STMicroelectronics STM819MM6F

Overview

STM819MM6F from STMicroelectronics is a 5 V microprocessor supervisory IC with battery switchover, active-low and active-high reset outputs (RST/RST), manual reset input (MR), power-fail comparator (PFI/PFO), and battery freshness seal. It guarantees RST assertion down to VCC = 1.0 V, features 200 ms typical reset timeout (trec), and operates from –40 °C to +85 °C for industrial embedded systems requiring non-volatile SRAM backup.

For engineers reviewing the STM819MM6F datasheet, STM819MM6F pinout, STM819MM6F application, or STM819MM6F equivalent, key selection considerations include its dual-reset output architecture, absence of watchdog timer, PFI/PFO threshold behavior at 2.4 V, and MR-driven manual reset timing with internal 40 kΩ pull-up - all critical for reliable power monitoring in battery-backed memory systems.

Technical Context

The STM819MM6F implements a precision voltage reference and comparator to monitor VCC against a fixed reset threshold (VRST), asserting RST/RST when VCC falls below VRST or MR is pulled low. Its battery switchover circuit connects VOUT to VBAT (via ~100 Ω switch) when VCC drops below the lesser of VBAT and VRST, enabling seamless LPSRAM backup without external logic.

Unlike STM817/818 variants, it lacks watchdog timer and chip-enable gating (E/ECON), but includes dedicated push-button reset input (MR) with noise-immunity support and a power-fail comparator that asserts PFO when PFI < VPFI or VCC < 2.4 V - both functions implemented with internal hysteresis and push-pull outputs.

Key Specifications

Pinout & Package

STM819MM6F is housed in an 8-pin SO8 package (SOIC-8, 150 mil width), compliant with JEDEC MS-012 and RoHS standards. Pin assignments are validated per ST's DocID10522 Rev 11, Figure 5 and Table 3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM704M6F, STM819MM6F adds PFI/PFO for proactive power failure response and battery freshness seal for logistics efficiency; versus STM817MM6F, it trades watchdog capability for MR-driven field serviceability and sealed-battery readiness - making it optimal for maintenance-sensitive, battery-deployed industrial edge devices.

Availability

STM819MM6F is available at Aetrix Electronics and suitable for smart metering, industrial PLC I/O modules, point-of-sale terminals, and medical data loggers requiring stable component supply with long lifecycle assurance and RoHS-compliant packaging.

Supply support for STM819MM6F 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 STM8xx supervisor family targets industrial and embedded systems needing reliable, low-power, multi-function power monitoring - specifically engineered for battery-backed memory integrity, deterministic reset behavior, and seamless integration into space-constrained PCB layouts.

FAQ

Does STM819MM6F include a watchdog timer?

No. Unlike STM817/818, the STM819MM6F does not integrate a watchdog timer. Its functional scope is limited to voltage monitoring, manual reset (MR), dual-reset outputs, power-fail detection (PFI/PFO), and battery switchover - confirmed in Section 2.3 of DocID10522 Rev 11, which explicitly states "Watchdog input (NOT available on STM703/704/819)".

What is the purpose of the battery freshness seal feature?

The battery freshness seal prevents backup battery discharge during storage and shipment by disabling the switchover circuit until VCC is first applied and exceeds VRST. This allows manufacturers to pre-install batteries without sacrificing shelf life - activated only upon initial system power-up, as detailed in Section 2.12 of the datasheet.

Can VBAT exceed VCC in STM819MM6F?

Yes. The device permits VBAT > VCC, and its switchover logic selects the lesser of VBAT and VRST as the switchover voltage (VSO). This design maximizes battery life by delaying switchover until VCC drops close to the reset threshold, as specified in Section 2.4 and Figure 13 of the datasheet.

How is the MR input debounced?

MR debouncing is achieved through the internal reset timeout period (trec = 200 ms typ): reset remains asserted for the full trec duration after MR returns high, eliminating need for external RC networks. The 40 kΩ internal pull-up also provides noise immunity, and a 0.1 µF capacitor to ground is recommended only in high-noise or long-cable environments per Section 2.2.