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Front ends management

UM2231

14/26

UM2231 Rev 6

6 

Front ends management

RF input impedance is 50 

Ω

.

6.1 External 

LNA

External LNA means a passive antenna used with an LNA on the same PCB as Teseo-LIV3 
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.

Here is a block diagram describing the connection.

Figure 9. External LNA control

Содержание Teseo-LIV3F

Страница 1: ...andalone positioning receiver which embeds the new ST GNSS positioning engine capable of receiving signals from multiple satellite navigation systems This document is relevant for the following Teseo LIV3 modules In Figure 1 pinout of the module is represented as follows Figure 1 Teseo LIV3 pinout Table 1 Teseo LIV3 supported devices Device type Description Teseo LIV3F Tiny GNSS module flash based...

Страница 2: ...Reserved pin15 18 10 3 Interfaces 11 3 1 I2C pin16 17 11 3 2 UART pin2 3 11 4 I O pins 12 4 1 PPS pin4 12 4 2 Wake_Up pin5 12 4 3 SYS_RESETn pin9 12 4 4 RF_IN pin10 12 4 5 AntOFF pin13 12 5 Standby modes 13 5 1 Software standby 13 5 2 Hardware standby 13 6 Front ends management 14 6 1 External LNA 14 6 2 Active antenna 15 7 Reference schematic and BOM 16 7 1 Schematic 16 7 1 1 Bill of material 17 ...

Страница 3: ...s 3 8 Layout recommendation 19 9 Antenna recommendations 21 9 1 Patch antennas 21 9 1 1 Antenna on the opposite side 21 9 1 2 Antenna on the same side than Teseo LIV3 22 9 2 Chip antenna 23 9 3 Remote antenna 24 10 Revision history 25 ...

Страница 4: ...s UM2231 4 26 UM2231 Rev 6 List of tables Table 1 Teseo LIV3 supported devices 1 Table 2 Bill of material 17 Table 3 List of suggested antennas 21 Table 4 List of SMD antennas 23 Table 5 Document revision history 25 ...

Страница 5: ...ntrol 14 Figure 10 Active antenna current switch control 15 Figure 11 Active antenna current sense 15 Figure 12 General schematic 16 Figure 13 Placing parallel component pads on 50 ohms line 19 Figure 14 Reuse pads of one component on the line bypassing 19 Figure 15 Layout proposal 20 Figure 16 Pin1 gnd isolation example 20 Figure 17 Antenna vs Teseo LIV3 placement 21 Figure 18 Antenna on bottom l...

Страница 6: ...er line could degrade Teseo LIV3 sensitivity performance to avoid that it s recommended a 27 nH inductor Murata LQG15HS27NJ02 as shown in Figure 2 Inductor on VCC power line Figure 2 Inductor on VCC power line The suggested inductor on the VCC power line is able to recover interference coming from VCC power line 1 2 VBAT pin6 VBAT is the supply for the low power domain backup backup RAM and RTC VB...

Страница 7: ...attery is not rechargeable VBAT range can be from 2 1 V to 4 3 V 1 3 VCC_IO pin7 VCC_IO is 3 3 V Figure 3 shows the minimum connection to make Teseo LIV3 GNSS working Figure 3 Teseo LIV3 minimum connection 1 4 VCC_RF pin14 VCC_RF is an output image of VCC with a filtering for LNA or active antenna supply It can be filtered to remove high frequency noise as shown in Figure 4 ...

Страница 8: ...r size is 0401 1 0 0 5mm and capacitors are 0201 0 6 0 3mm In case VCC_IO is separate from VCC a serial 27nH inductor could also be planned for first PCBs If all 3 pins have common supply one single capacitor and one single inductor can be used If not it is recommended to duplicate the filtering 1 6 Current consumption optimization Use of an SMPS at 2 1 V to supply VCC is recommended to optimize c...

Страница 9: ...UM2231 Rev 6 9 26 UM2231 Power 24 Figure 6 Example of SMPS to improve current consumption If VCC_IO is also supplied by an SMPS this will reach the lowest current consumption ...

Страница 10: ...Reserved pin15 18 UM2231 10 26 UM2231 Rev 6 2 Reserved pin15 18 In Teseo LIV3 pin15 and 18 are reserved ...

Страница 11: ...Transmitter that supports much of the functionality of the industry standard 16C650 UART These UARTs vary from industry standard 16C650 on some minor points which are Receive FIFO trigger levels The deltas of the modem status signals are not available 1 5 stop bit is not supported Independent receive clock feature is not supported During prototyping stage for the first PCBs it is recommended to pl...

Страница 12: ...seo LIV3 for asynchronous wake up during standby software for instance It can be activated by a GPIO from host for instance Wake_Up signal is active high 4 3 SYS_RESETn pin9 It can force a Teseo LIV3 under reset Reset signal is active low Host processor must have full control of this pin to guarantee the Teseo LIV3F s firmware upgrade support It is mandatory only on Teseo LIV3F 4 4 RF_IN pin10 It ...

