Out in Front: March 1, 1996

Two A/D converters from Signal Processing Technologies provide fast conversions in eight-lead SOIC packages. The company is aiming both devices at handheld and desktop scanners, portable digital radios, and remote sensing. The SPT7730 is an 8-bit, 3M-sample/sec converter, requiring a clock at 12 times the conversion rate; the SPT7830 is a 10-bit, 2.5M-sample/sec converter that needs a clock at 14 times the conversion rate. Typical specifications for effective number of bits (ENOB), S/N ratio with 500-kHz input, and THD with 500-kHz input are 7.5 bits, 47 dB, and 60 dB, respectively, for the SPT7730, and 8.9 bits, 56 dB, and 63 dB, respectively, for the SPT7830. For dc performance, the maximum differential and integral nonlinearity figures are ±0.5/±0.5 LSBs for the 8-bit device and ±1.0/±1.5 LSBs for the 10-bit unit.

The 0 to +70° converters have serial interfaces that are compatible with the serial peripheral interface (SPI) or Microwire high-speed synchronous standard, and both have on-chip S/H circuitry. The SPT7730 uses a 3.3 or 5V supply, with power dissipations of 34 and 73 mW, respectively; the corresponding consumption values for the SPT7830 are 37 and 56 mW. The 8-bit, 3M-sample/sec SPT7730 converter costs $4.90 (1000), and the 10-bit, 2.5M-sample/sec SPT7830 converter costs $6.50.
—by Bill Schweber

Signal Processing Technology Corp, Colorado Springs, CO. (800) 643-3778.