3 Description

The DDC3256 is a 24-bit, 256-channel, current-input analog-to-digital (A/D) converter. It combines both, current-to-voltage conversion by current integration, and A/D conversion.

Up to 256 individual low-level current output devices, such as photodiodes, can be directly connected to its inputs and digitized in parallel (simultaneously).

For each of the 256 inputs, the device has one low noise and low power integrator designed to capture all the charge from the sensor. The integration time is adjustable from 50 μs to 1.6 ms, allowing currents in the order of fA to μA to be continuously measured with outstanding precision. The outputs of the integrators are digitized by on-chip low power ADCs and the converted digital codes are transmitted over a single LVDS pair designed to minimize noise coupling in environments with high channel count.

The DDC3256 operates from single 1.85-V supply. The device is specified from 0°C to 70°C operating temperature and available in a 13.2 × 17.2 mm² 336-ball 0.8 mm-pitch BGA. The on-chip reference buffer and bypass capacitors (on the BGA) help minimize the external component requirements and further reduce board space.