ICL7135 Intersil Device Information

ICL7135 Intersil Device Information

The Intersil ICL7135 precision A/D converter, with its multiplexed BCD output and digit drivers, combines dual-slope conversion reliability with ±1 in 20,000 count accuracy and is ideally suited for the visual display DVM/DPM market. The 2.0000V full scale capability, auto-zero, and auto-polarity are combined with true ratiometric operation, almost ideal differential linearity and true differential input. All necessary active devices are contained on a single CMOS lC, with the exception of display drivers, reference, and a clock.

  • Accuracy Guaranteed to ±1 Count Over Entire ±20000 Counts (2.0000V Full Scale)
  • Guaranteed Zero Reading for 0V Input
  • 1pA Typical Input Leakage Current
  • True Differential Input
  • True Polarity at Zero Count for Precise Null Detection
  • Single Reference Voltage Required
  • Overrange and Underrange Signals Available for Auto-Range Capability
  • All Outputs TTL Compatible
  • Blinking Outputs Gives Visual Indication of Overrange
  • Six Auxiliary Inputs/Outputs are Available for Interfacing to UARTs, Microprocessors, or Other Circuitry
  • Multiplexed BCD Outputs

Electronics Product Design Ideas

Electronics Product Design

When you wish to Begin to learn Electronics, first a short study of Physics is essential, secondly some Electronics theory. In the third stage build simple and small gadgets to learn Practical Electronics. Lastly to make your own product designs, a fundamental knowledge of Analog and Digital Electronics is the foundation for your next steps into Engineering a Design.

Applications and Components

The basic building blocks for most circuits are Chips or ICs. You can acquire considerable knowledge by studying Application notes of National Semiconductor and Texas Instruments to start with. When you want to build Embedded Microprocessor projects, you can study the documents at Atmel and Microchip to begin. The Specifications and Behavior of Passive Components like inductors, capacitors and Resistors; Discrete Semiconductors; Power Devices and RF Components have to be understood well, in order to design sturdy industrial grade products.

Advanced Engineering

The Technology related to the equipment used for Testing, Troubleshooting and Calibration is called Test & Measurement, Here we use Test Instruments like Oscilloscopes and Digital Multimeters. Medical Electronics and Military Designs require more meticulous, robust and dedicated designs with higher reliability and accuracy. In Medical electronics product safety is vital, Consumer products should be affordable without compromising Human Safety factors. Then you need to look into Usability or Ergonomics, which is a science that helps us develop practical and cost-effective products, which have an optimum Man-Machine Interface. EMI, ESD, RFI are other important aspects that deals with Electromagnetic, Electrostatic and RF; Noise and Interference; in the Stable performance of products in Real World Harsh Environments or the Reliable Transmission of data.

gEDA Project – Open Source EDA

The gEDA project is working on producing a full GPL’d suite of Electronic Design Automation tools. These tools are used for electrical circuit design, schematic capture, simulation, prototyping, and production.

gEDA – Electronic Design Automation

Currently, the gEDA project offers a mature suite of free software applications for electronics design, including schematic capture, attribute management, bill of materials (BOM) generation, netlisting into over 20 netlist formats, analog and digital simulation, and printed circuit board (PCB) layout.

gEDA Project’s Homepage

gEDA - Electronic Design Automation

gschem is the schematic capture program/tool which is part of gEDA. Its sole purpose is to facilitate the graphical input of components/circuits.

PCB is an interactive printed circuit board editor. PCB offers high end features such as an autorouter and trace optimizer which can tremendously reduce layout time. For custom requirements,

Icarus Verilog is a Verilog simulation and synthesis tool. It operates as a compiler, compiling source code written in Verilog (IEEE-1364) into some target format. For batch simulation, the compiler can generate an intermediate form called vvp assembly.

GTKWave is a fully featured GTK+ based waveform viewer. GTKWave is designed to handle many signals at once, it has three signal searching modes (Regular Expressions, Hierarchy, and Tree) as well as the ability to display data in many different formats.


PWM Control Circuit – TL494

PWM Control Circuit – TL494

  • Complete PWM Power-Control Circuitry
  • Uncommitted Outputs for 200-mA Sink or Source Current
  • Output Control Selects Single-Ended or Push-Pull Operation
  • Internal Circuitry Prohibits Double Pulse at Either Output
  • Variable Dead Time Provides Control Over Total Range
  • Internal Regulator Provides a Stable 5-V Reference Supply With 5% Tolerance
  • Circuit Architecture Allows Easy Synchronization

The TL494 incorporates all the functions required in the construction of a pulse-width-modulation (PWM) control circuit on a single chip. Designed primarily for power-supply control, this device offers the flexibility to tailor the power-supply control circuitry to a specific application.

The TL494 contains two error amplifiers, an on-chip adjustable oscillator, a dead-time control (DTC) comparator, a pulse-steering control flip-flop, a 5-V, 5%-precision regulator, and output-control circuits.

View Application Notes for PWM Power Supply Controllers

TL494 Related Links

Simple WorkBench Dual Power Supply

I will just explain part of this circuit. D9 and D10 provide a low cost -1.4 from -5 V. This is needed to reach near 0.00 for LM317 Min. setting. An LED also can be used with proper bias. Note that there is a Temperature Coefficient in ppm, see The Unusual Diode FAQ. but it may not matter upto 8 bits accuracy.

TIP2955 PDF, TIP3055 (NPN), TIP2955 (PNP) Complementary Silicon Power Transistors. It is a Darlington, that means good current gain. See Darlington transistor – Wikipedia. When current in R1 10E goes more than 50mA a voltage of 50mA X 10E = 500mV is applied across Emmiter-Base junction. So lower than 500mV no bias the tap is turned off, 500mV-700mV the tap starts turning on depending on type of transistor. The transistor is like a water Tap. So TIP2955 carries the major current burden thru the load allowing LM317 to do the decision making when to turn-on or off. It is analog control, it is not On-Off but linear-proportional. The LM317 is very cool as the burden is passed off to TIP2955 who will need a heatsink to keep going and deliver the power you want.

WorkBench Dual Power Supply

Put the filter caps appropriately. The Hum-Noise will be filtered. The cap after the regulator should be a small guy. The main filter cap after the Bridge can be as big as your cabinet or budget.

If you build it and wire it without designing a PCB, then make all wiring and connection very sound. The test of this ability you can know easily, If your project stops working after the last screw of the cabinet is tightened, Then we need to improve.

Astable Multivibrator with 555

This is a demo of the popular 555 timer. you can try out the project on this page by a javascript simulation.Press the Red button below to turn on the circuit press it again to turn off. The 555 can source (LED2) or Sink (LED1) upto 200mA.

Screenshot of Astable 555 Timer Flasher

Astable Multivibrator with 555

It can even drive a small motor or lamp with diodes added to protect from inductive kickback.Vary Ra, Rb and Ct with the controls given and see the change of frequency, period and duty cycle.

Astable Multivibrator with 555

This is a tutorial with calculator to help learn the application of 555 which is a very rare chip innovation. It is simple, versatile, flexible and programmable (by tweaking of pots).

Astable Multivibrato xml code