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AS5850A Digital X-ray Flat Panel Readout IC

256-channel low-noise charge-to-digital converter


  • Line times down to 20 µs, or 15 µs in ADC low-OSR mode
  • Binning mode (half the number of effective channels) for faster readout speed down to 10 µs
  • Selectable parameters: input charge range, holes or electrons polarity, detector timing, low-pass filter time constant and line time
  • Up to three different internal charge pump cycles for offset adjusting, signal emulation and switch charge injection compensation
  • Four power modes in addition to sleep and full power-down modes
  • Correlated Double Sampling for offset subtraction with programmable time constant


  • Flexible programming options to optimize for application needs
  • Suitable for a wide range of detector sizes, supporting line capacitances up to 200 pF
  • Best-in-class figure of merit for noise, power consumption and speed
  • High-speed for dynamic applications
  • Ultra-low power for portable applications
  • Low-noise for great image quality
  • Accurate temperature feedback
  • Chip-on-flex packaging for immediate integration into the detector

Product parameters

Applications Medical Imaging, Digital Radiography
Primary Function Charge-to-digital Converter
Channels 256 (240)
Resolution [bit] 16
Input Related Noise 500 electrons
Min. Power Consumption [mW per Channel] 1.1 - 3.1
Min. Integration Time / Line Time [µs] 15
Package Chip on Flex

General description

The AS5850A is a 16-bit, 256-channel low-noise charge-to-digital converter designed for use in digital X-ray systems. The high degree of programmability enables system performance optimization in a wide range of applications. The combination of fast speed, low noise and low power consumption maximizes the image quality and minimizes patient dose, exposure whilst improving the time to market.
Each channel front-end consists of a charge sensitive amplifier (CSA) and a correlated double sampler (CDS), that removes offset and flicker noise from the signal, which is then converted to digital. A fast and reliable LVDS interface transmits the output digital data off-chip. Built-in diagnostic functionalities enable error detection in the signal chain. Voltage references and a temperature sensor are included on the chip. An SPI interface allows easy programming of the device parameters.
Four different power modes allow the user to minimize the current consumption for the chosen speed. Line times of 20, 28.5, 40 and 80 μs require as little as 3.1, 2.6, 1.6 and 1.1 mW per channel respectively. A special ADC operation mode is also available, that decreases the minimum line time to 15 μs without increasing the power consumption. Additionally, it is possible to add together the charges in pairs of adjacent channels; with this binning, the fastest achievable line time is 10 μs.

This product suits for the following applications:

  • Static and dynamic digital X-rays
  • Digital radiography
  • Mammography
  • Fluoroscopy
  • Interventional X-ray imaging


Title Category Headline Buy
AS585x Eval Kit Application Board Evaluation Kit for AS585x

Technical documents

Type Description Language
Special Datasheet AS5850A Short Dataheet English

Environmental documents

Type Description Language
RoHS Certificate AS5850A RoHS Certificate English

Other information

Type Description Language
Block Diagram AS5850 Block Diagram English
Factsheet AS5850A Readout IC for X-ray flat panels English
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