SP6121CN-L Datasheet, PDF (32/42 Pages) Sipex Corporation – Low Voltage, Synchronous Step Down PWM Controller

Design Solution 20
Vin 3.0V-5.0 V
Cin
R1
47uF
10Ohm
Q1
FDS6375
C1 10uF
U1 SP6121
C1 ^{1 Vcc}
2.2uF _{2 GND}
PDRV ^{8 L1}
NDRV ^{7 4.7uH}
3 _VFB
ISET ⁶
C2 ⁴
1uF
COMP ISENSE
5
R4
10K
R2 4K ₂
-3
R3
4 _{OUT LMV321 545 Ohm}
5
+1
C3
1uF
L2
4.7uH
L1L2 (744870004)
Wurth Electronic
Q2
FDN337N
Cout
100uF
D2
5.1V
Vout
D1
Luxeon
Vref
Rref
0.1 Ohm
VFB=1.25V
Gain=1+R2/R3
I LED=Vref /0.1Ohm
=150mV/0.1Ohm
Figure 11. Application Schematic
Mar29-06
SP6121 Buck/Boost Circuit for LED Driver up to 1.5A
Page 4 of 4
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