STMicroelectronics STM818MDS6F

Overview

STM818MDS6F from STMicroelectronics is a 5 V microprocessor supervisory IC with integrated battery switchover, chip-enable gating, and watchdog timer - designed to non-volatilize external LPSRAM in industrial systems. It guarantees RST assertion down to VCC = 1.0 V, delivers 7 ns max chip-enable propagation delay, and features 200 ms typical reset timeout (trec) and 1.6 sec typical watchdog timeout.

For engineers reviewing the STM818MDS6F datasheet, STM818MDS6F pinout, STM818MDS6F application, or STM818MDS6F equivalent, key selection criteria include guaranteed low-VCC reset behavior, push-pull RST/RST outputs, battery-freshness seal support, and precise chip-enable gating timing for LPSRAM write-protection during power transitions.

Technical Context

The STM818 implements dual reset outputs (RST active-low, RST active-high), both push-pull, with independent assertion logic tied to VCC monitoring, MR input, and watchdog timeout. Its internal precision voltage reference compares VCC against VRST (~4.63 V typ) and triggers trec-limited reset pulses on violation.

Unlike other members of the family (e.g., STM817/819), STM818 integrates E/ECON signal path: E serves as chip-enable input, and ECON delivers a conditioned, reset-synchronized enable output with 15 µs minimum hold time - enabling deterministic gating of LPSRAM CE during reset recovery without external logic.

Key Specifications

Pinout & Package

STM818MDS6F is housed in an SO8 (Small Outline 8-pin) package per JEDEC MS-012, with gull-wing leads, 1.27 mm pitch, and 5.0 mm × 4.0 mm body size.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar supervisor-with-battery-switchover applications.

Compared with STM817MDS6F and STM819MDS6F, STM818MDS6F uniquely combines watchdog supervision, chip-enable gating with sub-10 ns timing, and dual reset outputs - making it the only option in the family for deterministic, firmware-transparent LPSRAM protection during power failure and recovery sequences.

Availability

STM818MDS6F is available at Aetrix Electronics and suitable for industrial PLC memory backup, medical device data retention, and smart meter firmware recovery requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for STM818MDS6F 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The STM690/703/802/817/818/819 supervisor product line targets robust power-monitoring and non-volatile memory protection in harsh environments, with emphasis on guaranteed reset behavior, low-power battery operation, and seamless switchover reliability.

FAQ

What is the function of the E and ECON pins on STM818MDS6F?

E is the chip-enable input that controls LPSRAM access; ECON is its conditioned output, which remains low for ≥15 µs after reset deassertion and only goes high when both E is high and reset is inactive. This prevents premature LPSRAM access during MCU initialization, eliminating need for external timing circuits or firmware delays.

Does STM818MDS6F support power-fail detection like other devices in the family?

No - STM818MDS6F does not include PFI or PFO pins. Unlike STM817/819, it omits the power-fail comparator to prioritize chip-enable gating and watchdog functionality. Power-fail warning must be implemented externally if required in the system design.

How does the battery freshness seal work on STM818MDS6F?

The battery freshness seal prevents backup battery discharge during storage by disabling VBAT-to-VOUT conduction until VCC first exceeds VRST. It is activated automatically on initial power-up and can be reinitialized per Section 2.12 of the datasheet using a controlled VCC ramp sequence, extending shelf life beyond 5 years.

Can STM818MDS6F operate without a backup battery connected?

Yes - VBAT and VOUT may be tied to VCC if no battery is used. In this configuration, the device functions as a standard 5 V supervisor with watchdog and dual reset outputs, retaining all timing and reset guarantees except battery switchover. The E/ECON path remains fully operational for LPSRAM gating.