STMicroelectronics M48T58Y-70PC1

Overview

M48T58Y-70PC1 from STMicroelectronics is a 5.0 V, 64 Kbit (8 Kb × 8) non-volatile TIMEKEEPER® SRAM integrating ultra-low-power static RAM, real-time clock, power-fail control circuitry, and on-board lithium battery + quartz crystal in a single CAPHAT™ DIP package. It provides BCD-coded time/date registers (year, month, day, date, hour, minute, second), frequency test output (FT), automatic write protection during VCC drop, and pin/function compatibility with JEDEC-standard 8 Kb × 8 SRAMs - used in industrial control panels requiring persistent timekeeping and data retention during mains failure.

For engineers reviewing the M48T58Y-70PC1 datasheet, M48T58Y-70PC1 pinout, M48T58Y-70PC1 application, or M48T58Y-70PC1 equivalent, this device serves as a self-contained, battery-backed memory-and-clock solution for legacy embedded systems where socket compatibility with standard SRAMs, deterministic power-fail response, and long-term RTC accuracy without external components are critical selection criteria.

Technical Context

The M48T58Y-70PC1 integrates a 8184 × 8 BiPORT™ SRAM array and a 32.768 kHz quartz oscillator-based RTC chain on a single die, with time registers mapped to upper memory addresses (1FF8h–1FFFh). Clock updates occur once per second via internal control logic that writes current BCD time values into dedicated RAM locations - not hardware counters - enabling standard SRAM read/write access patterns.

Its power management includes dual-threshold voltage sensing: VPFD (power-fail deselect) window of 4.2 V ≤ VPFD ≤ 4.5 V ensures write protection before switchover, while VSO (battery switchover) triggers automatic battery activation below ~4.2 V. The integrated CAPHAT™ DIP package houses the IC, crystal, and 48 mAh lithium button cell in one hermetically sealed 28-pin plastic DIP (PCDIP28) unit.

Key Specifications

Pinout & Package

Package: PCDIP28 (28-pin plastic DIP, 600 mil width) with integrated CAPHAT™ housing containing quartz crystal and lithium button cell.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar non-volatile timekeeping SRAM applications.

Compared with DS12887A-150+, M48T58Y-70PC1 offers tighter 70 ns timing and true integration (no external crystal/battery), while versus M48T35Y-70PC1 it delivers double SRAM capacity without changing board layout or power architecture - making it optimal for mid-complexity industrial timekeeping upgrades.

Availability

M48T58Y-70PC1 is available at Aetrix Electronics and suitable for industrial HMI panels, energy metering systems, and legacy PLC backplanes requiring stable component supply, long-lifecycle support, and guaranteed availability of CAPHAT™-integrated TIMEKEEPER® solutions.

Supply support for M48T58Y-70PC1 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 analog, microcontroller, power, and memory products for industrial, automotive, and consumer markets.

M48T58Y-70PC1 belongs to ST's TIMEKEEPER® family - engineered specifically to merge non-volatile SRAM and real-time clock functionality into single-package, socket-compatible solutions for legacy system modernization and long-lifecycle industrial applications.

FAQ

What is the function of the FT pin on M48T58Y-70PC1?

The FT (Frequency Test) pin is an open-drain output delivering a 32.768 kHz square wave directly from the internal crystal oscillator. It enables real-time verification of oscillator health and calibration without requiring external test equipment - critical for field-deployed systems where periodic RTC validation is mandated by safety or regulatory standards.

How does the M48T58Y-70PC1 handle century rollover in year 2100?

It implements century bit (CB) control via the Century Enable Bit (CEB) in register 1FF8h. When CEB = 1, CB toggles automatically at each century boundary (e.g., 2000→2100); when CEB = 0, CB remains static. This behavior is documented in ST application note AN923 and ensures compliant BCD year representation across 2000/2100 transitions.

Can the M48T58Y-70PC1 be used without the internal battery?

No - the CAPHAT™ DIP package integrates the lithium battery as a permanent, non-removable element. Operation without battery is not supported: the device relies on it for data retention during VCC loss and continuous RTC operation. Removing or disabling the battery voids data retention guarantees and may cause undefined behavior during power transitions.

What is the significance of the VPFD voltage range being 4.2 V to 4.5 V?

This narrow VPFD window ensures deterministic write protection activation just before VCC drops to levels where SRAM data integrity becomes unreliable. Unlike wider thresholds, this 300 mV band prevents premature lockout during transient noise while guaranteeing protection before the 4.2 V switchover point - essential for preserving clock and memory state during marginal power conditions.