SARA-R4 series - System Integration Manual
UBX-16029218 - R06
Design-in
Page 40 of 102
C5
C3
C6
GND
SARA-R4 series
52
VCC
53
VCC
51
VCC
USB
Supply
θ
U1
PG
STAT2
STA1
VDD
C1
5V0
THERM
Vss
Vbat
Li-Ion/Li-Pol
Battery Pack
D1
B1
C2
Li-Ion/Li-Polymer
Battery Charger IC
D2
PROG
R1
C4
Figure 13: Li-Ion (or Li-Polymer) battery charging application circuit
Reference
Description
Part Number - Manufacturer
B1
Li-Ion (or Li-Polymer) battery pack with 470
NTC
Generic manufacturer
C1, C2
1 µF Capacitor Ceramic X7R 16 V
Generic manufacturer
C3
15 pF Capacitor Ceramic C0G 0402 5% 50 V
GRM1555C1H150JA01 - Murata
C4
68 pF Capacitor Ceramic C0G 0402 5% 50 V
GRM1555C1H680JA01 - Murata
C5
10 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R71C103KA01 - Murata
C6
100 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R71C104KA01 - Murata
D1, D2
Low Capacitance ESD Protection
CG0402MLE-18G - Bourns
R1
10 k
Resistor 0.1 W
Generic manufacturer
U1
Single Cell Li-Ion (or Li-Polymer) Battery Charger IC
MCP73833 - Microchip
Table 11: Suggested components for Li-Ion (or Li-Polymer) battery charging application circuit
2.2.1.7
Guidelines for external battery charging and power path management circuit
Application devices where both a permanent primary supply / charging source (e.g. ~12 V) and a rechargeable
back-up battery (e.g. 3.7 V Li-Pol) are available at the same time as possible supply source, should implement a
suitable charger / regulator with integrated power path management function to supply the module and the
whole device while simultaneously and independently charging the battery.
Figure 14 reports a simplified block diagram circuit showing the working principle of a charger / regulator with
integrated power path management function. This component allows the system to be powered by a permanent
primary supply source (e.g. ~12 V) using the integrated regulator which simultaneously and independently
recharges the battery (e.g. 3.7 V Li-Pol) that represents the back-up supply source of the system: the power path
management feature permits the battery to supplement the system current requirements when the primary
supply source is not available or cannot deliver the peak system currents.
A power management IC should meet the following prerequisites to comply with the module
VCC
requirements
summarized in Table 6:
High efficiency internal step down converter, compliant with the performances specified in section 2.2.1.2
Low internal resistance in the active path Vout – Vbat, typically lower than 50 m
High efficiency switch mode charger with separate power path control
