LENA-R8 series - System integration manual
UBX-22015376 - R02
Design-in
Page 38 of 116
C1-Public
show an example of a low-cost power supply circuit,
where the
VCC
module supply is provided by an LDO linear regulator capable of delivering the specified
highest peak / pulse current, with the proper power handling capability. The regulator described in this
example supports a limited input voltage range and it includes internal circuitry for current and
thermal protection.
It is recommended to configure the LDO linear regulator to generate a voltage supply value slightly
below the maximum limit of the module VCC normal operating range (e.g., ~4.1 V as in the circuit
described in
). This reduces the power on the linear regulator and improves the
whole thermal design of the supply circuit.
5V
C1
IN
OUT
ADJ
GND
1
2
4
5
3
C2
R1
R2
U1
EN
LENA-R8 series
52
VCC
53
VCC
51
VCC
GND
Figure 21: Example of a low cost VCC supply application circuit using an LDO linear regulator
Reference
Description
Part number
–
manufacturer
C1, C2
10 µF Capacitor Ceramic X5R 0603 20% 6.3 V
GRM188R60J106ME47
–
Murata
R1
27 k
Resistor 0402 5% 0.1 W
Various manufacturers
R2
4.7 k
Resistor 0402 5% 0.1 W
Various manufacturers
U1
LDO Linear Regulator ADJ 3.0 A
LP38501ATJ-ADJ/NOPB
–
Texas Instrument
Table 11: Components for a low cost VCC supply application circuit using an LDO linear regulator
☞
See the section
, and in particular
, for the parts recommended to be
provided if the application device integrates an internal antenna.
2.2.1.4
Guidelines for VCC supply circuit design using a rechargeable battery
Rechargeable Li-ion or Li-Pol batteries connected to the
VCC
pins should meet the following
prerequisites to comply with the module
VCC
requirements summarized in
•
Maximum pulse and DC discharge current
: the rechargeable Li-ion battery with its related output
circuit connected to the
VCC
pins must be capable of delivering a pulse current as the maximum
peak / pulse current consumption during a Tx burst at the maximum Tx power specified in the
LENA-R8 series data sheet
, and must be capable of extensively delivering a DC current as the
maximum average current consumption specified in the LENA-R8 series data sheet
. The
maximum discharge current is not always reported in the data sheets of batteries, but the
maximum DC discharge current is typically almost equal to the battery capacity in amp-hours
divided by 1 hour.
•
DC series resistance
: the rechargeable Li-ion battery with its output circuit must be capable of
avoiding a VCC voltage drop below the operating range summarized in
bursts.