STMicroelectronics STM704TM6F

Overview

STM704TM6F from STMicroelectronics is a 3 V industrial-grade microprocessor supervisory IC with battery switchover, active-low push-pull RST output, manual reset (MR) input, power-fail comparator (PFI/PFO), and guaranteed reset assertion down to VCC = 1.0 V. It delivers 200 ms typical reset timeout (trec), 0.4 µA typical battery supply current, and operates from –40 °C to +85 °C in SO8 package for embedded systems requiring reliable power monitoring and non-volatile SRAM backup.

For engineers reviewing the STM704TM6F datasheet, STM704TM6F pinout, STM704TM6F application, or STM704TM6F equivalent, key selection criteria include its dual-supply switchover architecture (VCC/VBAT → VOUT), absence of watchdog timer (distinguishing it from STM690/802/804/805), push-pull PFO output, and MR-driven reset timing compliance with IEC 61000-4-2 ESD immunity requirements.

Technical Context

The STM704 implements a precision voltage reference and comparator to monitor VCC against a fixed reset threshold (VRST ≈ 2.93 V), asserting RST low when VCC drops below VRST or MR is pulled low. Its internal trec generator ensures minimum 200 ms reset pulse width after power-up or MR release, independent of VCC slew rate.

Automatic battery switchover activates when VCC falls below VSW = 2.4 V, connecting VBAT to VOUT via an integrated P-channel MOSFET switch (R_ON ≈ 100 Ω); Vccsw provides a complementary logic-level signal indicating switchover state for external PMOS gate control up to 75 mA load.

Key Specifications

Pinout & Package

STM704TM6F is housed in an 8-pin SO8 (Small Outline Integrated Circuit) package, 3.9 mm × 4.9 mm body, 1.27 mm pitch, RoHS-compliant lead-free finish. Pin 1 is marked by a beveled corner or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TRD2T and TPS3808G12DBVR, STM704TM6F uniquely integrates VCC/VBAT switchover, push-pull PFO warning, and guaranteed 1.0 V reset - making it the only option among the three that fully supports autonomous, long-term SRAM data retention during extended power loss.

Availability

STM704TM6F is available at Aetrix Electronics and suitable for smart metering, industrial PLCs, medical monitors, and POS terminals requiring stable component supply with guaranteed long-term availability and RoHS-compliant manufacturing.

Supply support for STM704TM6F 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 silicon solutions for automotive, industrial, and consumer markets since 1987.

The STM690/704/795/802/804/805/806 family was engineered specifically for microprocessor-based systems needing integrated power supervision, non-volatile SRAM backup, and early power-fail detection - targeting industrial and metering applications demanding high reliability and low power.

FAQ

What is the function of the Vccsw pin on STM704TM6F?

Vccsw is a push-pull output that goes high when VOUT switches from VCC to VBAT, and low when VOUT reverts to VCC. It provides a logic-level signal to drive the gate of an external PMOS transistor, enabling higher-current backup supply paths (>75 mA) beyond the internal 100 Ω switch's capability. This pin is essential for systems requiring >100 mA SRAM backup current.

Does STM704TM6F include a watchdog timer?

No. STM704TM6F does not include a watchdog timer - this feature is explicitly excluded per the datasheet (Section 2.3: "NOT available on STM704/795/806"). Unlike STM690/802/804/805 variants, STM704 relies solely on VCC monitoring and MR input for reset generation, simplifying design where software-controlled watchdog supervision is handled externally or omitted.

Can VBAT exceed VCC on STM704TM6F?

Yes. VBAT may safely exceed VCC (up to 5.5 V), and the device will still perform automatic switchover when VCC falls below VSW = 2.4 V. The internal P-channel MOSFET prevents reverse current flow from VBAT to VCC. This allows use of higher-voltage backup sources (e.g., 3.6 V LiSOCl₂ cells) while powering the main system from 3.3 V, enhancing design flexibility in battery-critical applications.

How is the reset timeout (trec) triggered and timed?

trec is a fixed 200 ms (typ) internal timer activated each time RST is asserted - whether by VCC falling below 2.93 V, MR being pulled low, or power-up sequencing. The timer starts upon VCC crossing VRST during power-up or MR release, and holds RST low for the full duration regardless of VCC stability. It resets if VCC drops again before timeout completion, ensuring robust reset hold under noisy or fluctuating supply conditions.