STMicroelectronics STM32L021D4P7

Overview

STM32L021D4P7 from STMicroelectronics is an ultra-low-power 32-bit Arm® Cortex®-M0+ microcontroller in UFQFPN20 (3×3 mm) package, featuring 16 KB Flash, 2 KB SRAM, 512 B EEPROM with ECC, 12-bit ADC (1.14 Msps), and hardware AES-128 encryption. It operates from 1.65 V to 3.6 V across –40 °C to 125 °C and targets battery-powered sensor nodes and smart meters requiring sub-µA standby current (0.23 µA).

For engineers reviewing the STM32L021D4P7 datasheet, STM32L021D4P7 pinout, STM32L021D4P7 application, or STM32L021D4P7 equivalent, key selection criteria include verified ultra-low-power mode timing (5 µs wakeup from Flash), 23 I/Os with 5V tolerance, integrated RTC + backup registers, and dual ultra-low-power comparators with wake-up capability down to 1.65 V.

Technical Context

The STM32L021D4P7 implements a tightly coupled Arm Cortex-M0+ core running at up to 32 MHz, supported by multiple clock sources: factory-trimmed 16 MHz HSI (±1%), 32 kHz LSE for RTC calibration, and multispeed MSI (65 kHz–4.2 MHz). Its power architecture includes five BOR thresholds, programmable PVD, and dynamic voltage scaling enabling optimized current draw per operating mode.

Peripheral interconnect uses a dedicated AHB/APB matrix supporting concurrent DMA transfers across ADC, USART, SPI, I²C, timers, and AES. The device integrates a 7-channel DMA controller with priority arbitration, CRC calculation unit, and 96-bit unique ID - all designed for deterministic real-time execution in constrained energy environments.

Key Specifications

Pinout & Package

STM32L021D4P7 is housed in a 20-pin Ultra Thin Fine Pitch Quad Flat No-lead (UFQFPN20) package, 3 × 3 mm, 0.5 mm pitch, ECOPACK®2 compliant. This compact, leadless package supports high-density PCB layouts and automated reflow assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM32L011D4P7, the STM32L021D4P7 adds 512 B EEPROM and doubles RAM, enabling local data logging without external memory; versus STM32L031F6P7, it trades memory capacity and package type for lower unit cost and smaller board area in space-constrained designs.

Availability

STM32L021D4P7 is available at Aetrix Electronics and suitable for smart utility metering, wireless sensor nodes, industrial asset tracking, and low-power human interface devices requiring stable component supply throughout product lifecycles.

Supply support for STM32L021D4P7 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, MEMS, and automotive semiconductors since 1987.

The STM32L0 series targets ultra-low-power embedded applications demanding extended battery life, robust security, and industrial-grade reliability - with the STM32L021D4P7 optimized for cost-sensitive, space-constrained endpoints in metering and IoT edge nodes.

FAQ

What is the maximum operating frequency of the STM32L021D4P7?

The STM32L021D4P7 runs its Arm Cortex-M0+ core at up to 32 MHz, achievable across the full 1.65–3.6 V supply range and –40 °C to 125 °C temperature range. This frequency is sustained using the 16 MHz HSI oscillator with PLL multiplication or external clock sources, with performance validated per ST's electrical characteristics tables (Section 6.3.8).

Does the STM32L021D4P7 support USB or CAN interfaces?

No, the STM32L021D4P7 does not integrate USB or CAN peripherals. Its communication interfaces are limited to one USART (ISO 7816/IrDA capable), one LPUART, one SPI (16 Mbit/s), and one I²C (SMBus/PMBus). These were selected to minimize silicon area and power consumption for basic connectivity in ultra-low-power endpoints.

How many I/O pins are available in the UFQFPN20 package?

The STM32L021D4P7 in UFQFPN20 provides 18 usable I/O pins: PA0–PA7 (8), PA9–PA15 (7), plus PB0–PB1 (2), and NRST (1). One pin (PA15) serves dual function as Boot0, and PA13/PA14 are reserved for SWD debug - all 23 GPIOs listed in the datasheet are not physically accessible in this 20-pin variant.

Is the 512 B EEPROM truly independent of Flash endurance limits?

Yes, the 512 B data EEPROM is implemented as a separate memory array with dedicated ECC and endurance rated for 100,000 write/erase cycles and 20-year data retention at 85 °C (per Section 6.3.42 of DocID027982 Rev 5). It operates independently of Flash memory, allowing frequent parameter updates without impacting firmware storage longevity.