With the launch of its new family of ultra-low-power 32-kHz oscillators (XOs), SiTime Corp. is expanding its kHz portfolio from mobile IoT-consumer to automotive applications. The SiT1881 oscillators deliver high accuracy time keeping for advanced driver assistance systems (ADAS), infotainment, instrument clusters, and electronic control units (ECUs).
(Source: SiTime)
Building the SiT1881 oscillator family from the ground up for automotive applications, the MEMS oscillators deliver a combination of 4× better stability and up to 20% lower power, compared with quartz devices, helping to extend system battery life.
In addition, the timing devices are 30% smaller than quartz devices. They are housed in a QFN package that measures 1.2 × 1.1 × 0.55-mm (1.32 mm2 footprint, 0.67 mm3 volume).
Another standout feature is its stability. The SiT1881 offers a ±50 ppm frequency stability over the extended temperature range of -40oC to 105oC. The series is AEC-Q100 Grade 2 qualified and offers high reliability with 2 billion hours MTBF.
SiTime said the SiT1881 is the industry’s smallest, ultra-low-power 32.768-kHz automotive XO designed to operate over a wide voltage and temperature range. The family offers a voltage range of 1.14 V to 3.63 V.
“It’s a brand-new design. We started from the ground up and optimized all the circuits,” said Piyush Sevalia, EVP marketing, SiTime. This includes developing a new PLL architecture, enhancing the temperature compensation algorithms, and ensuring power utilization.
The new device has very specific features for automotive applications, said Sevalia. For example, it’s packaged in a QFN instead of a CSP package; the temperature range is extended from -40°C to 105°C, compared with -40°C to 85°C for previous products, and it is AEC-100 qualified, he said.
“In the past, we had 32-kHz oscillators for mobile and IoT markets and the power consumption was typically around 1 µA and for this one we’ve cut the power in half to 490 nA,” he said.
This is about 20% lower power than the lowest quartz device and it is 30% smaller, he added.
“When you talk about a stability of 50 ppm over the entire operating temperature range the best you’re going to see from quartz [devices] will be 200 ppm, and more likely in the 250-ppm range, so we’re at least 4× better, and even 5-6× better,” said Sevalia.
Value proposition
The SiT1881 solves four key areas of automotive timing challenges: stability, power, reliability, and size. This combination of much better stability under different operating conditions, much lower power, and much smaller size each on its own stands strongly, but together they become a potent combination that’s just not available from anybody else, Sevalia said.
Even though each one of the specs is better than the quartz industry, the combination is even more difficult to meet, he said. “That is why I think we’re creating a new class of products that are just not out there, which we call precision timing solutions. We’ve solved a major customer problem and that is the whole intent of the precision timing category.”
Automotive timing applications. Click for a larger image. (Source: SiTime)
SiTime also offers value on the supply-chain side. “We have virtually infinite capacity, and we have programmability, which allows us to configure the devices.” Programmable options include frequency, stability, voltage, temperature, and output type.
SiTime has a supply chain that’s completely independent from quartz device manufacturers, said Sevalia. “We manufacture our devices at TSMC in two different fabs, and we assemble our devices in [several] semiconductor assembly houses – Carsem, UTAC, and ASE – with multiple sourcing. We also have the ability to program our devices so in all of these aspects we are delivering real value to the customers where they can rely on us to give them supply when nobody else can.”
SiTime also has its own MEMS process, which was developed at Bosch.
From a price point of view, there is a premium to pay for the value and peace of mind. “The premium is reasonable, and it is something that we believe we need to be paid for,” he said.
Demand for timing devices will continue to grow. The automotive electronics segment is expected to continue on its double-digit growth path over the next three years as semiconductor content per vehicle increases as the industry transitions to electric and autonomous vehicles, according to Gartner. The semiconductor content per vehicle is expected to increase from $712 in 2022 to $931 in 2025.
For power savings electronic subsystems need to be turned on and off frequently and accurately, said Sevalia. “The 32-kHz XO is the time keeping element, and is always-on, so its accuracy and power consumption play a significant role in reducing overall system power.”
Target 32-kHz oscillator automotive applications. Click for a larger image. (Source: SiTime)
Sevalia said the number of timing chips in vehicles has increased from 20 in 2018 to about 35-60 in 2022 and is projected to reach 125+ by 2026.
SiTime has several new products on the roadmap for this year and a lot more innovation in the pipeline. “We spend more than anybody else on R&D for timing and that is yielding all the tremendous products that we’re going to introduce including this one.”
Sevalia said the company has improved stability by 10,000× and jitter performance by 1,000× over the past 15 years.
The SiT1881 was under development for 15 months. It is currently undergoing characterization and preliminary datasheets are available. Engineering samples will be available through SiTimeDirect, starting Nov. 1, 2022. Volume production is expected in Q2 2023. Click here for the datasheet.
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