Ublox SARA-N4 Series, Руководство по системной интеграции

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SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R11 Design-in Page 71 of 157
2.2.1.9 Guidelines for removing VCC supply
Removing the VCC power can be useful to minimize the current consumption when the SARA-R4/N4 series
modules are switched off or when the modules are in deep sleep Power Saving Mode.
In applications in which the module is paired to a host application processor equipped with a RTC, the
module can execute standard PSM procedures, store NAS protocol context in non-volatile memory, and
rely on the host application processor to run its RTC and to trigger wake-up upon need. The application
processor can disconnect the
VCC supply source from the module and zero out the module’s PSM current.
The VCC supply source can be removed using an appropriate low-leakage load switch or p-channel MOSFET
controlled by the application processor as shown in Figure 26 , given that the external switch has provide:

Very low leakage current (for example, less than 1
µ
A), to minimize the current consumption

Very low R
DS(ON)
series resistance (for example, less than 50 m

), to minimize voltage drops
 Adequate maximum Drain current (see the SARA-R4/N4 series Data Sheet [1] for module current
consumption figures)
C3
GND
C2 C1 C4
SARA-R4/ N4
52
VCC
53
VCC
51
VCC
VCC Supply Source
GND
C5
U1
VOUT VIN
VBIAS
ON
CT
GND
4
V_INT
15
PW R_ON
R1
R2
T1
GPIO
Applicat ion
Processor
GPIO
GPIO
+
Figure 26: Example of application circuit for VCC supply removal
Reference Description Part Number - Manufacturer
C1 100
µ
F Capacitor Tantalum B_SIZE 20% 6.3V 15m

T520B107M006ATE015 – Kemet
C2 10 nF Capacitor Ceramic X7R 0402 10% 16 V GRM155R71C103KA01 - Murata
C3 100 nF Capacitor Ceramic X7R 0402 10% 16 V GRM155R61A104KA01 - Murata
C4 68 pF Capacitor Ceramic C0G 0402 5% 50 V GRM1555C1H680JA01 - Murata
C5 15 pF Capacitor Ceramic C0G 0402 5% 25 V GRM1555C1E150JA01 - Murata
R1, R3 47 k  Resistor 0402 5% 0.1 W RC0402JR-0747KL - Yageo Phycomp
R2 10 k  Resistor 0402 5% 0.1 W RC0402JR-0710KL - Yageo Phycomp
T1 NPN BJT Transistor BC847 - Infineon
U1 Ultra-Low Resistance Load Switch TPS22967 - Texas Instruments
Table 18: Components for VCC supply removal application circuit