STMicroelectronics STM818LM6E

Overview

STM818LM6E from STMicroelectronics is a 5 V microprocessor supervisory IC with integrated battery switchover, chip-enable gating for external LPSRAM, and dual active-low/high reset outputs. It features 200 ms typical reset timeout (trec), 1.6 s watchdog timer, and guaranteed RST assertion down to VCC = 1.0 V - used in industrial embedded systems requiring non-volatile SRAM retention during power loss.

For engineers reviewing the STM818LM6E datasheet, STM818LM6E pinout, STM818LM6E application, or STM818LM6E equivalent, key selection criteria include chip-enable propagation delay (7 ns max), battery switchover hysteresis, push-pull RST/RST drive capability, and compatibility with 5 V LPSRAM backup architectures.

Technical Context

The STM818LM6E implements a precision voltage comparator monitoring VCC against a 4.65 V reset threshold (VRST), with automatic switchover to VBAT when VCC falls below the lesser of VRST or VBAT. Its dedicated E/ECON circuitry provides synchronized chip-enable gating with 7 ns maximum propagation delay, enabling deterministic LPSRAM access control during reset transitions.

Unlike other members of the STM8xx family, STM818LM6E excludes PFI/PFO functionality but includes both WDI watchdog input and MR manual reset input. All RST and RST outputs are push-pull, ensuring robust drive strength without external pull-ups, and operate across –40 °C to +85 °C industrial temperature range.

Key Specifications

Pinout & Package

STM818LM6E is housed in an 8-pin SO8 (Small Outline) package with standard 1.27 mm pitch, RoHS-compliant lead-free finish, and JEDEC MS-012AC mechanical outline.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor supervisory applications.

Compared with STM817LM6E and STM802L, STM818LM6E uniquely delivers chip-enable gating with sub-10 ns timing control - essential for systems requiring atomic SRAM access during power transitions - while omitting PFI/PFO to reduce pin count and simplify layout.

Availability

STM818LM6E is available at Aetrix Electronics and suitable for industrial PLCs, medical infusion pumps, smart energy meters, and automotive telematics modules requiring stable component supply with long-term lifecycle support.

Supply support for STM818LM6E 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, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The STM8xx supervisor family targets industrial and medical systems requiring guaranteed reset behavior, battery-backed memory integrity, and deterministic timing during power anomalies - with STM818LM6E optimized for LPSRAM gating-critical applications.

FAQ

What is the function of the E and ECON pins on STM818LM6E?

E is the chip-enable input that directly controls LPSRAM access; ECON is its conditioned output, delayed and synchronized with reset release. When E is low and reset is inactive, ECON goes low within 7 ns. If reset is asserted, ECON remains low for 15 µs after reset deassertion or until E goes high - ensuring LPSRAM is disabled during reset recovery.

Does STM818LM6E support supercapacitor backup instead of a battery?

Yes - STM818LM6E supports supercapacitor backup on VBAT. The device's 0.4 µA typical battery current and automatic switchover logic make it compatible with 0.1–1 F supercaps. Application Note AN2829 confirms use with 0.47 F Supercap™ devices, with VBAT clamped at 5.5 V maximum and switchover hysteresis optimized for gradual discharge profiles.

How does the watchdog timer interact with the reset outputs?

The watchdog timer triggers RST/RST assertion when WDI remains static for ≥1.6 s. Reset remains active for the full 200 ms trec period, independent of WDI state. During reset, the watchdog is held inactive; it resumes counting only after RST returns to its inactive state - preventing spurious timeouts during MCU reboot sequences.

Can STM818LM6E be used without a backup battery?

Yes - VBAT and VOUT can be tied to VCC for systems without backup memory. In this configuration, VOUT follows VCC directly, RST/RST operate normally, and all supervisory functions (reset, watchdog, chip-enable gating) remain fully functional. No external components are required for basic operation.