STMicroelectronics STM690SM6E

Overview

STM690SM6E from STMicroelectronics is a 3 V microprocessor supervisory IC with integrated battery switchover, active-low RST output, manual reset (MR), watchdog timer (1.6 s typ), and power-fail comparator (PFI/PFO). It guarantees reset assertion down to VCC = 1.0 V and delivers <40 µA typical supply current for low-power embedded systems requiring reliable power monitoring and SRAM backup control.

For engineers reviewing the STM690SM6E datasheet, STM690SM6E pinout, STM690SM6E application, or STM690SM6E equivalent, key selection criteria include guaranteed reset at 1.0 V VCC, 200 ms typical reset timeout (trec), automatic VCC-to-VBAT switchover at 2.4 V, 0.4 µA battery supply current, and compatibility with external LPSRAM in industrial temperature range (–40 °C to +85 °C).

Technical Context

The STM690SM6E implements a precision voltage reference and comparator to monitor VCC against a fixed reset threshold (VRST ≈ 2.63 V), asserting RST when VCC drops below VRST or during MR activation. Its internal trec generator ensures minimum 200 ms reset pulse width after power-up or fault recovery.

A dedicated watchdog circuit monitors WDI transitions; absence of edge activity for ≥1.6 s triggers reset. The PFI/PFO comparator provides early power-fail warning by detecting VCC falling below 2.4 V or PFI dropping below VPFI (typically 1.25 V), with push-pull PFO output.

Key Specifications

Pinout & Package

STM690SM6E is housed in an 8-pin SO8 (Small Outline Integrated Circuit) package, measuring 4.9 mm × 3.9 mm × 1.75 mm, with 1.27 mm lead pitch and gull-wing leads compatible with standard reflow soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX690EPA+ and TPS3808G12DBVR, STM690SM6E uniquely integrates battery switchover, watchdog, and dual-mode reset (RST/RST) in one SO8 package-enabling compact, self-contained SRAM supervision without external FETs or timing components.

Availability

STM690SM6E is available at Aetrix Electronics and suitable for industrial PLC I/O modules, smart meter data loggers, medical infusion pump controllers, and automotive telematics ECUs requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for STM690SM6E 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.

STM690SM6E belongs to ST's supervisor IC product line, engineered specifically for robust, low-power microprocessor monitoring and non-volatile SRAM backup in space-constrained industrial and medical systems.

FAQ

What is the function of the Vccsw pin on STM690SM6E?

Vccsw is a push-pull output that goes high when VOUT switches to VBAT (i.e., during battery backup mode) and low when VOUT is sourced from VCC. It is designed to drive the gate of an external PMOS transistor, enabling higher output current (>75 mA) to external LPSRAM when the internal VOUT switch is insufficient.

Can STM690SM6E operate without a backup battery?

Yes. When no battery is used, connect both VBAT and VOUT pins directly to VCC. In this configuration, the device functions as a standard 3 V supervisor with RST, MR, WDI, and PFI/PFO features, while disabling battery switchover logic and maintaining full reset supervision down to VCC = 1.0 V.

Is the watchdog timer on STM690SM6E disableable?

No-the watchdog timer cannot be disabled. It remains active whenever VCC is powered and WDI is not toggled within 1.6 s. Leaving WDI floating will cause continuous reset assertion; it must be actively driven with edges (e.g., from MCU GPIO) or tied to a clock source to prevent unintended resets.

How does the PFI input differ from monitoring VCC directly?

PFI provides an independent analog input referenced to a 1.25 V internal threshold, allowing custom power-fail detection (e.g., monitoring a different rail or using a resistor divider for adjustable trip point), whereas VCC monitoring is fixed at 2.4 V switchover and 2.63 V reset thresholds-enabling dual-layer power integrity validation.