FEATURES

MEASURE FOUR LOW-LEVEL CURRENTS

FUNCTION

±0.01% of Reading ±0.5ppm of FSR

APPLICATIONS

Protected by US Patent #5841310

Dual

Switched

Integrator

Dual

Switched

Integrator

∆Σ

Modulator

Digital

Filter

Digital

Input/Output

FORMAT

DCLK

DCLK

DVALID

DOUT

DOUT

DIN

DIN

Control

IN3

IN1

VREF

DVDD

AVDD

DGND

AGND

Dual

Switched

Integrator

Dual

Switched

Integrator

∆Σ

Modulator

Digital

Filter

IN4

IN2

CLK

CONV

RANGE0

RANGE1

RANGE2

TEST

CLK_4X

HISPD/LOPWR

RESET

DESCRIPTION

The DDC114 is a 20-bit, quad channel, current-input

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

current-to-voltage and A/D conversion so that four

low-level current output devices, such as photodiodes, can

be directly connected to its inputs and digitized.

For each of the four inputs, the DDC114 provides a

dual-switched integrator front-end. This design allows for

continuous current integration: while one integrator is

being digitized by the onboard A/D converter, the other is

integrating the input current. Adjustable full-scale ranges

from 12pC to 350pC and adjustable integration times from

50

µs to 1s allow currents from fAs to µAs to be measured

with outstanding precision. Low-level linearity is

±0.5ppm

of the full-scale range and noise is 5.2ppm of the full-scale

range.

Two modes of operation are provided. In Low-Power

mode, total power dissipation is only 13.5mW per channel

with a maximum data rate of 2.5kSPS. High-Speed mode

supports data rates up to 3.125kSPS with a corresponding

dissipation of 18mW per channel.

The DDC114 has a serial interface designed for

daisy-chaining in multi-device systems. Simply connect

the output of one device to the input of the next to create

the chain. Common clocking feeds all the devices in the

chain so that the digital overhead in a multi-DDC114

system is minimal.

The DDC114 is a single-supply device using a +5V analog

supply and supporting a +2.7V to +5.25V digital supply.

Operating over the industrial temperature range of −40

°C

to +85

°C, the DDC114 is offered in a QFN-48 package.

DDC114

SBAS255C − JUNE 2004 − REVISED APRIL 2009

Quad Current Input, 20-Bit

Analog-To-Digital Converter

www.ti.com

Copyright

 2004−2009, Texas Instruments Incorporated

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments

semiconductor products and disclaimers thereto appears at the end of this data sheet.

All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date. Products

conform to specifications per the terms of Texas Instruments standard warranty.

Production processing does not necessarily include testing of all parameters.