VRGND

IN1

Configuration

and

control

Dual

Switched

Integrator

IN2

IN3

IN16

Dual

Switched

Integrator

Dual

Switched

Integrator

Dual

Switched

Integrator

Serial

Interface

IN253

Dual

Switched

Integrator

IN254

IN255

IN256

Dual

Switched

Integrator

Dual

Switched

Integrator

Dual

Switched

Integrator

SD ADC

SD ADC

SDOUT

SCLK

RESET

CLKP/CLKM

CONV

DOUT

AVDD

+2.5V

AVEE

-2.5V

AVDD_18

DVDD

AGND

DGND

SEN

SDIN

QGND

VREF_IN

100nF 100nF 100nF 100nF

EN

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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.

DDC2256A

SLASED4B – MARCH 2016 – REVISED MAY 2016

DDC2256A 256-Channel, Current-Input Analog-To-Digital Converter

1

1 Features

1

•

Single-Chip Solution to Directly Measure 256 Low-

Level Currents Simultaneously

•

User Adjustable Full-Scale Range

•

Adjustable Speed with Integration Times as Low

as 58.8 µs (17 KSPS per channel) with 24 bit

Resolution

•

Power Dissipation as Low as 1.7mW/channel

•

Integral Linearity: ±0.025% of Reading ±1 ppm of

Full Scale Reading (all channels active)

•

Low Noise

•

24 bit ADC

•

No Charge Loss and Simultaneous Sampling

•

On-board Temperature Sensor

•

In-Package Bypass Capacitors and Reference

Buffer to Reduce PCB Area and Design

Complexity

•

Serial LVDS and CMOS Output Interface Option

2 Applications

•

CT Scanner Data Acquisition System

•

Photodiode Sensors

•

X-ray Detection Systems

•

Optical Fiber Power Monitoring

•

Mutichannel Current/Voltage Instrumentation

3 Description

The DDC2256A is a 24-bit, 256-channel, current-

input analog-to-digital (A/D) converter. It combines

both

current-to-voltage

integration

and

A/D

conversion so that 256 individual low-level current

output devices, such as photodiodes, can be directly

connected to its inputs and digitized in parallel

(simultaneously).

For each of the inputs, the DDC2256A has one low

noise/low power integrator designed to capture all the

charge from the sensor. The integration time is

adjustable from 58.8

μs to 100 ms, allowing currents

from fA to uA to be continuously measured with

outstanding precision. The outputs of the integrators

are digitized by sixteen 24-bit low power ADCs and

all the resulting data is output over a single LVDS

serial interface pair designed to minimize noise

coupling in environments with high channel count.

The DDC2256A operates from ±2.5-V analog supply,

1.8-V analog supply (AVDD_18) and 1.8-V digital

supply (DVDD). The device is specified from 0°C to

70°C operating temperature and available in a 14 x

board reference buffer and bypass capacitors help

minimize the external component requirements and

further reduce board space.

To request a full data sheet or other design

resources: request DDC2256A

Device Information (1)

PART NUMBER

PACKAGE

BODY SIZE (NOM)

DDC2256A

NFBGA (323)

16.0 mm x 14.0 mm

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

Block Diagram