STMicroelectronics STM690TM6E

Overview

STM690TM6E from STMicroelectronics is a 3 V industrial-grade microprocessor supervisor IC with integrated battery switchover, dual reset outputs (active-low RST and active-high RST), manual reset input (MR), watchdog timer (1.6 s typ), and power-fail comparator (PFI/PFO). It guarantees RST assertion down to VCC = 1.0 V and supports external LPSRAM non-volatilization in embedded systems requiring reliable power monitoring and backup switching.

For engineers reviewing the STM690TM6E datasheet, STM690TM6E pinout, STM690TM6E application, or STM690TM6E equivalent, this device serves as a precision voltage-monitoring supervisor for MCU reset control, SRAM backup management, and early power-fail warning - with confirmed parameters including 200 ms typical reset timeout (trec), 0.4 µA battery supply current, and –40 °C to +85 °C operating range.

Technical Context

The STM690TM6E implements a precision voltage reference and comparator to monitor VCC against a fixed reset threshold (VRST); it asserts RST/RST when VCC falls below VRST, MR is pulled low, or the watchdog times out. Its internal trec generator ensures minimum 200 ms reset pulse width after any trigger event.

Battery switchover is managed via a P-channel MOSFET switch between VCC and VBAT, routing supply to VOUT based on VCC vs. VSW (2.4 V) comparison. The PFI/PFO comparator provides early power-fail detection independent of VCC monitoring, with push-pull PFO output and 1.5 µs typical propagation delay.

Key Specifications

Pinout & Package

STM690TM6E is housed in an 8-pin SO8 (Small Outline) package (ECOPACK® compliant, RoHS-compliant), with 1.27 mm pitch and standard JEDEC MS-012AC footprint. Pin 1 is PFO; pin 8 is VBAT. All pins support 3 V operation with internal pull-ups on MR and E inputs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX690EPA+ and TPS3808G33DBVR, STM690TM6E uniquely integrates battery switchover, dual reset polarity, and independent PFI/PFO - enabling single-chip SRAM non-volatilization and predictive power-loss response not achievable with either alternative.

Availability

STM690TM6E is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic devices, smart energy meters, and automotive telematics units requiring stable component supply, long-term lifecycle support, and guaranteed RoHS compliance.

Supply support for STM690TM6E 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, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The STM690 series belongs to ST's precision voltage supervisor product line, engineered specifically for robust power monitoring and SRAM backup control in mission-critical embedded systems operating across extended industrial temperature ranges.

FAQ

What is the function of the VCCSW pin on STM690TM6E?

VCCSW is a push-pull status indicator that goes high when VOUT switches from VCC to VBAT, and low when VOUT reverts to VCC. It is designed to drive the gate of an external PMOS transistor, enabling higher output current (>75 mA) for SRAM backup rails where the internal switch is insufficient.

Can STM690TM6E operate without a backup battery connected?

Yes - VBAT and VOUT can both be tied to VCC if no battery backup is required. In this configuration, the device functions as a standard 3 V supervisor with RST/RST, MR, WDI, and PFI/PFO functionality, while maintaining full reset timing and power-fail detection capabilities.

How does the watchdog timer interact with the manual reset input (MR)?

When MR is asserted (low), the watchdog timer is disabled and reset is immediately triggered. The timer remains inactive until MR returns high and VCC stabilizes above VRST; only then does it resume counting. This prevents spurious timeouts during intentional manual resets.

Is the PFI input internally biased, and what happens if left unconnected?

PFI has no internal bias and must be actively driven or grounded. If left floating, unpredictable PFO behavior may occur due to noise coupling. ST recommends connecting PFI to ground when unused to ensure PFO remains high and avoids false power-fail assertions.