Telit EVK2 User Guide
1vv0300704 Rev.13- 2012/06/25
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved
page
25 of 149
5.4.
Application Notes
5.4.1.
Li-Ion Battery Pack
The 3.7V Li-Ion rechargeable Battery Pack should be connected directly to PL107 connector.
Remember to use the connection cables as short as possible, with the appropriate conductors
gauge and the other attributes, such as device power budget and cable flexibility, in order to
match the specified voltage drop (especially during the high current absorption periods).
To obtain the best performance we suggest a capacity of
1000 mAh
(
not lower than 500 mAh
).
5.4.2.
About Current Charger
With a
+6V Current Unlimited Source
connected to PL103 connector, the battery pack will
be directly charged through
VBATT connector pins
of the Telit Modules
,
under control of the
Internal Charge Algorithm
(only on models where is implemented).
Depending of the size, the Li-Ion cell manufacturers suggest a charge current value not
greater than
1,5C
(C= Capacity of the battery pack, expressed in mAh); even if a lower
current means a longer charging time, a current equal to
0,5C
is considered to be a good
choice.
With reference to the schematic diagram
30276SE11139A –sheet1
, the Current Limiting
Circuit (
Q102, Q103, R106, R107, R108, R109, R110, R111, R112, R113, C105
) sets the maximum value
of the Charge Current in respect to the law:
where
R par
Vbe Q
I ch
102
R113
R112,
R111,
//R110,
R par
With the default values, the charge current will be
470mA, which will charge Battery
Packs with a capacity from 350mAh to 1000mAh,
without any dissipation problem
.
If a higher capacity Battery Pack is needed, you must increment the Time Out in the Telit
Modules.
WARNING:
SET THE MAXIMUM VOLTAGE
of the
CURRENT UNLIMITED SOUCE
lower then
+8V.
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
Downloaded from
