STMicroelectronics STM705M6E

Overview

STM705M6E from STMicroelectronics is a 5 V precision voltage supervisor IC with active-low RST, active-high RST, watchdog timer (1.6 s typ), manual reset input (MR), and power-fail comparator (PFI/PFO). It guarantees RST assertion down to VCC = 1.0 V and operates from –40 °C to 85 °C in industrial environments. Used in microprocessor-based systems requiring reliable power-on reset, brownout detection, and system-level fault recovery.

For engineers reviewing the STM705M6E datasheet, STM705M6E pinout, STM705M6E application, or STM705M6E equivalent, key selection criteria include reset threshold accuracy (4.50–4.75 V), trec timing (200 ms typ), push-pull RST/RST outputs, MR debounced interface capability, and PFI threshold stability across temperature.

Technical Context

The STM705M6E integrates a precision voltage reference comparator for VCC monitoring, a 1.6 s watchdog timer with WDI edge-triggered clearing, and independent power-fail detection using VPFI = 1.25 V (typ). Its dual RST outputs support bidirectional MCU reset I/O interfacing via external series resistor.

Reset assertion is guaranteed down to VCC = 1.0 V at TA = 0–85 °C; trec is internally generated and temperature-stable (210–240 ms range). The MR input features an internal 40 kΩ pull-up, enabling direct switch-to-ground connection without external components.

Key Specifications

Pinout & Package

STM705M6E is housed in an 8-pin TSSOP package (3 mm × 3 mm body, 0.65 mm pitch), RoHS-compliant and lead-free per Directive 2011/65/EU.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809SEUR+T and TPS3808G18DBVR, STM705M6E delivers integrated watchdog, dual reset polarity, and dedicated power-fail detection in a single TSSOP-8 package-reducing BOM count and PCB footprint while enabling safer, more responsive system supervision.

Availability

STM705M6E is available at Aetrix Electronics and suitable for industrial PLC controllers, automotive body control modules, medical infusion pumps, and point-of-sale terminals requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for STM705M6E 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 STM70x family was engineered specifically for robust microprocessor supervision in noise-prone, thermally variable environments-emphasizing guaranteed reset behavior, low-power operation, and integration of watchdog and power-fail monitoring in compact packages.

FAQ

What is the function of the WDO pin on STM705M6E?

The WDO (Watchdog Output) pin is a push-pull output that goes low when the watchdog timer expires (after ~1.6 s of no WDI transition). It remains low until a rising or falling edge is detected on WDI. Unlike RST, WDO returns high immediately when VCC exceeds VRST-even during ongoing reset assertion-making it suitable for feeding back into MR to trigger system reset only when watchdog timeout occurs.

Can STM705M6E operate with a 3.3 V supply?

No. STM705M6E is specified exclusively for 5 V operation (VCC = 4.5–5.5 V). Its internal voltage reference, comparators, and output drivers are optimized for this range. Attempting 3.3 V operation will result in unreliable reset assertion, failure to guarantee RST down to 1.0 V, and potential non-compliance with trec and watchdog timing specifications.

How does the power-fail comparator (PFI/PFO) differ from the VCC monitor?

The PFI/PFO circuit uses a separate 1.25 V internal reference (VPFI) independent of the 4.50–4.75 V VCC reset threshold (VRST). This allows early detection of upstream supply degradation-e.g., monitoring a 12 V rail via resistor divider-so PFO can assert before VCC falls below VRST, enabling preemptive system actions like data save or graceful shutdown.

Is STM705M6E pin-compatible with STM706M6E?

Yes-both share identical TSSOP-8 pinout and package dimensions. However, STM706M6E has a lower VRST range (4.25–4.50 V) and supports automotive temperature grade (–40 °C to +125 °C), whereas STM705M6E is rated for industrial grade (–40 °C to +85 °C) and targets 4.50–4.75 V VCC rails. Electrical substitution requires verification of reset threshold compatibility in the target system.