DDC2256A - 256-Channel, Current-Input Analog-To-Digital Converter

The DDC2256A is a 24-bit, 256-channel, current-input analog-to-digital (A/D) converter. It combines both current-to-voltage integration and A/D conversion so that 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 inputs, the DDC2256A has one low noise/low power integrator designed to capture all the charge from the sensor. The integration time is adjustable from 58.8μs to 100 ms, allowing currents from fA to µA to be continuously measured with outstanding precision. The outputs of the integrators are digitized by sixteen 24-bit low power ADCs and all the resulting data is output over a single LVDS serial interface pair designed to minimize noise coupling in environments with high channel count.

The DDC2256A operates from ±2.5-V analog supply, 1.8-V analog supply (AVDD_18) and 1.8-V digital supply (DVDD). The device is specified from 0°C to 70°C operating temperature and available in a 14 × 16 mm² 323-ball 0.8 mm-pitch BGA. Finally, the on board reference buffer and bypass capacitors help minimize the external component requirements and further reduce board space.

To request a full data sheet or other design resources: request DDC2256A

• Single-Chip Solution to Directly Measure 256 Low-
  Level Currents Simultaneously
• User Adjustable Full-Scale Range
• Adjustable Speed with Integration Times as Low
  as 58.8 µs (17 KSPS per channel) with 24 bit
  Resolution
• Power Dissipation as Low as 1.7mW/channel
• Integral Linearity: ±0.025% of Reading ±1 ppm of
  Full Scale Reading (all channels active)
• Low Noise
• 24 bit ADC
• No Charge Loss and Simultaneous Sampling
• On-board Temperature Sensor
• In-Package Bypass Capacitors and Reference
  Buffer to Reduce PCB Area and Design Complexity
• Serial LVDS and CMOS Output Interface Option