1 Features
1• 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-todigital
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 goldbumped
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