Lantronix PNT-SG3FS Installation manual

PNT-SG3FS GNSS Module
Hardware User Guide
Part Number PMD-00144
Revision A October 2022

PNT-SG3FS GNSS Module Hardware User Guide 2
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PNT-SG3FS GNSS Module Hardware User Guide 3
Revision History
Date
Rev.
Comments
October 2022
A
Initial release.
For the latest revision of this product document, please check our online documentation at
www.lantronix.com/support/documentation.

PNT-SG3FS GNSS Module Hardware User Guide 4
Table of Contents
List of Figures _____________________________________________________________ 6
List of Tables ______________________________________________________________ 7
1. Introduction 8
Overview _________________________________________________________________ 8
2. Power 9
VCC _____________________________________________________________________ 9
VBAT ____________________________________________________________________ 9
VCC_IO __________________________________________________________________ 9
VCC_RF ________________________________________________________________ 10
Power Supply Design Reference______________________________________________ 12
Current Consumption Optimization ____________________________________________ 12
3. Interfaces 13
I2C _____________________________________________________________________ 13
UART ___________________________________________________________________ 13
4. I/O Pins 14
PPS ____________________________________________________________________ 14
WakeUP_________________________________________________________________ 14
nRESET_________________________________________________________________ 14
RF_IN __________________________________________________________________ 15
AntOFF _________________________________________________________________ 15
Reserved ________________________________________________________________ 15
5. Standby Modes 16
6. Front End Management 17
Passive Antenna __________________________________________________________ 17
External LNA _____________________________________________________________ 17
Active Antenna ___________________________________________________________ 18
7. Reference Schematic and BOM 21
Schematic _______________________________________________________________ 21
Bill of Materials ___________________________________________________________ 22
8. Layout Recommendations 23
9. Antenna Recommendations 24
Patch Antenna ____________________________________________________________ 24

PNT-SG3FS GNSS Module Hardware User Guide 5
Chip Antenna _____________________________________________________________ 27
Remote Antenna __________________________________________________________ 27

PNT-SG3FS GNSS Module Hardware User Guide 6
List of Figures
Figure 1: PNT-SG3FS Pin Out____________________________________________________ 8
Figure 2: PNT-SG3FS Minimum Functional Connections ______________________________ 10
Figure 3: VCC_RF Output Supply Filtering _________________________________________ 11
Figure 4: Power Supply Filtering _________________________________________________ 12
Figure 5: Example of SMPS to Improve Current Consumption __________________________ 12
Figure 6: WakeUP Internal Circuitry ______________________________________________ 14
Figure 7: PNT-SG3FS Passive Antenna Connection _________________________________ 17
Figure 8: External LNA Connection _______________________________________________ 18
Figure 9: Active Antenna with Current Switch Control_________________________________ 19
Figure 10: Active Antenna Current Sense Without On-Module Antenna Sensing____________ 19
Figure 11: General Schematic ___________________________________________________ 21
Figure 12: PNT-SG3FS PCB layout example _______________________________________ 23
Figure 13: Parallel Component Pads Position _______________________________________ 23
Figure 14: Bypass Component Pads Position _______________________________________ 23
Figure 15: Antenna and PNT-SG3FS - Opposite Placement ___________________________ 24
Figure 16: Patch Antenna and PNT-SG3FS, Opposite Side Placement Example ___________ 25
Figure 17: 25×25mm SMD Antenna and PNT-SG3FS, Same Side Placement Example ______ 26
Figure 18: Chip Antenna and PNT-SG3FS, Same Side Layout Example __________________ 27

PNT-SG3FS GNSS Module Hardware User Guide 7
List of Tables
Table 1. VCC Voltage Characteristics Against VCC_IO ________________________________ 9
Table 2. VBAT Voltage Characteristics Against VCC_IO _______________________________ 9
Table 3. VCC_IO Supported Voltage Range _________________________________________ 9
Table 4. PNT-SG3FS Carrier BOM _______________________________________________ 22
Table 5. PNT-SG3FS Compatible Patch Antennas (Opposite Side Mount) ________________ 24
Table 6. PNT-SG3FS Compatible Patch Antennas (Same Side Mount)___________________ 26

