u-blox LARA-R2 series System Integration Manual page 73

2.2.1.7 Additional guidelines for VCC supply circuit design of LARA-R211 modules
LARA-R211 modules provide separate supply inputs over the VCC pins (see Figure 3):

VCC pins #52 and #53 represent the supply input for the internal RF power amplifier, demanding most of
the total current drawn of the module when RF transmission is enabled during a voice/data call

VCC pin #51 represents the supply input for the internal baseband Power Management Unit and the internal
transceiver, demanding minor part of the total current drawn of the module when RF transmission is
enabled during a voice/data call
All the VCC pins are in general intended to be connected to the same external power supply circuit, but separate
supply sources can be implemented for specific (e.g. battery-powered) applications considering that the voltage
at the VCC pins #52 and #53 can drop to a value lower than the one at the VCC pin #51, keeping the module
still switched-on and functional. Figure 31 describes a possible application circuit.
Li-Ion/Li-Pol
Battery
Figure 31: VCC circuit example with separate supply for LARA-R211 modules
Reference Description
C1
330 µF Capacitor Tantalum D_SIZE 6.3 V 45 m
C2 10 nF Capacitor Ceramic X7R 0402 10% 16 V
C3 100 nF Capacitor Ceramic X7R 0402 10% 16 V
C4 68 pF Capacitor Ceramic C0G 0402 5% 50 V
C5 15 pF Capacitor Ceramic C0G 0402 5% 25 V
C6 8.2 pF Capacitor Ceramic C0G 0402 5% 50 V
C7 10 µF Capacitor Ceramic X5R 0603 20% 6.3 V
C8 22 µF Capacitor Ceramic X5R 1210 10% 25 V
C9 10 pF Capacitor Ceramic C0G 0402 5% 25 V
D1 Schottky Diode 40 V 1 A
L1
10 µH Inductor 20% 1 A 276 m
R1 1 M Resistor 0402 5% 0.063 W
R2
412 k Resistor 0402 5% 0.063 W
U1 Step-up Regulator 350 mA
Table 24: Example of components for VCC circuit with separate supply for LARA-R211 modules
2.2.1.8 Guidelines for external battery charging circuit
LARA-R2 series modules do not have an on-board charging circuit. Figure 32 provides an example of a battery
charger design, suitable for applications that are battery powered with a Li-Ion (or Li-Polymer) cell.
In the application circuit, a rechargeable Li-Ion (or Li-Polymer) battery cell, that features proper pulse and DC
discharge current capabilities and proper DC series resistance, is directly connected to the VCC supply input of
UBX-16010573 - R02
L1 D1
Step-up
Regulator
VIN SW
SHDNn
FB
C7
GND
U1
+
C1 C2
LARA-R2 series - System Integration Manual
51
R1
C9
C8
R2
52
53
C3 C4 C5 C6
Part Number - Manufacturer
T520D337M006ATE045 - KEMET
GRM155R71C103KA01 - Murata
GRM155R61A104KA01 - Murata
GRM1555C1H680JA01 - Murata
GRM1555C1E150JA01 - Murata
GRM1555C1H8R2DZ01 - Murata
GRM188R60J106ME47 - Murata
GRM32ER61E226KE15 - Murata
GRM1555C1E100JA01 - Murata
SS14 - Vishay General Semiconductor
SRN3015-100M - Bourns Inc.
RC0402FR-071ML - Yageo Phycomp
RC0402FR-07412KL - Yageo Phycomp
AP3015 - Diodes Incorporated
Objective Specification
LARA-R211
VCC
VCC
VCC
GND
Design-in
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