MAX14752 Datasheet, PDF (13/15 Pages) Maxim Integrated Products – 8-Channel/Dual 4-Channel 72V Analog Multiplexers

8-Channel/Dual 4-Channel
72V Analog Multiplexers
Detailed Description
The MAX14752/MAX14753 are 8-to-1 and dual 4-to-1
high-voltage analog multiplexers. Both devices feature
60Ω (typ) on-resistance with 0.03Ω (typ) on-resistance
flatness. These low on-resistance multiplexers conduct
equally well in either direction.
The MAX14752 is an 8-to-1 multiplexer and MAX14753
is a dual 4-to-1 multiplexer. Both devices operate with
dual supplies of ±10V to ±36V or a single supply of
+20V to +72V. Both devices can also operate with
unbalanced supplies, such as +36V and -10V. These
multiplexers support rail-to-rail input and output signals.
The control logic level is defined via the EN input. These
devices do not require power-supply sequencing.
Applications Information
Current Through the Mux
The current flowing through each on-channel of the
MAX14752/MAX14753 multiplexers must be limited to
±5mA for normal operation. If the current exceeds this
limit, an internal leakage current from that channel to
V_SS appears. Larger input current does not destroy the
device if the max power dissipation is not exceeded.
Input Voltage Clamping
For applications that require input voltages beyond the
normal operating voltages, the internal input diodes to
V_DD and V_SS can be used to limit the input voltages. As
shown in Figure 11, series resistors can be employed at
the inputs to limit the currents flowing into the diodes dur-
ing undervoltage and overvoltage conditions. Choose the
limiting resistors such that the input currents are limited to
I_{IN_}(max) = 100mA. The values of the current limit resis-
tors can be calculated as the larger of R_LIM+ and R_LIM-.
R_LIM+
=
V_IN (max)–V_DD
I_{IN_} (max)
R_LIM-
=
V_SS –V_IN (min)
I_{IN_} (max)
During an undervoltage or overvoltage condition, the
input impedance is equal to R_LIM. The additional power
dissipation due to the fault currents needs to be calcu-
lated. The MAX14752/MAX14753 multiplexer operates
normally on a channel that is on during an overvoltage
or undervoltage clamping condition on a second chan-
nel that is not switched.
Beyond-the-Rail Input
If input voltages are expected to go beyond the supply
voltages, but within the absolute maximum supply volt-
ages of the MAX14752/MAX14753, add two diodes in
series with the supplies as shown in Figure 12.
During undervoltage and overvoltage events, the internal
diodes pull V_DD/V_SS supplies up/down. An advantage of
this scheme is that the input impedance is high and
currents do not flow though the MAX14752/MAX14753
during overvoltage and undervoltage events. The input
voltages must be limited to the voltages specified in the
Absolute Maximum Ratings section.
V_DD
R_LIM
R_LIM
R_LIM
R_LIM
R_LIM
R_LIM
R_LIM
R_LIM
MAX14752
OUT
CONTROL
V_SS
S0 S1 S2 EN GND
Figure 11. Input Overvoltage and Undervoltage Clamping
______________________________________________________________________________________ 13