Ublox SARA-R4 Series System Integration Manual

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 µA), 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
C2C1 C4
SARA-R4/N4
52
VCC
53
VCC
51
VCC
VCC Supply Source
GND
C5
U1
VOUTVIN
VBIAS
ON
CT
GND
4
V_INT
15
PWR_ON
R1
R2
T1
GPIO
Application
Processor
GPIO
GPIO
+
Figure 26: Example of application circuit for VCC supply removal
Reference
Description
Part Number - Manufacturer
C1
100 µF 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

Ublox SARA-R4 Series Specifications

General

Brand	Ublox
Model	SARA-R4 Series
Category	Control Unit
Language	English