1FEATURES

2? Single-Chip Solution to Directly Measure 32

Low-Level Currents

? High-Precision, True Integrating Function

? Integral Linearity:

±0.025% of Reading ±1.0ppm of FSR

? Very Low Noise: 5.3ppm of FSR

? Low Power: 7mW/channel

? Adjustable Full-Scale Range

? Adjustable Speed

– Data Rate up to 6kSPS

– Integration Times as low as 166.5ms

? Daisy-Chainable Serial Interface

? In-Package Bypass Capacitors Simplify PCB

Design

APPLICATIONS

? CT Scanner DAS

? Photodiode Sensors

? X-Ray Detection Systems

DESCRIPTION

The DDC232 is a 20-bit, 32-channel, current-input

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

current-to-voltage and A/D conversion so that 32

separate low-level current output devices, such as

photodiodes, can be directly connected to its inputs

and digitized.

For each of the 32 inputs, the DDC232 provides a

dual-switched integrator front-end. This configuration

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 integration times range from 166ms to 1s,

allowing currents from fAs to mAs to be continuously

measured with outstanding precision.

The DDC232 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-DDC232 system is minimal.

The DDC232 uses a +5V analog supply and a +2.7V

to +3.6V digital supply. Operating over the

temperature range of 0°C to +70°C, the DDC232 BGA-64 package is offered in two versions: the

DDC232C for low-power applications, and the

DDC232CK when higher speeds are required.