1. Laboratory for Perceptual Robotics – Department of Computer Science Embedded Systems Semiconductors

2. Laboratory for Perceptual Robotics – Department of Computer Science Transistors active components that can increase the power of a signal bipolar transistor: Si (silicon) semiconductor - tetravalent, has 4/8 electrons in its outer most (valence) shell P (phosphorus) - pentavalent, has 5/8 electrons in its valence shell, which implies it has an extra loosely bound electron B (boron) - trivalent, has 3/8 valence electrons…it’s also conducting (has “holes” in the electron cloud) Silicon is special doped with phosphorus becomes “N” type semiconductor doped with boron becomes “P” type semiconductor only semiconductor that forms an insulating oxide layer

3. Laboratory for Perceptual Robotics – Department of Computer Science Diodes charge distribution + --+ non-conducting + --+ + reverse bias + --+ conducting +-- forward bias Si PN anode + cathode -- + depletion region

4. Laboratory for Perceptual Robotics – Department of Computer Science diodes are rated by the amount of current they can handle small signal diodes ~100mA power diodes ~ 1000’s of Amps and the maximum reverse voltage they can withstand ~ 75-80V If you can measure a reverse current --- bad diode Diodes + -- non-conducting +-- reverse bias I=0 I conducting + -- forward bias R arrow points in the direction of current flow

5. Laboratory for Perceptual Robotics – Department of Computer Science Diode Impedance breakdown voltage ~75V reverse biased I current through diode V voltage drop across diode Kirchoff’s laws don’t apply if 10mA is flowing through the diode,  V d ~0.5V forward biased

6. Laboratory for Perceptual Robotics – Department of Computer Science Rectifiers - how would you do it? ~ R load AC V load t

7. Laboratory for Perceptual Robotics – Department of Computer Science Rectifiers V load t R load ~ AC two diode drops

8. Laboratory for Perceptual Robotics – Department of Computer Science Rectifiers V load t R load ~ AC ripple

9. Laboratory for Perceptual Robotics – Department of Computer Science Rectifiers V load t R load ~ AC ripple +5V diode clamp: when V >= 5.6V diode is conducting

10. Laboratory for Perceptual Robotics – Department of Computer Science Zener Diode let current go through backwards, while maintaining a near constant voltage If I > 20-50mA, “pop” + -- I R V in voltage regulator V out ~zener voltage(5-6V)

11. Laboratory for Perceptual Robotics – Department of Computer Science Diodes - LEDs I conducting + -- forward bias R forward  V ~ 1.5-2.5 V current must be limited to 5-20mA stress limit 20-50mA blue higher  V green yellow orange red longer wavelength red/green polarity indicators +--

12. Laboratory for Perceptual Robotics – Department of Computer Science Flyback Diode transistor opens: V=L dI/dt creates large (negative) polarization of the inductor, overstressing the transistor switch flyback diode clamps inductor voltage at (V+ 0.6) creates conduction path to dissipate the high tension charge

13. Laboratory for Perceptual Robotics – Department of Computer Science IR Bumper - Modulated Transmitter S1 on off +5VDC 270  0.001  F 6.9K  5K  pot 100K 