Ublox LEA-M8F Hardware Integration Manual
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Ublox LEA-M8F Hardware Integration Manual

U-blox m8 time and frequency reference gnss module
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LEA-M8F
u-blox M8 time and frequency reference
GNSS module
Hardware Integration Manual
Abstract
This document describes the hardware features and design-in
aspects for the LEA-M8F time and frequency reference module. This
device incorporates the u-blox M8 concurrent GNSS IC that can
receive GPS, GLONASS, BeiDou and QZSS signals. It provides a low
phase noise 30.72MHz system reference oscillator disciplined by
GNSS, a precise and jitter-free time-pulse and features high
sensitivity signal acquisition and single satellite timing with
automatic hold over during signal outage.
www.u-blox.com
UBX-14000034 - R03

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Summary of Contents for Ublox LEA-M8F

  • Page 1 Abstract This document describes the hardware features and design-in aspects for the LEA-M8F time and frequency reference module. This device incorporates the u-blox M8 concurrent GNSS IC that can receive GPS, GLONASS, BeiDou and QZSS signals. It provides a low phase noise 30.72MHz system reference oscillator disciplined by...
  • Page 2 LEA-M8F - Hardware Integration Manual Document Information Title LEA-M8F Subtitle u-blox M8 time and frequency reference GNSS module Document type Hardware Integration Manual Document number UBX-14000034 Revision and Date 19-Aug-2014 Document status Early Production Information Document status explanation Objective Specification Document contains target values.

  • Page 3: Table Of Contents

    LEA-M8F - Hardware Integration Manual Contents Contents ..........................3 Hardware description ....................5 Overview .............................. 5 Architecture ............................6 Pin description for LEA-M8F designs ..................... 7 Connecting power ..........................8 1.4.1 VCC .............................. 8 1.4.2 V_BCKP ............................8 1.4.3 VCC_RF ............................8 Interfaces ..............................
  • Page 4 LEA-M8F - Hardware Integration Manual EOS/ESD/EMI precautions ........................23 Applications with cellular modules ...................... 26 Appendix .......................... 28 Recommended parts ............................28 Manufacturer ........................28 Order No........................... 28 Comments ......................... 28 Related documents......................29 Revision history ........................ 29 Contact ..........................30...

  • Page 5: Hardware Description

    This allows measurements from macro-sniff, Synchronous Ethernet or packet timing to be combined with measurements from GNSS. The industry standard LEA form factor in the leadless chip carrier (LCC) package makes the LEA-M8F easy to integrate, while combining exceptional timing and frequency performance with highly flexible design and connectivity options.

  • Page 6: Architecture

    LEA-M8F - Hardware Integration Manual 1.2 Architecture Figure 1 shows a block schematic view of the module’s internal organization. Figure 1: LEA-M8F Block Diagram The device contains all the elements required to implement a multi-GNSS frequency and time synchronization system. It comprises a u-blox M8030 GNSS receiver, RF LNA/SAW filter and disciplined VCTCXO. A FLASH memory contains the FTS firmware and provides configuration storage.

  • Page 7: Pin Description For Lea-M8F Designs

    LEA-M8F - Hardware Integration Manual 1.3 Pin description for LEA-M8F designs Function Description Remarks Power Supply Voltage Provide a clean and stable supply. Ground Assure a low impedance GND connection to all GND pins of the module, preferably with a large ground.

  • Page 8: Connecting Power

    The LEA-M8F module includes a Universal Asynchronous Receiver Transmitter (UART) serial interface RxD/TxD supporting configurable baud rates. See the LEA-M8F Data Sheet [1] for the supported baud rates. The signal input and output levels are 0 V to VCC with inverted logic. An interface based on RS232 standard levels (+/- 12 V) can be implemented using level shifters such as a Maxim MAX3232.

  • Page 9: Display Data Channel (Ddc)

    LDO (U1) to pin 24 (VDD_USB) to regulate the 5 V VBUS down to a nominal 3.3 V for the module. The LEA-M8F module USB interface is intended to be used as a USB self-powered device deriving its power supply from VCC.

