This document summarizes a student capstone project to design a commercially feasible LED driver circuit of less than 15 watts. The project was completed by a group of 4 students. Their design focused on creating a low-cost circuit that maintains constant current and monitors temperature. Their buck converter topology achieved 72.4% efficiency, lower than existing flyback designs, at a manufacturing cost of 34.7 Taka per unit. Future work could focus on increasing efficiency further and adding smart features like sensors.

1. 1
United International University
EEE400: Capstone Project

2. Title of the Project:
Commercially Feasible LED Driver Circuit (<15 Watt)
Group Members:
Name ID
Md. Ragib Noor (Chair*) 021 151 093
Tofael Ahmmed (Recorder*) 021 151 103
Md. Tawhid Hasan (Member) 021 151 010
Md. Mohiuddin Parvez (Member) 021 151 097
Coordinator : Dr. Khawza Iftekhar Uddin Ahmed
Mentor: Dr. Md. Rukonuzzaman
Group: 181-16

3. An Ideal LED Driver.
➝ Controls power of LED lights
➝ Keeps current constant
➝ Maintain LED lights health by
maintain power flow.
➝ Senses bulb temperature.
3

4. Why LED is better?
4
Factor
Incandescent lamps CFL LED lights
Life span (avrg) 1200 hr. 8000 hr. 50,000 hr.
Power consumption
(Equivalent to 60
watt)
60 watt 13-15 watt 6-8 watt
Emission of CO2 4000 lb/yr 1020 lb/yr 510 lb/yr
Durability not durable
(contains glass and
filament)
not durable
(contains glass)
very durable (can
handle jarring and
bumping)

5. Problem Statement
1. Exixting model have low efficiency and
poor power factor.
2. Led driver cost high.
5

6. 6
Motivation & Importance
• Demand is high.
• Govt. losing money while importing.
• LED technology is much better than CFL or
Fluorescent lamps.

7. 7
Literature review:
1. LED driver circuit with PWM output .
3. Led driver circuit for life extension
2. Commercial power LED
constant current driver

8. Goals for overall project.
8
Designing a device with
•Low manufacturing cost
•Comparatively high efficiency
• High reliability and sustainability

9. 9
Feedback path
Recommend value in datasheet should be 2~5kΩ.
Used in this design RFBL= 2.2k Ω
VOVP=1.3 × 60= 72;
Current sense resistor:
VREF: Internal reference voltage, typically
0.2V
Rcs: The current sensing resistor value
Iout= 185 mA
Design Method of major components:

10. Design Method of major
components:
Inductor:
(Vin -Vout)*Ton = L ×Ipk
=> L= 2.4 mH max
Output Capacitor:
∆𝑉 =
𝑉𝑠 × 𝑉𝑠 − 𝑉𝑎
8𝐶𝐿𝑓2 𝑉𝑠
10

11. Internal block diagram
➝ Circuit starts when vcc
pin reaches the
threshold.
➝ Then the mosfet
chops down the
voltage.
➝ CS pin senses current
from inductor.
➝ FB pin detects the
overvoltage protection
11

12. 12
Working principle
AC-DC DC-DC

13. Cost analysis compared to other
topologies:
➝ Buck Driver (BP2328)
(Tk. 8.20 )
➝ MOSFET include in ic.
➝ No physical
transformer
➝ Total component cost:
➝ AC-DC conversion
cost= Tk. 7.8
➝ DC-DC conversion
cost= Tk. 30
➝ Flyback Driver
(UC3845) (Tk. 12.00)
➝ External Mosfet
(IRF BC30) needed (Tk
28)
➝ Physical transferrer
used (high loss and
cost)
➝ AC-DC conversion
cost= Tk. 7.8
➝ DC-DC conversion
cost= Tk. 45
13

14. Results
➝ Low manufacturing
cost
➝ Total cost per piece
= tk. 34.7
➝ Comparatively high
efficiency
➝ Achieved efficiency,
η = 72.4 %
14

15. Loss analysis
➝ Major losses of components
15
Bridge Rectifier loss 0.3 W
Freewheeling diode loss 0.598 W
Inductor copper loss 0.234 W
MosFET loss 0.026W
Output capacitor loss 0.612 W
Total Loss 1.78 W
AC-DC DC-DC
0.3 W 1.48 W
Power used AC-DC loss DC-DC loss

16. Our design
Buck Topology
Higher Efficincy (72.4%)
Mass production cost= Tk
34.7.
No physical transformer.
Mosfet included in IC.
Comparion between our model and
existing models is costing:
Exiting drivers
Flyback Topology
Low Efficincy
Import cost > Tk. 50
Physiscal transformer used
(high loss and cost)
Need external mosfet
16

17. PO Mapping
17
• PO1 : Engineering Knowledge
Used previous knowlegdge
• PO2: Problem Analysis
Analyzed the problem intensively
• PO3: Design/development of solutions
Designed the whole device.

18. PO Mapping
18
• PO4: Investigation
Surveyed market thoroughly.
• PO5: Modern tool usage
Used proteus, LCR meter,
Multimeter, Analog and Digital Wattmeter
• PO6: The engineer and society
Makes high efficiency lighting
more effordable.

19. PO Mapping
19
• PO7: Environment and sustainability
High Sustainability, Eco Friendly Device
• PO8: Ethics
Followed code of conduct, No ethical conflicts.
• PO9: Individual work and teamwork
Conducted several meetings, spent total 485
hours as team.

20. 20
PO Mapping
• PO10: Communication
Communication with mentor, submitted reports,
presentations
• PO11: Project management
and finance
Managed the project and maintain the financial
aspects .
• PO12: Lifelong learning
Power Electronics is a vast subject, needs more
research.

21. Sustainable
Development Goals
➝Goal 9 Targets:
• Promote sustainable
industrialization
• Enhance scientific research
• Upgrade the technological
capabilities of industrial
sectors
21

22. 22
Future Improvement
1. Increase efficiecny.
2. Increase watt limit with low cost.
3. Design smart led driver using
sensor.

23. 23

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