An internal test current source is provided for basic func-
tionality testing and diagnostics. This approximately 100nA
current source is pin activated and sums with the external
input current.
Figure 3 shows a more detailed circuit configuration of the
DDC101. The single integration capacitor, C
INT
, and the
D/A converter have been replaced with a high resolution
Capacitor Digital-to-Analog Converter (CDAC). By switch-
ing between ground and V
REF
the binary weighted capacitor
array of the CDAC accumulates the input signal’s charge to
keep the comparator input at virtual ground.
+V
S
DDC101
Test Current
Reset
CDAC
C
INT
ANALOG
In
Buffer
High
Resolution
Digital Out
3rd Order Digital
Integration,
Tracking and
Control Logic
18 Bits
Digital
Filter
20 Bits
Serial I/O
Register
DATA
INPUT
DATA
OUTPUT
Oversampled
Digital Out
Sensor
ANALOG
COMMON
Comparator
TEST
In
V
REF
SYSTEM System Control
CLOCK
DATA
DATA
TRANSMIT CLOCK
FIGURE 3. DDC101 Detailed Circuit Diagram.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN
assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject
to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not
authorize or warrant any BURR-BROWN product for use in life support devices and/or systems.
®
3
DDC101
ETC [ ETC ]
