Integrated Circuit provides strain gage measurement.
Press Release Summary:
Model PS02 digital ASIC supports 2 full bridges or 4 half bridges. It determines resistor ratio from precise time interval measurement, delivering up to 18-bit resolution of 1,000µ strain. Depending on application, total current of system can be reduced to 5 µA. Model PS02 offers programmable update rates to 20 kHz and includes serial SPI interface. It is suited for load cells, force sensors, pressure sensors, general strain gage amplifiers, and capacitive sensors.
Original Press Release:
New Time-to-Digital ASIC for Precision Strain Gage Measurement Supports Two Full Bridges or Four Half Bridges to Span a Greater Number of Advanced Scale Applications
ACAM PS02 provides low current draw and fast update times, CMOS technology for longer battery life on scales, pressure transducers
September 2003 - ACAM has upped the ante for flexible PICOSTRAIN strain gage measurement, supporting two full bridges or four half bridges on its new PS02 ASIC. The PS02 is a powerful, purely digital chip with no analog circuitry for accurate strain gage measurement at low current draw. It provides added capacity needed for devices with multiple sensors or applications requiring system redundancy, offering software-selectable resolution and update rates. The PS02 is ideal for load cells, force sensors, pressure sensors, general strain gage amplifiers, capacitive sensors and a similar battery driven devices. The ACAM PS02 is available exclusively in the U.S. through Transducers Direct, experts in signal time-of-flight technology for pressure, position and magnetostrictive transducers.
The PS02 determines resistor ratio from a highly precise time interval measurement, delivering up to 18 bit resolution of 1000µ strain. For applications requiring high updates rates, it can provide 11.5 bit resolution at 4 kHz. This yields advantages of faster updates and lower total current requirements, while eliminating complex analog circuitry to simplify integration. The different performance options are easily set through software.
Measuring only 9 mm-square, the compact PS02 is ideal for consumer and industrial products, such as weight scales, postage scales, pressure transducers and load cells. Strain gages used with the PS02 require no separate power supply or reference voltage, and connect directly to the chip. The chip can work with two full bridges or four half bridges, and the user determines how much current is supplied to the strain gage. Depending on the application, the total current of the system can be reduced to only 5 µA. Battery-powered devices, such as those using 3V lithium coin cells, can extend battery life of up to 10X, depending on the application, due to lower current draw versus analog circuitry.
The PS02 offers programmable update rates up to 20 kHz. Digital design provides excellent output stability over a wide operating temperature range of -40 to 120°C. The PS02 has a 48 TQFP enclosure and serial SPI interface. It supports separate temperature measurement of the load cell.
The optional PSA1 setup and evaluation board shortens development time for devices using the PS02 chip by allowing all of the chip's setup parameters to be quickly configured and checked via a graphical PC interface. The affordable PSA1 connects to a PC via RS232 cable and operates in a Windows® environment. It can also be used as a stand-alone unit with 0 to 10 VDC analog output. Several settings for core and I/O supply voltage can be selected with jumpers. Additional jumpers allow current measurement, and two clocks with 32,768 Hz (low power mode) or 10 MHz (high power mode) are available to provide a reference frequency.
Transducers Direct has the PS02 chip available for immediate shipping with a price of $7.50 each @ 1,000 pieces, but offers significant discounts for larger-volume OEM orders.
For more information on the PS02 time-to-digital ASIC, contact: Rob Matthes, President, Transducers Direct; 1120 Cottonwood Dr.; Cincinnati, OH 45140. Tel: 513-583-9491. Fax: 513-583-9476. Email: rmatthes@transducersdirect.com. Internet: www.transducersdirect.com.
