LENA-R8 series - System integration manual
UBX-22015376 - R02
Design-in
Page 35 of 116
C1-Public
•
PWM mode operation
: it is preferable to select regulators with a Pulse Width Modulation (PWM)
mode. While in connected mode, the Pulse Frequency Modulation (PFM) mode and PFM/PWM
modes transitions must be avoided in order to reduce noise on the
VCC
voltage profile. Switching
regulators that are able to switch between low ripple PWM mode and high ripple PFM mode can
be used, provided that the mode transition occurs when the module changes status from the
idle/active modes to connected mode. It is acceptable to use a regulator that switches from the
PWM mode to the burst or PFM mode at an appropriate current threshold.
and the components listed in
show an example of a high reliability power supply
circuit, where the
VCC
module is supplied by a step-down switching regulator capable of delivering
the specified maximum peak / pulse current to the
VCC
pins, with low output ripple and with fixed
switching frequency in PWM mode operation greater than 1 MHz.
LENA-R8 series
12V
C5
R3
C4
R2
C2
C1
R1
VIN
RUN
VC
RT
PG
SYNC
BD
BOOST
SW
FB
GND
6
7
10
9
5
C6
1
2
3
8
11
4
C7
C8
D1
R4
R5
L1
C3
U1
52
VCC
53
VCC
51
VCC
GND
Figure 18: Example of high reliability VCC supply application circuit using a step-down regulator
Reference
Description
Part number
–
manufacturer
C1
10 µF Capacitor Ceramic X7R 5750 15% 50 V
C5750X7R1H106MB
–
TDK
C2
10 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R71C103KA01
–
Murata
C3
680 pF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R71H681KA01
–
Murata
C4
22 pF Capacitor Ceramic C0G 0402 5% 25 V
GRM1555C1H220JZ01
–
Murata
C5
10 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R71C103KA01
–
Murata
C6
470 nF Capacitor Ceramic X7R 0603 10% 25 V
GRM188R71E474KA12
–
Murata
C7
22 µF Capacitor Ceramic X5R 1210 10% 25 V
GRM32ER61E226KE15
–
Murata
C8
330 µF Capacitor Tantalum D_SIZE 6.3 V 45 m
T520D337M006ATE045
–
KEMET
D1
Schottky Diode 40 V 3 A
MBRA340T3G
–
ON Semiconductor
L1
10 µH Inductor 744066100 30% 3.6 A
744066100
–
Wurth Electronics
R1
470 k
Resistor 0402 5% 0.1 W
Various manufacturers
R2
15 k
Resistor 0402 5% 0.1 W
Various manufacturers
R3
22 k
Resistor 0402 5% 0.1 W
Various manufacturers
R4
390 k
Resistor 0402 1% 0.063 W
Various manufacturers
R5
100 k
Resistor 0402 5% 0.1 W
Various manufacturers
U1
Step-Down Regulator MSOP10 3.5 A 2.4 MHz
LT3972IMSE#PBF
–
Linear Technology
Table 8: Components for high reliability VCC supply application circuit using a step-down regulator
☞
, and in particular
, for the parts recommended to be
provided if the application device integrates an internal antenna.