STMicroelectronics STM817MM6F

Overview

STM817MM6F from STMicroelectronics is a 5 V microprocessor supervisory IC with integrated battery switchover, power-fail comparator (PFI/PFO), and watchdog timer. It provides active-low and active-high reset outputs (RST/RST), guarantees RST assertion down to VCC = 1.0 V, and supports external LPSRAM backup via VOUT with 200 ms typical reset timeout (trec). Used in industrial embedded systems requiring reliable power monitoring and non-volatile SRAM retention during main supply loss.

For engineers reviewing the STM817MM6F datasheet, STM817MM6F pinout, STM817MM6F application, or STM817MM6F equivalent, this page delivers verified functional identity, SO8 package mapping, confirmed pin roles (MR, WDI, RST, RST, VOUT, VBAT, PFI, PFO), battery switchover behavior, and real-world design implications for reset timing, watchdog supervision, and power-fail warning integration.

Technical Context

The STM817MM6F implements dual-reset architecture with push-pull RST and RST outputs, enabling simultaneous reset signaling to multiple voltage domains or logic families. Its precision reset comparator monitors VCC against a 4.65 V threshold (VRST) with hysteresis, while the power-fail comparator triggers PFO at VPFI = 2.4 V (or VSO when VBAT < VRST).

Backup switchover uses an internal P-channel MOSFET switch (100 Ω typical on-resistance) between VCC/VBAT and VOUT, activated when VCC falls below the lesser of VBAT and VRST. The 1.6 sec typical watchdog timer clears on WDI edge transitions and asserts reset if unattended - a critical safety feature for locked-up microcontrollers in unattended equipment.

Key Specifications

Pinout & Package

STM817MM6F is housed in an industry-standard 8-pin SO8 (Small Outline) package (ECOPACK® compliant, RoHS-compliant, 150 mil width). Pin spacing is 1.27 mm, body dimensions are 4.9 mm × 6.0 mm × 1.75 mm (max), and thermal resistance (θ_JA) is 150 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX692AESA+ and TPS3823-50DBVR, STM817MM6F uniquely integrates battery switchover, power-fail warning, and watchdog supervision in one SO8 package - reducing BOM count, PCB area, and validation effort for systems requiring coordinated power integrity and data retention.

Availability

STM817MM6F is available at Aetrix Electronics and suitable for industrial PLC controllers, medical infusion pumps, smart energy meters, and factory automation HMIs requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for STM817MM6F 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 specializing in automotive, industrial, and power management solutions, with over 45 years of analog and mixed-signal IC innovation.

The STM817 series belongs to ST's microprocessor supervisory product line, designed specifically for robust power monitoring, non-volatile SRAM backup, and fail-safe system recovery in harsh industrial environments.

FAQ

What is the function of the E and ECON pins on STM817MM6F?

E is the chip-enable input that controls gating of the external LPSRAM. When E is low and reset is not asserted, ECON goes low to enable SRAM access. During reset or when E is high, ECON remains high (or pulled up to VOUT), disabling SRAM writes. This prevents memory corruption during power transitions or MCU initialization.

Does STM817MM6F support battery freshness seal functionality?

Yes - STM817MM6F includes a battery freshness seal that prevents initial battery discharge during storage and shipment. The seal is disabled automatically upon first VCC application above VRST, ensuring zero battery drain until system activation. This feature is confirmed in Section 2.12 of the official datasheet (DocID10522 Rev 11).

How does the power-fail comparator (PFI/PFO) interact with the reset function?

PFI and PFO operate independently of the reset generator. PFO asserts low when PFI < 2.4 V or VCC < VSO, providing early warning of power degradation - typically 10–50 ms before VCC reaches VRST. Reset (RST/RST) triggers only when VCC falls below VRST = 4.65 V. This separation allows firmware to execute save routines before reset occurs.

Can STM817MM6F be used without a backup battery?

Yes - VBAT and VOUT can both be tied to VCC if no battery is required. In this configuration, VOUT remains powered by VCC, and all supervisory functions (reset, watchdog, PFI/PFO) operate normally. The device guarantees RST assertion down to VCC = 1.0 V even without battery support, maintaining reliability in brownout conditions.