256 channel, 20-kSPS current-input analog-to-digital converter | ZWX | 336 | 0 to 70

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 mm 2 336-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.