Analog-to-Digital Converter June 2001

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Analog Devices, Inc. offers a feature-rich analog-to-digital converter (ADC) for general-purpose data acquisition applications, including industrial power metering, instrumentation, and motion control. The six-input channel, programmable, AD73360 analog front end (AFE) features an on-chip programmable input gain amplifier (PGA) that allows low-level transducer amplitude signals to be connected to analog inputs.

Offering six 16-bit analog-to-digital (A/D) channels, the device features a serial port (SPORT), which reportedly allows direct, easy interface to digital signal processors (DSPs) or microcontrollers. It operates at 2.7-5.5 V and has six ADC channels, which provide 77 dB signal-to-noise ratio (SNR) over a voiceband signal bandwidth. Each channel features a PGA with gain settings in eight stages ranging from 0-38 dB. An on-chip reference voltage is programmable to accommodate either 3- or 5-V operation. Idle channels can be powered-down when not required, thereby reducing power consumption. Internally, the six channels are separate with channel-to-channel crosstalk of -83 dB, inherently allowing for simultaneous sampling, which is said to be important for fast control loops and noise cancellation, and for applications such as power metering, where phase delay between conversions is undesirable.

Each channel's low group delay can be critical in closed-loop applications, such as vector motor control, where the drive circuitry's currents and voltages are fed back to control the motor's torque and flux. The unit's sample rates are programmable, ranging from the standard voiceband of 8 kSPS and extending up to 64 kSPS. The SPORT data rates are also programmable for glueless interface with fast DSPs as well as for slower microcontrollers.