STMicroelectronics STM705DS6F

Overview

STM705DS6F from STMicroelectronics is a 5 V precision voltage supervisor IC with active-low RST and active-high RST outputs, 4.50–4.75 V reset threshold, 200 ms typical reset timeout (trec), and integrated watchdog timer (1.6 s timeout). It monitors VCC for out-of-tolerance conditions in microprocessor-based systems and asserts reset during power-up, brownout, or software hang events - commonly used in industrial control modules and embedded instrumentation.

For engineers reviewing the STM705DS6F datasheet, STM705DS6F pinout, STM705DS6F application, or STM705DS6F equivalent, key selection criteria include its dual-reset output polarity, guaranteed RST assertion down to VCC = 1.0 V, push-pull PFO/WDO outputs, manual reset input with internal pull-up, and power-fail comparator for early supply degradation detection.

Technical Context

The STM705DS6F integrates a precision bandgap reference, dual comparators (VCC monitor and independent PFI threshold), a 1.6 s watchdog timer with WDI edge-sensitive clearing, and trec generator ensuring minimum 200 ms reset pulse width after VCC recovery or MR release. Its logic diagram confirms independent paths for reset assertion via VCC drop, MR low, or WDO-triggered MR (when externally wired).

All outputs - RST, RST, WDO, and PFO - are push-pull, eliminating need for external pull-ups. The device guarantees valid RST assertion down to VCC = 1.0 V at industrial temperature range (–40 °C to +85 °C), and supports noise-immune MR interfacing via optional 0.1 µF capacitor to ground.

Key Specifications

Pinout & Package

STM705DS6F is housed in an 8-pin TSSOP package (3 mm × 3 mm body, DS suffix per ST's ordering scheme), optimized for high-density PCB layouts while maintaining SOIC-compatible footprint compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX692ESA+ and TPS3808G33DBVR, STM705DS6F uniquely delivers dual-reset polarity, integrated PFI/PFO, and 5 V operation in a space-saving TSSOP8 - making it optimal for industrial 5 V systems requiring both brownout immunity and predictive power failure response.

Availability

STM705DS6F is available at Aetrix Electronics and suitable for industrial PLC I/O modules, medical infusion pump controllers, automotive body control modules, and point-of-sale terminal power management requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for STM705DS6F 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 microcontrollers, power management ICs, sensors, and analog chips for industrial, automotive, and consumer markets.

The STM70x family targets robust microprocessor supervision in mission-critical embedded systems, emphasizing precision threshold accuracy, guaranteed low-VCC reset behavior, and integrated fault-detection features like watchdog and power-fail monitoring.

FAQ

Can STM705DS6F operate with a 3.3 V supply?

No. STM705DS6F is specified exclusively for 5 V operation (4.5–5.5 V range). Its internal voltage reference, comparators, and output drivers are calibrated for this range. Applying 3.3 V will result in invalid reset assertion, undefined watchdog behavior, and potential failure to meet trec or VRST specifications. Use TPS3808G33DBVR or MAX6326 for 3.3 V systems.

How is the watchdog timer disabled?

The watchdog timer is disabled by leaving WDI floating or tri-stating its driving source. ST specifies maximum leakage current ≤10 µA and load capacitance ≤200 pF for reliable disablement. Do not tie WDI permanently high or low - that causes continuous 1.8 s reset cycles when WDO is connected to MR.

What is the purpose of the dual RST and RST outputs?

RST (active-low) and RST (active-high) provide complementary reset signals to accommodate MCUs with either active-low or active-high reset pin requirements - or bidirectional reset I/Os. The 4.7 kΩ series resistor solution shown in Figure 11 avoids contention when driving such pins, eliminating need for external inverters or level shifters.

Does STM705DS6F support automotive temperature range?

No. STM705DS6F is rated for –40 °C to +85 °C (industrial grade). Only the STM706 variant offers automotive qualification (–40 °C to +125 °C). Using STM705DS6F outside its specified temperature range risks incorrect reset threshold tracking, increased trec drift, and unreliable watchdog timeout - especially above 85 °C.