onsemi MC14490DWG Contact Bounce Eliminator IC: Datasheet, Application Circuit, and Pinout Configuration

Mechanical switches are a fundamental component in countless electronic systems, but they suffer from a common, persistent issue: contact bounce. This phenomenon causes a single button press to generate multiple rapid on/off signals instead of one clean transition, leading to faulty data entry, system errors, and unreliable operation. To solve this problem efficiently, onsemi (formerly ON Semiconductor) offers the MC14490DWG, a dedicated CMOS Contact Bounce Eliminator integrated circuit. This IC provides a robust and straightforward solution for conditioning noisy switch inputs, ensuring a single, clean output pulse for every mechanical actuation.

The MC14490DWG is housed in a 16-pin Wide SOIC (DWG) package, making it suitable for automated PCB assembly. Its operation is centered around an internal oscillator and a set of six shift registers, one for each of its six independent channels. The oscillator's frequency, which determines the bounce suppression time, is set by an external resistor (`R_x`) and capacitor (`C_x`) connected to pins 15 and 16. This allows designers to tailor the debounce period from milliseconds to hundreds of milliseconds to suit specific switch characteristics.

Pinout Configuration and Functionality

Understanding the pinout is crucial for effective implementation. The MC14490DWG features six identical debounce circuits.

Pins 1-6 (A-F): These are the raw, noisy switch inputs. Each input has an internal pull-up resistor, typically requiring just a simple switch connected to ground.

Pins 7, 9, 11, 13, 14, 17 (A'-F'): These are the corresponding clean, debounced outputs. The output logic state changes only after the input has remained stable for the time period set by R_x and C_x.

Pin 8 (Vss): Ground reference.

Pin 16 (Cx): Capacitor connection for the oscillator.

Pin 15 (Rx): Resistor connection for the oscillator.

Pin 10 (NC): No Connection.

Pin 18 (Vdd): Positive supply pin, typically from +3V to +18V, offering broad compatibility with various logic families.

Key Datasheet Specifications

The datasheet provides essential parameters for design:

Supply Voltage Range (Vdd): 3.0V to 18V

Input Voltage Range (Vin): -0.5V to Vdd + 0.5V

Debounce Time (Tdeb): Set by Tdeb ≈ K R_x C_x, where K is a constant derived from the internal design.

Operating Temperature Range: -40°C to +85°C

Package Type: 16-Pin Wide SOIC (DWG)

Typical Application Circuit

A standard application circuit is remarkably simple. For a single switch:

1. Connect one side of the switch to Input A (Pin 1).

2. Connect the other side of the switch to ground (Vss).

3. Connect a capacitor (e.g., 0.1µF) between Pin 16 (Cx) and ground.

4. Connect a resistor (e.g., 1MΩ) between Pin 15 (Rx) and ground. This RC combination sets the debounce time.

5. The clean, debounced signal is available at Output A' (Pin 7) for use by a microcontroller, counter, or other logic circuitry.

The remaining five channels can be used independently for other switches, all sharing the same oscillator.

ICGOODFIND Summary

The onsemi MC14490DWG is a highly effective and versatile solution for mitigating switch contact bounce. Its key advantages include six independent channels integrated into a single package, a wide operating voltage range for compatibility with modern and legacy systems, and a user-programmable debounce period via external RC components. For engineers and designers, this IC simplifies design-in, reduces software overhead for debouncing, and significantly improves system reliability in applications ranging from industrial control panels and automotive interfaces to consumer appliances and instrumentation.

Keywords: Contact Bounce Eliminator, Debounce IC, MC14490DWG, Mechanical Switch Debouncing, onsemi