DDC264 Datasheet, PDF (10/26 Pages) Texas Instruments – 64-Channel, Current-Input Analog-to-Digital Converter

DDC264
SBAS368C – MAY 2006 – REVISED JULY 2011
www.ti.com
THEORY OF OPERATION
General Description
A dual switched integrator input channel for the
DDC264 is shown in Figure 19. The DDC264
contains 64 identical input channels that perform the
function of current-to-voltage integration followed by a
multiplexed A/D conversion. Each input has two
integrators so that the current-to-voltage integration
can be continuous in time. The DDC264 continuously
integrates the input signal by switching integrations
between side A and side B.
For example, while side A integrates the input signal,
the side B outputs are digitized by the onboard ADC.
This integration and A/D conversion process is
controlled by the convert pin, CONV. The results from
side A and side B of each signal input are stored in a
serial output shift register. The DVALID output goes
low when the shift register data are ready to be
retrieved.
Input
Current ^IN1
Photodiode
Side A Integrator
QGND
To ADC
Side B Integrator
QGND
Figure 19. Dual Switched Integrator Architecture
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