Texas Instruments NE556DB

Overview

NE556DB from ON Semiconductor is a dual bipolar 555 timer IC in SO-14 package, providing two independent monostable and astable timing circuits with 200 mA sink/source output drive, ±10 ppm/°C temperature stability, and 0.75% initial timing accuracy in monostable mode. It operates from 4.5 V to 16 V and supports precise time delays from microseconds to hours in industrial control relays and pulse generation.

For engineers reviewing the NE556DB datasheet, NE556DB pinout, NE556DB application, or NE556DB equivalent, this page delivers verified electrical parameters, dual-section timing behavior, SO-14 terminal mapping, real-world circuit configurations (e.g., tone burst, sequential timing), and validated alternative parts for legacy design continuity and supply chain resilience.

Technical Context

The NE556DB integrates two independent 555-style timing sections sharing a common VCC and GND, each with dedicated Trigger, Threshold, Control Voltage, Reset, Discharge, and Output pins. Each section features two precision comparators referenced to fixed 1/3 and 2/3 VCC thresholds, an RS flip-flop, and a high-current totem-pole output stage.

Timing operation is resistor–capacitor dependent: monostable mode uses one RA and C per section (t = 1.1·RA·C); astable mode uses RA, RB, and C (f = 1.44 / [(RA + 2RB)·C], duty cycle = (RA + RB) / (RA + 2RB)). Reset functionality allows asynchronous interruption of timing cycles without affecting the other section.

Key Specifications

Pinout & Package

NE556DB is housed in a 14-pin SOIC (Small Outline Integrated Circuit) package per ON Semiconductor Case 751A, with 1.27 mm pitch, 8.55–8.75 mm body length, and surface-mount compatibility.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-timing circuit applications.

Compared with LM556CN and ICM7556IPD, the NE556DB uniquely balances high-current drive (200 mA), TTL compatibility, and industrial-grade temperature stability - making it the only option for legacy relay-control and robust dual-timing applications requiring direct load interfacing.

Availability

NE556DB is available at Aetrix Electronics and suitable for industrial time-delay relays, tone burst generators, dual-phase clock distribution, sequential test equipment, and solid-state control systems requiring stable component supply across extended production lifecycles.

Supply support for NE556DB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

ON Semiconductor (now part of onsemi) is a global semiconductor supplier specializing in power management, analog, sensor, and timing solutions for automotive, industrial, and cloud infrastructure markets.

The NE556DB belongs to the legacy MC3456/NE556 dual timer product line, designed specifically for high-reliability, discrete-component-replacement timing functions in industrial controls, test equipment, and electro-mechanical interfaces.

FAQ

What is the maximum operating supply voltage for NE556DB?

The NE556DB supports a maximum supply voltage of +16 V DC, as specified in its Absolute Maximum Ratings table. Operation above this level risks permanent damage to internal comparators and output transistors. For reliable long-term use, maintain VCC ≤ 15 V, especially under elevated temperature conditions where power dissipation increases. The NE556DB datasheet confirms this limit applies uniformly across both timer sections and all operating modes.

Can NE556DB drive a 12 V relay coil directly?

Yes, the NE556DB can drive a typical 12 V relay coil directly: its output sinks or sources up to 200 mA at VCC = 15 V, exceeding the 15–50 mA hold current of most industrial relays. When used in monostable mode with a 10 kΩ series resistor, the NE556DB provides sufficient peak current for relay pull-in while limiting steady-state dissipation. Always verify coil resistance and ensure GND and VCC paths are adequately decoupled to prevent false triggering.

Does NE556DB support independent reset for each timer section?

Yes, the NE556DB provides fully independent Reset inputs: Pin 4 (Reset A) controls Timer A, and Pin 12 (Reset B) controls Timer B. Each accepts a logic-low signal (0.4–1.0 V) to immediately discharge its associated timing capacitor and force its output low - without affecting the other timer's state or timing cycle. This enables asynchronous fault recovery in dual-channel safety systems, as confirmed in the General Operation section and Figure 2 schematic.

What is the timing accuracy of NE556DB in astable mode?

In astable mode, the NE556DB exhibits ±2.25% initial timing accuracy (typical), with ±150 ppm/°C temperature drift and ±0.3%/V supply voltage sensitivity, per Electrical Characteristics Table. These values assume RA and RB between 2.0 kΩ and 100 kΩ and C = 0.01 μF. Accuracy improves with tighter-tolerance external resistors and NP0/C0G capacitors; matching RA and RB between sections reduces inter-channel timing skew to within ±1.0%.

Is NE556DB pin-compatible with the original NE556?

Yes, the NE556DB is a direct pin-compatible replacement for the through-hole NE556 in SO-14 package. Its pinout matches the industry-standard dual 555 layout (Pins 1–7 for Timer A, Pins 8–14 for Timer B), and all electrical specifications - including trigger thresholds, output drive, and timing equations - are identical. ON Semiconductor explicitly states "Direct Replacement for NE556/SE556 Timers" in the datasheet header, confirming full functional and mechanical interchangeability.