STMicroelectronics M48T37Y-70MH1E

Overview

M48T37Y-70MH1E from STMicroelectronics is a 256 Kbit (32 K × 8) battery-backed TIMEKEEPER® SRAM integrating ultra-low-power real-time clock, power-fail control, watchdog timer, and microprocessor reset-operating at 4.5–5.5 V with VPFD = 4.2–4.5 V and crystal accuracy ±20 ppm over –40°C to +85°C. It delivers nonvolatile timekeeping and memory retention for industrial control panels requiring tamper-resistant timestamping, firmware logging, and power-loss resilience.

For engineers reviewing the M48T37Y-70MH1E datasheet, M48T37Y-70MH1E pinout, M48T37Y-70MH1E application, or M48T37Y-70MH1E equivalent, key selection criteria include battery-backed RTC accuracy, write-protection voltage threshold (VPFD), SOH44 package compatibility with SNAPHAT® top, and alarm interrupt behavior in backup mode.

Technical Context

The device integrates a 32,768 Hz quartz oscillator, BiPORT™ dual-port SRAM array, and voltage-sensing circuitry that triggers automatic write protection when VCC drops into the 4.2–4.5 V VPFD window. Its clock registers (7FF1h–7FFFh) store BCD-formatted century, year, month, date, day, hour, minute, and second, updated once per second by dedicated hardware logic-not software polling.

Power management includes seamless switchover to internal lithium battery below VSO (typically 4.25 V), sustaining data and clock operation for ≥7 years at 25°C. The IRQ/FT pin serves dual function: open-drain alarm interrupt or frequency test output for software calibration, while RST provides power-on reset valid even during battery backup.

Key Specifications

Pinout & Package

The M48T37Y-70MH1E is housed in a 44-pin SOIC (SOH44) package with gold-plated sockets for mating to a separate SNAPHAT® top containing the 32.768 kHz crystal and lithium battery. This modular design enables post-reflow assembly to avoid thermal damage to battery/crystal during SMT reflow.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS1307+DS1248, M48T37Y-70MH1E reduces component count and improves brownout resilience via integrated VPFD and oscillator; versus M48T59Y-70MH1E, it trades memory capacity for lower cost and power in space-constrained designs where 32 KB suffices.

Availability

M48T37Y-70MH1E is available at Aetrix Electronics and suitable for industrial control panels, medical infusion pumps, smart energy meters, and telecom base station controllers requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.

Supply support for M48T37Y-70MH1E 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 specializing in automotive, industrial, and power management ICs, with broad portfolio coverage from microcontrollers to analog and mixed-signal devices.

The M48T37Y-70MH1E belongs to ST's TIMEKEEPER® family-designed specifically for embedded systems demanding highly integrated, battery-backed real-time clock and nonvolatile memory in a single monolithic solution.

FAQ

What is the purpose of the SNAPHAT® top, and is it included with M48T37Y-70MH1E?

The SNAPHAT® top (e.g., M4T28-BR12SH) contains the 32.768 kHz crystal and lithium battery, and mounts directly onto the SOH44 package after reflow soldering to prevent thermal damage. It is ordered separately-M48T37Y-70MH1E ships as the bare SOIC; SNAPHAT® is not included in the same reel or tube.

How does the VPFD voltage range affect system-level brownout response?

VPFD (4.2–4.5 V) defines the precise window where the IC automatically disables writes and places outputs in high-Z state. This prevents partial writes during marginal VCC conditions. System designers must ensure power supply decoupling minimizes noise-induced false VPFD triggers, as transients within this window force immediate write protection.

Can the alarm function operate while the main VCC supply is disconnected?

Yes-the alarm remains fully functional in battery backup mode. When VCC falls below VSO (~4.25 V), the internal lithium cell powers the RTC and alarm logic, allowing IRQ/FT to assert on match even with VCC = 0 V. This enables autonomous wake-up or event signaling without host processor involvement.

What is the significance of the "70" in the part number M48T37Y-70MH1E?

The "70" denotes the –70 speed grade: maximum 70 ns access time for both READ and WRITE operations at 4.5–5.5 V and 0–70°C ambient. This guarantees timing compatibility with 14 MHz+ microcontrollers without wait-state insertion, distinguishing it from the slower –100 grade variant.