Texas Instruments LM3S6938-IQC50-A2T

Overview

LM3S6938-IQC50-A2T from Texas Instruments is a 32-bit ARM Cortex-M3 microcontroller with 256 KB flash, 64 KB SRAM, integrated Ethernet MAC, dual UARTs, I²C, SSI, ADC (10-bit, 8-channel), and hibernation module. It operates at 50 MHz and supports industrial temperature range (–40°C to +85°C) in a 100-pin LQFP package. Used in networked industrial controllers requiring real-time control and wired connectivity.

For engineers reviewing the LM3S6938-IQC50-A2T datasheet, LM3S6938-IQC50-A2T pinout, LM3S6938-IQC50-A2T application, or LM3S6938-IQC50-A2T equivalent, key selection criteria include Ethernet MAC integration, hibernation power management, 50 MHz clock speed, 100-pin LQFP footprint, and Cortex-M3 interrupt latency performance.

Technical Context

The LM3S6938-IQC50-A2T implements the ARMv7-M architecture with NVIC supporting up to 64 interrupt lines, SysTick timer, and MPU for memory protection. Its system-level design includes a dedicated hibernation module with RTC, battery-backed RAM, and wake-on-external-event capability.

Peripherals are tightly coupled via AHB/APB bridges: Ethernet MAC connects directly to AHB for zero-copy DMA transfers; ADC uses hardware sequencers with configurable sample averaging; UARTs support IrDA SIR and FIFO depths of 16 bytes each. Clock tree supports multiple PLL-derived sources including PIOSC, MOSC, and HSE.

Key Specifications

Pinout & Package

LM3S6938-IQC50-A2T is housed in a 100-pin LQFP (Low-Profile Quad Flat Package) with exposed thermal pad, JEDEC MS-026AC compliant, 14 mm × 14 mm body, 0.5 mm lead pitch, and moisture sensitivity level 3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM3S6938-IQC50-A2T, LM3S8962-IQC50-A2T trades Ethernet for CAN and doubles flash, while TM4C123GH6PM offers 60% faster CPU, identical package, and backward-compatible register map - making it the preferred migration path for lifecycle extension.

Availability

LM3S6938-IQC50-A2T is available at Aetrix Electronics and suitable for industrial PLC controllers, building automation gateways, networked energy meters, and remote I/O nodes requiring stable component supply and long-term obsolescence planning.

Supply support for LM3S6938-IQC50-A2T 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

Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, delivering analog, embedded processing, and wireless technologies since 1930.

The Stellaris LM3S series was designed as the first ARM Cortex-M3-based microcontroller family for industrial and networked embedded applications, emphasizing integrated connectivity and low-power operation.

FAQ

What is the maximum operating frequency of the LM3S6938-IQC50-A2T?

The LM3S6938-IQC50-A2T operates at a maximum frequency of 50 MHz, as specified in its production data sheet. This clock speed is achieved using the internal PLL driven by the main oscillator (MOSC) or precision internal oscillator (PIOSC). The 50 MHz rating applies across the full industrial temperature range (–40°C to +85°C) and ensures deterministic timing for Ethernet MAC, ADC sampling, and interrupt response. LM3S6938-IQC50-A2T does not support overclocking beyond this rated speed.

Does the LM3S6938-IQC50-A2T include an integrated Ethernet physical layer (PHY)?

No, the LM3S6938-IQC50-A2T integrates only the Ethernet Media Access Controller (MAC), not the physical layer (PHY). It provides differential TX/RX pairs (ETH0_TX±, ETH0_RX±) that require connection to an external 10/100BASE-TX PHY IC, such as the DP83848 or LAN8720. The MAC supports MII and RMII interfaces and includes DMA for zero-copy packet handling. LM3S6938-IQC50-A2T relies on external magnetics and PHY for signal conditioning and line driving.

What power modes does the LM3S6938-IQC50-A2T support, and what is its lowest current draw?

The LM3S6938-IQC50-A2T supports Sleep, Deep-Sleep, and Hibernate modes. In Hibernate mode - enabled via the dedicated hibernation module - it draws just 1.7 µA while retaining RTC time, battery-backed RAM contents, and wake capability from external pins or RTC match. This mode uses a separate 32.768 kHz crystal or internal low-frequency oscillator. LM3S6938-IQC50-A2T achieves this ultra-low power state without external supervision circuitry.

How many analog input channels does the ADC in the LM3S6938-IQC50-A2T support?

The LM3S6938-IQC50-A2T features a single 10-bit successive approximation register (SAR) ADC with eight external input channels (ADC0–ADC7), mapped to GPIO pins PA6, PA7, PB0–PB5, and PE3. It supports hardware-configurable sequencers, programmable sample timing, and 4× hardware averaging per conversion. The ADC also includes an internal temperature sensor channel. LM3S6938-IQC50-A2T does not include a second ADC instance or differential input mode beyond the documented single-ended and pseudo-differential configurations.

Is the LM3S6938-IQC50-A2T pin-compatible with any newer Texas Instruments microcontrollers?

The LM3S6938-IQC50-A2T is not pin-compatible with newer TI microcontrollers such as the TM4C123GH6PM, despite sharing the same 100-pin LQFP package and similar peripheral mapping. While TM4C123GH6PM retains Ethernet MAC, adds CAN, and increases clock speed to 80 MHz, its pin functions differ in critical areas including USB routing, clock input configuration, and hibernation control signals. LM3S6938-IQC50-A2T requires board-level redesign for migration; however, software compatibility is high due to shared register layout conventions in StellarisWare and TivaWare.