And Stellaris Makes Four: TI Acquires Luminary Micro, Expands MCU Lineup

Submitted by BDTI on Wed, 06/17/2009 - 20:00

Earlier this month Texas Instruments announced that it had acquired Luminary Micro, a start-up fabless semiconductor vendor that sold ARM Cortex-M3-based microcontrollers. Luminary’s “Stellaris” family of Cortex-M3 MCUs has been on the market since 2006. Current Stellaris chips operate at up to 50 MHz; TI expects to sample 80 and 100 MHz chips later this year. Stellaris chip prices range from $1.00 - $7.00 in 10K quantities. TI has also announced Stellaris-based development kits starting at $99.

With the Luminary acquisition, TI now has four distinct MCU architectures: The 32-bit Cortex-M3-based Stellaris, the 32-bit ‘C28x, the dual-core, Cortex-R4-based 32-bit TMS570, and the 16-bit MSP430. (TI also sells the older 16-bit ‘C24x family, but says it is not recommended for new designs.).  Both the ‘C28x and the TMS570 are available in floating-point versions.  The only hole remaining in TI’s MCU lineup is in 8-bit MCUs, a market segment that is currently dominated by Microchip. TI says that it has no plans to offer 8-bit chips; the company believes that many 8-bit customers are migrating to 16-bit chips because they offer better performance for a similar price.

Table 1 provides a comparison of TI MCU families.

Chip family

Data format

(Qty 10K)

Max Clock



32-bit fixed

$1.00 - $7.00

50 MHz

Cost-sensitive applications with significant control processing requirements

‘C28x families:




32-bit fixed
32-bit fixed
32-bit float

$1.50 - $20.00



150 MHz
60 MHz
300 MHz

‘C28x chips target a wide range of applications, from low-cost motor control to high-performance, real-time control

(dual Cortex-R4)

32-bit fixed/float

$5.00 - $25.00

64 MHz

Primarily automotive


16-bit fixed

$0.50 - $9.00

27 MHz

Low-power, portable applications


Three of TI’s MCU architectures are pure microcontrollers (Stellaris, MSP430, TMS570) while the ‘C28x has a more DSP-oriented data path. TI also offers low-cost, low-power ‘C55x-based DSP chips that are often used in similar applications. (In fact, TI just announced two new low-power chip variants in the ‘C55x family, characterizing them as “complementary” to the MSP430.)

TI is the only chip vendor that offers a continuum of MCU/DSP architectures, and the company is clearly pushing hard into the MCU market.  This is bad news for other MCU vendors – TI is a formidable competitor, with enormous resources and expertise in developing and supporting embedded processor families and reaching out to a large and diverse customer base.

The challenge facing TI and its customers is that these product lines are largely incompatible with one another.  In addition, the sheer number of different architectures may make it hard for TI’s MCU customers to figure out which chip to choose. Historically TI had a similar approach to DSP processors, offering many different architectures to address many application areas. In recent years, however, TI has largely consolidated around the ‘C64x/C67x architecture and, to a lesser extent, the ‘C55x. With its expanding MCU lineup, TI seems to be headed back in the other direction.

As we’ve written before, even low-end MCUs are often called upon to handle DSP tasks, which is why both Microchip and ST have recently announced DSP libraries for their MCUs. Not surprisingly, TI says that it is developing DSP software components for the new Stellaris chips (the company already offers DSP software components for its ‘C28x and ‘C24x families).

Software libraries are one way to differentiate the Stellaris chips from the growing field of Cortex-M3-based MCUs, (such as those from NXP, ST, Toshiba, and others); Atmel has taken another tack by offering high-speed USB interfaces on its new Cortex-M3 MCUs.  With so many Cortex-M3 MCUs on the market, the question isn’t so much “Who has the best processor,” but “Who’s going to make it the easiest to get my application up and running.”  This is an area where TI has often shined in the past, by nurturing a complete ecosystem around its chips. We wonder, however, whether TI has chosen to offer more architectures than it can effectively support, and whether its customers will be more excited or confused.

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