ICL7104 Intersil, ICL7104 Datasheet - Page 20

• Manufacturer Part Number: ICL7104
• Description: 14-Bit/16-Bit/ Microprocessor- Compatible/ 2-Chip/ A/D Converter
• Manufacturer: Intersil

Power Supply Sequencing
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.
DIGITAL
LOGIC
V
IN
+
-
FILTER
CAP
I/P
DIG GND
ICL7104
AN GND
ICL7104
PIN 35
PIN 2
ICL8052/ICL7104, ICL8068/ICL7104
C
8068 PIN 2
AZ
COMP
FIGURE 16. GROUNDING SEQUENCE
(IF USED)
BUFF
-IN
BUFF
OUT
DEVICE PIN
5-25
REF
VOLTAGE
V
REF
Application Notes
Some application notes that may be found useful are listed
here:
NOTE #
AN016
AN017
AN018
AN030
+5V SUPPLY BYPASS CAPACITOR(S)
REFERENCE
“Selecting A/D Converters”, by Dave
Fullagar
“The Integrating A/D Converter”, by Lee
Evans
“Do’s and Don’ts of Applying A/D
Converters,” by Peter Bradshaw and Skip
Osgood
“Building a Battery-Operated Auto
Ranging DVM with the ICL7106”
EXTERNAL
(IF USED)
AN GND
ICL7104
PIN 35
DESCRIPTION
+15V
BOARD
-15V
EDGE
AnswerFAX
DOC. #
9016
9017
9018
9030
SUPPLY
RETURN