STMicroelectronics STM6779TWB6F

Overview

STM6779TWB6F 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 open-drain active-low 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 portable systems and networking equipment requiring reliable multi-rail power sequencing and reset control.

For engineers reviewing the STM6779TWB6F datasheet, STM6779TWB6F pinout, STM6779TWB6F application, or STM6779TWB6F equivalent, key selection criteria include its dual fixed-threshold monitoring (VCC1/VCC2), 0.626 V internal reference for RSTIN, MRC-based manual reset delay support, SOT23-6 open-drain output configuration, and guaranteed RST state down to VCC ≥ 0.8 V.

Technical Context

The STM6779TWB6F implements three independent voltage monitoring paths: VCC1 (factory-trimmed threshold from 4.63 V to 1.58 V), VCC2 (factory-trimmed 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 block that asserts RST low if any monitored rail falls below its threshold or MR is pulled low.

It integrates a programmable manual reset delay via the MRC pin-capacitor-connected to VSS-enabling delay times from 6 µs up to ~4 s (e.g., 3.3 µF yields ~4 s). The open-drain RST output requires an external pull-up to VCC1 and remains valid as long as VCC1 or VCC2 ≥ 0.8 V, ensuring robust reset assertion during brownout conditions.

Key Specifications

Pinout & Package

SOT23-6 (WB) package: 6-pin surface-mount, 1.3 mm × 2.9 mm footprint, 1.45 mm height, lead pitch 0.95 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM6779TWB6F, TPS3808G33DBVR omits VCC2/RSTIN monitoring and MRC delay, limiting it to single-rail use; MAX6816EUT+T provides no voltage supervision at all and serves only as an MR input conditioner - neither matches the triple-monitoring, capacitor-delayed reset functionality required for complex multi-rail systems.

Availability

STM6779TWB6F is available at Aetrix Electronics and suitable for industrial gateways, portable medical devices, set-top boxes, and wireless access points requiring stable component supply across extended production lifecycles.

Supply support for STM6779TWB6F 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 sensing solutions for industrial, automotive, and consumer markets.

The STM67xx family was developed specifically for ultra-low-power, multi-rail power supervision in space-constrained portable and networking equipment - emphasizing factory-trimmed accuracy, guaranteed reset behavior at low VCC, and integrated manual reset delay.

FAQ

What is the function of the MRC pin on STM6779TWB6F?

The MRC pin enables capacitor-programmable delay of the manual reset response. When a capacitor is connected between MRC and VSS, pressing the MR button initiates RST assertion only after the capacitor charges to threshold - providing adjustable hold time from 6 µs to several seconds. No internal delay circuitry is active if MRC is left floating.

Does STM6779TWB6F require an external pull-up resistor on the RST pin?

Yes. STM6779TWB6F features an open-drain RST output and requires an external pull-up resistor to VCC1. A 10 kΩ resistor is recommended for most applications; value selection balances rise time and power consumption. Unlike push-pull variants, this configuration supports wired-OR reset bus architectures.

Can STM6779TWB6F monitor a 1.8 V supply as VCC2?

Yes. VCC2 thresholds are factory-programmed and include 1.8 V among standard options (range: 3.08 V to 0.79 V). The exact threshold is laser-trimmed during production and marked on the device; ordering code suffixes indicate selected VCC2 threshold - confirm via ST's ordering information table (Doc ID 11469 Rev 8, Table 11).

How does STM6779TWB6F ensure valid reset output during brownout?

STM6779TWB6F guarantees correct RST logic state (low or high-impedance) whenever VCC1 or VCC2 ≥ 0.8 V. This is achieved through internal low-VCC biasing and comparator design - enabling reliable reset assertion even as supplies dip below nominal levels, unlike supervisors requiring ≥ 1.2 V for functional operation.