STMicroelectronics STM1818RWX7F

Overview

STM1818RWX7F from STMicroelectronics is a low-power, open-drain active-low reset supervisor IC with manual reset detect functionality, designed for monitoring 3.3 V/3.0 V supply rails in microcontroller-based systems. It features a factory-trimmed 3.06 V reset threshold (±2.5% accuracy), 100 ms minimum reset pulse width, 4 µA typical supply current, and guaranteed operation down to VCC = 1.0 V over –40 °C to +105 °C. It is used in portable embedded systems requiring reliable power-on reset and user-initiated recovery.

For engineers reviewing the STM1818RWX7F datasheet, STM1818RWX7F pinout, STM1818RWX7F application, or STM1818RWX7F equivalent, key selection criteria include its bidirectional RST pin with 1.5 µs manual reset detection, internal 5.5 kΩ pull-up resistor, SOT23-3 package compatibility, and immunity to sub-20 µs VCC transients - critical for robust MCU supervision in space-constrained industrial and consumer designs.

Technical Context

The STM1818RWX7F implements a precision voltage comparator with a factory-trimmed 3.06 V threshold and hysteresis-free monitoring, coupled with a trec timer that enforces ≥100 ms reset assertion after VCC recovery or manual RST pin activation. Its reset logic is fully autonomous - no external components required for basic supervision.

Unlike push-pull variants, the device uses an open-drain RST output with integrated 5.5 kΩ pull-up to VCC, enabling direct interface with bidirectional MCU reset pins and supporting manual reset initiation via external switch debouncing. The 1.5 µs minimum low pulse on RST triggers a full 100 ms reset cycle, independent of VCC level as long as VCC ≥ 1.0 V.

Key Specifications

Pinout & Package

STM1818RWX7F is housed in a 3-pin SOT23-3 (WX) package - compact, surface-mount, and RoHS-compliant - with pin 1 designated as RST, pin 2 as VCC, and pin 3 as VSS.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX809TRD3T and TPS3808G30DBVR, STM1818RWX7F uniquely integrates manual reset detection, internal pull-up, and precise 3.06 V threshold in SOT23-3 - delivering lower system-level BOM cost, smaller footprint, and faster field-service recovery without compromising brownout immunity or temperature stability.

Availability

STM1818RWX7F is available at Aetrix Electronics and suitable for industrial PLC I/O modules, portable medical monitors, smart energy meters, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for STM1818RWX7F 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 specializing in power management, microcontrollers, and analog ICs, with strong focus on industrial, automotive, and embedded applications.

STM181x is ST's low-power reset supervisor product line, engineered specifically for reliable power-on, brownout, and manual reset generation in resource-constrained microcontroller systems - emphasizing precision, ultra-low IQ, and minimal external component count.

FAQ

What is the exact reset threshold voltage for STM1818RWX7F?

The STM1818RWX7F has a factory-trimmed nominal reset threshold of 3.06 V, with ±2.5% accuracy guaranteed over the full –40 °C to +105 °C operating temperature range. This value is confirmed in Table 6 and Section 1.2.4 of the official STMicroelectronics datasheet (Doc ID11464 Rev 8), and applies specifically to the STM1818 variant within the STM181x family.

Does STM1818RWX7F require an external pull-up resistor on the RST pin?

No. STM1818RWX7F includes an internal 5.5 kΩ pull-up resistor from RST to VCC, as explicitly stated in Section 1.2.4 and Figure 6 of the datasheet. This eliminates the need for an external pull-up component, simplifying design and reducing PCB area - a key differentiator versus alternatives like MAX809 or TPS3808.

How does the manual reset detection work on STM1818RWX7F?

The RST pin functions bidirectionally: it outputs active-low reset and accepts manual reset input. When externally pulled low for ≥1.5 µs, the device asserts a full 100 ms reset pulse - with built-in debounce to reject mechanical switch bounce. This behavior is documented in Sections 2.2 and Figure 9 of the datasheet and requires no external timing components.

Can STM1818RWX7F operate reliably during severe VCC transients?

Yes. STM1818RWX7F is designed to ignore negative-going VCC transients ≤20 µs in duration when the overdrive is ≤100 mV below the reset threshold, as shown in Figure 19 of the datasheet. This immunity is achieved through internal comparator hysteresis and filtering, ensuring no false resets during switching noise or load dump events in industrial or automotive environments.