PSpice Application Notes

APPLICATION NOTE 2 + R_open = 100MEG ; open circuit contact resistance + R_close= .05 ; closed circuit contact resistance * electrical model of coil v_winding coila a1 0 r_winding a1 a2 {R_coil} l_winding a2 coilb {L_coil} * make a voltage from the current e_cc cc 0 value = {limit(I(v_winding),-3*I_pull,3*I_pull)} r_cc cc 0 1k * use digital to create a switch with hysteresis o_mag cc 0 relay_1 DGTLNET=d digio_1 * by using min/max delay we can use a single N-device to simulate both * the no and nc contacts. u_dly buf dpwr dgnd d cnt relay_2 digio_1 MNTYMXDLY=4 n_cnt com no nc relay_3 DGTLNET=cnt digio_1 .model relay_1 doutput ( + s0name="0" s0vlo={-I_pull} s0vhi={I_pull} + s1name="1" s1vlo={I_drop} s1vhi={4*I_pull} + s2name="1" s2vlo={-4*I_pull} s2vhi={-I_drop} + timestep={T_make/1000} + ) .model relay_2 ugate ( + tplhmn={T_break} tphlmn={T_break} + tplhmx={T_make} tphlmx={T_make} + ) .model relay_3 dinput ( + s0name="0" s0tsw={T_make/1000} s0rlo={R_open} s0rhi={R_close} + s1name="1" s1tsw={T_make/1000} s1rlo={R_close} s1rhi={R_open} + s2name="R" s2tsw={T_make/1000} s2rlo={R_open} s2rhi={R_open} + s3name="F" s3tsw={T_make/1000} s3rlo={R_open} s3rhi={R_open} + s4name="X" s4tsw={T_make/1000} s4rlo={R_open} s4rhi={R_open} + s5name="Z" s5tsw={T_make/1000} s5rlo={R_open} s5rhi={R_open} + ) .model digio_1 uio .ends * End of RELAY_SPDT_BHV model Model of a Relay (with Contact Bounce) In some systems the previous model is too simple, since it does not include contact bounce. This model includes contact bounce for a specified period of time after the contacts close. The contact bounce is created by taking a digital contact close signal and converting it to an analog ramp using a Digital to Analog conversion device. The analog ramp forms the input to a table-controlled voltage source. The table creates a bounce output voltage which is then converted to digital to square it up. The digital value is used to control another Digital to Analog conversion device which models the contacts. Note: Contact bounce is caused by the physical bouncing of the electrical contacts as they close. It looks electrically as if the relay contacts close and open several times in quick succession before they remain closed. * End of RELAY_DPDT_BHV model * Behavioral model of a relay with contact bounce. .subckt RELAY_SPDT_BHV_BOUNCE coila coilb no nc com + PARAMS:

• Cover