1 Features

• 256 Channels
• On-Chip, 16-Bit ADC
• Photodiode Short Immunity
• Column Short Immunity
• High Performance:
  • Noise: 758 e-RMS with 28-pF Sensor Capacitor in 1.2-pC Range
  • Integral Nonlinearity:
    ±2 LSB with Internal 16-Bit ADC
  • Minimum Scan Time:
    • 37.9 µs in Normal Mode
    • 20 µs in 2x Binning Mode
• Integration:
  • Eight Selectable Full-Scale Ranges:
    0.15 pC (Min) to 9.6 pC (Max)
  • Built-In Correlated Double Sampler
  • 2x Binning (Averages Charge of Two Adjacent Channels) for Faster Throughput
  • Pipelined Integrate and Read: Allows Data Read During Integration
• Flexibility:
  • Electron and Hole Integration
• Low Power:
  • 2.9 mW/Ch with ADC
  • 2.3 mW/Ch without ADC
  • 0.1 mW/Ch in Nap Mode
  • Total Power-Down Feature
• 22-mm × 5-mm Gold-Bump Die,
  Suitable for TCP and COF

2 Application

Flat-Panel, X-Ray Detector

3 Description

The AFE1256 is a 256-channel, analog front-end (AFE) designed to suit the requirements of flat-panel detectors (FPDs) based on digital X-ray systems. The device includes 256 integrators, a programmable gain amplifier (PGA) for full-scale, charge-level selection, a correlated double sampler (CDS) with dual banking, 256:4 analog multiplexers, and four 16-bit, successive-approximation register (SAR) analog-to-digital converters (ADCs) onboard. Serial data from the ADCs are available in SPI™ format.

Hardware-selectable integration polarity allows for the integration of positive or negative charge and provides more flexibility in system design. The Nap feature enables substantial power saving. This power savings is especially useful in battery-powered systems.

The device is available as a 22-mm × 5-mm gold-bumped die and a 38-mm × 28-mm, COF-314 TDS package in singulated forms.

To request a full data sheet or other design resources: request AFE1256

1. For all available packages, see the package option addendum at the end of the data sheet.
2. Product-preview device.

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AFE1256 Schematic