AD7716:  CMOS, 4-Channel, 22-Bit Data Acquisition System

The AD7716 is a signal processing block for data acquisition systems. It is capable of processing four channels with bandwidths of up to 584 Hz. Resolution is 22 bits and the usable dynamic range varies from 111 dB with an input bandwidth of 36.5 Hz to 99 dB with an input bandwidth of 584 Hz.

The device consists of four separate A/D converter channels that are implemented using sigma-delta technology. Sigma-delta ADCs include on-chip digital filtering and, thus, the system filtering requirements are eased.

Three address pins program the device address. This allows a data acquisition system with up to 32 channels to be set up in a simple fashion. The output word from the device contains 32 bits of data. One bit is determined by the state of the D_IN1 input and may be used, for example, in an ECG system with an external pacemaker detect circuit to indicate that the output word is invalid because of the presence of a pacemaker pulse.