1. Introduction
PNT-SG3FS GNSS Module Hardware User Guide 8
1. Introduction
Overview
This document is relevant to PNT-SG3FS, a Global Navigation Satellite System (GNSS)
standalone module with an integrated Teseo III receiver from ST Microelectronics. The multi-
constellation receiver can track up to 32 satellite signals in view across GPS L1C/A, BeiDou
B1, Galileo E1B/C, GLONASS L1OF, SBAS L1C/A (WAAS, EGNOS, MSAS, GAGAN), and
QZSS L1C/A bands. The module supports Differential GPS (DGPS) data according to RTCM
10402.3. Assisted GNSS algorithms support extended ephemeris data using local autonomous
or server-assisted based solutions for fast Time to First Fix (TTFF) operation.
The module can output measurement data (carrier phase) supporting RTK/PPP client
algorithms for precise positioning applications.
The module supports 1.8V or 3.3V power supply domains and an embedded 16Mb flash
memory that enables support for many features including data logging, geofencing, odometer,
5 day autonomous assisted GNSS, and firmware updates. The PNT-SG3FS module further
integrates a temperature compensated crystal oscillator (TXCO) for navigation performance
and stability, and a real-time clock (RTC) oscillator with a clock-trimming feature to
compensate for the accuracy of the 32.768 kHz crystal in timing applications.
Figure 1 shows the pin out of the module.
Figure 1: PNT-SG3FS Pin Out

2. Power
PNT-SG3FS GNSS Module Hardware User Guide 9
2. Power
The PNT-SG3FS is supplied with 3 power pins: VCC (pin 8), VCC_IO (pin 7), and VBAT (pin 6).
VCC
VCC (pin 8) is the main supply. The VCC voltage range differs depending on the voltage of
VCC_IO, as shown in Table 1 below.
Table 1. VCC Voltage Characteristics Against VCC_IO
Symbol Parameter VCC_IO Min Typ Max Unit
VCC Digital supply voltage 1.8 1.755 1.8 4.2 V
VCC Digital supply voltage 3.3 3.0 3.3 4.2 V
During startup or low power application, current can change suddenly. It is important that supply
IC can provide this current variability.
VBAT
VBAT (pin 6) is the supply for the low-power domain backup: backup RAM and RTC.
VBAT can be either connected to VCC, or it can be connected to a dedicated always-on power
supply. Supplying power to VBAT during low-power mode enables fast recovery of GNSS fix.
VBAT prevents current flow when VBAT is lower than VCC. This is important when VBAT is
supplied with a small battery, especially if the battery is not rechargeable.
The VBAT voltage range differs depending on the voltage of VCC_IO, as shown in Table 2 below.
Table 2. VBAT Voltage Characteristics Against VCC_IO
Symbol Parameter VCC_IO Min Typ Max Unit
VBAT Backup input supply
voltage
1.8 1.755 1.8 4.2 V
VBAT Backup input supply
voltage
3.3 3.0 3.3 4.2 V
VCC_IO
The VCC_IO (pin 7) voltage range is shown in Table 3 below.
Table 3. VCC_IO Supported Voltage Range
Symbol Parameter Min Typ Max Unit
VCC_IO IO supply voltage 1.755 1.8 1.98 V
VCC_IO IO supply voltage 3.0 3.3 3.6 V

2. Power
PNT-SG3FS GNSS Module Hardware User Guide 10
Note: VCC_IO must be equal to or lower than VCC and VBAT. Refer to Table 14-1 and Table
14-2 in PNT-SG3FS datasheet for associated limits.
Figure 2 below shows the minimum functional connections needed for the PNT-SG3FS.
VCC_RF
VCC_RF (pin 14) is an output image of VCC with filtering for LNA or active antenna supply as
shown in Figure 3 below.
It can be filtered to remove high-frequency noise. This filtering can be planned and not mounted.
Figure 2: PNT-SG3FS Minimum Functional Connections

2. Power
PNT-SG3FS GNSS Module Hardware User Guide 11
Figure 3: VCC_RF Output Supply Filtering

2. Power
PNT-SG3FS GNSS Module Hardware User Guide 12
Power Supply Design Reference
If power supply is undisturbed, no filtering is required. Nevertheless, it could be planned for a first
PCB wave to have soldering pads as shown in Figure 4 below for filtering. A 27nH inductor can
be 0 ohms and replace by a line for a second PCB.
If one wave is planned, use only capacitor footprint and not the inductor.
Figure 4: Power Supply Filtering
Current Consumption Optimization
Use of an SMPS at 1.8V to supply VCC is recommended to optimize current consumption.
Figure 5 is an application example with an external switching voltage regulator in order to achieve
an efficiency around 85%.
Figure 5: Example of SMPS to Improve Current Consumption
If VCC_IO is also supplied via an SMPS, this will enable the lowest current consumption.
1MΩ
4.7µF
V
IN
2. 3V – 5. 5V
470nH
ST1S15J18R
MODE
A1
SW
B1
FB
C1
V
IN
A2
EN B2
GND C2
4.7µF
LQ M2 1P NR4 7M C0 D

