AFE3256 256-Channel, Analog Front-End for Digital X-Ray, Flat-Panel Detectors

1 Features

• 256 channels

• On-chip, 16-bit ADC

• High performance:

– Noise: 440 electrons RMS

(1.2-pC input charge range)

– Low correlated noise

– Full-channel integral nonlinearity:

±2 LSB at 16 bit

– Scan time: < 16 μs to 204.8 μs

• Integration:

– Programmable full-scale input charge range:

0.3pC to 12.5pC with resolution of 0.3pC

– Internal timing generator (TG)

– Built-in correlated double sampler

– Software programmable electron or hole

integration mode

– Pipelined integrate-and-read for improved

throughput—data-read during integration

– Serial LVDS output

– On-chip temperature sensor

• Simple power supply scheme:

– Single 1.85V power supply operation

• Multiple power modes with power consumption

ranging from 1mW/ch to 2mW/ch

• Power-down modes: sleep and standby

• Binning mode support

• Custom chip-on-film (COF) packages

2 Applications

• Flat-panel, X-ray detectors

• Charge detectors

• Capacitance measurement

3 Description

The AFE3256 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, correlated double

samplers (CDSs) with dual banking, and 256:2 analog

multiplexers. The device also features two 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 device, also commonly referred to as a readout

integrated circuit (ROIC), optimizes the overall system

performance using features such as multiple power

modes and in-system debug options.

The sleep and standby modes enable substantial

power saving which is critical for battery-powered

systems.

Package Information

PART NUMBER

PACKAGE(1)

PACKAGE SIZE(2)

AFE3256

TFU (COF, 320) 38mm × 28mm

AFE3256

TFV (COF, 315) 48mm x 17.33mm

(1)

For all available packages, see the package option

addendum at the end of the data sheet.

(2)

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

includes pins, where applicable.

ADC[1:0]

LVDS

Serializer

Timing and Control

MCLK, SYNC, TP_SEL

Reference

Voltage

VREF

AFE3256

DCLKP

DCLKM

DOUTP

DOUTM

FCLKP

FCLKM

SDATA, SDOUT, SCLK, SEN

SPI

ADC

Pixel Cap

[255:0]

Integrators

and CDS

255 to 0

256:2

MUX

TFT Switch

AVSS

AVDD

AFE3256 Block Diagram

AFE3256

SBASAV9A – OCTOBER 2023 – REVISED APRIL 2024

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.