SH3000UM SEMTECH [Semtech Corporation], SH3000UM Datasheet - Page 15

• Manufacturer Part Number: SH3000UM
• Manufacturer: SEMTECH [Semtech Corporation]

Programmable Spectrum Spreading (continued)
Spectrum Spreading is created by varying the frequency of the HF oscillator with a pseudo-random sequence (with
a zero-average DC component). The Maximum-Length Sequence (MLS) 8-bit random number generator, clocked by
32.768kHz, is used. Only four, fi ve, six, or seven bits of the generated 8-bit random number are used, according to the
confi guration setting.
Maximum fl uctuations of the frequency depend on the selected frequency range and the position within the range.
Selecting the HF oscillator frequency to be near the high end of the range limits the peak variations to 0.1%, ±0.2%,
±0.4%, or ±0.8% (corresponding to the confi guration setting).
©2006 Semtech Corp.
POWER MANAGEMENT
POWER MANAGEMENT
Application Information
En
0
1
1
1
1
Setting
CFG1
0
0
1
1
x
(continued)
CFG0
0
1
0
1
x
Table 2 - EMI reduction with Spectrum Spreading
Bandwidth kHz
Spreading
128
256
Off
32
64
15
Peak EMI Reduction
(guaranteed db)
-12
-3
-6
-9
0
Peak EMI Reduction
(measured db)
-10
-15
-3
-7
0
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SH3003