Ublox SARA-G300 - Page 110

SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R26 Design-in
Page 110 of 217
Battery charging is managed in three phases:
 Pre-charge constant current (active when the battery is deeply discharged): the battery is charged with a
low current, set to 10% of the fast-charge current
 Fast-charge constant current: the battery is charged with the maximum current, configured by the value
of an external resistor to a value suitable for the application
 Constant voltage: when the battery voltage reaches the regulated output voltage (4.2 V), the current is
progressively reduced until the charge termination is done. The charging process ends when the charging
current reaches the 10% of the fast-charge current or when the charging timer reaches the value configured
by an external capacitor
Using a battery pack with an internal NTC resistor, the MP2617 can monitor the battery temperature to protect
the battery from operating under unsafe thermal conditions.
Several parameters as the charging current, the charging timings, the input current limit, the input voltage limit,
the system output voltage can be easily set according to the specific application requirements, as the actual
electrical characteristics of the battery and the external supply / charging source: proper resistors or capacitors
must be accordingly connected to the related pins of the IC.
C9 C12
GND
C11C10 C13
SARA-G3 / SARA-U2
52
VCC
53
VCC
51
VCC
+
Primary
Source
R3
U1
EN
ILIM
ISET
TMR
AGND
VIN
C2C1
12V
NTC
PGND
SW
SYS
BAT
C4
R1
R2
D1
θ
Li-Ion/Li-Pol
Battery Pack
B1
C5
Li-Ion/Li-Polymer Battery
Charger / Regulator with
Power Path Managment
VCC
C3 C6
L1
BST
D2
VLIM
R4
R5
C7 C8
Ferrite Bead
or 0Ω
Figure 50: Li-Ion (or Li-Polymer) battery charging and power path management application circuit
Reference
Description
Part Number - Manufacturer
B1
Li-Ion (or Li-Polymer) battery pack with 10 k NTC
Various manufacturer
C1, C5, C6
22 µF Capacitor Ceramic X5R 1210 10% 25 V
GRM32ER61E226KE15 - Murata
C2, C4, C10
100 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R61A104KA01 - Murata
C3
1 µF Capacitor Ceramic X7R 0603 10% 25 V
GRM188R71E105KA12 - Murata
C7, C12
56 pF Capacitor Ceramic C0G 0402 5% 25 V
GRM1555C1E560JA01 - Murata
C8, C13
15 pF Capacitor Ceramic C0G 0402 5% 25 V
GRM1555C1E150JA01 - Murata
C9
330 µF Capacitor Tantalum D_SIZE 6.3 V 45 m
T520D337M006ATE045 - KEMET
C11
10 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R71C103KA01 - Murata
D1, D2
Low Capacitance ESD Protection
CG0402MLE-18G - Bourns
R1, R3, R5
10 k Resistor 0402 5% 1/16 W
RC0402JR-0710KL - Yageo Phycomp
R2
1.0 k Resistor 0402 5% 0.1 W
RC0402JR-071K0L - Yageo Phycomp
R4
22 k Resistor 0402 5% 1/16 W
RC0402JR-0722KL - Yageo Phycomp
L1
1.2 µH Inductor 6 A 21 m 20%
7447745012 - Wurth
U1
Li-Ion/Li-Polymer Battery DC/DC Charger / Regulator
with integrated Power Path Management function
MP2617 - Monolithic Power Systems (MPS)
Table 31: Suggested components for Li-Ion (or Li-Polymer) battery charging and power path management application circuit