STMicroelectronics M48T18-150PC1

Overview

M48T18-150PC1 from STMicroelectronics is a 64 Kbit (8 Kb × 8) non-volatile TIMEKEEPER® SRAM integrating ultra-low-power real-time clock, battery-backed memory, power-fail detection, and on-board crystal in a CAPHAT™ DIP package. It delivers ±1 minute/month clock accuracy at 25 °C, supports BCD-coded time/date registers (year, month, day, hour, minute, second), and provides automatic WRITE protection during VCC drop below 4.2 V. It serves as a drop-in replacement for DS1643 in industrial control panels requiring persistent timekeeping and data retention during main power loss.

For engineers reviewing the M48T18-150PC1 datasheet, M48T18-150PC1 pinout, M48T18-150PC1 application, or M48T18-150PC1 equivalent, this page details its BYTEWIDE™ RAM interface timing (tAVQV = 150 ns), VPFD window (4.2–4.5 V), integrated lithium cell + 32.768 kHz crystal, BiPORT™ clock register architecture, and CAPHAT™ DIP mechanical compatibility with legacy 28-pin sockets.

Technical Context

The M48T18-150PC1 integrates a static RAM array and quartz-controlled oscillator on a single die, with clock data mapped to memory-mapped registers (1FF8h–1FFFh) accessible via standard SRAM read/write cycles. Its BiPORT™ architecture allows simultaneous clock register access and SRAM operation without bus contention.

Power management includes dual-threshold voltage sensing: VPFD (4.2–4.5 V) triggers automatic chip deselect and WRITE protection, while VSO switching activates internal battery backup to sustain clock and memory retention. The INT pin provides open-drain power-fail interrupt with 10–40 µs delay before chip disable.

Key Specifications

Pinout & Package

Package: PCDIP28 - 28-pin plastic DIP with integrated CAPHAT™ housing containing lithium button cell and 32.768 kHz crystal. Dimensions: 600 mil width, 0.3 inch body height, 0.1 inch lead pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar non-volatile real-time clock + SRAM applications.

Compared with DS1643-150+, the M48T18-150PC1 reduces component count and improves long-term reliability via integration; compared with M48T35Y-150PC1, it offers lower cost and simpler qualification for commercial-temperature applications without needing expanded memory.

Availability

M48T18-150PC1 is available at Aetrix Electronics and suitable for smart energy meters, industrial PLC HMIs, point-of-sale terminals, and medical diagnostic devices requiring stable component supply across multi-year production cycles.

Supply support for M48T18-150PC1 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power management ICs, sensors, and analog/mixed-signal products for industrial, automotive, and consumer markets.

The TIMEKEEPER® product line targets applications demanding autonomous, battery-backed timekeeping and non-volatile data storage-designed specifically for metering, industrial control, and medical instrumentation where system-level power resilience is critical.

FAQ

What is the battery chemistry and expected service life of the M48T18-150PC1?

The M48T18-150PC1 integrates a lithium manganese dioxide (Li-MnO₂) button cell rated for ≥10 years of data retention at 25 °C under continuous VCC dropout conditions. Battery capacity is 48 mAh, and shelf life exceeds 10 years when stored at ≤30 °C. No user-replaceable battery slot exists-the entire CAPHAT™ DIP is a sealed, factory-assembled unit.

How does the M48T18-150PC1 handle leap years and month-end rollovers?

Hardware logic inside the M48T18-150PC1 automatically adjusts for 28-, 29- (leap year), 30-, and 31-day months through year 2100. This behavior is implemented in silicon-not firmware-so no host processor intervention is required. The RTC updates all calendar registers simultaneously every second, ensuring atomic transitions like February 28 → March 1.

Can the M48T18-150PC1 operate without an external crystal or battery?

No. The M48T18-150PC1 requires its integrated CAPHAT™ housing, which contains both the 32.768 kHz quartz crystal and lithium battery. There is no provision for external crystal connection or battery bypass. Removing or disabling either component voids RTC functionality and invalidates data retention guarantees.

Is the M48T18-150PC1 RoHS compliant and lead-free?

Yes. The M48T150PC1 conforms to RoHS Directive 2011/65/EU and is lead-free at the second-level interconnect (solder joints). The PCDIP28 package uses matte tin finish on leads, and all internal materials-including battery electrolyte and crystal mount-are RoHS-compliant. Full compliance documentation is available upon request.