ICL8052 Datasheet, PDF (20/21 Pages) Intersil Corporation – 14-Bit/16-Bit, Microprocessor- Compatible, 2-Chip, A/D Converter

ICL8052/ICL7104, ICL8068/ICL7104
Power Supply Sequencing
Application Notes
Because of the nature of the CMOS process used to
fabricate the ICL7104, and the multiple power supplies
used, there are certain conditions of these supplies under
which a disabling and potentially damaging SCR action can
occur. All of these conditions involve the V+ supply (Norm
+5V) being more positive than the V++ supply. If there is
any possibility of this occurring during start-up, shut down,
under transient conditions during operation, or when insert-
ing a PC board into a “hot” socket, etc., a diode should be
placed between V+ and V++ to prevent it. A germanium or
Schottky rectifier diode would be best, but in most cases a
silicon rectifier is adequate.
Analog and Digital Grounds
Extreme care must be taken to avoid ground loops in the
layout of ICL8068 or ICL8052/7104 circuits, especially in
16-bit and high sensitivity circuits. It is most important that
return currents from digital loads are not fed into the analog
ground line. A recommended connection sequence for the
ground lines is shown in Figure 16.
Some application notes that may be found useful are listed
here:
NOTE #
DESCRIPTION
AnswerFAX
DOC. #
AN016 “Selecting A/D Converters”, by Dave
Fullagar
9016
AN017 “The Integrating A/D Converter”, by Lee
Evans
9017
AN018 “Do’s and Don’ts of Applying A/D
Converters,” by Peter Bradshaw and Skip
Osgood
9018
AN030 “Building a Battery-Operated Auto
Ranging DVM with the ICL7106”
9030
+
I/P
V_IN
-
FILTER
CAP
BUFF
OUT
PIN 35
ICL7104
AN GND _CAZ
BUFF
-IN
(IF USED)
8068 PIN 2
COMP
REF
VOLTAGE
V_REF
EXTERNAL
REFERENCE
(IF USED)
PIN 35
ICL7104
AN GND
+15V
-15V
BOARD
EDGE
DIGITAL
LOGIC
DIG GND
ICL7104
PIN 2
DEVICE PIN
+5V SUPPLY BYPASS CAPACITOR(S)
FIGURE 16. GROUNDING SEQUENCE
SUPPLY
RETURN
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