bridge.cir		H-Bridge Spice Circuit

.width 80

**** PWM Waveform ****
* Squarewave 1kHz, 50% duty cycle
VS 7 0 PULSE 0 18V 0s 1us 1us .5ms 1ms

* Source Impedance
RS 7 6 10k
* This resistor imulates the impedance of the PWM source
* as well as limits current to a more realistic value

**** Power Supply ****
VCC 1 0 DC 18V

**** Half-Bridge Circuit ****
* node 6 is the output of the square wave generator
* node 1 is V+, 18v
* node 0 is ground.

*Left Side

X1 2 1 1 irf9540n
X3 5 6 0 irf540

*Right Side

X2 2 0 1 irf9540n
X4 5 0 0 irf540

**** Dummy Load ****
* A Dummy load of 10 ohms is being used to demonstrate
* circuit response to PWM

Ra 2 5 10

* Note that actual motor parameters are much more complex,
* and include back EMF generated and terminal inductance.
* To simulate a motor in the circuit (running at constant
* speed), you can comment out the above Ra, and include the
* following circuit:

*Ra 2 3 13.6
*Xa 3 4 0.89
*VE 4 5 8.96V

* These parameters were derived from the MAXON A-Max 22
* #110124 datasheet. To find the induced EMF voltage (VE),
* divide the desired RPM (9970 max) by the speed constant, 
* 558 RPM/V. EG: (5000 RPM)/(558 RPM/V) = 8.96V

**************************
.TRAN 0.01MS 2MS 0.5MS 0.01MS
.AC DEC 5 10 10MEG 

**** TRANSISTOR MODELS ****

.PROBE
.include irf540.spi
.include irf9540n.spi
.END