diodes and leds
DESCRIPTION
Diodes and LEDs. Discussion D8.1 Kerns & Irwin Sections 10-1 -- 10-5, 10-10. Covalent bonds -- Insulator. http://electronics.howstuffworks.com/diode1.htm. Semiconductors. Adding a very small amount of B or Ga to Si makes a p-type semi-conductor with a missing electron (a hole). - PowerPoint PPT PresentationTRANSCRIPT
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Diodes and LEDs
Discussion D8.1
Kerns & Irwin
Sections 10-1 -- 10-5, 10-10
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http://electronics.howstuffworks.com/diode1.htm
Covalent bonds -- Insulator
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Semiconductors
Adding a very small amount of P or As to Si makes an n-type semi-conductor with an extra electron
Adding a very small amount of B or Ga to Si makes a p-type semi-conductor with a missing electron (a hole)
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Diodes
http://www.mtmi.vu.lt/pfk/funkc_dariniai/diod/index.html
+ -
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Light Emmitting DiodeLED
+ -
h
http://electronics.howstuffworks.com/led1.htm
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Turning on an LED
+5VR LED
PLD output pin
+5VR LED
PLD output pin
1
0
+5V
+0.2V+1.7V
No current
Currentlight
no light
R =voltagecurrent
=5 1.7
15 x 10 -3 = 220 ohms
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Turning on an LED
This is whatwe use in Lab
CPLD output pin0 V R
No Current
LED
no light
CPLD output pin+3.2 V R
Current
LED
light
R = voltage = 3.2 - 1.9 = 325 ohms current 4 x 10^-3
+1.9 V 0 V
0 V
0
1
R = 330 ohms