In one traditional model for ASIC development, a customer provides a set of chip performance specifications and the ASIC design house goes off and designs the ASIC on its own. However, when Emerson Process Management discovered a sudden need for a sensor interface chip, it realized that the typical 18- to 24-month ASIC development cycle would be far too slow. Instead, the industrial automation specialist collaborated with AMI Semiconductor, a designer and manufacturer of mixed-signal and structured digital ICs, to deliver a sensor interface ASIC in just 10 months.
According to AMI, the same type of collaborative process could be used to develop a power management device or other type of mixed-signal IC. The company offers a 100-V process capability in its product portfolio.
The Marble sensor IC is a critical component of Emerson’s Rosemount 3051C pressure transmitter, which is used in industrial process control and flow measurements. When Emerson received an unexpected end-of-life notice from the chip’s supplier, a pending shortage of the device threatened to shut down production of the pressure transmitter. However, Emerson leveraged an established relationship with AMI, which allowed Emerson and AMI to share design methodologies and accelerate the ASIC development process.
In November 2003, Emerson began its efforts to develop the replacement ASIC. Emerson developed a high-end layout for the analog portion of the chip and generated VHDL code for the digital section. In April 2004, AMI started its portion of the chip design, which included doing the digital layout. In May, Emerson engineers inserted design-for-test vectors into the digital block and performed design rule checking on the analog cells.
AMI completed the chip design review in early July and completed the layout in August. By September, AMI was able to supply samples of the ASIC. These prototypes were subsequently approved by Emerson and the chips were soon put into production. In addition, to its work in developing the ASIC, AMI worked with Emerson engineers to develop a production test for the chip.
The sensor IC uses two 16-bit sigma-delta a-d converters (ADCs). One ADC translates a differential capacitor measurement from the transducer to a digital serial peripheral interface (SPI) output. The second ADC converts the input from a platinum resistive temperature (PRT) device, which offers compensation for the capacitive transducer.
For more information, visit www.amis.com.