STMicroelectronics STM708TM6E

Overview

STM708TM6E 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 manual reset input (MR). It monitors VCC for out-of-tolerance conditions down to 1.0 V and asserts RST/RST during brownout, watchdog timeout (not applicable to STM708), or MR activation. Used in industrial controllers and embedded systems requiring reliable power-on reset and early power-fail warning.

For engineers reviewing the STM708TM6E datasheet, STM708TM6E pinout, STM708TM6E application, or STM708TM6E equivalent, key selection criteria include reset threshold accuracy (3.00–3.15 V), guaranteed RST assertion down to VCC = 1.0 V, push-pull RST/RST outputs, PFI/PFO undervoltage detection capability, and SO8/TSSOP8 package compatibility with legacy 3 V microcontroller reset interfaces.

Technical Context

The STM708TM6E implements a dual-reset architecture with independent active-low (RST) and active-high (RST) outputs, both asserted simultaneously during VCC undervoltage or MR activation. Its precision bandgap reference drives two comparators: one for VCC monitoring (VRST = 3.00–3.15 V) and another for PFI threshold (VPFI ≈ 1.25 V), enabling independent power-fail detection without sharing the reset comparator.

No internal watchdog timer is present - unlike STM706T/S/R and STM706P, the STM708 series omits WDI/WDO functionality. The device guarantees valid RST output down to VCC = 1.0 V across –40 °C to +85 °C, using internal charge-pump circuitry to maintain logic-level drive capability during deep brownout conditions.

Key Specifications

Pinout & Package

STM708TM6E is available in an 8-pin SOIC (SO8) package with 150 mil body width and standard 1.27 mm pitch. Pin assignments are fully defined per STMicroelectronics DocID10518 Rev 14.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM706TM6F, STM708TM6E trades watchdog capability for reduced pin count and elimination of WDI/WDO routing complexity; versus MAX6326US31D3+, it provides dual-reset polarity and PFI/PFO for advanced power sequencing - making it optimal for systems requiring coordinated reset and predictive power-fail response.

Availability

STM708TM6E is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic instruments, smart energy meters, and automotive body control modules requiring stable component supply with long-term lifecycle assurance.

Supply support for STM708TM6E 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 components for industrial, automotive, and consumer markets.

The STM70x supervisor family targets robust power monitoring in resource-constrained embedded systems, emphasizing precision threshold stability, low power consumption, and dual-output flexibility for heterogeneous reset architectures.

FAQ

What is the function of the NC pin on STM708TM6E?

Pin 7 is a no-connect (NC) terminal with no internal bond wire or circuit connection. It must remain electrically floating and unconnected on the PCB. STMicroelectronics confirms this pin serves no functional purpose and is reserved for future product variants - connecting it to any net may cause undefined behavior or damage.

Can STM708TM6E be used with a 3.3 V microcontroller?

Yes - STM708TM6E is specified for 3 V operation with VRST = 3.00–3.15 V, making it compatible with 3.3 V systems where the supply rail tolerances allow sustained operation above 3.15 V during normal conditions. Its RST/RST outputs are push-pull and fully compatible with 3.3 V logic levels, and guaranteed operation down to VCC = 1.0 V ensures robustness during brownout.

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

The PFI/PFO comparator operates independently of the VCC monitor - VPFI ≈ 1.25 V is fixed and unrelated to VRST. When PFI falls below VPFI, PFO goes low but does not directly assert RST or RST. To trigger reset on power-fail, PFO must be externally connected to MR. This separation allows flexible system-level response: e.g., PFO can generate an interrupt while MR remains unconnected until critical threshold is crossed.

Is there a watchdog timer in STM708TM6E?

No - STM708TM6E does not include a watchdog timer. Unlike STM706T/S/R and STM706P, the STM708 series omits WDI and WDO pins entirely. This is confirmed in the device summary table and block diagram (Figure 2 and Figure 8), which show no watchdog circuitry. Systems requiring watchdog functionality must select STM706T/S/R or STM706P variants instead.