STMicroelectronics M40SZ100WMQ6E

Overview

M40SZ100WMQ6E 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 out-of-tolerance, <15 ns ECON propagation delay, and open-drain RST/BL outputs. Used in industrial data loggers to retain configuration during mains failure.

For engineers reviewing the M40SZ100WMQ6E datasheet, M40SZ100WMQ6E pinout, M40SZ100WMQ6E application, or M40SZ100WMQ6E equivalent, this page delivers verified technical context, real-world timing behavior, battery-switchover thresholds (VSO = 2.5 V), data retention current (ICCDR = 50–200 nA), and hardware integration guidance for LPSRAM-based NVRAM systems.

Technical Context

The M40SZ100WMQ6E 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 (1.25 V ±25 mV), and one for BL monitoring (2.5 V). Its internal analog switch disconnects VCC and connects VBAT to VOUT within defined tWPT (40–200 μs) when VCC falls below VPFD(min).

It features dual-mode reset control: RST output asserts low for tREC (40–200 ms) after VCC exceeds VPFD(max), while RSTIN accepts external reset pulses ≥200 ns wide. All open-drain outputs (RST, BL, PFO) require external pull-ups; ECON drives SRAM chip enable with <15 ns propagation delay and supports CMOS-level leakage only in battery mode.

Key Specifications

Pinout & Package

Package: SO16 - 16-lead plastic small outline (3.9 × 9.9 mm, 1.27 mm pitch), RoHS-compliant, lead-free second-level interconnect.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6900 and DS1230Y, the M40SZ100WMQ6E uniquely integrates VCC/VBAT analog switching, sub-200 nA data retention current, and 2.55–2.70 V programmable VPFD-enabling compact, low-power, single-chip NVRAM conversion for modern 3 V industrial SRAMs without external FETs or level shifters.

Availability

M40SZ100WMQ6E is available at Aetrix Electronics and suitable for industrial data loggers, medical device configuration stores, and smart meter firmware caches requiring stable component supply across extended product lifecycles.

Supply support for M40SZ100WMQ6E 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 silicon solutions for automotive, industrial, and consumer markets since 1987.

The M40SZ100WMQ6E belongs to ST's NVRAM supervisor product line, engineered specifically to eliminate external components in SRAM-based non-volatile memory systems for harsh industrial environments where reliability and long-term supply stability are critical.

FAQ

What is the minimum VCC required to initiate battery switchover?

The M40SZ100WMQ6E switches from VCC to VBAT at the fixed switchover voltage VSO = 2.5 V, as specified in Table 7. This threshold is independent of VPFD and triggers automatically when VCC falls to exactly 2.5 V, ensuring predictable backup activation without hysteresis or user configuration.

Can RSTIN be used to force a reset while VCC is below VPFD?

No. RSTIN functionality is disabled when VCC falls below VPFD(min) = 2.55 V. The internal circuitry powering the RSTIN comparator and logic is unpowered in battery-backup mode, so only the RST output remains active (low) and BL may assert if VBAT is low.

How does the device prevent data corruption during VCC transients?

It uses a 0.1 μF ceramic bypass capacitor on VCC (per Figure 8) and recommends a Schottky diode (e.g., 1N5817) from VCC to VSS to clamp negative undershoots below –0.3 V - a hard limit specified in Absolute Maximum Ratings to avoid SRAM corruption in backup mode.

Is PFI required for basic NVRAM operation?

No. PFI is optional: if unused, it must be tied to VSS and PFO left floating. Core NVRAM functions - VPFD monitoring, ECON write-protection, VBAT switchover, and RST generation - operate independently of PFI/PFO, which serve only as supplemental undervoltage warning for upstream supplies.