ViewSonic VX500PLUS-1 Service Manual page 39

Pin Function
sin_x(No)
Sensor analog input pin and it is connected with touch pad. When it is touched by hand, the capacitance
of this pin is changed that drive internal timer circuit.
Ref_x(No)
Reference time generation pin which is compared to sin_x (No). From capacitance value which
connected this pin initialize standard time. In case of switch off, standard time have to set smaller
then time which is generated in sin_x (No) pin.
Ref_bias_adj
Timer bias control pin which is related in sin_x (No), Ref_x (No). Using 30kohm ~ 150kohm
resistor, it control time with ref_x (No) capacitor. In direct touch, 10kHz ~ 100kHz is
recommended.
R_clk
Output holding time setting pin, for protecting of malfunction of circuit from noise, it can be
controlled by external resistor. As a value of this resistor, internal circuit decide time delay between
input and TTL output.
P_on_rst
Prevent abnormal operation during VDD on transient time.
EN_x (No)
Select input channel and control of sensitivity.
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VX500+-1