STMicroelectronics M40SZ100WMQ6F

Overview

M40SZ100WMQ6F from STMicroelectronics is a 3 V non-volatile RAM (NVRAM) supervisor IC that converts standard low-power SRAMs into battery-backed NVRAMs. It provides precision power monitoring (VPFD = 2.55–2.70 V), automatic write-protection during VCC undervoltage, <15 ns chip enable propagation delay, and open-drain RST/BL outputs - used in industrial data loggers to retain critical sensor history during mains failure.

For engineers reviewing the M40SZ100WMQ6F datasheet, M40SZ100WMQ6F pinout, M40SZ100WMQ6F application, or M40SZ100WMQ6F equivalent, this page delivers verified technical context, real-world timing behavior (tWPT = 40–200 μs, tCER = 40–120 ms), battery-low monitoring at ~2.5 V, and SO16 package integration guidance for LPSRAM-based backup memory systems.

Technical Context

The M40SZ100WMQ6F integrates four independent comparators: one for VPFD-based power-fail detection (2.55–2.70 V), one for VSO switchover (2.5 V), one for PFI threshold (1.225–1.275 V), and one for BL monitoring (~2.5 V). Its ECON output follows E input during normal operation but forces inactive within tWPT ≤ 200 μs when VCC falls below VPFD(min).

During power failure, it disconnects VCC from VOUT and switches to VBAT at VSO = 2.5 V, supplying up to 100 μA in battery backup mode (VOHB = 2.5–3.5 V). The RST output remains low for tREC = 40–200 ms after VCC exceeds VPFD(max), ensuring microprocessor stabilization before release.

Key Specifications

Pinout & Package

Package: SO16 - 16-lead plastic small outline (ECOPACK®, RoHS-compliant, body size 9.9 × 3.9 mm, pitch 1.27 mm).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NVRAM supervisor applications.

Compared with MAX6900AESA+ and DS1230Y-100+, the M40SZ100WMQ6F uniquely combines 3 V operation, programmable VPFD/PFI thresholds, dual reset control (RST/RSTIN), and periodic BL self-test - making it the only option supporting predictive battery maintenance and early power-fail warning in compact LPSRAM-based recorders.

Availability

M40SZ100WMQ6F is available at Aetrix Electronics and suitable for industrial data loggers, medical device memory backup, smart meter firmware storage, and avionics black box recorders requiring stable component supply across extended product lifecycles.

Supply support for M40SZ100WMQ6F 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, designing and manufacturing analog, microcontroller, power, and memory solutions for industrial, automotive, and consumer markets.

The M40SZ100W belongs to ST's NVRAM supervisor product line - engineered specifically to convert off-the-shelf LPSRAMs into cost-effective, long-life non-volatile memory subsystems for mission-critical data retention.

FAQ

What is the minimum VCC voltage required to maintain ECON active and prevent unintended SRAM write-protection?

ECON remains active only while VCC stays above VPFD(min) = 2.55 V. Below this threshold, ECON is forced inactive within tWPT ≤ 200 μs to protect SRAM contents. The device guarantees write-protection activation before VCC reaches 2.50 V, and VSO switchover occurs at 2.5 V to sustain VOUT from VBAT.

How does the BL pin behave during battery replacement, and what pull-up is recommended?

The BL pin is an open-drain output that asserts low when VBAT < ~2.5 V and remains low until battery replacement is completed and a subsequent power-up or 24-hour self-test confirms healthy voltage. A 10 kΩ pull-up resistor to VCC is recommended to ensure rise time < 1 μs and noise immunity in noisy industrial environments.

Can the M40SZ100WMQ6F supervise multiple SRAMs simultaneously?

Yes - the datasheet explicitly states it can control one SRAM directly, or two SRAMs if placed in parallel (sharing E, VOUT, and ground). Each SRAM must have chip-enable-driven input disable architecture; fast SRAMs without this feature are incompatible due to uncontrolled address/data bus activity during backup.

Is external hysteresis required on the PFI pin, and what happens to PFO during battery backup?

No external hysteresis is needed: PFI has built-in 20–70 mV hysteresis for noise immunity. During battery backup (VCC < VPFD(min)), the PFI comparator disables and PFO remains low regardless of PFI voltage - eliminating false alarms. Upon power return, PFO is held high for tREC before resuming comparison.