STMicroelectronics STM706SM6F

Overview

STM706SM6F from STMicroelectronics is a precision 3 V supply voltage supervisor IC with active-low reset (RST), watchdog timer, manual reset input (MR), and power-fail comparator (PFI/PFO). It asserts reset for VCC < 3.00 V (typ.), provides 200 ms reset timeout (trec), 1.6 s watchdog timeout, and operates from –40 °C to +85 °C. Used in industrial microcontroller systems requiring reliable power-on reset and brownout protection.

For engineers reviewing the STM706SM6F datasheet, STM706SM6F pinout, STM706SM6F application, or STM706SM6F equivalent, key selection criteria include reset threshold accuracy (±2.5% over temperature), guaranteed RST assertion down to VCC = 1.0 V, push-pull RST/RST outputs, low 40 µA quiescent current, and compatibility with SO8/TSSOP8 PCB footprints.

Technical Context

The STM706SM6F integrates a precision bandgap reference, dual comparators (VCC monitor and PFI threshold), a 1.6 s watchdog timer with WDI edge-sensitive clearing, and independent MR gating logic. Its RST output remains asserted during VCC undervoltage, MR low, or watchdog timeout - with trec timing initiated only upon VCC recovery or MR release.

It features two reset outputs: open-drain-compatible RST (active-low) and push-pull RST (active-high, not present on STM706SM6F per pinout and device summary), plus dedicated PFO with internal pull-up and MR input with 40 kΩ internal pull-up. The PFI comparator uses a fixed 1.25 V reference independent of VRST.

Key Specifications

Pinout & Package

STM706SM6F is housed in an 8-pin SOIC (SO8) package with 150 mil body width, compliant with JEDEC MS-012. Pin pitch is 1.27 mm; package dimensions are 4.9 mm × 3.9 mm × 1.75 mm (max).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6326US31D3+ and TPS3808G33DBVR, STM706SM6F uniquely combines fixed-accuracy 3.00 V reset, integrated watchdog, and independent PFI/PFO in one SO8 footprint - enabling single-chip brownout, lockup, and predictive power failure handling without external components.

Availability

STM706SM6F is available at Aetrix Electronics and suitable for industrial controllers, medical devices, and smart metering systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for STM706SM6F 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, specializing in microcontrollers, power management, and analog/mixed-signal ICs for industrial, automotive, and consumer markets.

The STM70x series was designed specifically for robust microprocessor supervision in harsh industrial environments - emphasizing guaranteed reset behavior across voltage and temperature extremes, minimal external components, and functional safety readiness.

FAQ

Can STM706SM6F be used with a 3.3 V microcontroller supply?

Yes. STM706SM6F's 3.00–3.15 V reset threshold is intentionally set below 3.3 V nominal to ensure reset assertion before the MCU enters undefined operation. Its RST output is push-pull and compatible with 3.3 V logic levels, and it guarantees valid reset assertion down to VCC = 1.0 V - making it suitable for 3.3 V systems with brownout margins.

How is the watchdog timer disabled on STM706SM6F?

The watchdog timer is disabled by allowing the WDI pin to float. Internal leakage limits (<10 µA) and load capacitance (<200 pF) must be observed. When WDI is left unconnected or tri-stated, the 1.6 s timer remains cleared and does not trigger WDO. This is confirmed in Section 2.2 and Figure 28 of the official datasheet.

What is the function of the PFI and PFO pins in a typical application?

PFI accepts a divided-down version of the unregulated input supply, comparing it to a fixed 1.25 V internal reference. When PFI falls below that threshold, PFO goes low - providing early warning of impending power failure before VCC drops to the 3.00 V reset level. This allows the MCU to save data or enter safe state prior to hard reset.

Does STM706SM6F require external capacitors for stable operation?

No external timing capacitors are required. The 200 ms reset timeout (trec) and 1.6 s watchdog period are internally generated. A 0.1 µF bypass capacitor on VCC is recommended per standard analog IC practice, and a 0.1 µF capacitor from MR to GND is optional for noise immunity in electrically noisy environments - but neither is mandatory for basic functionality.