MUX508 Datasheet, PDF (23/37 Pages) Texas Instruments – Low-Capacitance, Low-Charge-Injection, Precision, Analog Multiplexers

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MUX508, MUX509
SBAS758A – JANUARY 2016 – REVISED MARCH 2016
9.3 Feature Description
9.3.1 Ultralow Leakage Current
The MUX50x provide extremely low on- and off-leakage currents. The MUX50x are capable of switching signals
from high source-impedance inputs into a high input-impedance op amp with minimal offset error because of
these ultralow leakage currents. Figure 37 shows typical leakage currents of the MUX50x versus temperature.
900
600
300
0
±300
I_D(ON)+
I_D(OFF)+
I_S(OFF)+
I_S(OFF)±
±600
±900
±75 ±50 ±25
I_D(OFF)±
I_D(ON)±
0 25 50 75 100 125 150
Temperature (ƒC)
C006
Figure 37. Leakage Current vs Temperature
9.3.2 Ultralow Charge Injection
The MUX50x have a simple transmission gate topology, as shown in Figure 38. Any mismatch in the stray
capacitance associated with the NMOS and PMOS transistors creates an output level change whenever the
switch is opened or closed.
OFF ON
CGSN
CGDN
S
D
CGSP
CGDP
OFF ON
Figure 38. Transmission Gate Topology
The MUX50x have special charge-injection cancellation circuitry that reduces the source-to-drain charge injection
to as low as 0.3 pC at V_S = 0 V, and ±0.6 pC in the full signal range, as shown in Figure 39.
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