CC864-DUAL Hardware User Guide
1vv0300791 Rev 4.4 – 2011-01-26
Reproduction forbidden without Telit Communications S.p.A’s. written authorization - All Rights Reserved.
Page 23 of 63
3.3.1.
+5V Input Source Power Supply Design Guidelines
The desired output for the power supply is 3.8V, hence there’s not a big difference
between the input source and the desired output so a linear regulator can be used.
When using a linear regulator, a proper heat sink may be required.
A bypass low ESR capacitor must be provided to cut the current absorption peaks
close to the CC864-DUAL; a 100µF tantalum (or equivalent) capacitor is suited for
this purpose.
Verify that the low ESR capacitor on the power supply output (usually a tantalum) is
rated to at least 10V.
A protection diode should be inserted close to the power input to protect the module
from power polarity inversion.
A typical example of a linear regulator with 5V input is below:
3.3.2.
+12V Input Source Power Supply Design Guidelines
The desired output for the power supply is 3.8V. Due to the large difference between
the input voltage and the desired output, a linear regulator should not be used.
A switching power supply is preferred because of its better efficiency with the 1A
peak current load drawn by the CC864-DUAL.
When using a switching regulator, a 500 KHz or more switching frequency regulator
is preferable because of its smaller inductor size and faster transient response. This
allows the regulator to respond quickly to current peaks.
In any case the frequency and switching design selection is application specific
because the switching frequency could also generate EMC interference, which must
be taken into account.