Ublox SARA-G450 Series - Page 59

SARA-G450 - System integration manual
UBX-18046432 - R08 Design-in Page 59 of 143
C1-Public
 PWM mode operation: it is preferable to select regulators with Pulse Width Modulation (PWM)
mode. While in connected mode Pulse Frequency Modulation (PFM) mode and PFM/PWM mode,
transitions must be avoided to reduce the noise on the VCC voltage profile. Switching regulators
that are able to switch between low ripple PWM mode and high efficiency burst or PFM mode can
be used, provided the mode transition occurs when the module changes status from idle/active
mode to connected mode (where current consumption increases to a value greater than 100 mA):
it is permissible to use a regulator that switches from the PWM mode to the burst or PFM mode
at an appropriate current threshold (e.g. 60 mA).
Figure 23 and the components listed in Table 13 show an example of a high reliability power supply
circuit, where the module VCC is supplied by a step-down switching regulator capable of delivering
the VCC pins with the specified maximum peak / pulse current, with low output ripple and with fixed
switching frequency in PWM mode operation greater than 1 MHz.
SARA-G450
12V
C5
R3
C4
R2
C2C1
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 23: Suggested schematic design for the VCC voltage 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
2322-705-87474-L - Yageo
R2
15 k resistor 0402 5% 0.1 W
2322-705-87153-L - Yageo
R3
22 k resistor 0402 5% 0.1 W
2322-705-87223-L - Yageo
R4
390 k resistor 0402 1% 0.063 W
RC0402FR-07390KL - Yageo
R5
100 k resistor 0402 5% 0.1 W
2322-705-70104-L - Yageo
U1
Step-down regulator MSOP10 3.5 A 2.4 MHz
LT3972IMSE#PBF - Linear Technology
Table 13: Suggested components for the VCC voltage supply application circuit using a step-down regulator