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university:tools:m1k:alice-ltc1043-analog-mux-ug [15 Apr 2021 20:20]
Doug Mercer created
university:tools:m1k:alice-ltc1043-analog-mux-ug [17 Apr 2021 20:23]
Doug Mercer [Building the Mux]
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 There is a solder jumper, SJ1, in series with the CH-A AWG output pin between the right angle connector to the M1k and the female header. Leave this jumper open and connect the second from the top pin on the female header to digital I/O pin 0 when using the board in the Alternate Sweep configurations. To use the board in the Chop Sweep configuration,​ short the jumper. There is a solder jumper, SJ1, in series with the CH-A AWG output pin between the right angle connector to the M1k and the female header. Leave this jumper open and connect the second from the top pin on the female header to digital I/O pin 0 when using the board in the Alternate Sweep configurations. To use the board in the Chop Sweep configuration,​ short the jumper.
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 +{{ :​university:​tools:​m1k:​alice-ltc1043-analog-mux-fig10.png?​375 |}}
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 +<WRAP centeralign>​LTC1043 multiplexer PCB connected to M1k</​WRAP>​
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 =====Be Aware when using Chop Sweep Mode===== =====Be Aware when using Chop Sweep Mode=====
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 **Here is something to be aware of when using the Mux in Chop Sweep mode.** **Here is something to be aware of when using the Mux in Chop Sweep mode.**
  
-The Mux switches in conjunction with the 100 pF input capacitance of the BIN pin (and AIN) form a rudimentary Sample and Hold circuit. When the first Mux switch is closed the input capacitance is charged up to the voltage on that Mux input. When the first switch is opened and the second switch to the other Mux input is closed the input capacitance is still charged to the first Mux input voltage. If the second Mux input is floating the first input Mux voltage (or most of it) will still be on the input capacitance and appear in the trace of the second Mux channel. Unless the second Mux input is driven by a source with low enough impedance to discharge / recharge the input capacitance to the new voltage.+The Mux switches in conjunction with the 100 pF input capacitance of the BIN pin (and AIN) form a rudimentary Sample and Hold circuit ​(see figure 1 in the [[university:​courses:​alm1k:​alm-signals-labs:​alm-tha-lab|Track and Hold Amplifier Lab]]). When the first Mux switch is closed the input capacitance is charged up to the voltage on that Mux input. When the first switch is opened and the second switch to the other Mux input is closed the input capacitance is still charged to the first Mux input voltage. If the second Mux input is floating the first input Mux voltage (or most of it) will still be on the input capacitance and appear in the trace of the second Mux channel. Unless the second Mux input is driven by a source with low enough impedance to discharge / recharge the input capacitance to the new voltage.
  
 The Mux switches in conjunction with the 100 pF input capacitance of the BIN pin (and AIN) also form a switched capacitor resistor ( see this lab on [[university:​courses:​alm1k:​alm-signals-labs:​alm-switched-cap-filter-lab|switched capacitor circuits]] ). This switched capacitor resistor appears across the pair of Mux inputs as shown in figure 9. In the case of a switched capacitor resistor we know that the apparent value of the resistance is: The Mux switches in conjunction with the 100 pF input capacitance of the BIN pin (and AIN) also form a switched capacitor resistor ( see this lab on [[university:​courses:​alm1k:​alm-signals-labs:​alm-switched-cap-filter-lab|switched capacitor circuits]] ). This switched capacitor resistor appears across the pair of Mux inputs as shown in figure 9. In the case of a switched capacitor resistor we know that the apparent value of the resistance is:
university/tools/m1k/alice-ltc1043-analog-mux-ug.txt · Last modified: 17 Apr 2021 20:23 by Doug Mercer