The DDC1128 is a 20-bit, 128-channel, current-input analog-to-digital (A/D) converter. It
combines both current-to-voltage and A/D conversion so that 128 separate low-level current output
devices, such as photodiodes, can be directly connected to its inputs and digitized.
For each of the 128 inputs, the DDC1128 uses the proven dual switched integrator
front-end. This configuration allows for continuous current integration: while one integrator is
being digitized by the onboard A/D converter, the other is integrating the input current. This
architecture provides both a stable offset and a loss-less collection of the input current.
Adjustable integration times range from 160µs to 1s, allowing currents from fAs to µAs to be
continuously measured with outstanding precision.
The DDC1128 has a serial interface designed for daisy-chaining in multi-device systems.
Simply connect the output of one device to the input of the next to create the chain. Common
clocking feeds all the devices in the chain so that the digital overhead in a multi-DDC1128 system
The DDC1128 operates from a +5 V analog supply and a 2.7 V to 3.6 V digital supply, it is
specified from 0°C to 70°C operating temperature and it is available in a 9 × 9
mm2 192-ball BGA, which includes on board bypass capacitors to help
minimize the external component requirements and further reduce board space.
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