Low-Voltage, Single-Supply
Multiplexer and Switch
__________Applications Information
Power-Supply Considerations
The MAX4524/MAX4525’s construction is typical of
most CMOS analog switches. They have two supply
pins: V+ and GND. V+ and GND are used to drive the
internal CMOS switches and set the limits of the analog
voltage on any switch. Reverse ESD-protection diodes
are internally connected between each analog signal
pin and both V+ and GND. If any analog signal
exceeds V+ or GND, one of these diodes will conduct.
During normal operation, these (and other) reverse-
biased ESD diodes leak, forming the only current drawn
from V+ or GND.
Virtually all the analog leakage current comes from the
ESD diodes. Although the ESD diodes on a given sig-
nal pin are identical, and therefore fairly well balanced,
they are reverse-biased differently. Each is biased by
either V+ or GND and the analog signal. This means
that leakage will vary as the signal varies. The differ-
ence in the two diode leakages to the V+ and GND
pins constitutes the analog signal-path leakage current.
All analog leakage current flows between each pin and
one of the supply terminals, not to the other switch ter-
minal. This is why both sides of a given switch can
show leakage currents of either the same or opposite
polarity.
MAX4524/MAX4525
______________________________________________Test Circuits/Timing Diagrams
V+
V+
V
ADD
50Ω
V+
ADDA
ADDB
NO0
NO1–NO2
V+
V
ADD
0V
V
NO0
90%
90%
V
OUT
35pF
300Ω
50%
MAX4524
INH
GND
NO3
COM
V
OUT
0V
t
TRANS
t
TRANS
V+
V+
V
ADD
50Ω
V+
ADD
NO
V
ADD
0V
V
NC
50%
90%
90%
MAX4525
INH
GND
NC
COM
V+
V
OUT
35pF
300Ω
V
OUT
0V
t
TRANS
t
TRANS
REPEAT TEST FOR EACH SECTION.
Figure 1. Address Transition Time
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
