Delta-Sigma ADC Calibrates External Loop Components

The LTC2449 8 kHz, 16-channel delta-sigma a/d converter reduces the cost and increases the performance of precision designs by automatically calibrating and removing offsets and drifts from the entire external analog signal chain. A new multiplexer architecture allows external components to be included within the ADC loop. Any combination of 16 single-ended or 8 differential gains can be accurately digitized. A 4 kHz conversion rate together with a patented No Latency architecture allows all 16 channels to be scanned in 4 ms, avoiding digital filter settling problems found in conventional delta-sigma converters. The device?s programmable filter permits tailoring twenty different speed/resolution combinations to individual channels. For low-frequency sensors such as thermocouples, strain gages and RTDs, the ADC can perform 500,000 counts on a ±50 mV sensor input, or 25 million counts on a full-scale input, and simultaneous 50/60 Hz line frequency-noise rejection. For high-speed sampling, 17 effective bits are provided at an 8 kHz output rate. The ADC comes in a 38-pin QFN package screened for industrial and commercial temperature ranges. Price is $7.15 each/1,000. LINEAR TECHNOLOGY CORP., Milpitas, CA. (408) 432-1900.