5321824 INC 2A KMUTT

1. [INC 281 MULTIDISCIPLINARY WORKSHOP WEEKLY REPORT] March 15, 2012
Name-Surname Mutchima Bangkha
Student ID. 53211824
Group Name Is
Engineering Team Jane, Best, Not, Su, Jum-O, Love, Tew, Go, Nut
Members and Benz
Product Design Sa-tang, Ped, Fon, Tip, Earng [ID] and Mind
Team Members [interior]
Weekly Progress
This week I am looking for more LEDs and LED driver circuit. For LCD driver
circuit , it depend on quantity of LEDs in that circuit. If we know that quantity so we can
control the current for usinng to each LEDs.
The voltage , current of LEDs are alomost like diode. The current is approximately
exponentail function of voltage,so if you change small voltage it will chage the current too.
This is the reason why LEDs need to connect with the constand-voltage sources. The
Series resistors are a simple way to passively stabilize the LED current.
An active constant-current regulator is common for using for high power LEDs.
Low drop-out (LDO) constant current regulators also allow the total LED voltage to be a
higher fraction of the power supply. And switched-mode power supplies are used in some
LED flashlights. OR can use BJT to control current.
Series resistor calculation How does LED work?
Resistance(R) =
voltage
drop
The LED voltage drop is the forward voltage drop across
LED, LED current is desired current.
The formula can be explained considering the LED as a Ω
And we apply Kirchhoff's voltage law (KVL) and also R is the
unknown quantity
BJT
Engineering Analysis
Strong Point
- Can calculate easy if it isn’t complex.
Week Point
- Need to wait the design because we don’t know quantity and quality.
Next Week Job
I will learn more LEDs or the other device which can use replace LEDs.
Department of Control System and Instrumentation Engineering
KING MONGKUT’s UNIVERSITY OF TECHNOLOGY THONBURI