STMicroelectronics STM708SDS6F

Overview

STM708SDS6F from STMicroelectronics is a 3 V precision voltage supervisor IC with dual active-low and active-high reset outputs, 200 ms reset timeout, power-fail comparator (PFI/PFO), and no watchdog timer. It monitors VCC for out-of-tolerance conditions down to 1.0 V and asserts RST/RST during brownout, manual reset, or power-fail detection. Used in industrial controllers and embedded systems requiring reliable power-on reset and early power-loss warning.

For engineers reviewing the STM708SDS6F datasheet, STM708SDS6F pinout, STM708SDS6F application, or STM708SDS6F equivalent, key selection criteria include reset threshold accuracy (2.88–3.00 V), guaranteed reset assertion below 1.0 V VCC, TSSOP8 package compatibility, and absence of watchdog functionality compared to STM706 variants.

Technical Context

The STM708SDS6F implements a dual-comparator architecture: one precision bandgap reference comparator for VCC monitoring (VRST = 2.88–3.00 V) and a separate independent comparator for PFI (VPFI ≈ 1.25 V). Reset assertion is latched and timed by an internal trec generator ensuring ≥200 ms minimum pulse width.

It features push-pull RST and RST outputs, MR input with internal 40 kΩ pull-up, and PFO output that remains high until PFI falls below VPFI - enabling early undervoltage warning before VCC collapse. Unlike STM706 series, it omits WDI/WDO pins and associated watchdog logic.

Key Specifications

Pinout & Package

STM708SDS6F is housed in an 8-pin TSSOP package (3 mm × 3 mm body, DS suffix), RoHS-compliant and lead-free. Pin spacing is 0.65 mm, with exposed pad option not supported.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM706SDS6F, STM708SDS6F removes watchdog circuitry to reduce complexity and leakage, while retaining identical reset accuracy and PFI/PFO functionality; versus TPS3808G30DBVR, it adds dual-reset flexibility and dedicated power-fail signaling at the cost of larger TSSOP8 footprint.

Availability

STM708SDS6F is available at Aetrix Electronics and suitable for industrial PLC controllers, smart energy meters, medical handheld diagnostics, and factory automation I/O modules requiring stable component supply and long-term lifecycle support.

Supply support for STM708SDS6F 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, and analog/mixed-signal devices for industrial, automotive, and consumer markets.

The STM70x supervisor family targets robust power monitoring in resource-constrained embedded systems, emphasizing precision threshold stability, ultra-low quiescent current, and dual-output flexibility for mixed-logic environments.

FAQ

What is the function of the NC pin on STM708SDS6F?

Pin 8 is designated NC (no connect) and is internally unconnected. It must remain electrically floating - no routing, soldering, or grounding is permitted. This pin exists solely for mechanical symmetry in the TSSOP8 package and has zero electrical function.

Can STM708SDS6F be used with a 3.3 V system?

Yes - its VCC monitor threshold range (2.88–3.00 V) is specifically designed for 3 V nominal systems, but it operates reliably across VCC = 1.0–5.5 V. At 3.3 V, the supervisor remains fully functional with guaranteed reset assertion and 40 µA supply current; however, the reset will trigger only if VCC drops below 2.88 V.

How does the power-fail comparator interact with the reset outputs?

PFO is asserted low when PFI falls below VPFI (~1.25 V), but this does not directly trigger RST or RST. To generate reset on power-fail, PFO must be externally connected to MR. The supervisor itself does not auto-assert reset based on PFI - it provides only the warning signal.

Is there a version of STM708 with watchdog functionality?

No - STM708 variants (T/S/R) exclude watchdog circuitry entirely. The STM706 series (e.g., STM706SDS6F) provides identical reset and PFI/PFO features plus WDI/WDO pins and 1.6 s watchdog timer. Selection depends strictly on whether software hang detection is required.