232, 8051, Microcontroller, Regulator IC, H-Bridge, L293

Note: Click these label/tags to view all related posts. Tags: GeneralReview

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