Страница 13: ...dby Software standby is activated by the binary for periodic standby More details of how to set it are in the Software Manual As HW standby all supplies are kept ON Periodic fixes are from 5 s up to 24 hours between 2 fixes It ensures a current below 20 µA on Teseo LIV3 Be careful that VCC_RF is ON during this standby then in case of active antenna or external LNA it is important to switch them OF...

Страница 14: ...NA External LNA means a passive antenna used with an LNA on the same PCB as Teseo LIV3 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 Here is a block diagram describing the connection Figure 9 External LNA control ...

Страница 15: ... power operating mode the active antenna can be used with a switch to cut the current flow Figure 10 Active antenna current switch control To improve the functionality a current limiter could be used in order to prevent any short circuit on the antenna see Figure 11 Figure 11 Active antenna current sense ...

Страница 16: ...Reference schematic and BOM UM2231 16 26 UM2231 Rev 6 7 Reference schematic and BOM 7 1 Schematic Figure 12 General schematic ...

Страница 17: ...pF C0G Murata GCM1555C1H121JA16 TDK CGA2B2C0G1H 121J050BA L1 10 µH Surface mount magnetically shielded wire wound inductor for power line applications 10 µ 1 4 A TDK LTF5022T 100M1R4 LC L2 5n6H Surface mount wire wound inductor 5n6H 3 0 76 A Coilcraft 0402CS 5N6XJLU Murata LQW15AN5N6 G80D 00 21 L3 27 nH Unshielded Multilayer Inductor 27 nH 350 mA 460 mOhm Max 0402 1005 Metric Murata LQG15HS27NJ02 ...

Страница 18: ...NASS Galileo and Compass BGA725L6 Infineon BGA725L6 Z1 B4327 Automotive SAW RF filter for GPS COMPASS GLONASS Epcos B39162B4327P810 U3 LIV3 TESEOIII module SMPS version ST LIV3 Table 2 Bill of material continued Refs Value Description Manufacturing 1 Manufacturing 2 Name Part number Name Part number ...

Страница 19: ...ponent pads on 50 ohms line For 50 ohms line bypassing it s suggested to superimpose the pad of one component on the pad of the other one as in Figure 14 Figure 14 Reuse pads of one component on the line bypassing Place ground vias below Teseo LIV3 all around and in the middle and also around the 3 ground pins The following layout presents layout recommendation to ensure the best performances of T...

Страница 20: ...it is important to have an isolation of the power ground Pin1 Don t connect it directly to ground One or two vias from Top assuming Teseo LIV3 is on Top to Bottom without any ground connection and then a second via from Bottom to GND plane can be used without any connection on top as shown in Figure 16 Figure 16 Pin1 gnd isolation example It is important to have 50 ohms RF traces width as close as...

Страница 21: ...S performances Patch antennas are with pin soldered on the PCB on the opposite side where it is mounted the Teseo LIV3 and other RF components as shown in figure Figure 17 Figure 17 Antenna vs Teseo LIV3 placement The Table 3 gives antenna part number compatible Figure 18 is an example of layout with Antenna on opposite side of the components Table 3 List of suggested antennas Manufacter Part numb...

Страница 22: ...arger than the antenna side it will improve the antenna performance Antenna is usually glued and soldered with the pin It is necessary to follow the layout recommendations in Chapter 8 9 1 2 Antenna on the same side than Teseo LIV3 In case of antenna on the same side of the Teseo LIV3 the best performance can be obtained if the antenna is placed more than 2cm far from Teseo LIV3 The Table 4 gives ...

Страница 23: ...has to be empty of copper below the antenna position with a certain aperture For Teseo LIV3 usage the recommendations to follow are in Chapter 9 1 2 Antenna on the same side than Teseo LIV3 The best performance can be obtained if the antenna is placed more than 2cm far from Teseo LIV3 The Figure 20 shows the example of chip antenna Taoglas GGBLA 01 A GPS Glonass Beidou mounted on the edge of the P...

Страница 24: ...3 Remote antenna Remote antenna means antenna connected to PCB where Teseo LIV3 is soldered with an RF connector The best performance can be obtained if the remote antenna is placed more than 2cm far from Teseo LIV3 In case of active antenna there s no need to mount LNA on the PCB In case of passive antenna it is much better to mount external LNA and SAW filter in front of the Teseo LIV3 ...

Страница 25: ... 05 Oct 2018 4 Updated Section 1 4 VCC_RF pin14 and Section 1 5 Power supply design reference Updated Figure 3 Figure 4 and Figure 5 Updated Section 3 2 UART pin2 3 and added Section 4 1 PPS pin4 Updated value in Section 6 1 External LNA and updated Section 6 2 Active antenna Updated Section 7 Reference schematic and BOM Added Section 9 Antenna recommendations Minor text changes 29 Nov 2018 5 Upda...

Страница 26: ...ers are solely responsible for the choice selection and use of ST products and ST assumes no liability for application assistance or the design of Purchasers products No license express or implied to any intellectual property right is granted by ST herein Resale of ST products with provisions different from the information set forth herein shall void any warranty granted by ST for such product ST ...

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