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nte955mc-cmos-timing-circuit

4 min read

Important Note

This entire repo was AI created - including all of the data within. The intent was to A) help me with my personal electronics inventory; and B) see how I could use AI to make that process a bit easier. DO NOT TRUST!

NTE955MC - CMOS Timing Circuit (555 Equivalent)

Details

  • Location: Cabinet-3, Bin 33, Section F
  • Category: Logic ICs
  • Brand: NTE Electronics
  • Part Number: NTE955MC
  • Package: 8-DIP
  • Quantity: 2
  • Status: Available
  • Price Range: $1.00-3.00
  • Datasheet: NTE955MC Datasheet
  • Product URL: https://www.nteinc.com/

Description

The NTE955MC is a CMOS timing circuit IC that is functionally equivalent to the popular NE555/SE555 timer but implemented with CMOS technology. This provides significant advantages including ultra-low power consumption, improved noise immunity, and better temperature stability compared to standard bipolar 555 timers. The IC can operate in both monostable (one-shot) and astable (oscillator) modes, making it versatile for timing, pulse generation, and PWM applications.

Specifications

Electrical Characteristics

  • Supply Voltage (VCC): 3V ~ 15V (some variants up to 18V)
  • Quiescent Current: ~100µA typical (ultra-low power)
  • Output Drive Current: 10-20mA (source/sink capability)
  • Input Impedance: Very high (CMOS inputs)
  • Operating Temperature: Typically -40°C to +85°C
  • Noise Immunity: High due to CMOS design

Physical Characteristics

  • Package: 8-pin DIP (Dual In-line Package)
  • Dimensions: 0.300” (7.62mm) width
  • Pin Pitch: 0.100” (2.54mm)
  • Lead Material: Standard DIP leads

Key Features

  • CMOS implementation of 555 timer functionality
  • Ultra-low power consumption
  • High noise immunity and temperature stability
  • Pin-compatible with standard 555 timers
  • Wide operating voltage range
  • Improved performance over bipolar timers

Pinout Diagram

    NTE955MC 8-Pin DIP
    ┌─────────────┐
GND │1          8│ VCC
TRG │2          7│ DIS
OUT │3          6│ THR
RST │4          5│ CONT
    └─────────────┘

Pin Descriptions

PinNameDescription
1GNDGround connection
2TRGTrigger input (active LOW)
3OUTOutput (HIGH/LOW)
4RSTReset input (active LOW)
5CONTControl voltage input
6THRThreshold input
7DISDischarge transistor output
8VCCPositive supply voltage

Operating Modes

Monostable Mode (One-Shot Timer)

  • Function: Produces single output pulse when triggered
  • Timing: T = 1.1 × R × C
  • Applications: Delay circuits, pulse stretching, debouncing

Astable Mode (Oscillator)

  • Function: Continuous square wave output
  • Frequency: f = 1.44 / ((R1 + 2×R2) × C)
  • Duty Cycle: D = (R1 + R2) / (R1 + 2×R2)
  • Applications: Clock generation, PWM, LED flashers

Applications

Common use cases for the NTE955MC:

  • Low power timing circuits
  • Battery-powered oscillators
  • Pulse width modulation (PWM)
  • Delay and timing generators
  • Clock signal generation
  • LED flashers and blinkers
  • Voltage-controlled oscillators (VCO)
  • Precision timing applications

Circuit Examples

Basic Astable Oscillator

VCC ---- R1 ---- DIS (Pin 7) ---- R2 ---- THR (Pin 6) & TRG (Pin 2)
THR/TRG ---- Timing Capacitor ---- GND
CONT (Pin 5) ---- 0.01µF ---- GND (noise filtering)
RST (Pin 4) ---- VCC (or control switch)
OUT (Pin 3) ---- Load (LED + resistor, etc.)

Monostable Timer

VCC ---- R ---- DIS (Pin 7) & THR (Pin 6)
THR ---- Timing Capacitor ---- GND
TRG (Pin 2) ---- Input trigger signal
RST (Pin 4) ---- VCC
CONT (Pin 5) ---- 0.01µF ---- GND
OUT (Pin 3) ---- Load

PWM Generator

Standard astable configuration with:
CONT (Pin 5) ---- Variable voltage (0.33×VCC to 0.67×VCC)
Control voltage varies duty cycle
Output frequency remains relatively constant

Design Calculations

Monostable Timing

T = 1.1 × R × C
Where:
- T = output pulse width (seconds)
- R = timing resistor (ohms)
- C = timing capacitor (farads)

Astable Frequency

f = 1.44 / ((R1 + 2×R2) × C)
Where:
- f = frequency (Hz)
- R1, R2 = timing resistors (ohms)
- C = timing capacitor (farads)

Duty Cycle

D = (R1 + R2) / (R1 + 2×R2) × 100%
For 50% duty cycle: R1 << R2

Technical Notes

Important considerations for the NTE955MC:

  • Low Power: Ideal for battery-powered applications
  • CMOS Inputs: High impedance, sensitive to static
  • Decoupling: Use 0.1µF capacitor between VCC and GND
  • Control Voltage: Pin 5 can be used for frequency/timing modulation
  • Reset Function: Pin 4 must be HIGH for normal operation
  • Temperature Stability: Better than bipolar 555 timers

Advantages Over Standard 555

The CMOS implementation provides:

  • Ultra-low power consumption (100µA vs 3mA for bipolar)
  • Higher input impedance (better noise immunity)
  • Improved temperature stability
  • Lower supply current variation
  • Better performance at low voltages
  • Reduced power supply noise

Tags

timing-circuit, cmos-timer, 555-equivalent, low-power, nte-electronics cabinet-3 bin-33 status-available

Notes

The NTE955MC is an excellent modern replacement for traditional 555 timers, especially in low-power applications. Having this CMOS timing circuit in your collection provides access to precision timing functionality with minimal power consumption. It’s perfect for battery-powered projects, portable devices, and applications where power efficiency is important. The pin compatibility with standard 555 timers makes it a drop-in replacement for existing circuits while providing superior performance. This IC is ideal for learning timing circuit principles, creating efficient oscillators, and building low-power control systems. The ultra-low quiescent current makes it particularly valuable for always-on timing applications where battery life is critical.

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