STMicroelectronics M48T35AV-10MH6F

Overview

M48T35AV-10MH6F from STMicroelectronics is a 3.3 V, 256 Kbit (32 K × 8) non-volatile TIMEKEEPER® SRAM integrating ultra-low-power static RAM, real-time clock, power-fail control, and on-board lithium battery + crystal in a CAPHAT™ DIP-28 package. It provides BCD-coded time/date registers (year/month/day/hour/minute/second), battery low flag (BOK), frequency test output, and automatic write protection during V_CC brownout - deployed in industrial control panels requiring persistent timekeeping and data retention during mains failure.

For engineers reviewing the M48T35AV-10MH6F datasheet, M48T35AV-10MH6F pinout, M48T35AV-10MH6F application, or M48T35AV-10MH6F equivalent, this device serves as a JEDEC-standard 32 K × 8 SRAM drop-in replacement with integrated RTC functionality, supporting BYTEWIDE™ memory-mapped clock access at addresses 7FF8h–7FFFh and requiring no external timing components or backup power circuitry.

Technical Context

The M48T35AV-10MH6F integrates a 32,768 Hz quartz oscillator, BiPORT™ dual-port SRAM array, voltage-sense switching circuitry, and lithium cell into a single monolithic die. Its clock chain updates eight BCD time registers once per second, while the SRAM operates with standard asynchronous READ/WRITE timing - all synchronized to a shared V_CC supply and protected by VPFD-triggered write disable.

Power management is hardware-automated: when V_CC drops below V_SO (2.7 V min), the internal battery takes over; below VPFD (≤3.0 V), chip deselect and WRITE protection activate; and the BOK flag asserts if battery voltage falls below ~2.5 V - enabling deterministic low-battery detection without software polling overhead.

Key Specifications

Pinout & Package

Package: 28-pin plastic DIP (PCDIP28), CAPHAT™ format - fully encapsulates silicon die, 32.768 kHz crystal, and 48 mAh lithium button cell in one hermetically sealed unit.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS12887A-100+, the M48T35AV-10MH6F eliminates external components and supports modern 3.3 V systems; versus M48T59Y-70MH6F, it trades memory density for lower cost and reduced power draw in space-constrained applications.

Availability

M48T35AV-10MH6F is available at Aetrix Electronics and suitable for industrial HMI panels, energy metering systems, and programmable logic controllers requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant manufacturing.

Supply support for M48T35AV-10MH6F 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, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The M48T35AV belongs to ST's TIMEKEEPER® family - engineered specifically for applications demanding integrated, maintenance-free real-time clocking and non-volatile memory in a single package, with emphasis on reliability under power interruption.

FAQ

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

The BOK flag is a hardware-generated status indicator that asserts when the internal lithium battery voltage drops below ~2.5 V. It is detected by reading any memory location and verifying whether the data matches its bitwise complement - a failed check signals low battery. The flag blocks the first WRITE attempt after power-up and clears automatically upon successful write, enabling fail-safe initialization without external monitoring circuitry.

Can the M48T35AV-10MH6F operate without the internal battery?

No - the internal 48 mAh lithium battery is permanently sealed within the CAPHAT™ DIP-28 package and powers the RTC and SRAM during V_CC loss. The device cannot retain time or data without it. Battery replacement is not user-serviceable; the entire CAPHAT™ unit must be replaced as a single component if end-of-life is reached.

How is clock calibration performed?

Calibration is achieved by writing values to the CAL[3:0] bits (D3–D0) in the control register at address 7FF8h. These 4-bit trim settings adjust the oscillator's effective load capacitance digitally, improving accuracy from ±35 ppm to +1/–2 ppm at 25°C. Calibration requires no external components and persists across power cycles, stored in non-volatile SRAM.

Is the M48T35AV-10MH6F compatible with standard SRAM interfaces?

Yes - it is pin- and function-compatible with JEDEC-standard 32 K × 8 SRAMs (e.g., 62256). All control signals (E, G, W), address lines (A0–A14), and data lines (DQ0–DQ7) follow standard asynchronous SRAM timing, including t_AVAV = 100 ns. The only behavioral difference is the presence of time registers at 7FF8h–7FFFh, which behave identically to regular memory locations during READ/WRITE.