Texas Instruments NE556DRG4

Overview

NE556DRG4 from Texas Instruments is a dual precision timer IC containing two independent NE555-compatible timing circuits in a single 14-pin SOIC package, operating from 4.5 V to 16 V with ±200 mA output drive capability and TTL-compatible outputs. It supports both astable and monostable operation for timing intervals ranging from microseconds to hours, and is widely used in pulse-width modulation, missing-pulse detection, and sequential timing control.

For engineers reviewing the NE556DRG4 datasheet, NE556DRG4 pinout, NE556DRG4 application, or NE556DRG4 equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative parts, and supply-chain support details specific to the NE556DRG4 variant.

Technical Context

The NE556DRG4 integrates two identical, electrically isolated 555-style timers sharing only VCC and GND. Each timer features independent TRIG, THRES, CONT, RESET, DISCH, and OUT pins, enabling fully decoupled timing functions - e.g., one timer as a clock source and the other as a pulse-width modulator. The internal comparators reference 1/3 VCC (trigger) and 2/3 VCC (threshold), adjustable via CONT.

Timing stability relies on external RC networks: monostable mode uses one resistor and capacitor (t_w ≈ 1.1 × R_AC_T); astable mode uses two resistors and one capacitor (f ≈ 1.44 / (R_A + 2R_B)C_T). Supply voltage sensitivity is ≤0.5 %/V and temperature coefficient is ≤150 ppm/°C over 0°C to 70°C - confirmed for the NE556 grade.

Key Specifications

Pinout & Package

NE556DRG4 is housed in a 14-pin SOIC (D) package with 1.27 mm pitch, 8.65 mm × 3.91 mm body size, and exposed pad not present. Pin numbering follows standard SOIC top-view convention (pin 1 at notch end, counterclockwise).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual timer applications.

Compared with NE556N and LM556CN, the NE556DRG4 provides superior thermal performance in SOIC packaging, guaranteed TI manufacturing traceability, and full alignment with the NE556 family's documented timing tolerances - making it the preferred choice for volume SMT production where reliability and consistency are critical.

Availability

NE556DRG4 is available at Aetrix Electronics and suitable for pulse-width modulation, missing-pulse detection, and sequential timing applications requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for NE556DRG4 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 delivering analog, embedded processing, and connectivity solutions with over 90 years of innovation in precision analog design.

The NE556DRG4 belongs to TI's legacy precision timer product line, engineered specifically for robust, low-cost, dual-function timing in commercial-grade instrumentation, industrial controls, and consumer electronics.

FAQ

What is the maximum operating supply voltage for NE556DRG4?

The absolute maximum supply voltage for NE556DRG4 is 18 V, but the recommended operating range is 4.5 V to 16 V per TI SLFS023I Section 5.3. Operation above 16 V risks exceeding safe power dissipation limits in the SOIC package and may degrade long-term reliability. For designs targeting 15 V nominal rails, NE556DRG4 remains fully functional and stable.

Can NE556DRG4 operate in astable mode with duty cycle less than 50%?

Yes, NE556DRG4 supports astable operation with duty cycles below 50% by configuring RA < RB in the standard two-resistor timing network. Equation (5) in Section 6.3.2 confirms duty cycle = RB / (RA + 2RB); setting RA = 1 kΩ and RB = 10 kΩ yields ~48% duty cycle. However, duty cycles below 10% produce inconsistent output due to comparator storage time limitations - verified in Section 7.2.1.

Is the CONT pin required to be bypassed in NE556DRG4 designs?

Yes, TI explicitly recommends decoupling the CONT pin to ground with a capacitor (typically 0.01 µF ceramic) to suppress noise-induced timing jitter - stated in Figure 6-3 Note A and Section 6.3.2. Omitting this capacitor increases susceptibility to EMI and supply ripple, causing measurable drift in threshold/trigger levels and degrading timing accuracy beyond the rated 150 ppm/°C spec.

Does NE556DRG4 support true 5 V logic interfacing without level shifters?

Yes, NE556DRG4 is fully compatible with 5 V TTL and CMOS logic families. Its TRIG and THRES thresholds are ~1.67 V and ~3.33 V at VCC = 5 V (Section 5.5), well within standard TTL input high/low margins. Output VOH exceeds 2.75 V at IOH = –100 mA, ensuring robust high-level drive into 5 V logic inputs - confirmed in Table 5-5.

What is the minimum recommended timing capacitor value for NE556DRG4?

TI does not specify a hard minimum capacitor value, but practical use requires CT ≥ 100 pF to avoid parasitic effects dominating timing accuracy. Section 5.6 specifies switching characteristics with CL = 15 pF, and Figure 7-1 shows CT = 0.1 µF in PWM examples. Capacitors below 100 pF increase sensitivity to stray capacitance and layout-dependent errors - limiting achievable precision in production designs using NE556DRG4.