  • Page 10: Ddc Interface For External Dac Control

    The D_SEL pin selects the available communication interfaces available at the module pins. This allows a choice between UART+DDC or SPI control of the module, see Table 3 below. If D_SEL is left open both UART and DDC are available. If pulled low, a single SPI interface is available. See the LEA-M8F Data Sheet [1]. Information...

  • Page 11: Freq_Phase_In0 / Exint0, Freq_Phase_In1 / Extint1

    LEA-M8F - Hardware Integration Manual PIN 5 (D_SEL) = “high” (left open) PIN 5 (D_SEL) = “Low” (connected to GND) DDC SDA SPI CS DDC SCL SPI CLK UART TX SPI MISO UART RX SPI MOSI Table 3: D_SEL pin configuration 1.6.3 FREQ_PHASE_IN0 / EXINT0, FREQ_PHASE_IN1 / EXTINT1...

  • Page 12: Design

    LEA-M8F - Hardware Integration Manual 2 Design 2.1 Layout: Footprint and paste mask This section describes the footprint and provides recommendations for the paste mask for the u-blox M8F LCC module. These are recommendations only and not specifications. Note that the copper and solder masks have the same size and position.

  • Page 13: Antenna Connection And Ground Plane Design

    2.1.2 Antenna connection and ground plane design The LEA-M8F module can be connected to passive patch or active antennas. The RF connection is on the PCB and connects the RF_IN pin with the antenna feed point or the signal pin of the connector, respectively. Figure 7 illustrates connection to a typical five-pin RF connector.
  • Page 14 Wrong better best Figure 9: Recommended micro strip routing to RF pin (for exact pin orientation see LEA-M8F Data Sheet [1]) • Do not route the RF-connection underneath the receiver. The distance of the micro strip line to the ground plane on the bottom side of the receiver is very small (some 100 µm) and has huge tolerances (up to 100%).

  • Page 15: Antenna Micro Strip Connection

    LEA-M8F - Hardware Integration Manual • In order to avoid reliability hazards, the area on the PCB under the receiver should be entirely covered with solder mask. Vias should not be open. Do not route under the receiver. 2.1.3 Antenna micro strip connection There are many ways to design wave-guides on printed circuit boards.

  • Page 16: Gnss Antenna Connection

    Figure 12 shows a minimal setup for a design with a good GNSS patch antenna. Figure 12: Module design with passive antenna (for exact pin orientation see the LEA-M8F Data Sheet Use an antenna that has sufficient bandwidth to receive all GNSS constellations. See the recommended types in the Appendix.

  • Page 17: Active Antenna Connection

    RF_IN pin for antenna LNA biasing, see Figure 13 below. Figure 13: Active antenna design, external supply from VCC_RF (for exact pin orientation see LEA-M8F Data Sheet [1]) For powering an active antenna with an alternative voltage to the module VCC, use an external supply as shown in Figure 14.

  • Page 18: Migration To U-Blox M8 Modules

    For software migration details, see the u-blox 7 to u-blox M8 Software Migration Guide [4]. 3.2 Hardware migration LEA-6T -> LEA-M8F This section compares the functionality when a design is migrated from a LEA-6T to a LEA-M8F. Most pins are compatible however, the following items have changed:- •...

  • Page 19: Supply Voltage

    0/ EXTINT0 Timepulse/TP2/ Timepulse signal Timepulse is TP2 Timepulse Timepulse signal SAFEBOOT_N SAFEBOOT_N Must float during reset (see 1.6.5) Table 4: Pin-out comparison LEA-6T vs. LEA-M8F Information to u-blox M8 modules UBX-14000034 - R03 Early Production Migration Page 19 of 30...

