SI9160 Datasheet, PDF (11/11 Pages) Vishay Siliconix – Controller for RF Power Amplifier Boost Converter

100
f = 600 kHz
90
80
f = 1 MHz
f = 1.4 MHz
70
f = 1.8 MHz
60
50
40
30
0.0
V_IN = 3.6
V_OUT = 5 V
0.2
0.4
0.6
0.8
1.0
Output Current (A)
FIGURE 6. Efficiency of Si9160 and Si6801 Boost converter
at various fixed frequencies
Si9160
Vishay Siliconix
CH1
CH2
500 ns/DIV
CH1: Output Ripple (50 mV/DIV)
CH2: P- and N-Channel Drain Voltage (2 V/DIV)
FIGURE 7. Output noise of the Si9160 demo board
50 mV
5 mV
<1 mV
Noise Floor
Switching Frequency = 1 MHz
1 kHz
10 kHz
100 kHz
1 MHz
10 MHz
FIGURE 8. Spectrum response for the Si9160 demo board output voltage
100 MHz
50 mV
5 mV
<1 mV
Noise Floor
Switching Frequency = 1 MHz
1 MHz
2 MHz
3 MHz
5 MHz
FIGURE 9. Higher resolution of noise spectrum
10 MHz
Conclusion
Switching at high, known frequencies results in a smaller
footprint while maintaining high efficiency. Efficiencies at high
switching frequencies can be improved by using Si6801
optimized low gate charge and low gate resistance MOSFET.
Additionally, synchronization to an external high frequency
clock eliminates or greatly reduces any radio interference
concerns and pushes harmonics out beyond signal
processing frequencies.
Document Number: 70029
S-40700—Rev. H, 19-Apr-04
www.vishay.com
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