STMicroelectronics STM819LM6F

Overview

STM819LM6F from STMicroelectronics is a 5 V industrial-grade microprocessor supervisory IC with integrated battery switchover, active-low and active-high reset outputs, manual reset input (MR), power-fail comparator (PFI/PFO), and battery freshness seal - designed for non-volatile SRAM backup in embedded systems requiring reliable power monitoring and fail-safe reset assertion down to VCC = 1.0 V.

For engineers reviewing the STM819LM6F datasheet, STM819LM6F pinout, STM819LM6F application, or STM819LM6F equivalent, this device supports critical system-level functions including power-fail warning, push-button reset, battery-backed memory retention, and guaranteed reset assertion during brownout - all in an SO8 package with industrial temperature range (–40 °C to +85 °C).

Technical Context

The STM819LM6F implements dual-reset architecture with push-pull RST (active-low) and RST (active-high) outputs, both asserted for ≥200 ms (typ) after power-up, brownout, or MR activation. Its internal precision voltage comparator monitors VCC against a 4.65 V reset threshold (VRST) with hysteresis, ensuring stable reset release above VRST + 150 mV.

It integrates a dedicated power-fail comparator (PFI/PFO) with VPFI = 2.4 V (typ), independent of VCC monitoring, enabling early warning of supply collapse. Unlike STM817/818, it lacks watchdog timer and chip-enable gating - confirmed by logic diagram Figure 2 and Table 1 - and relies solely on MR for manual reset initiation.

Key Specifications

Pinout & Package

STM819LM6F is housed in an 8-pin SO8 (Small Outline) package per Table 8 and Figure 43, with standard 1.27 mm pitch, gull-wing leads, and JEDEC MS-012AC compliance. Thermal resistance θJA = 150 °C/W enables operation at full rating without heatsink in typical PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM819LM6F, STM817LM6F adds watchdog capability but removes MR - making it incompatible with user-initiated reset workflows - while MAX809TRD3 sacrifices all advanced features (battery switchover, dual reset, PFI) for minimal footprint and cost, limiting use to non-backup, single-rail systems.

Availability

STM819LM6F is available at Aetrix Electronics and suitable for smart energy metering, industrial PLC controllers, medical infusion pumps, and automotive body control modules requiring stable component supply with guaranteed long-term availability and RoHS-compliant packaging.

Supply support for STM819LM6F 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 sensing solutions for industrial, automotive, and consumer markets.

The STM8xx supervisor family targets robust power management in resource-constrained embedded systems, emphasizing battery-backed memory integrity, deterministic reset timing, and industrial-grade reliability without external components.

FAQ

What is the function of the VOUT pin on STM819LM6F?

VOUT is the switched output that supplies external low-power static RAM (LPSRAM). It automatically connects to VCC when main supply is valid, and seamlessly switches to VBAT during power failure. This eliminates need for external diode-OR or MOSFET switchover circuits, and supports backup currents up to 20 mA with <100 Ω on-resistance.

Does STM819LM6F include a watchdog timer?

No. STM819LM6F does not include a watchdog timer - confirmed by its absence in Table 1 (Device Summary), logic diagram Figure 2, and Section 2.3 which explicitly states "NOT available on STM703/704/819". Watchdog functionality is present only in STM690A/692A/802/805/817/818 variants.

How does the battery freshness seal work on STM819LM6F?

The battery freshness seal prevents VBAT discharge during storage by disabling switchover until VCC first exceeds VRST (4.65 V). Once powered, the seal is activated and VOUT begins switching normally. Re-sealing requires cycling VCC off/on per Section 2.12 - enabling multi-year shelf life for sealed assemblies with installed coin cells.

Can PFI and PFO be used independently of the main reset function?

Yes. PFI/PFO operate independently from VCC monitoring and reset generation. PFO asserts low when PFI < 2.4 V or VCC < VSO, regardless of whether reset is active. This allows use as a standalone power-fail interrupt source for MCU firmware to initiate data save routines before reset occurs.