STMicroelectronics STM708M6E

Overview

STM708M6E from STMicroelectronics is a 5 V precision voltage supervisor IC with dual reset outputs (active-low RST and active-high RST), power-fail comparator (PFI/PFO), manual reset input (MR), and no watchdog timer. It asserts reset for VCC < 4.25 V (typical threshold 4.375 V), guarantees RST assertion down to VCC = 1.0 V, and features 200 ms typical reset timeout (trec). It is used in industrial microcontroller systems requiring reliable power-on and brownout reset control.

For engineers reviewing the STM708M6E datasheet, STM708M6E pinout, STM708M6E application, or STM708M6E equivalent, key selection considerations include its dual-polarity reset outputs, absence of watchdog functionality (vs. STM705/706), precise 4.25–4.50 V reset threshold range, and compatibility with bidirectional MCU reset pins via series resistor isolation.

Technical Context

The STM708 is a dedicated voltage supervisor with two independent reset outputs: an open-drain or push-pull active-low RST and a push-pull active-high RST. Its internal precision comparator monitors VCC against a fixed 4.25–4.50 V threshold, with guaranteed reset assertion down to VCC = 1.0 V at industrial temperatures (–40 °C to +85 °C).

It integrates a power-fail comparator (VPFI = 1.25 V ±1.5%) with separate PFI input and push-pull PFO output, plus a manual reset input (MR) with internal 40 kΩ pull-up. Unlike STM705/706/813L, it omits watchdog circuitry - confirmed by device summary Table 1 and logic diagram Figure 2.

Key Specifications

Pinout & Package

STM708M6E is housed in an 8-pin TSSOP package (3 mm × 3 mm body, 0.65 mm pitch), per ST's mechanical data Table 8 and Figure 6. Pin functions are validated from datasheet Section 2 ("Pin descriptions") and Figure 6 (TSSOP8 connections).

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM706M6F, STM708M6E removes watchdog overhead for simpler firmware; compared with MAX692CPA+, it adds PFI/PFO and dual RST outputs at no pin-count penalty - making it optimal for new industrial designs requiring robust, feature-complete supervision.

Availability

STM708M6E is available at Aetrix Electronics and suitable for industrial automation controllers, medical diagnostic instruments, automotive body control modules, and point-of-sale terminals requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for STM708M6E 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The STM70x family targets cost-effective, high-reliability power supervision in resource-constrained embedded systems - emphasizing precision threshold accuracy, guaranteed low-VCC reset behavior, and minimal external component count.

FAQ

Does STM708M6E include a watchdog timer?

No. STM708M6E does not incorporate a watchdog timer - confirmed by device summary Table 1 (no "√" in WDI/WDO columns) and logic diagram Figure 2. This distinguishes it from STM705/706/813L variants. Watchdog functionality must be implemented externally or via MCU peripherals if required.

What is the function of the NC pin on STM708M6E?

Pin 3 is designated NC (No Connect) per datasheet Table 3 and Figure 6. It is internally unconnected and must remain floating - no routing, termination, or grounding is permitted. This pin exists for package compatibility across the STM70x family but carries no electrical function in STM708.

Can STM708M6E drive both RST and RST simultaneously into the same microcontroller?

No - driving both outputs into one MCU reset pin causes signal contention. The datasheet explicitly recommends isolating each output with a 4.7 kΩ series resistor when interfacing with bidirectional reset I/O (Section 3.7, Figure 11). RST and RST serve distinct logic families or subsystems, not redundant paths to the same pin.

How is the power-fail comparator (PFI/PFO) calibrated and used in practice?

PFI compares applied voltage against a factory-trimmed 1.25 V ±1.5% internal reference (VPFI). In practice, PFI connects to a resistor divider from the main supply rail so that PFI voltage crosses 1.25 V ~5–15 ms before VCC drops below 4.25 V. PFO then pulls low to trigger firmware save routines or auxiliary shutdown logic - verified in Figure 9 and Section 3.5.