Texas Instruments LM3S310-IQN25-C2T

Overview

LM3S310-IQN25-C2T from Texas Instruments is a 32-bit ARM Cortex-M3 microcontroller with 25 MHz maximum CPU frequency, 32 KB flash memory, 8 KB SRAM, and integrated peripherals including UART, SSI, PWM, analog comparators, and GPIO. It operates from 3.3 V supply and targets embedded control in industrial sensors, motor drives, and power management systems.

For engineers reviewing the LM3S310-IQN25-C2T datasheet, LM3S310-IQN25-C2T pinout, LM3S310-IQN25-C2T application, or LM3S310-IQN25-C2T equivalent, key selection criteria include its 25 MHz clock rating, QFN-25 package footprint, integrated analog comparator inputs, single UART channel, and absence of ADC or USB interface - critical for resource-constrained real-time control designs.

Technical Context

The LM3S310-IQN25-C2T implements the ARM Cortex-M3 processor core with Thumb-2 instruction set, NVIC interrupt controller, SysTick timer, and MPU for memory protection. It supports sleep modes (sleep/deep-sleep) with wake-up via GPIO, UART, or timer events.

Peripherals include one UART (with FIFO and modem control signals), one SSI (SPI-compatible master/slave), two 16-bit PWM generator blocks (each supporting up to two outputs), and two analog comparators with internal voltage reference. No on-chip ADC, DAC, or USB PHY is present.

Key Specifications

Pinout & Package

The LM3S310-IQN25-C2T is housed in a 4×4 mm, 25-pin QFN package with an exposed thermal pad (EP). Pin count and layout are optimized for minimal PCB area while supporting essential I/O and debug interfaces.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM3S1138-IQN25-C2T and TM4C123GH6PM, the LM3S310-IQN25-C2T delivers minimal-feature real-time control at lowest BOM cost and smallest footprint - ideal where ADC, USB, or high clock speed are unnecessary.

Availability

LM3S310-IQN25-C2T is available at Aetrix Electronics and suitable for industrial sensor nodes, brushless DC motor controllers, power supply monitors, and programmable logic relays requiring stable component supply and long-term obsolescence management.

Supply support for LM3S310-IQN25-C2T 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 leader specializing in analog, embedded processing, and connectivity technologies with decades of industrial and automotive qualification experience.

The Stellaris LM3S series was designed as entry-level ARM Cortex-M3 microcontrollers targeting cost-sensitive, space-constrained embedded control applications where simplicity, reliability, and toolchain maturity were prioritized over feature expansion.

FAQ

What is the maximum operating frequency of the LM3S310-IQN25-C2T?

The LM3S310-IQN25-C2T has a maximum CPU clock frequency of 25 MHz, derived from its internal PLL or direct crystal oscillator input. This rating is validated across the full industrial temperature range (–40°C to +85°C) and 3.0–3.6 V supply. The LM3S310-IQN25-C2T does not support overclocking beyond this specification, and system timing margins for UART baud generation, PWM period accuracy, and GPIO toggle rates are all calculated based on this 25 MHz limit.

Does the LM3S310-IQN25-C2T include an analog-to-digital converter (ADC)?

No, the LM3S310-IQN25-C2T does not integrate an ADC. It features two analog comparators with internal 1.25 V reference and hysteresis control, but lacks sampling circuitry, sample-and-hold, or digital conversion logic. For designs requiring digitized analog signals, external ADCs or migration to variants like LM3S1138-IQN25-C2T (which includes an 8-channel 10-bit ADC) is necessary. The LM3S310-IQN25-C2T's comparator outputs can drive GPIO interrupts or PWM fault inputs directly.

What debug interface does the LM3S310-IQN25-C2T support?

The LM3S310-IQN25-C2T supports both SWD (Serial Wire Debug) and JTAG interfaces via dedicated pins on Port D (PD0–PD3), enabling full-featured debugging with TI's Code Composer Studio or third-party ARM tools. No external debug probe is required beyond standard SWD/JTAG headers, and the interface remains active during all non-shutdown sleep modes. The LM3S310-IQN25-C2T does not require separate debug enable fuses or configuration bits - debug access is enabled by default after reset.

Is the LM3S310-IQN25-C2T pin-compatible with other Stellaris QFN-25 devices?

Yes, the LM3S310-IQN25-C2T shares identical pinout and package dimensions (QFN-25, 4×4 mm) with other LM3Sx10 and LM3Sx38 variants in the same package option, including LM3S1138-IQN25-C2T and LM3S3748-IQN25-C2T. Signal mapping for VDD, GND, RESET, OSC0/OSC1, and primary GPIO ports is consistent. However, alternate function assignments (e.g., SSI vs. UART mapping on PA pins) and peripheral enablement differ - firmware and board layout must verify functional compatibility per device datasheet.

What is the purpose of the exposed thermal pad (EP) on the LM3S310-IQN25-C2T package?

The exposed thermal pad (EP) on the LM3S310-IQN25-C2T is internally connected to GND and serves as the primary thermal conduction path from the die to the PCB. To ensure reliable operation at maximum ambient temperature, the EP must be soldered to a solid copper ground plane with ≥4 thermal vias (0.3 mm diameter) connecting to inner or bottom-layer ground planes. Omitting EP connection risks junction temperature exceeding 125°C under sustained 25 MHz operation, potentially triggering thermal shutdown or reducing long-term reliability. The LM3S310-IQN25-C2T datasheet specifies EP solder mask opening and stencil design guidelines.