AD7788:  16-Bit, Single-Channel, Ultra Low Power, Sigma Delta A/D Converter

The AD7788/AD7789 are low-power, complete analog front ends for low frequency measurement applications. The device consumes 65 µA of current typically when operated with a 3 V power supply and 75 µA typical when operated with a 5 V power supply. The AD7789 contains a 24-bit S-D ADC with one differential input, which is unbuffered. The AD7788 is a 16-bit version of the AD7789. The AD7788 has a peak-to-peak resolution of 16 bits while the AD7789 has a peak to peak resolution of 19 bits, which is equivalent to an effective resolution of 21.5 bits.

The device operates from an internal clock. Therefore, the user does not have to supply a clock source to the device. The output data rate is 16.6 Hz which gives simultaneous 50 Hz/60 Hz rejection. Power supply monitoring can also be performed with the part.

The part can be used in single conversion mode whereby the device powers up, performs a single conversion and then returns to powerdown mode. Alternatively, it can be operated in continuous mode. In continuous conversion mode, the part can be configured to continuously read i.e. the conversions are placed on the serial bus automatically as soon as a conversion is complete (the user does not need to write to the ADC to read the data), assuming that the serial clock is applied to the device.

The AD7788/AD7789 is housed in a 10-lead MSOP package.