STMicroelectronics SN250QT

Overview

SN250QT from STMicroelectronics is a single-chip ZigBee®/IEEE 802.15.4 SoC integrating a 2.4GHz transceiver, 16-bit XAP2b microprocessor, 128KB Flash, 5KB SRAM, and hardware-accelerated AES encryption. It delivers −97 dBm RX sensitivity (1% PER), +3 dBm nominal TX power, and deep-sleep current of 1.0 µA - enabling battery-powered wireless sensor nodes for home automation and asset tracking.

For engineers reviewing the SN250QT datasheet, SN250QT pinout, SN250QT application, or SN250QT equivalent, this page provides verified technical context on its low-IF radio architecture, integrated MAC offload, dual serial controllers with DMA, 17 GPIOs with alternate functions, and hardware debug via SIF - all critical for ZigBee stack integration and ultra-low-power system design.

Technical Context

The SN250QT implements a low-IF super-heterodyne receiver with differential RF paths, integrated VCO/loop filter, and digital calibration logic - enabling coexistence with 802.11g/Bluetooth in the 2.4GHz ISM band. Its hardware MAC handles ACK generation, clear-channel assessment, automatic backoff, and packet filtering to meet IEEE 802.15.4-2003 timing constraints.

The XAP2b CPU operates in two privilege modes: System Mode (full chip access for ZNet stack) and Application Mode (restricted memory/register access for user code), enforcing runtime stability. Clocking supports 24MHz crystal (±20ppm), optional 32.768kHz crystal, and internal RC oscillator - with dedicated 1.8V supplies for RF, core, flash, and analog blocks.

Key Specifications

Pinout & Package

SN250QT uses a 48-pin QFN package (7 mm × 7 mm, 0.5 mm pitch) with exposed thermal pad (Pin 49). Pin functions are configurable via GPIO_CFG register; multiple peripherals share pins through software-selectable alternate functions.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ZigBee SoC applications.

Compared with EM357-RTR and CC2530F256, SN250QT uniquely integrates a voltage regulator, boost-mode RF tuning, and non-intrusive SIF debug - making it optimal for compact, battery-constrained, and protocol-debug-intensive ZigBee designs where supply simplicity and development velocity are prioritized.

Availability

SN250QT is available at Aetrix Electronics and suitable for home automation sensor nodes, industrial asset trackers, smart lighting controls, and building energy monitors requiring stable component supply across multi-year production cycles.

Supply support for SN250QT 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, specializing in microcontrollers, power management, and wireless solutions for industrial and consumer markets.

SN250QT belongs to ST's ZigBee SoC product line, designed specifically to integrate radio, processing, memory, and security into a single low-power device for standards-compliant mesh networking in resource-constrained endpoints.

FAQ

Does SN250QT require an external 24MHz crystal?

Yes - the SN250QT requires a 24MHz crystal connected to OSCA/OSCB pins for primary system clock generation. The crystal must meet ±20ppm tolerance and use recommended load capacitance per ST's reference design. An external clock signal may substitute, but crystal operation is mandatory for ZigBee timing compliance and RF stability.

Can SN250QT operate without the 32.768kHz crystal?

Yes - the 32.768kHz crystal on OSC32A/OSC32B is optional. When omitted, the internal RC oscillator provides sleep timer functionality with ±5% accuracy. For applications requiring precise timekeeping (e.g., scheduled wake-up within ±100 ppm), the external crystal must be installed and enabled via register configuration.

What debug interfaces does SN250QT support?

SN250QT supports only the non-intrusive Serial Interface (SIF) - using SIF_CLK, SIF_MOSI, SIF_MISO, and nSIF_LOADB pins. It does not support JTAG or SWD. SIF enables full-speed programming, real-time register inspection, and Packet Trace Interface (PTI) streaming without halting the XAP2b core - essential for debugging time-critical ZigBee protocol behavior.

Is the AES accelerator usable outside the ZNet stack?

Yes - the hardware AES module is accessible via memory-mapped registers and can be invoked directly by application firmware for custom encryption/decryption tasks. It supports ECB, CBC, and CTR modes with 128-bit keys. Usage requires explicit initialization and key loading; no ZNet stack dependency exists for basic AES operations.