MCP1650DM-LED2 Microchip Technology, MCP1650DM-LED2 Datasheet - Page 14

• Manufacturer Part Number: MCP1650DM-LED2
• Description: BOARD DEMO FOR MCP1650 WHITE LED
• Manufacturer: Microchip Technology

Specifications of MCP1650DM-LED2

• Current - Output / Channel: 15mA
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 32.4V
• Features: Dimmable
• Voltage - Input: 2.7 ~ 4.5V
• Utilized Ic / Part: MCP1650
• Core Chip: MCP1650
• Topology: Boost
• Output Current: 560mA
• No. Of Outputs: 1
• Input Voltage: 2.7V To 5.5V
• Kit Contents: Board
• Development Tool Type: Hardware - Eval/Demo Board
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

MCP1650 Multiple White LED Demo Board User’s Guide
DS51586A-page 10
The equation for the energy flowing into the inductor is given below. The power in the inductor is
equal to the inductor energy times the switching frequency (F
The peak inductor current is:
Using a standard inductor value of 4.7 µH, the power in the inductor is calculated.
There is a second operating point that needs to be addressed when V
duty cycle is 56%.
For both operating points, the inductor power is close to the necessary maximum input
power, forcing the converter to operate in Continuous Current mode. Therefore, a
4.7 µH inductor is too large and the peak input current needs to be increased. A 3.3 µH
inductor is selected.
Now that the inductor energy is greater than the maximum required input energy, the
converter will operate in Discontinuous Current mode.
Energy (2.7V) = 0.880 µ-Joules
Energy (3.8V) = 0.854 µ-Joules
Energy (2.7V) = 1.256 µ-Joules
Energy (3.8V) = 1.219 µ-Joules
Power (2.7V) = 0.66W
Power (3.8V) = 0.640W
Power (2.8V) = 0.942W
Power (3.8V) = 0.914W
I
I
I
I
PK
PK
PK
PK
(2.7V) = 0.612A
(3.8V) = 0.603A
(2.7V) = 0.872A
(3.8V) = 0.859A
T
T
T
ON
ON
ON
= (1/F
= (1/F
= (1/F
SW
SW
SW
) * Duty Cycle
) * Duty Cycle
) * Duty Cycle
Power
Energy
P
P
P
I
PK
IN
IN
IN
=
=
=
=
=
=
----------------------- -
Efficiency
0.486w
-----------------
0.608 watts
Energy F
V
--------
1
-- -
2
80%
L
IN
P
OUT
L I
T
ON
PK
SW
2
SW
).
© 2005 Microchip Technology Inc.
IN
is 3.8V and the