3. Interfaces
PNT-SG3FS GNSS Module Hardware User Guide 13
3. Interfaces
I2C
I2C (pins 16, 17) is in slave only.
Internal pull-up resistors on VCC_IO are present. It is important to avoid having other pull-ups for
current leakage in low-power mode.
UART
The UARTs (Universal Asynchronous Receiver/Transmitter) (pins 2, 3) support many of the same
functions as the industry-standard 16C650 UART.
The PNT-SG3FS UARTs vary from the 16C650 on some minor points:
♦ Receive FIFO trigger levels
♦ Internal register map address space, and bit function of each register
♦ Deltas of modem status signals are not available
♦ 1.5 stop bits are not supported
♦ Independent receive clock feature is not supported

4. I/O Pins
PNT-SG3FS GNSS Module Hardware User Guide 14
4. I/O Pins
PPS
PPS (pin 4) is the time pulse every one second. It can be configured with different conditions of
pulses.
WakeUP
WakeUP (pin 5) is an external interrupt used to wake up the PNT-SG3FS for asynchronous wake-
up during standby.
If not used, leave it floating.
Internal circuitry, shown in Figure 6 below, is done with resistor bridge to ensure 1V ± 0.25V level.
Take care to not change the resistor bridge value to be outside of this 0.75V - 1.25V range.
Figure 6: WakeUP Internal Circuitry
nRESET
nRESET (pin 9) can force a PNT-SG3FS under reset.
Reset signal is active low.
The host processor must have full control of this pin to support firmware upgrades.

4. I/O Pins
PNT-SG3FS GNSS Module Hardware User Guide 15
RF_IN
RF_IN (pin 11) is the RF input.
No DC is present in the RF input. Decoupling capacitor inside.
AntOFF
AntOFF (pin 13) is a GPIO used to switch OFF external LNA or switch OFF current for the active
antenna.
A 10kOhm pull down is necessary to ensure a low level during standby period.
Reserved
Pins 15 and 18 are reserved, and both must be left floating.

5. Standby Modes
PNT-SG3FS GNSS Module Hardware User Guide 16
5. Standby Modes
Standby mode is the mode where only low power backup domain is running. It means VBAT must
be always maintain. It allows to have very low current consumption and fast GNSS reacquisition
at the end of the standby time due to RTC.
The PNT-SG3FS offers three different standby modes:
♦ Hardware OFF standby
♦ Hardware standby
♦ Software standby
As IO buffers are not supplied during standby mode, it is important to keep all IO without external
voltage to avoid any current leakage. UART-RX is an exception that can be left high.
Please refer to the PNT-SG3FS datasheet and software user guide for more information on these
standby modes.

6. Front End Management
PNT-SG3FS GNSS Module Hardware User Guide 17
6. Front End Management
RF input impedance is 50 ohms.
Passive Antenna
A passive antenna, as shown in Figure 7 below, can be directly connected to the PNT-SG3FS.
Take care that the antenna is close to the module. In addition, an impedance-matching
component might be necessary to match the antenna.
Figure 7: PNT-SG3FS Passive Antenna Connection
External LNA
External LNA means a passive antenna used with an LNA on the same PCB as the PNT-SG3FS
module. To optimize power consumption during low-power mode if needed, the LNA should have
an enable pin compatible with VCC_IO to be switched OFF/ON.
Figure 8 below shows a block diagram of the LNA connection.

6. Front End Management
PNT-SG3FS GNSS Module Hardware User Guide 18
Figure 8: External LNA Connection
Active Antenna
PNT-SG3FS Module Without Current-Sensing
To optimize current during low-power operating mode, the active antenna can be used with a
switch to cut the current flow as shown in Figure 9 below.

6. Front End Management
PNT-SG3FS GNSS Module Hardware User Guide 19
Figure 9: Active Antenna with Current Switch Control
To improve the functionality, a current limiter like that shown in Figure 10 below can be used.
Figure 10: Active Antenna Current Sense Without On-Module Antenna Sensing

6. Front End Management
PNT-SG3FS GNSS Module Hardware User Guide 20
To prevent a short circuit on the antenna, use the antenna detect configuration script:
# GPIO High/Low status
206 -> fffffeff
207 -> 00000000
# Activate and configure antenna sensing
226 -> 3483F01F
# Antenna status message
228 -> 00020010
# Configure GPIO
242 -> 18140008
243 -> 01030001
244 -> 00000101
# GPIO alternate function
253 -> FFF7C3F0
254 -> 00100000