1 Features
• 256 Channels
• On-Chip, 16-Bit ADC
• Photodiode Short Immunity
• High Performance:
– Noise: 750 Electrons RMS
(1.2-pC Input Charge Range)
– Low Correlated Noise
– Integral Nonlinearity:
±2 LSB with Internal 16-Bit ADC
– Scan Time: < 20 μs to 204.8 μs
• Integration:
– Six Selectable, Full-Scale Input Ranges:
0.6 pC (Minimum) to 9.6 pC (Maximum)
– 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
• Low Power Consumption
• Nap and Total Power-Down Modes
• Custom Chip-On-Film (COF) Packages

2 Applications
• Flat-Panel, X-Ray Detectors
• Charge Detectors
• Capacitance Measurement

3 Description
The AFE2256 is a 256-channel, analog front-end
(AFE) designed to suit the requirements of flat-panel
detector (FPD) based digital x-ray systems. The
device includes 256 integrators, a programmable gain
amplifier (PGA) for full-scale charge level selection,
a correlated double sampler with dual banking, and
256:4 analog multiplexers.
The device also features four 16-bit successiveapproximation
register (SAR) analog-to-digital
converters (ADCs). Serial data from the ADCs are
available in low-voltage differential signaling (LVDS)
format.
The nap and power-down modes enable substantial
power savings, and are especially useful in batterypowered
systems.
To request a full datasheet or other design resources:
request AFE2256