Texas Instruments LMC555IM/NOPB

Overview

LMC555IM/NOPB from Texas Instruments is a CMOS timer IC providing precision monostable and astable timing functions with 1.5V–15V supply operation, <1 mW typical power dissipation at 5V, 3 MHz maximum astable frequency, and pin-for-pin compatibility with legacy 555 timers in SOIC-8 packaging. It serves as a low-power replacement for time-delay generation, pulse width modulation, and sequential timing in battery-powered and space-constrained systems.

For engineers reviewing the LMC555IM/NOPB datasheet, LMC555IM/NOPB pinout, LMC555IM/NOPB application, or LMC555IM/NOPB equivalent, key selection criteria include its 1.5V minimum operating voltage, sub-100 pA trigger/threshold currents, 75 ppm/°C timing stability, and verified compatibility with TTL/CMOS logic at 5V - all critical for low-voltage, high-accuracy timing designs.

Technical Context

The LMC555IM/NOPB implements a dual-comparator + SR latch architecture with internal resistor divider (1/3 V+, 2/3 V+) to enable precise threshold and trigger detection. Its CMOS input stage delivers ultra-low leakage (<10 pA) at trigger, threshold, and reset pins, enabling long RC time constants without drift.

Timing accuracy is maintained across supply and temperature via supply-independent charge/discharge thresholds and 75 ppm/°C thermal coefficient. Output drive supports ±2 mA at 5V with 0.3–0.6 V_OL, while discharge transistor operates as open-collector with 150–300 mV saturation at 10 mA.

Key Specifications

Pinout & Package

LMC555IM/NOPB uses an 8-pin SOIC (D package), 4.9 mm × 6.0 mm body size, with gull-wing leads and standard JEDEC MS-012AC footprint. Pin 1 is bottom-left corner when notch faces up.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NE555P and TLC555CD, the LMC555IM/NOPB delivers the lowest supply current, widest supply range, highest frequency, and tightest timing stability - making it optimal for next-generation low-power, high-accuracy timing where board space and energy efficiency are constrained.

Availability

LMC555IM/NOPB is available at Aetrix Electronics and suitable for precision timing, pulse generation, and time delay generation requiring stable component supply across industrial, medical, and portable electronics programs.

Supply support for LMC555IM/NOPB 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 emphasis on reliability, longevity, and industrial-grade performance.

The LMC555IM/NOPB belongs to TI's precision timer product line, engineered specifically to replace legacy bipolar 555s with CMOS efficiency while preserving functional and pinout compatibility for seamless migration.

FAQ

What is the minimum operating voltage for the LMC555IM/NOPB?

The LMC555IM/NOPB operates down to 1.5 V, verified per TI's SNAS558N datasheet Section 5.3. This enables direct use with single-cell alkaline, NiMH, or LiFePO₄ batteries without voltage boosting. At 1.5 V, supply current remains only 200 µA typical, and timing accuracy is preserved via supply-independent internal references. The LMC555IM/NOPB maintains full functionality-including trigger detection, output drive, and discharge switching-across this entire 1.5 V to 15 V range.

Is the LMC555IM/NOPB pin-compatible with the classic NE555?

Yes, the LMC555IM/NOPB is explicitly pin-for-pin compatible with the NE555, LM555, and SE555 in SOIC-8 (D) packaging, as confirmed in TI's datasheet Section 7.3.2 and Pin Configuration Figure 4-1. All eight pins-GND, TRIGGER, OUTPUT, RESET, CONTROL VOLTAGE, THRESHOLD, DISCHARGE, and V+-map identically in function and physical location. No PCB layout changes are required when upgrading from NE555 to LMC555IM/NOPB, though decoupling capacitor placement should follow TI's layout guidelines in Section 8.4.

What is the maximum astable frequency achievable with the LMC555IM/NOPB?

The LMC555IM/NOPB achieves a maximum astable frequency of 3 MHz at 5 V supply, as specified in Section 5.6 Switching Characteristics of the SNAS558N datasheet. This value is measured using TI's maximum frequency test circuit with CL = 10 pF. The 3 MHz capability exceeds that of bipolar 555 timers (typically ≤ 100 kHz) and most other CMOS variants (e.g., TLC555 at 2 MHz), enabling high-resolution PWM, ultrasonic drivers, and fast clock synthesis in compact designs.

How does the LMC555IM/NOPB achieve low timing drift over temperature?

The LMC555IM/NOPB achieves 75 ppm/°C timing stability (Section 5.6) through matched CMOS comparator thresholds referenced to an internal resistor divider whose ratio is inherently temperature-stable. Unlike bipolar timers, its threshold and trigger voltages scale precisely with V+, eliminating supply-induced timing variation. Combined with low thermal resistance (R_θJA = 138.9 °C/W for SOIC-8), this ensures minimal drift across –40°C to +125°C - a key advantage of the LMC555IM/NOPB in automotive and industrial environments.

Can the LMC555IM/NOPB drive TTL and CMOS logic directly?

Yes, the LMC555IM/NOPB OUTPUT pin is fully compatible with both TTL and CMOS logic families at 5 V supply, as stated in Section 1 Features and verified in Section 5.5 Electrical Characteristics. At 5 V, it sources 2 mA (V_OH = 4.4 V min) and sinks 8 mA (V_OL = 0.6 V max), meeting standard TTL VOH/VOL and CMOS VIH/VIL thresholds. This eliminates need for external buffer stages when interfacing with microcontrollers, FPGAs, or logic gates - a core design benefit of the LMC555IM/NOPB.