STMicroelectronics M40Z300WMQ6E

Overview

M40Z300WMQ6E from STMicroelectronics is a 3.0 V to 3.6 V non-volatile SRAM supervisor IC that converts standard low-power SRAMs into NVRAMs via automatic power-fail detection, battery switchover, and write-protection control. It supports up to eight SRAMs using dual-device parallel decoding, features open-drain RST and BL outputs, and delivers ≤12 ns chip enable propagation delay (at 5.0 V reference). It is used in industrial data loggers requiring persistent memory during brownout events.

For engineers reviewing the M40Z300WMQ6E datasheet, M40Z300WMQ6E pinout, M40Z300WMQ6E application, or M40Z300WMQ6E equivalent, this page provides verified technical context, real-world timing behavior, battery-backed retention architecture, and validated alternative options for legacy system maintenance and BOM continuity planning.

Technical Context

The M40Z300WMQ6E implements precision voltage monitoring with two selectable power-fail thresholds (VPFD = 2.5–2.7 V at THS = VOUT; 2.8–3.0 V at THS = VSS), enabling deterministic SRAM write-protection before data corruption occurs. Its internal analog comparator triggers switchover from VCC to lithium battery (via B+ and B− terminals) at VSO ≈ 2.4 V, sustaining VOUT at VOHB ≥ 2.0 V under IOUT2 load.

It integrates a 2-input A/B decoder driving four conditioned chip enable outputs (E1CON–E4CON) with address-decode timing tEDH/tEDL < 15 ns, and includes open-drain RST (tREC = 120 ms) and BL (battery low < 2.5 V) outputs with factory-programmed 24-hour self-test intervals. All outputs remain functional down to VCC = VSS.

Key Specifications

Pinout & Package

Package: 16-lead SOIC (SO16, MQ suffix), body width 150 mils; designed for direct connection to external user-supplied lithium battery via dedicated B+ and B− pins (pins 9 and 8 respectively for M40Z300W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with M40Z300WMQ6E, MAX6900 offers lower component count but sacrifices VPFD flexibility and battery health monitoring, while DS1230Y provides integration at the cost of voltage inflexibility and non-replaceable power - making M40Z300WMQ6E uniquely suited for maintainable, multi-voltage industrial NVRAM upgrades.

Availability

M40Z300WMQ6E is available at Aetrix Electronics and suitable for industrial data loggers, medical device memory backup, programmable logic controllers, and smart meter firmware storage requiring stable component supply across extended product lifecycles.

Supply support for M40Z300WMQ6E 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, specializing in automotive, industrial, and power management ICs with strong emphasis on reliability and longevity.

M40Z300WMQ6E belongs to ST's legacy NVRAM supervisor product line, engineered specifically for industrial and medical systems requiring guaranteed data retention during unpredictable power interruptions.

FAQ

What is the function of the THS pin on M40Z300WMQ6E?

The THS (Threshold Select) pin configures both the operating VCC range and the power-fail detection threshold VPFD. When tied to VSS, it selects VPFD = 2.8–3.0 V and VCC = 3.0–3.6 V; when tied to VOUT, it selects VPFD = 2.5–2.7 V and VCC = 2.7–3.3 V. This dual-role design enables precise matching to system-level brownout margins without external components.

Can M40Z300WMQ6E support more than four SRAMs?

Yes - two M40Z300WMQ6E devices can be operated in parallel using shared A/B decoder inputs and independent E1CON–E4CON outputs, enabling control of up to eight SRAMs. Each device drives four SRAMs, and the parallel configuration maintains synchronized write-protection across all eight during power failure.

Why must B− be isolated from VSS on M40Z300W?

For M40Z300W, B− is internally routed exclusively to the battery monitoring circuit and must not be shorted to VSS to avoid leakage paths that compromise battery voltage measurement accuracy and cause false BL assertions. The datasheet explicitly prohibits connecting B− to pin 8 (VSS), requiring separate PCB routing to the battery cathode.

How does the BL pin indicate battery health?

The BL pin is an open-drain output that pulls low when the battery voltage falls below ~2.5 V, detected during power-up or during factory-programmed 24-hour intervals. It remains asserted until battery replacement and subsequent verification, providing actionable feedback for preventive maintenance without requiring external monitoring circuitry.