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TLC555 Pinout and CMOS Timer Circuit Diagrams

cmos timer tlc555 circuit design oscillator components

The TLC555 is a CMOS version of the popular 555 timer integrated circuit (IC). It’s widely used in various timer, delay, pulse generation, and oscillator applications. Its low power consumption and high precision make it particularly well-suited for battery-operated devices.

Features of TLC555 CMOS Timer

Low Power Consumption: Compared to the standard 555 timer, the TLC555 consumes significantly less power, making it ideal for portable applications.
Wide Supply Voltage Range: Operates from 2V to 15V, providing flexibility in design.
High Accuracy: Offers improved timing accuracy with a typical timing error of less than 1%.
Temperature Stability: Better temperature stability due to its CMOS technology, allowing for reliable operation over a wide temperature range.
Versatile Operating Modes: Can be configured in various modes:
- Astable Mode: Generates a continuous square wave output.
- Monostable Mode: Produces a single pulse of a specific duration in response to a trigger input.
Rail-to-Rail Output: The output can swing from the negative supply voltage to the positive supply voltage, enabling better interfacing with various devices.
Built-in Voltage Divider: Internal resistors create a voltage divider, which can be used to set the threshold and trigger levels.

TLC555 Pin Diagram

The TLC555 is available in an 8-pin Dual In-line Package (DIP) or Surface Mount (SOIC) configuration. Below is the pin configuration.

TLC555 pin diagram

The figure above depicts the TLC555 pin diagram. Here’s a breakdown of each pin:

Pin number	Name	Description
1	GND	Ground reference pin
2	TRIG	Trigger input for initiating timing in monostable mode
3	OUT	Output pin that delivers the timer’s output
4	RESET	Active-low reset pin to stop the timer
5	CONT	Control voltage input for modifying timing (optional)
6	THRES	Threshold input for the timing circuit
7	DISCH	Discharge pin to reset the timing capacitor
8	V_DD	Supply voltage pin (2V to 15V)

Working Principle and Application

The TLC555 timer operates based on the charging and discharging of an external capacitor connected to the THRESHOLD and DISCHARGE pins. In astable mode, the capacitor charges through resistors connected to the V_DD and discharges through another resistor, creating a continuous output square wave. In monostable mode, a trigger signal at the TRIG pin initiates a timing cycle, generating a pulse output for a duration determined by the external resistor and capacitor.

The TLC555 can be configured as an astable multivibrator to create a simple LED flasher circuit. The frequency of the output square wave can be calculated as per the following formula:

$f = \frac{1.44}{(R_1 + 2R_2)C_1}$

Other Applications

Monostable Mode: Used for creating time delays, such as turning on a device for a specific duration when a button is pressed.
Frequency Generators: Can be used in tone generators and sound-producing circuits.
Pulse Width Modulation (PWM): Utilized in motor speed control applications.

Conclusion

The TLC555 CMOS timer is a versatile and efficient timer IC, suitable for various timing and control applications in modern electronic designs. Its low power consumption, wide voltage range, and reliable performance make it a valuable component for engineers and hobbyists alike.