STMicroelectronics STM6778TWWB6F

Overview

STM6778TWWB6F from STMicroelectronics is a dual ultra-low voltage supervisor IC with push-button reset and factory-programmed delay option, monitoring primary supply (VCC1) at 2.93 V and secondary supply (VCC2) at 1.58 V, featuring active-low push-pull RST output, manual reset (MR), and delayed manual reset (MRC) input - used in battery-powered networking equipment to ensure reliable power-on sequencing and brownout recovery.

For engineers reviewing the STM6778TWWB6F datasheet, STM6778TWWB6F pinout, STM6778TWWB6F application, or STM6778TWWB6F equivalent, key selection criteria include dual-supply threshold accuracy (±1.5% over temperature), guaranteed RST state down to VCC ≥ 0.8 V, 13.2/210/900 ms programmable power-up delay options, and SOT23-6 package compatibility with space-constrained embedded designs.

Technical Context

The STM6778 implements independent comparators for VCC1 and VCC2 with factory-trimmed thresholds (2.93 V and 1.58 V respectively), plus logic-controlled reset assertion via MR and MRC inputs. Its internal trec generator provides three fixed delay options (13.2 ms, 210 ms, 900 ms typ) after all monitored supplies exceed thresholds and MR returns high.

Reset output is push-pull active-low, referenced to VCC1, and guaranteed functional when VCC1 or VCC2 ≥ 0.8 V. The MRC pin enables external capacitor-based delay of manual reset initiation (≥6 µs), with typical 4 s delay using 3.3 µF to VSS - supporting user-triggered system recovery without firmware intervention.

Key Specifications

Pinout & Package

SOT23-6 (WB) package - 6-pin surface-mount plastic package with 1.27 mm pitch, 2.9 mm × 1.6 mm footprint, and 1.1 mm max height, optimized for automated assembly and high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6816EUT+T and TPS3808G18DBVR, STM6778TWWB6F uniquely delivers factory-trimmed dual-threshold monitoring, push-pull RST, and capacitor-delayed MR in a single SOT23-6 package - reducing design complexity for multi-rail embedded systems requiring deterministic, hardware-gated reset behavior.

Availability

STM6778TWWB6F is available at Aetrix Electronics and suitable for networking equipment power sequencing, set-top box brownout recovery, and battery-powered IoT gateway designs requiring stable component supply and long-term industrial-grade availability.

Supply support for STM6778TWWB6F 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The STM67xx family targets ultra-low-power, dual-supply supervision in space-constrained portable and networking devices - emphasizing factory-trimmed accuracy, minimal external components, and guaranteed operation across industrial temperature ranges.

FAQ

What is the function of the MRC pin on STM6778TWWB6F?

The MRC (Manual Reset Delay) pin accepts an external capacitor connected to VSS to delay the assertion of the RST output after MR is activated. With a 3.3 µF capacitor, it provides ~4 s delay; minimum delay is 6 µs when MRC is left open. This prevents false resets from mechanical switch bounce and enables timed recovery sequences without firmware involvement.

Can STM6778TWWB6F monitor a 1.2 V supply rail?

No - STM6778TWWB6F has fixed factory-programmed thresholds: VCC1 = 2.93 V and VCC2 = 1.58 V. It cannot monitor 1.2 V directly. For sub-1.5 V rails, use the RSTIN pin (available on STM6779/80 variants) with an external resistor divider referenced to the 0.626 V internal comparator reference.

Is the RST output compatible with 5 V tolerant microcontrollers?

Yes - the push-pull RST output is referenced to VCC1 and sinks/source current within VCC1 range (0.8–5.5 V). When VCC1 = 3.3 V, RST swings fully between 0 V and 3.3 V. For 5 V microcontrollers, ensure the reset pin is 3.3 V tolerant or add a level-shifting buffer; do not connect directly to non-tolerant 5 V inputs.

How does STM6778TWWB6F behave during power-down?

When VCC1 or VCC2 drops below its threshold, RST is immediately driven low. The output remains asserted until both supplies rise above their thresholds AND MR returns high - then trec begins counting. RST state is guaranteed down to VCC ≥ 0.8 V, ensuring clean reset assertion even during deep brownout.