AFE2256 256-Channel, Analog Front-End for Digital X-Ray, Flat-Panel Detectors

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 successive-

approximation

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 battery-

powered systems.

To request a full datasheet or other design resources:

request AFE2256

Package Information

PART NUMBER

PACKAGE(1)

PACKAGE SIZE(2)

AFE2256

TDU (COF, 320) 38.00 mm × 28.00 mm

TDR (COF, 325) 48.35 mm × 21.5 mm

TBN (COF, 325) 48.35 mm × 21.5 mm

(1)

For all available packages, see Section 6.

(2)

The package size (length × width) is a nominal value and

includes pins, where applicable.

16-Bit

ADC[3:0]

ADC

ADC

LVDS

Serializer

Timing and Control

MCLK, SYNC, TP_SEL

Reference

Voltage

VREF

AFE2256

DCLK_P,

DCLK_M

DOUT_P,

DOUT_M

FCLK_P,

FCLK_M

SDATA, SDOUT, SCLK, SEN

SPI

ADC

Pixel Cap

[255:0]

Integrators

and CDS

255 to 0

MUX

TFT Switch

Copyright © 2016, Texas Instruments Incorporated

AFE2256 Block Diagram

AFE2256

SBAS693C – MARCH 2015 – REVISED DECEMBER 2023

An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.