SP6121CN-L Datasheet, PDF (26/42 Pages) Sipex Corporation – Low Voltage, Synchronous Step Down PWM Controller

Circuit Performance
Start up
In order to soft-start the converter, use a 1µF capacitor between the COMP pin
and GND. The COMP pin is actually the internal output of the error amplifier. This
high capacitance value will act as a local integrator, slowing down any fast
variation due to start up or transients.
VIN
VOUT
VSENSE
IIN
1A/div
Start up VIN=5.0V
VIN
VOUT
VSENSE
IIN
1A/div
Start up VIN=3.3V
LED Efficiency vs Output Load
100
90
80
70
Iout=1.0A
60
Iout=1.5A
50
3.0
3.2
3.4
3.6
3.8
4.0
4.2
4.4
4.6
4.8
5.0
Output Load (mA)
Nov 28 06 AppNote: SP6121 as a Synchronous Buck-Boost LED Driver
Page 6
© 2006 Sipex Corporation