STMicroelectronics STM819LDS6F

Overview

STM819LDS6F from STMicroelectronics is a 5 V industrial-grade microprocessor supervisor IC with integrated battery switchover, active-low and active-high reset outputs (RST/RST), manual reset input (MR), power-fail comparator (PFI/PFO), and battery freshness seal - designed for non-volatile SRAM backup in embedded systems requiring reliable power monitoring and fail-safe reset assertion down to VCC = 1.0 V.

For engineers reviewing the STM819LDS6F datasheet, STM819LDS6F pinout, STM819LDS6F application, or STM819LDS6F equivalent, this device delivers deterministic reset timing (200 ms trec), low quiescent current (40 µA typ), battery backup current as low as 0.4 µA, and guaranteed RST assertion during brownout - critical for industrial control, metering, and data-logging systems with external LPSRAM.

Technical Context

The STM819LDS6F implements dual-reset architecture with push-pull RST and RST outputs, enabling simultaneous reset signaling to multiple voltage domains or legacy-compatible logic families. Its precision reset comparator monitors VCC against a 4.65 V threshold (±1.5% accuracy) and asserts reset within 10 µs of threshold violation.

It integrates a dedicated MR input with internal 40 kΩ pull-up, supporting momentary switch-based manual reset without external components. Unlike watchdog-equipped variants (e.g., STM817), STM819 lacks WDI functionality - confirmed by datasheet Section 2.3 and Figure 2 - simplifying system-level watchdog management while retaining full power-fail detection via PFI/PFO with 2.4 V threshold and 10 µs response time.

Key Specifications

Pinout & Package

STM819LDS6F is housed in an 8-pin SO8 (Small Outline) package per JEDEC MS-012, with 1.27 mm pitch, gull-wing leads, and RoHS-compliant lead-free finish. Thermal resistance θJA = 150 °C/W supports operation up to +85 °C ambient without forced airflow.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM809LDS6F and MAX809TRD3T, STM819LDS6F uniquely combines dual-reset signaling, manual reset, power-fail detection, and battery freshness seal in a single SO8 package - making it the only option among the three that fully supports robust LPSRAM backup in industrial data retention systems.

Availability

STM819LDS6F is available at Aetrix Electronics and suitable for smart metering, industrial PLCs, medical data loggers, and building automation controllers requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.

Supply support for STM819LDS6F 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.

STM819 belongs to ST's legacy supervisor product line targeting industrial-grade power monitoring and reset generation for systems using external low-power SRAM - emphasizing reliability, low quiescent current, and extended temperature operation.

FAQ

Does STM819LDS6F include a watchdog timer?

No. STM819LDS6F does not incorporate a watchdog timer - this function is explicitly excluded per datasheet Section 2.3 and Figure 2, which confirm "WDI not available on STM703/704/819". The device relies on external MCU or system-level watchdog supervision, simplifying timing-critical design while retaining full reset, power-fail, and battery switchover functionality.

What is the purpose of the battery freshness seal in STM819LDS6F?

The battery freshness seal prevents initial discharge of the backup battery during storage and shipment. It remains inactive until VCC first exceeds the reset threshold (4.65 V), at which point the internal circuitry enables VBAT connection to VOUT. This extends shelf life of coin-cell batteries by eliminating standby current draw prior to system deployment - critical for metering and industrial products with multi-year logistics chains.

Can STM819LDS6F drive both 3.3 V and 5 V logic inputs simultaneously?

Yes. STM819LDS6F provides both active-low RST and active-high RST push-pull outputs referenced to VOUT (which tracks VCC or VBAT). When VCC = 5 V, RST swings 0–5 V and RST swings 0–5 V, enabling direct interfacing with 5 V MCUs and 3.3 V peripherals via level-shifting resistors or compatible input thresholds - confirmed by absolute maximum ratings and DC characteristics tables in the datasheet.

How does the power-fail comparator (PFI/PFO) interact with the reset function?

The PFI/PFO comparator operates independently of the reset generator: PFO asserts low when PFI < 2.4 V or VCC falls below switchover voltage (VSO), but this does not trigger RST/RST. Instead, PFO serves as an early warning signal - allowing firmware to initiate data save routines before VCC crosses the 4.65 V reset threshold. This two-stage alert mechanism prevents data loss during gradual power decay, as verified in Figure 13 and Section 2.8 of the datasheet.