STMicroelectronics STM802MM6F

Overview

STM802MM6F from STMicroelectronics is a 5 V microprocessor supervisory IC with battery switchover, active-low and active-high reset outputs (RST/RST), watchdog timer (1.6 s typ), power-fail comparator (PFI/PFO), and guaranteed RST assertion down to VCC = 1.0 V. It monitors VCC for out-of-tolerance conditions and automatically switches external LPSRAM supply from VCC to VBAT during power failure - used in industrial embedded systems requiring nonvolatile SRAM retention during brownout.

For engineers reviewing the STM802MM6F datasheet, STM802MM6F pinout, STM802MM6F application, or STM802MM6F equivalent, this device delivers precise reset timing (200 ms trec typ), ultra-low battery current (0.4 µA typ), push-pull RST/RST outputs, and integrated power-fail warning - critical for reliable boot sequencing and data integrity in battery-backed memory systems.

Technical Context

The STM802 implements dual-reset architecture with independent active-low (RST) and active-high (RST) outputs, both push-pull, asserted when VCC falls below VRST (~4.63 V), on MR low, or after watchdog timeout. Its internal precision voltage reference and comparator ensure reset validity across –40 °C to +85 °C, with guaranteed assertion down to VCC = 1.0 V when VBAT > 1 V.

Battery switchover uses a P-channel MOSFET switch connecting VOUT to VCC above VSO (lesser of VBAT and VRST) and to VBAT below VSO, enabling seamless LPSRAM backup without external diodes. The power-fail comparator triggers PFO low when PFI < VPFI or VCC drops below 2.4 V, providing early warning before reset activation.

Key Specifications

Pinout & Package

STM802MM6F is housed in an 8-pin SO8 (Small Outline) package per JEDEC MS-012, with 1.27 mm pitch, body size 4.9 × 6.0 mm, and gull-wing leads suitable for automated assembly and reflow soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809SEUR+T and TPS3808G12QDBVRQ1, STM802MM6F uniquely integrates battery switchover, dual-reset outputs, watchdog, and power-fail comparator in one SO8 package - eliminating four discrete functions and reducing BOM count in SRAM-retentive systems.

Availability

STM802MM6F is available at Aetrix Electronics and suitable for industrial PLCs, medical data loggers, and smart metering systems requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for STM802MM6F 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 STM802 belongs to ST's supervisor IC product line, engineered specifically for robust power monitoring and nonvolatile memory protection in harsh industrial environments with extended temperature and reliability requirements.

FAQ

What is the function of the VOUT pin on STM802MM6F?

VOUT is the switched output that supplies external LPSRAM. When VCC is above the switchover voltage (VSO), VOUT connects to VCC through an internal P-channel MOSFET. When VCC drops below VSO, VOUT automatically connects to VBAT, preserving SRAM data without external diodes or controllers. VSO is set to the lesser of VBAT and VRST to maximize battery life.

Can the watchdog timer be disabled, and how?

Yes, the watchdog timer is disabled when the WDI pin is left floating or tri-stated. Internal leakage current must remain below 10 µA and load capacitance under 200 pF. Driving WDI continuously high or low will cause periodic reset pulses every ~1.8 s (tWD + trec), so disconnection-not static bias-is the correct disable method.

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

PFI and PFO operate independently of the reset comparator. PFO goes low when PFI < VPFI (2.4 V typ) or VCC falls below 2.4 V, providing early warning up to hundreds of milliseconds before VCC reaches the 4.63 V reset threshold. This allows time-critical actions like EEPROM save before reset assertion, without affecting RST timing or behavior.

Is STM802MM6F pin-compatible with other devices in the STM8xx family?

STM802MM6F shares the same SO8 pinout and core functionality (RST/RST, MR, WDI, PFI/PFO, VOUT, VCC, VSS) with STM690A, STM692A, STM704, and STM805L/M variants. However, STM818 adds E/ECON pins, and STM703/704 omit WDI - so direct substitution requires verification of feature enablement and reset polarity (STM805 has active-high-only RST).