SP6121CN-L Datasheet, PDF (30/42 Pages) Sipex Corporation – Low Voltage, Synchronous Step Down PWM Controller

Design Solution 20
LED Efficiency vs Input Voltage
100
90
80
70
Iout=1.0A
Iout=1.5A
60
50
3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0
Input Voltage (V)
Figure 1. Efficiency Graph
Input Current vs Input Voltage
3.0
Iout=1.5A
2.5
Iout=1.0A
2.0
1.5
1.0
0.5
3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0
Input Voltage (V)
Figure 2. Input Current Graph
PDRV
NDRV
I L2
1A/div
I L1
1A/div
Figure 3. Switching Behaviors
Vin=5V, Iout=1.5A
PDRV
NDRV
I L2
1A/div
I L1
1A/div
Figure 4. Switching Behaviors
Vin=3.3V, Iout=1.5A
Primary
P FET
Secondary
N FET
Primary
P FET
Secondary
N FET
Figure 5. Switch Node
Vin=5.0V, Iout=1.5A
Figure 6. Switch Node
Vin=3.3V, Iout=1.5A
Mar29-06
SP6121 Buck/Boost Circuit for LED Driver up to 1.5A
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Sipex Corporation