AFE2257

• 256 Channels
• On-chip, 16-bit ADC
• Photodiode short immunity
• High performance:
  • Noise: < 600 electrons
  • Low correlated noise
  • Full-channel integral nonlinearity:
    ±2 LSB with internal 16-Bit ADC
  • Scan time: < 20 µs to > 250 µs
• Integration:
  • Programmable full-scale input charge range:
    < 1 pC to > 25 pC
  • Internal timing generator (TG)
  • Built-in correlated double sampler
  • Pipelined integrate-and-read for improved throughput—data-read during integration
  • Serial LVDS output
• Simple power-supply scheme:
  • AVDD1 = 1.85 V
  • AVDD2 = 3.3 V or 4.75 V
• Low power consumption
• Nap and total power-down modes
• Pin compatible to AFE2256

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The AFE2257 is a 256-channel charge readout IC (ROIC) designed for flat-panel detector (FPD) based digital x-ray systems. The device includes 256 integrators, correlated double samplers (CDSs) with dual banking, and 256:4 analog multiplexers.

The device also features four 16-bit successive-approximation register (SAR) analog-to-digital converters (ADCs). Serial data from the ADCs are available in low-voltage differential signaling (LVDS) format.

The device optimizes the overall x-ray system performance using features such as multiple power modes and in-system debug options. The nap and power-down modes enable substantial power savings, and are especially useful in battery-powered systems.