Data Sheet 256-Channel, 16-Bit, Charge-to-Digital AFE on Flex ADAS1256 FEATURES GENERAL DESCRIPTION 256-channel, charge-to-digital conversion on a single chip 16-bit resolution with no missing codes Simultaneous sampling User adjustable full-scale range up to 32 pC Down to 22 µs line time Ultralow noise: 560 e− at 2 pC range INL ± 2.5 LSB or 57.5 ppm, ADC included Multiple functional power modes: 1 mW/channel to 3 mW/channel Multiple power-down and sleep modes: down to 0.005 mW/channel Measurement of electron or hole collected charge Tested and delivered on high density system on flex (SOF) LVDS/CMOS self-clocked serial interface SPI daisy-chain configuration registers On-board AFE timing sequencer On-board temperature sensor and reference buffer The ADAS1256 is a 256-channel, 16-bit, digital X-ray analog front end (AFE) that integrates the complete charge-to-digital conversion signal chain on a single chip. It enables a wide range of digital X-ray modalities, including portable radiology and mammography as well as high speed fluoroscopy and cardiac imaging. The ADAS1256 is delivered on a high density systemon-flex (SOF) package that can be directly mounted on a digital X-ray panel. All converted channel results are output on a single LVDS self-clocked serial interface that significantly reduces external hardware. An SPI-compatible serial interface allows configuration of the AFE, using the SDI input. The SDO output allows the user to daisy-chain several AFEs on a single 3-wire bus. An integrated AFE timing sequencer controls the sampling activity of the analog front end (AFE). The sequencer is programmed via the SPI port and is timed by a single clock, ACLK. APPLICATIONS Digital X-ray panel Photodiode sensors array CT scanner High channel count, data acquisition systems (current or voltage input) FUNCTIONAL BLOCK DIAGRAM TO NEXT SDI AVDDI AVDD5F AVDD5B AVDD DVDD5 DVDD TO ALL AFEs SDO IN255 –VBIAS SDI ADC IFS CDS DATA PROCESSING IFS CDS RESET DOUTA/DOUTB DCLK TO ADCs AND DAC IFS CDS FPGA ACLK SYNC IOVDD ADC VIO IOGND SDI SOF REF_TFT REF_ADC VT AVSSI TFT PANEL LVDS/CMOS INTERFACE CS SYSTEM MOTHERBOARD 4.096V FROM PREVIOUS SDO FROM DOUT OF OTHER AFEs 11198-001 IN128 SCK CONFIGURATION CDS FLEX INTERFACE IN127 IFS HIGH DENSITY CUSTOM FLEX INTERFACE IN0 Figure 1. Rev. Sp0 Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 ©2012 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com ADAS1256 Data Sheet NOTES ©2012 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D11198F-0-11/12(Sp0) Rev. Sp0 | Page 2 of 2