STMicroelectronics STM706RM6E

Overview

STM706RM6E from STMicroelectronics is a 3 V precision 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 < 2.88 V (S-grade threshold), provides 200 ms reset timeout (trec), 1.6 s watchdog timeout, and operates from –40 °C to +85 °C. Used in industrial controllers to ensure reliable MCU boot and brownout recovery.

For engineers reviewing the STM706RM6E datasheet, STM706RM6E pinout, STM706RM6E application, or STM706RM6E equivalent, key selection criteria include reset threshold tolerance (±2.5%), guaranteed RST assertion down to VCC = 1.0 V, push-pull RST/RST outputs, PFI comparator reference (1.25 V), and SO8/TSSOP8 package compatibility with legacy 3.3 V embedded systems.

Technical Context

The STM706RM6E implements a dual-comparator architecture: one monitors VCC against a precision bandgap reference (VRST = 2.88–3.00 V) to trigger RST, while a second compares PFI against a separate 1.25 V reference to drive PFO. Its watchdog timer resets on WDI edge transitions and clears during RST assertion.

Reset timing uses an internal RC-based trec generator ensuring 200 ms (typ.) delay after VCC rise or MR release; RST remains asserted until trec completes, even if VCC rises above VRST mid-timing. The MR input includes a 40 kΩ internal pull-up, enabling direct switch-to-ground connection without external biasing.

Key Specifications

Pinout & Package

STM706RM6E is housed in an 8-pin SOIC (SO8) package with 150-mil body width, RoHS-compliant lead-free finish, and standard JEDEC MS-012AC footprint. Pin 1 is marked with a beveled corner or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6361LUR29+T and TPS3808G33DBVR, STM706RM6E uniquely integrates three supervisory functions-precision reset, watchdog, and power-fail comparator-in a single SO8 package, enabling coordinated system-level fault response without external components or timing compromises.

Availability

STM706RM6E is available at Aetrix Electronics and suitable for industrial controllers, smart energy meters, medical diagnostic equipment, and programmable logic controller (PLC) CPU modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for STM706RM6E 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 devices for industrial, automotive, and consumer markets.

The STM70x series was developed specifically for robust, low-component-count microprocessor supervision in harsh industrial environments, emphasizing guaranteed reset behavior, wide VCC operating margin, and integrated fault-detection features.

FAQ

What is the exact reset threshold voltage range for STM706RM6E?

The STM706RM6E is an "S-grade" device with a guaranteed reset threshold range of 2.88 V to 3.00 V at TA = –40 °C to +85 °C. This is confirmed in Table 1 and Section 1 of the datasheet (DocID10518 Rev 14), where "S" denotes the 2.88–3.00 V variant. The part number suffix "RM6E" maps to SO8 packaging and industrial temperature grade.

Does STM706RM6E include both RST and RST outputs?

No. STM706RM6E provides only the active-low RST output (pin 7) and does not assert RST (pin 2). Per Table 3 and Figure 3 of the datasheet, pin 2 is designated NC for STM706R/S/T variants. The RST output is exclusive to STM706P and STM708 devices, which are functionally distinct parts with different reset polarity configurations.

Can the watchdog timer be disabled without hardware modification?

Yes. The watchdog timer is automatically disabled when the WDI pin (pin 6) is left floating or tri-stated, provided leakage current stays below 10 µA and load capacitance remains under 200 pF. This is documented in Section 3.3 and Figure 28 of the datasheet. No resistor pull-up/down or solder bridge is required - high-impedance WDI state suffices.

What is the recommended layout practice for the PFI input to avoid noise coupling?

Place the PFI voltage divider (typically two resistors from VCC to GND) as close as possible to the PFI pin (pin 3), with short, direct traces. Route PFI away from switching nodes or clock lines, and avoid sharing ground paths with high-current circuits. If noise is observed, add a 100 pF ceramic capacitor from PFI to VSS - this is explicitly recommended in application note AN2827 for STM70x stability.