STMicroelectronics STM708SAM6F

Overview

STM708SAM6F from STMicroelectronics is a 3 V precision voltage supervisor IC with dual active-high/active-low reset outputs, power-fail comparator (PFI/PFO), and no watchdog timer. It monitors VCC for out-of-tolerance conditions (reset threshold: 2.88 V ≤ VRST ≤ 3.00 V for 'S' variant), asserts RST/RST for ≥200 ms after power-up or fault, and operates from –40 °C to +85 °C. Used in industrial controllers and embedded systems requiring reliable power-on reset and early brownout warning.

For engineers reviewing the STM708SAM6F datasheet, STM708SAM6F pinout, STM708SAM6F application, or STM708SAM6F equivalent, key selection criteria include reset threshold accuracy, dual-reset polarity support, PFI/PFO timing behavior, and guaranteed RST assertion down to VCC = 1.0 V - critical for robust microprocessor initialization in noisy or marginally regulated environments.

Technical Context

The STM708SAM6F implements a dual-comparator architecture: one precision bandgap-based reference (VRST) for VCC supervision and a separate independent reference (VPFI ≈ 1.25 V) for power-fail detection. Its reset logic guarantees RST remains high and RST low during VCC < VRST, with trec = 200 ms (typ.) timeout after VCC recovery.

Unlike STM706 variants, it omits watchdog functionality (no WDI/WDO pins) but retains MR input for manual reset, push-pull PFO output, and internal 40 kΩ MR pull-up. Pin configuration matches STM708T/S/R family: RST and RST are both present, PFI feeds VPFI comparator, and PFO asserts low when PFI < VPFI.

Key Specifications

Pinout & Package

STM708SAM6F 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 dot or bevelled corner; pin numbering follows counter-clockwise convention from top-left.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3 V supervisor applications.

Compared with STM708SAM6F, STM706SM6F adds watchdog capability but sacrifices RST polarity flexibility, while TPS3808G33DBVR reduces supply current significantly but eliminates power-fail monitoring - trade-offs center on fault coverage breadth versus static power budget.

Availability

STM708SAM6F 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 STM708SAM6F 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 supervisor family targets cost-sensitive, space-constrained embedded systems needing reliable power-on reset, brownout protection, and early power-fail indication - with emphasis on industrial-grade reliability and minimal external components.

FAQ

What is the function of the NC pin on STM708SAM6F?

Pin 8 is designated NC (No Connect) and is internally unbonded. It serves no electrical or thermal purpose and must remain unconnected on the PCB. Routing traces or applying solder to this pin may cause mechanical stress or contamination without functional benefit.

Can PFO be used to trigger a system reset without external components?

Yes. PFO is a push-pull output that can be directly connected to the MR pin. When PFI falls below VPFI (≈1.25 V), PFO asserts low, causing MR to go low and initiating a full reset sequence with trec timing - no pull-up resistor or logic gate required.

How does STM708SAM6F differ from STM706 variants in watchdog capability?

STM708SAM6F has no watchdog timer - pins WDI and WDO are omitted. In contrast, STM706T/S/R and STM706P include WDI/WDO with 1.6 s timeout. This makes STM708SAM6F appropriate for systems relying solely on power supervision, not software hang detection.

Is the 200 ms reset timeout (trec) adjustable externally?

No. The 200 ms (typ.) reset timeout is internally generated and fixed. It cannot be modified with external capacitors or resistors. Designers must verify that this duration satisfies the target MCU's minimum reset pulse width requirement, typically found in its datasheet.