  • Page 20: Product Handling

    4.1 Packaging, shipping, storage and moisture preconditioning For information pertaining to reels and tapes, Moisture Sensitivity levels (MSL), shipment and storage information, as well as drying for preconditioning see the LEA-M8F Data Sheet [1]. Population of Modules When populating the modules, make sure that the pick and place machine is aligned to the copper pins of the module and not on the module edge.
  • Page 21 LEA-M8F - Hardware Integration Manual Cooling phase A controlled cooling avoids negative metallurgical effects (solder becomes more brittle) of the solder and possible mechanical tensions in the products. Controlled cooling helps to achieve bright solder fillets with a good shape and low contact angle.
  • Page 22 LEA-M8F - Hardware Integration Manual Repeated reflow soldering Only single reflow soldering processes are recommended for boards populated with u-blox M8 modules. u-blox M8 modules should not be submitted to two reflow cycles on a board populated with components on both sides in order to avoid upside down orientation during the second reflow cycle.

  • Page 23: Eos/Esd/Emi Precautions

    EOS/ESD/EMI handling and protection measures. To prevent overstress damage at the RF_IN of your receiver, never exceed the maximum input power (see LEA-M8F Data Sheet 0). Electrostatic discharge (ESD) Electrostatic discharge (ESD) is the sudden and momentary electric current that flows between two objects at different electrical potentials caused by direct contact or induced by an electrostatic field.
  • Page 24 LEA-M8F - Hardware Integration Manual • When handling the RF pin, do not come into contact with any charged capacitors and be careful when contacting materials that can develop charges (e.g. patch antenna ~10 pF, coax cable ~50 - 80 pF/m, soldering iron, …) •...
  • Page 25 LEA-M8F - Hardware Integration Manual EOS protection measures For designs with GNSS positioning modules and wireless (e.g. GSM/GPRS) transceivers in close proximity, ensure sufficient isolation between the wireless and GNSS antennas. If wireless power output causes the specified maximum power input at the GNSS RF_IN to be exceeded, employ EOS protection measures to prevent overstress damage.

  • Page 26: Applications With Cellular Modules

    LEA-M8F - Hardware Integration Manual Example of EMI protection measures on the RX/TX line using a ferrite bead: >10mm BLM15HD102SN1 Figure 18: EMI Precautions VCC can be protected using a feed thru capacitor. For electromagnetic compatibility (EMC) of the RF_IN pin, refer to section Soldering.
  • Page 27 LEA-M8F - Hardware Integration Manual Figure 20: In-band jamming sources Measures against in-band jamming include: • Maintaining a good grounding concept in the design • Shielding • Layout optimization • Filtering • Placement of the GNSS antenna • Adding a CDMA, GSM, WCDMA band pass filter before handset antenna Out-band jamming Out-band jamming is caused by signal frequencies that are different from the GNSS carrier (see Figure 21).

  • Page 28: Appendix

    LEA-M8F - Hardware Integration Manual Appendix Recommended parts Recommended parts are selected on a data sheet basis only. Other components may also be used. Manufacturer Part ID Remarks Parameters to consider Diode ESD9R3.3ST5G Standoff Voltage>3.3 V Low Capacitance < 0.5 pF Semiconductor ESD9L3.3ST5G...

  • Page 29: Related Documents

    LEA-M8F - Hardware Integration Manual Related documents LEA-M8F Data Sheet, Doc. No. UBX-14001772 u-blox M8 Receiver Description Protocol Specification, Doc. No. UBX-14002171 ublox M8F Applications Guide, Doc No. UBX-14001603 u-blox 7 to u-blox M8 Software Migration Guide, Doc. No. UBX-13003254 GPS Antenna Application Note, Docu.

  • Page 30: Contact

    LEA-M8F - Hardware Integration Manual Contact u-blox Offices North, Central and South Headquarters Asia, Australia, Pacific America Europe, Middle East, Africa u-blox Singapore Pte. Ltd. Phone: +65 6734 3811 u-blox America, Inc. u-blox AG E-mail: info_ap@u-blox.com Phone: +1 703 483 3180...

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