Low-Power, High-Speed ADCs Housed In Tiny Package

In addition to claiming to be the world's first such devices housed in 6-lead SOT-23 packages, the AD7476 8-bit, AD7477 10-bit and AD7478 12-bit A/D converters also boast a fast throughput rate and low power dissipation. The 1 MSPS devices consume just 4.8 mW at 3V and are capable of operating over 2.35V to 5.25V supply range. Based on a successive-approximation architecture, the new ADCs have no pipeline delays, and their low-noise, wide bandwidth, track/hold amplifiers permit them to handle inputs with frequencies in excess of 1 MHz. With an analog input of 100 kHz, the signal-to-noise ratio is an impressive 70 dB for the AD7476 8-bit ADC. The 6-lead SOT-23s replace existing 8-lead SOIC packages, reducing real estate requirements for the ADCs by up to 75%. Three pins are for supply, ground and analog input, while the remaining three provide a serial interface in which the conversion clock is derived from the serial interface clock. This arrangement permits designers to control conversion rate, power down and data transfer functions. Applications for the converters range from low-rate sensor monitoring to high-speed signal processing. Designed for the industrial temperature range (-40°C to 85°C), the devices cost $0.95, $2.50 and $4.00 each/1,000, respectively.