SCLS542B − SEPTEMBER 2003 − REVISED JANUARY 2004
SN74HC4851
8 CHANNEL ANALOG MULTIPLEXER/DEMULTIPLEXER
WITH INJECTION CURRENT EFFECT CONTROL
APPLICATION INFORMATION
5V
VCC
Sensor
’HC4851
Channel 1
Channel 2
Channel 3
Channel 4
Channel 5
Channel 6
(8× Identical
Circuitry)
Channel 7
Channel 8
Common Out
A/D − Input
Microcontroller
VCC
Figure 3. Solution by Applying the ’HC4851 Multiplexer
Gate = VCC
(Disabled)
Disabled Analog Multiplex Input
VIN > VCC + 0.7 V
Common Analog Output
Vout > VCC
P+
+
+
+
P+
N − Substrate (on VCC potential)
Figure 4. Diagram of Bipolar Coupling Mechanism
(Appears if V
IN
Exceeds V
CC
, Driving Injection Current Into the Substrate)
8
POST OFFICE BOX 655303
•
DALLAS, TEXAS 75265
TI [ TEXAS INSTRUMENTS ]
