Texas Instruments SE555DG4

Overview

SE555DG4 from Texas Instruments is a precision bipolar 555 timer IC designed for military- and aerospace-grade timing applications requiring operation from –55°C to +125°C. It delivers monostable or astable timing from microseconds to hours, supports adjustable duty cycle via dual-resistor control, features TTL-compatible output capable of sinking or sourcing up to 200 mA, and operates across 4.5 V to 18 V supply range. It is used in ruggedized pulse-shaping, missing-pulse detection, and industrial control systems where extended temperature stability is critical.

For engineers reviewing the SE555DG4 datasheet, SE555DG4 pinout, SE555DG4 application, or SE555DG4 equivalent, this page provides verified electrical characteristics, thermal metrics, functional mode behavior, real-world timing accuracy data (±30 ppm/°C tempco, ±0.05%/V supply sensitivity), and validated alternative options for high-reliability analog timing design.

Technical Context

The SE555DG4 implements a bipolar transistor-based architecture with two comparators, an SR latch, and a push-pull output stage driving both OUT and DISCH terminals. Its internal resistor divider sets nominal trigger (≈⅓ VCC) and threshold (≈⅔ VCC) reference levels, which are modifiable via the CONT pin-enabling external voltage control of timing thresholds.

Timing intervals are determined by external RC networks: monostable mode uses one resistor and capacitor; astable mode uses two resistors and one capacitor to independently adjust frequency and duty cycle. The RESET input provides active-low asynchronous override of all timing states, while DISCH offers open-collector discharge path for capacitor reset.

Key Specifications

Pinout & Package

SE555DG4 is packaged in an 8-pin SOIC (D package) with gull-wing leads, 1.27 mm pitch, and JEDEC MS-012AC compliant outline. Thermal resistance R_θJA = 125.4°C/W enables operation at full rating with minimal heatsinking in standard PCB layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar precision timing applications.

Compared with NE555P and TLC555CP, SE555DG4 uniquely combines military-grade temperature range, bipolar output drive strength, and low parametric drift-making it the only option for high-reliability analog timing in harsh physical environments.

Availability

SE555DG4 is available at Aetrix Electronics and suitable for industrial controls, aerospace subsystems, and oilfield instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SE555DG4 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies with over 50 years of precision timer innovation.

The SE555 product line was engineered specifically for high-reliability analog timing in defense, space, and industrial systems where extended temperature operation, parameter stability, and long-term supply assurance are mandatory.

FAQ

What is the maximum supply voltage for SE555DG4?

The absolute maximum supply voltage for SE555DG4 is 18 V, with recommended operation from 4.5 V to 18 V. Exceeding 18 V risks permanent damage per Absolute Maximum Ratings. At 15 V, the device delivers full 200 mA output drive and maintains specified timing accuracy across its –55°C to +125°C range. SE555DG4's higher 18 V limit versus NE555 (16 V) supports legacy 15 V industrial rails with margin.

Does SE555DG4 support astable and monostable modes?

Yes, SE555DG4 fully supports both astable (free-running oscillator) and monostable (one-shot) configurations. In monostable mode, timing is set by one resistor and capacitor; in astable mode, frequency and duty cycle are independently controlled using two resistors and one capacitor. The internal comparator thresholds (≈⅓ VCC and ≈⅔ VCC) and RESET/CONT pins enable robust implementation of either mode in SE555DG4-based designs.

How does the CONT pin affect SE555DG4 timing behavior?

The CONT pin on SE555DG4 provides direct access to the internal voltage divider node, allowing external modification of the trigger and threshold reference levels. Applying a voltage to CONT changes both thresholds proportionally-enabling voltage-controlled oscillation, pulse-width modulation, and improved noise immunity when bypassed with a capacitor. This function is fully retained in SE555DG4 and operates across its full –55°C to +125°C temperature range.

What is the output current capability of SE555DG4?

SE555DG4 provides ±200 mA output drive capability on the OUT pin, with low-level output voltage ≤0.2 V at 100 mA (VCC = 15 V, TA = 25°C) and ≤0.8 V at 100 mA under full temperature range. This high-current capability allows SE555DG4 to directly drive relays, LEDs, and logic families without external transistors-reducing bill-of-materials count in ruggedized timing applications.

Is SE555DG4 pin-compatible with other 555 timers?

Yes, SE555DG4 in the SOIC-8 (D) package is pin-compatible with NE555P, NA555D, and SA555D. All share identical pin numbering, functions, and electrical interface for GND, TRIG, OUT, RESET, CONT, THRES, DISCH, and VCC. This allows drop-in replacement in existing designs-provided the extended temperature range and tighter parametric specs of SE555DG4 are leveraged for enhanced system reliability.