STMicroelectronics STM1816RWX7F

Overview

STM1816RWX7F from STMicroelectronics is an open-drain, active-low reset supervisor IC designed for 3.3 V/3.0 V power supply monitoring in microcontroller 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 to prevent code-execution errors during brownout and power-up sequences.

For engineers reviewing the STM1816RWX7F datasheet, STM1816RWX7F pinout, STM1816RWX7F application, or STM1816RWX7F equivalent, key selection criteria include its open-drain RST output with internal 5.5 kΩ pull-up, manual-reset compatibility with bidirectional MCU pins, immunity to sub-20 µs VCC transients, and SOT23-3 footprint compatibility with DS181x/MXD181x families.

Technical Context

The STM1816RWX7F implements a precision voltage comparator with a factory-trimmed 3.06 V reference, monitoring VCC and asserting an active-low reset signal when supply drops below threshold. Its reset timer guarantees ≥100 ms assertion after VCC recovery, with no external components required.

As an open-drain device with integrated 5.5 kΩ pull-up to VCC, it directly interfaces with bidirectional MCU reset pins without external biasing. Its reset comparator is immune to negative-going VCC transients ≤20 µs at 100 mV overdrive, and remains functional down to VCC = 1.0 V across full industrial temperature range.

Key Specifications

Pinout & Package

STM1816RWX7F is housed in a 3-pin SOT23-3 (WX) package - a surface-mount, space-constrained outline measuring 2.9 mm × 1.3 mm × 1.0 mm, optimized for high-density PCB layouts in portable electronics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM1816RWX7F, MAX809TRD3T reduces current draw but adds BOM cost and layout area for the pull-up resistor; TPS3808G30DBVR offers superior accuracy and flexibility at the expense of package size and design complexity.

Availability

STM1816RWX7F is available at Aetrix Electronics and suitable for industrial PLC I/O modules, portable medical monitors, automotive body control units, and smart home sensor hubs requiring stable component supply and long-term lifecycle support.

Supply support for STM1816RWX7F 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, specializing in microcontrollers, power management, and analog/mixed-signal ICs for industrial, automotive, and consumer markets.

The STM181x series was developed specifically as low-power, precision reset supervisors for microcontroller-based systems operating at 3.0 V, 3.3 V, and 5 V - prioritizing accuracy, transient immunity, and minimal footprint in space-constrained designs.

FAQ

What is the function of the internal 5.5 kΩ pull-up resistor on the RST pin?

The internal 5.5 kΩ pull-up resistor connects RST to VCC, enabling direct interfacing with bidirectional MCU reset pins without external components. It ensures the RST line defaults high when not actively driven low, supporting systems where the MCU may also drive the reset line - eliminating risk of contention and reducing BOM count.

Can STM1816RWX7F operate reliably during fast VCC transients?

Yes - the device rejects negative-going VCC transients ≤20 µs in duration when the overdrive is ≤100 mV below the 3.06 V threshold. This immunity is achieved through comparator hysteresis and internal filtering, preventing false resets caused by switching noise or load-dump events in industrial and automotive power domains.

Is an external pull-down resistor required for operation below 1.0 V VCC?

No - unlike push-pull variants, STM1816RWX7F's open-drain output naturally floats high when VCC < 1.0 V and cannot sink current. If system-level logic requires forced low state below 1.0 V, a 100 kΩ external pull-down to ground may be added, but this is rarely needed since most MCUs cease operation below 1.0 V.

How does STM1816RWX7F differ from STM1813/STM1818 in manual reset capability?

STM1816RWX7F lacks manual reset detect functionality - it only responds to VCC threshold violations. In contrast, STM1813/STM1818 assert reset when RST is pulled low for >1.5 µs, including debounced mechanical switch inputs. STM1816RWX7F is intended for automatic supervision only, simplifying design where user-initiated reset is handled elsewhere.