STMicroelectronics M48T35AV-10PC1

Overview

M48T35AV-10PC1 from STMicroelectronics is a monolithic 3.3 V, 256 Kbit (32 K × 8) non-volatile TIMEKEEPER® SRAM integrating ultra-low-power static RAM, real-time clock, power-fail control circuitry, and on-board lithium battery and crystal in a CAPHAT™ DIP-28 package. It provides BCD-coded timekeeping (year/month/day/hour/minute/second), battery low flag (BOK), frequency test output, and automatic WRITE protection during V_CC brownout - used in industrial control panels, medical instrumentation, and embedded systems requiring persistent time-stamped data logging.

For engineers reviewing the M48T35AV-10PC1 datasheet, M48T35AV-10PC1 pinout, M48T35AV-10PC1 application, or M48T35AV-10PC1 equivalent, this page delivers verified technical context, JEDEC-compatible SRAM timing, battery-backed clock register mapping, and validated alternatives for legacy system replacement and long-life design continuity.

Technical Context

The M48T35AV-10PC1 integrates a 32,768 Hz quartz oscillator with ±35 ppm initial accuracy (±1.53 min/month at 25°C), calibrated to ±1/–2 ppm via internal trim bits. Its BiPORT™ architecture maps clock registers (7FF8h–7FFFh) into upper SRAM address space, enabling byte-wide clock access using standard SRAM read/write cycles.

Power management includes VPFD (2.7–3.0 V) power-fail detection, automatic chip deselect and WRITE disable below VPFD(min), and seamless switchover to internal lithium battery at V_SO, sustaining data retention and RTC operation for ≥7 years without external power.

Key Specifications

Pinout & Package

Package: PCDIP28 (600 mil plastic DIP) with integrated CAPHAT™ housing containing lithium button cell and 32.768 kHz quartz crystal.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS1687-10+, M48T35AV-10PC1 offers tighter 100 ns timing, integrated CAPHAT™, and 3.3 V native operation; versus M48T35Y-10PC1, it eliminates secondary assembly steps but sacrifices field-replaceability - critical for 15+ year maintenance cycles.

Availability

M48T35AV-10PC1 is available at Aetrix Electronics and suitable for industrial control panels, medical diagnostic loggers, and energy meter firmware logging requiring stable component supply over extended product lifecycles.

Supply support for M48T35AV-10PC1 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 solutions for industrial, automotive, and embedded markets.

The TIMEKEEPER® product line delivers integrated RTC+memory ICs optimized for long-term reliability in mission-critical applications where data persistence and time accuracy must survive decades of intermittent power and temperature cycling.

FAQ

What is the function of the BOK (Battery OK) flag?

The BOK flag is a hardware status bit set automatically when V_CC rises post-power-loss and internal battery voltage falls below ~2.5 V. It blocks the first WRITE attempt after power-up until cleared by that WRITE, preventing corrupted time register updates due to insufficient battery charge. The flag resides in the control register (7FF8h, bit D5) and is read-only until cleared.

How does the M48T35AV-10PC1 handle leap years and century rollover?

It performs automatic month-length correction for 28-, 29- (leap year), 30-, and 31-day months. Century rollover is managed via the CENTURY ENABLE (CEB) and CENTURY BIT (CB) in register 7FF8h: when CEB=1, CB toggles at year 2000/2100 boundaries based on initial value, supporting accurate date tracking through year 2100 per AN923 guidance.

Can the internal crystal be replaced or recalibrated in-circuit?

No - the CAPHAT™ DIP-28 package integrates a factory-calibrated 32.768 kHz crystal sealed with the silicon and battery; it is not user-replaceable. However, internal calibration bits (bits D0–D3 in 7FF8h) allow software adjustment of oscillator frequency to achieve +1/–2 ppm accuracy at 25°C, as documented in Section 3.4 and Figure 10 of the datasheet.

Is the M48T35AV-10PC1 RoHS compliant and lead-free?

Yes - per Doc ID 6845 Rev 9, Section 8, the device is RoHS compliant with lead-free second-level interconnects. The CAPHAT™ DIP-28 package uses matte tin plating on leads and meets EU Directive 2011/65/EU requirements, including exemption 7a for lead in piezoelectric devices (crystal element).