Elec4430 INTEGRATED POWER ELECTRONICS
INTEGRATED POWER ELECTRONICS
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Elec4430 INTEGRATED POWER ELECTRONICS
Any late submission will immediately receive a 25% mark of deduction, and additional
25% mark of deduction will be applied for each additional 24 hours of late. Timestamp
recorded by Canvas is used to determine how late is your submission.
You are required to design a Buck converter using LTC3561 shown in the below figure. Based
on your assigned specification, you need to design the value of inductor (L), the value of output
capacitor (C), the value of upper feedback resistor (RTOP), and the value of timing resistor (Rt).
You need to come up with the value of pole capacitor (Cp) and the value of zero resistor (Rz) to
make sure the Buck converter has stable operation over all the given conditions.
Fig. 1: Schematic of Buck converter with LTC3561
Table I: Specifications of the DC-DC Converter
Specifications Requirements
Supply Voltage From 2.7 V to 4.2 V.
Switching Frequency (FSW) 1.0 MHz, 1.5 MHz, 2.0 MHz, or 2.5 MHz (fixed for each student).
Target Output Voltage (VO) 1.2 V, 1.5 V, 1.8 V, or 2.0 V (fixed for each student).
Maximum Load Current
(IOMAX)
0.5 A, 0.7 A, or 0.9 A (fixed for each student)
Buck converter must operate in CCM at 20% of Maximum Load
Current (e.g. 100 mA, 140 mA, or 180 mA) under entire supply
voltage range.
Peak-to-peak Output
Voltage Ripple (∆VOPP)
∆VOPP < 0.1 % of Target Output Voltage (VO) under entire supply
voltage range, and between 20% to 100% of Maximum Load
Current.
Stability
Use load current step between 20% to 100% of Maximum Load
current to test stability. Current step rise/fall time is set at 1A/µs
(e.g., rise/fall time sets to 0.4 µs for step between 100 mA and 500
mA). Make sure to test at both 2.7 V and 4.2 V Supply Voltage.
p. 2
You are required to submit your own design and report. You will be randomly assigned to
certain specifications with different Switching Frequency (FSW), Target Output Voltage (VO),
and Maximum Load Current (IOMAX). Detail specifications of each student is posted on the
Canvas. You have to submit the report (in PDF format) in no more than 15 pages and the
LTspice files (i.e. “.asc” files) to the Canvas. The report should include:
1. A schematic diagram including the controller and all component values (generated from
LTspice),
2. Calculation steps of values of different components such as the inductor (L), the output
capacitor (C), the upper feedback resistor (RTOP), and the timing resistor (Rt),
[ You must use 100k-Ohm for the lower feedback resistor (RBOT) ]
3. Simulation waveforms with clear labels, and numerical values of cursors:
a) Line regulation at the Maximum Load Current (Supply voltage is changed from 2.7 V to
4.2 V),
b) Load regulation at the nominal supply voltage of 3.6 V (Load is changed from 20% to
100% of the Maximum Load Current),
c) Inductor current at 20% of Maximum Load Current and the Worst-Case Supply Voltage
to show CCM operation,
d) 100% of Maximum Load Current and the Worst-Case Supply Voltage to show the Peak-
to-peak Output Voltage Ripple,
e) Stability by showing output voltage waveform under load current step between 20% and
100% of Maximum Load current at both 2.7 V Supply Voltage and 4.2 V Supply Voltage.
Current step rise/fall time MUST set at 1A/µs.
[ You can try to decrease the value of pole capacitor (Cp) by 10x or more, and run
simulation. Then you will know what instability is! ]
4. Submit your report and “.asc” files to the Canvas before the due date.