Texas Instruments LMC555CMM

Overview

LMC555CMM from Texas Instruments is a CMOS precision timer IC operating as a monostable or astable multivibrator, delivering 3 MHz maximum frequency, <1 mW typical power dissipation at 5 V, 1.5 V minimum supply voltage, and TTL/CMOS-compatible output-used in battery-powered pulse width modulators and low-voltage timing circuits.

For engineers reviewing the LMC555CMM datasheet, LMC555CMM pinout, LMC555CMM application, or LMC555CMM equivalent, key selection considerations include its DSBGA-8 package footprint (1.75 mm × 1.75 mm), sub-100 pA trigger/threshold input currents, ±1500 V HBM ESD rating, and compatibility with legacy 555-based designs requiring extended temperature range (–40°C to +85°C) and reduced supply current spikes.

Technical Context

The LMC555CMM implements a dual-comparator, SR latch, and open-drain discharge transistor architecture optimized for precise RC timing. Its internal voltage divider sets fixed 1/3 and 2/3 V+ thresholds, enabling accurate monostable delay (t_H = 1.1·R·C) and astable oscillation (f = 1.44/(R_A + 2R_B)·C).

TI's LMCMOS process enables operation down to 1.5 V while maintaining 75 ppm/°C timing stability and <0.3 %/V supply sensitivity. The device supports both edge-triggered monostable mode and free-running astable mode without external components beyond R and C networks.

Key Specifications

Pinout & Package

LMC555CMM is housed in an 8-bump DSBGA package (1.75 mm × 1.75 mm, 0.5 mm pitch), optimized for space-constrained portable electronics. The package uses bottom-side solder bumps and requires PCB pad layout per TI's YPB mechanical drawing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NE555P and TLC555CDR, the LMC555CMM uniquely combines DSBGA-8 packaging, 3 MHz capability, 1.5 V operation, and <10 pA input currents-making it optimal for miniaturized, ultra-low-power timing where board space and battery life are critical constraints.

Availability

LMC555CMM is available at Aetrix Electronics and suitable for portable medical devices, battery-powered IoT sensors, and wearable electronics requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LMC555CMM 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 designing analog, embedded processing, and connectivity technologies for industrial, automotive, and consumer applications.

The LMC555 belongs to TI's precision timer product line, engineered specifically to replace legacy bipolar 555 timers with CMOS efficiency while preserving functional equivalence and pin compatibility across SOIC, VSSOP, PDIP, and DSBGA packages.

FAQ

What is the minimum supply voltage for reliable operation of the LMC555CMM?

The LMC555CMM is specified to operate down to 1.5 V, with tested performance including timing accuracy, output drive, and input threshold levels fully characterized at this voltage. At 1.5 V, supply current remains below 200 µA typical, and trigger voltage is guaranteed between 0.4 V and 0.6 V-enabling direct integration with single-cell alkaline or LiFePO₄ batteries without regulation. This specification is confirmed in Section 5.3 of the SNAS558N datasheet.

Does the LMC555CMM require external components to function as a basic timer?

Yes, the LMC555CMM requires external passive components to define timing behavior: at minimum, one resistor and one capacitor for monostable operation, or two resistors and one capacitor for astable mode. Unlike integrated oscillator ICs, it relies on external RC networks for precision delay or frequency generation. The LMC555CMM itself contains no internal timing elements-its core function is comparator-based threshold detection and latch control, as detailed in Figure 7-1 and Section 7.4 of the datasheet.

Can the LMC555CMM replace a standard NE555 in an existing SOIC-8 PCB layout?

No-the LMC555CMM uses an 8-bump DSBGA package (YPB), not SOIC-8. For SOIC-8 compatibility, the correct part is LMC555CDR or LMC555CMX. The "CMM" suffix explicitly denotes the DSBGA variant (per TI's packaging nomenclature in Section 11). Attempting to mount LMC555CMM on an SOIC footprint will result in misalignment and solder joint failure. Always verify package code: D = SOIC, DGK = VSSOP, P = PDIP, YPB = DSBGA.

How does the CONTROL VOLTAGE pin affect timing accuracy in the LMC555CMM?

The CONTROL VOLTAGE pin (Pin 5) directly adjusts the internal 2/3 V+ and 1/3 V+ comparator reference thresholds. Applying an external voltage here linearly modulates output pulse width (in monostable mode) or pulse position (in astable mode), with timing shift proportional to the applied voltage. To maintain baseline accuracy, this pin must be bypassed with a 0.01 µF capacitor to ground; unfiltered DC or AC signals introduce jitter or drift, as documented in Section 8.2.3 and Figure 8-5 of the datasheet.

What thermal considerations apply to the LMC555CMM in DSBGA packaging?

The LMC555CMM in YPB (DSBGA) package has a junction-to-board thermal resistance (RθJB) of 31.2°C/W and junction-to-ambient (RθJA) of 102.3°C/W, per Section 5.4. Effective thermal management requires a solid copper pour on the PCB bottom layer beneath the package, connected via ≥4 thermal vias to internal ground planes. Unlike SOIC variants, DSBGA relies primarily on conduction through the PCB-not convection-so inadequate board copper will cause junction temperatures to exceed 125°C even at 568 mW max dissipation.