STMicroelectronics STM706RAM6F

Overview

STM706RAM6F 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), delivers 1.6 s watchdog timeout, and operates from –40 °C to +85 °C. Used in industrial controllers and embedded systems requiring reliable power-on reset and brownout protection.

For engineers reviewing the STM706RAM6F datasheet, STM706RAM6F pinout, STM706RAM6F application, or STM706RAM6F 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, MR debounced by internal 40 kΩ pull-up, and PFO's 1.25 V ±1.5% VPFI threshold for early power-fail warning.

Technical Context

The STM706RAM6F implements dual independent comparators: one for VCC monitoring (VRST = 3.00–3.15 V) and another for power-fail detection (VPFI = 1.25 V), each driving dedicated push-pull outputs. Its watchdog circuit monitors WDI transitions with 1.6 s timeout and clears on any edge - no external components required.

Reset assertion is guaranteed across full industrial temperature range and remains valid down to VCC = 1.0 V; trec is internally generated and temperature-stable (210–240 ms). The MR input includes an internal 40 kΩ pull-up, enabling direct switch-to-ground connection without external biasing.

Key Specifications

Pinout & Package

STM706RAM6F is housed in an 8-pin TSSOP package (3 × 3 mm body, DS variant), compatible with automated SMT assembly and offering 38% board area reduction versus SO8.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6369ESA+ and TPS3808G33DBVR, STM706RAM6F uniquely integrates VCC supervision, watchdog timer, and power-fail comparator in a single TSSOP8 package - eliminating three discrete functions and reducing validation effort for industrial systems requiring coordinated fault response.

Availability

STM706RAM6F is available at Aetrix Electronics and suitable for industrial controllers, medical diagnostic instruments, smart energy meters, and factory automation HMIs requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for STM706RAM6F 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/mixed-signal devices for industrial, automotive, and consumer markets.

The STM70x series was developed specifically for robust microprocessor supervision in harsh industrial environments, emphasizing guaranteed reset behavior under brownout, integrated watchdog reliability, and predictive power-fail response without external components.

FAQ

What is the function of the WDO pin on STM706RAM6F?

The WDO (Watchdog Output) pin is a push-pull active-low output that goes low when the WDI pin remains static for ≥1.6 s, indicating MCU lockup. It returns high immediately upon VCC recovery or WDI edge detection. To trigger system reset, WDO must be connected to the MR input; it does not assert RST autonomously.

Can STM706RAM6F monitor a 5 V supply?

Yes - STM706RAM6F operates with VCC from 1.0 V to 5.5 V and monitors its own supply rail. For 5 V systems, use the STM706T variant (3.00–3.15 V threshold) or STM706S (2.88–3.00 V); the RAM6F suffix confirms T-grade (3.00–3.15 V) configuration. Do not connect 5 V directly to PFI - use a resistor divider to scale to ≤1.25 V.

How is the reset timeout period (trec) determined?

trec is fixed internally at 200 ms (typical), with 210–240 ms variation over –40 °C to +85 °C per Figure 15. It is not adjustable externally. The timer starts when VCC rises above VRST and holds RST low for the full duration, ensuring sufficient time for microprocessor core and peripherals to initialize reliably.

Is the PFI input compatible with AC-coupled signals?

No - PFI is a DC-coupled comparator input referenced to a stable 1.25 V internal bandgap. It requires a steady DC voltage derived from a resistor divider across a DC supply rail. AC or transient-only signals will not produce valid PFO assertion; the input must remain below VPFI for ≥1 µs (per propagation delay specs) to guarantee response.