STMicroelectronics STM32L021K4T6

Overview

STM32L021K4T6 from STMicroelectronics is an ultra-low-power 32-bit Arm® Cortex®-M0+ microcontroller in UFQFPN32 (5 × 5 mm) package, featuring 16 KB Flash with ECC, 2 KB SRAM, 512 B EEPROM, 12-bit ADC (1.14 Msps), AES-128 hardware encryption, and operating down to 1.65 V across –40 to +125 °C. It targets battery-powered sensor nodes, smart meters, and wearable medical devices requiring sub-µA standby current (0.23 µA) and fast wakeup (5 µs).

For engineers reviewing the STM32L021K4T6 datasheet, STM32L021K4T6 pinout, STM32L021K4T6 application, or STM32L021K4T6 equivalent, key selection criteria include verified ultra-low-power mode current (0.23 µA Standby), 16 KB Flash with ECC integrity, 512 B EEPROM endurance (100k cycles), 12-bit ADC accuracy (±1.5 LSB INL), and hardware AES acceleration for secure firmware updates.

Technical Context

The STM32L021K4T6 integrates a single-core Arm Cortex-M0+ running up to 32 MHz with 0.95 DMIPS/MHz performance, supported by multiple clock sources: 32 kHz LSE for RTC, 16 MHz HSI16 (±1% factory-trimmed), and multispeed MSI (65 kHz–4.2 MHz). Its power architecture includes five BOR thresholds, programmable voltage detector (PVD), and dynamic voltage scaling for optimized active/low-power tradeoffs.

Peripheral interconnect uses a dedicated AHB/APB matrix enabling concurrent DMA transfers to ADC, USART, SPI, I²C, timers, and AES engine. The device supports true low-power operation: Stop mode with RTC + 2 KB RAM retention draws only 0.54 µA, and wakeup from Stop occurs in ≤5 µs via 16 configurable wakeup lines or two dedicated wakeup pins.

Key Specifications

Pinout & Package

STM32L021K4T6 is housed in a 32-pin UFQFPN (5 × 5 mm, 0.5 mm pitch) RoHS-compliant ECOPACK®2 package, optimized for space-constrained PCB layouts and thermal performance in compact battery-powered designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-power MCU applications.

Compared with STM32L021K4T6, STM32L011K4T6 trades EEPROM and memory for lower cost in minimal-feature deployments, while STM32L031K4T6 extends RAM headroom for richer firmware without changing pinout or power profile.

Availability

STM32L021K4T6 is available at Aetrix Electronics and suitable for smart utility metering, wearable health monitors, industrial wireless sensor nodes, and asset tracking beacons requiring stable component supply across automotive-grade temperature ranges and long-life battery operation.

Supply support for STM32L021K4T6 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 microcontrollers, power management ICs, sensors, and analog products for industrial, automotive, and consumer markets.

The STM32L0 Access line targets cost-sensitive, ultra-low-power applications demanding robustness, security, and longevity - delivering certified Arm Cortex-M0+ performance with integrated ECC, AES, and sub-µA power modes.

FAQ

Does STM32L021K4T6 support USB connectivity?

No, STM32L021K4T6 does not integrate a USB physical layer. While pins PA11 and PA12 are labeled USB_DM/DP in the generic pinout table, they are not functional for USB on this variant - the device lacks the required USB transceiver and associated registers. For USB-capable alternatives, consider STM32L053 or STM32L073 series.

What is the maximum ADC sampling rate with full 12-bit resolution?

The STM32L021K4T6 achieves 1.14 Msps (1,140,000 samples per second) at 12-bit resolution under typical conditions (VDD = 3.3 V, f_ADC = 16 MHz). This rate is maintained across the full 1.65–3.6 V supply range, with INL specified as ±1.5 LSB and ENOB of 11.2 bits at 10 kHz input frequency.

How is the 512 B EEPROM implemented and what is its endurance?

The 512 B EEPROM is implemented as a dedicated memory block with built-in ECC protection, rated for 100,000 write/erase cycles and 40-year data retention at 55 °C. It operates independently of Flash and supports byte-level writes, enabling reliable storage of calibration data, device IDs, and security keys without wear-leveling firmware overhead.

Can the STM32L021K4T6 operate reliably at 125 °C junction temperature?

Yes, STM32L021K4T6 is qualified for operation from –40 to +125 °C ambient temperature, with full specification compliance including Flash programming, EEPROM access, ADC accuracy, and ultra-low-power mode currents. Thermal derating is not required up to 125 °C, and the device maintains 0.54 µA Stop+RTC+2KB RAM current at maximum temperature.