STMicroelectronics M40Z300WMQ6F

Overview

M40Z300WMQ6F from STMicroelectronics is a 3.0 V to 3.6 V non-volatile SRAM supervisor IC that converts up to eight low-power SRAMs into NVRAMs using integrated power-switching and precision voltage monitoring. It features dual-threshold power-fail detection (VPFD = 2.5 V–2.7 V or 2.8 V–3.0 V), open-drain RST and BL outputs, and four conditioned chip-enable outputs (E1CON–E4CON) with ≤12 ns propagation delay. Used in industrial data loggers requiring battery-backed memory retention during brownouts.

For engineers reviewing the M40Z300WMQ6F datasheet, M40Z300WMQ6F pinout, M40Z300WMQ6F application, or M40Z300WMQ6F equivalent, this page delivers verified technical context, real-world timing behavior, battery-switchover thresholds, decoder truth table mapping, and validated alternatives for legacy NVRAM system redesigns.

Technical Context

The M40Z300WMQ6F implements a two-input A/B decoder to generate four independent conditioned chip-enable signals (E1CON–E4CON), enabling control of up to eight SRAMs when two devices operate in parallel. Its internal comparator monitors VCC against factory-trimmed VPFD thresholds selected via THS pin tied to VSS or VOUT.

During power failure, it forces E1CON–E4CON inactive within tWPT (≤10 µs), disconnects VCC from VOUT at VSO (~2.4 V), and switches to lithium battery supply (B+, B−) to maintain SRAM data retention. The RST output remains low for tREC (120 ms max) after VCC recovers above VPFD to ensure microprocessor stabilization.

Key Specifications

Pinout & Package

Package: 16-lead SOIC (SO16, MQ suffix), body width 150 mils; supports 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 M40Z300WMQ6F, MAX6900 eliminates external SRAM but sacrifices scalability and speed, while DS1230Y lacks 3 V support and precision VPFD tuning-making M40Z300WMQ6F the sole option for new 3.3 V industrial NVRAM designs requiring multi-SRAM coordination and battery health telemetry.

Availability

M40Z300WMQ6F is available at Aetrix Electronics and suitable for industrial data loggers, medical device memory backup, point-of-sale terminals, and smart meter firmware storage requiring stable component supply despite its "not recommended for new design" status.

Supply support for M40Z300WMQ6F 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 microcontrollers, power management ICs, and analog/mixed-signal devices for industrial, automotive, and consumer markets.

M40Z300WMQ6F belongs to ST's legacy NVRAM supervisor product line, engineered specifically to convert standard LP-SRAMs into robust, battery-backed memory subsystems for mission-critical data retention in brownout-prone environments.

FAQ

What is the function of the THS pin on M40Z300WMQ6F?

The THS (Threshold Select) pin configures the power-fail detection voltage (VPFD) range: tying THS to VSS selects 2.8 V–3.0 V, while tying it to VOUT selects 2.5 V–2.7 V. This dual-threshold capability allows precise brownout response tuning without external components, matching system-level rail tolerance requirements.

Can M40Z300WMQ6F support more than four SRAMs?

Yes-by placing two M40Z300WMQ6F devices in parallel with identical A/B decoder inputs, up to eight SRAMs can be controlled. Each device drives four conditioned chip-enable outputs (E1CON–E4CON), and the two sets operate synchronously under shared E and decoder signals per Figure 5 in the datasheet.

How does the battery-low (BL) pin behave during power-up versus periodic checks?

During power-up, BL asserts immediately if battery voltage is below ~2.5 V, indicating potential data integrity risk. During the scheduled 24-hour check, BL assertion signals end-of-life but does not compromise data since VCC is present; replacement is required before next backup event to maintain retention capability.

Is the M40Z300WMQ6F compatible with 2.7 V operation?

Yes-the device is fully specified from 2.7 V to 3.6 V per Table 4 and Table 6. At 2.7 V, VPFD remains within the 2.5 V–2.7 V range (THS = VOUT), and all DC/AC parameters including ICC (max 4 mA) and VOL (0.4 V) are guaranteed across the full temperature range (–40 °C to +85 °C).