SP6121CN-L Datasheet, PDF (23/42 Pages) Sipex Corporation – Low Voltage, Synchronous Step Down PWM Controller

the battery voltage. The converter will automatically adjust its Duty Cycle
depending on these factors. The below graph shows the area which will be used.
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
D : Duty Cycle
Note that the Duty Cycle will stay around 50%. This value will be used as a
reference for calculating the external components.
Boost Cell
Buck Cell
LED
Disconnect
OverVoltage
Protection
Current
sensing
Current
Sensing
Amplifier
SP6121 Buck-Boost Application Schematic
Nov 28 06 AppNote: SP6121 as a Synchronous Buck-Boost LED Driver
Page 3
© 2006 Sipex Corporation