STMicroelectronics STM6779SWB6F

Overview

STM6779SWB6F from STMicroelectronics is a triple ultra-low-voltage supervisor IC with push-button reset and delayed manual reset capability. It monitors primary (VCC1), secondary (VCC2), and adjustable tertiary (RSTIN) supply rails, features active-low open-drain RST output, 11 µA typical supply current at 3.6 V, and operates from –40 °C to +85 °C. It is used in battery-powered networking equipment for reliable power-on and brownout detection.

For engineers reviewing the STM6779SWB6F datasheet, STM6779SWB6F pinout, STM6779SWB6F application, or STM6779SWB6F equivalent, key selection criteria include its dual fixed-threshold monitoring (VCC1/VCC2), 0.626 V internal reference for RSTIN, MRC-based manual reset delay, SOT23-6 open-drain output configuration, and industrial-grade temperature range.

Technical Context

The STM6779SWB6F implements three independent voltage monitoring paths: VCC1 (factory-trimmed threshold from 4.63 V to 1.58 V), VCC2 (fixed threshold from 3.08 V to 0.79 V), and RSTIN (comparing external voltage against 0.626 V internal reference). All three comparators feed into a logic-controlled reset generator with guaranteed trec delay.

Its MRC pin enables user-configurable manual reset delay via external capacitor-6 µs minimum (MRC open) up to seconds (e.g., ~4 s with 3.3 µF)-while maintaining guaranteed RST assertion state down to VCC1 ≥ 0.8 V. The open-drain RST output requires an external pull-up to VCC1 and supports bi-directional processor reset interfaces.

Key Specifications

Pinout & Package

SOT23-6 (WB) package: 6-pin surface-mount, 1.3 mm × 2.9 mm footprint, 1.45 mm height, lead-free and RoHS compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM6779SWB6F, STM6780SWB6F provides identical feature set with different factory-set thresholds-enabling direct substitution when voltage trip points align-while TPS3808G33DBVR reduces cost and power but sacrifices multi-rail supervision and manual reset delay flexibility.

Availability

STM6779SWB6F is available at Aetrix Electronics and suitable for networking gateways, portable VoIP phones, industrial IoT controllers, and set-top boxes requiring stable component supply across extended product lifecycles.

Supply support for STM6779SWB6F 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, delivering silicon solutions for automotive, industrial, and consumer markets since 1987.

The STM67xx family was designed specifically for ultra-low-power, multi-rail supervision in space-constrained, battery-sensitive applications-including set-top boxes, portable communications, and embedded networking equipment.

FAQ

What is the function of the MRC pin on STM6779SWB6F?

The MRC (Manual Reset Capacitor) pin enables user-defined delay of the manual reset signal initiated at the MR pin. When connected to VSS via an external capacitor, it introduces a programmable delay-ranging from 6 µs (open) to several seconds (e.g., 3.3 µF yields ~4 s)-before RST asserts. This prevents spurious resets from momentary button presses and eliminates need for external timing circuitry.

Can STM6779SWB6F monitor a 1.0 V supply rail?

Yes. The RSTIN pin uses a 0.626 V internal reference voltage, allowing precise monitoring of sub-1 V rails via an external resistor divider. For example, to monitor a 1.0 V rail, use R1 = 590 kΩ and R2 = 1 MΩ to scale the rail down to 0.626 V at RSTIN. The device guarantees comparator accuracy over –40 °C to +85 °C with ±1.5% threshold tolerance.

Is an external pull-up resistor required for the RST output?

Yes. STM6779SWB6F features an active-low open-drain RST output, which requires an external pull-up resistor to VCC1. A 10 kΩ resistor is recommended for most applications. Without it, RST cannot drive high and will remain floating or weakly pulled low, preventing proper reset release to downstream processors or FPGAs.

How does STM6779SWB6F ensure reset validity during brownout?

STM6779SWB6F guarantees correct RST logic state (driven low or high-impedant) whenever VCC1 or VCC2 ≥ 0.8 V. This ensures deterministic reset behavior even during deep brownout conditions-critical for avoiding undefined processor states. Unlike many supervisors that fail silently below 1.2 V, this IC maintains functional supervision down to 0.8 V, verified across temperature and process corners.