Ublox MAX-8 Series Quick setup guide

MAX-8 / MAX-M8
u-blox 8 / M8 GNSS modules
Hardware Integration Manual

Abstract
This document describes the features and specifications of the u blox MAX-8 / MAX-
M8 module
series.
www.u-blox.com
UBX-15030059 - R05

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Document Information
Title MAX-8 / MAX-M8
Subtitle u-blox 8 / M8 GNSS modules
Document type Hardware Integration Manual
Document number UBX-15030059
Revision and date R05 7-Feb-2019
Document status Production Information
Product status Corresponding content status
In Development /
Prototype
Objective Specification Target values. Revised and supplementary data will be published later.
Engineering Sample Advance Information Data based on early testing. Revised and supplementary data will be published later.
Initial Production Early Production Information Data from product verification. Revised and supplementary data may be published later.
Mass Production /
End of Life
Production Information Document contains the final product specification.
This document applies to the following products:
European Union regulatory compliance
MAX-8 / MAX-M8 complies with all relevant requirements for RED 2014/53/EU. The MAX-8 / MAX-M8 Declaration of
Conformity (DoC) is available at www.u-blox.com within Support > Product resources > Conformity Declaration.
Product name Type number Firmware version PCN reference
MAX-M8C MAX-M8C-0-10 ROM SPG 3.01 UBX-16013125
MAX-M8W MAX-M8W-0-10 ROM SPG 3.01 UBX-16013125
MAX-M8Q MAX-M8Q-0-10 ROM SPG 3.01 UBX-16013125
MAX-8Q MAX-8Q-0-10 ROM SPG 3.01 N/A
MAX-8C MAX-8C-0-10 ROM SPG 3.01 N/A
u-blox or third parties may hold intellectual property rights in the products, names, logos and designs included in this
document. Copying, reproduction, modification or disclosure to third parties of this
document or any part thereof is only
permitted with the express written permission of u
-blox.
The information contained herein is provided “as is” and u
-blox assumes no liability for its use. No warranty, either express or
implied, is given, including but
not limited to, with respect to the accuracy, correctness, reliability and fitness for a particular
purpose of the information. This document may be revised by u
-blox at any time without notice. For the most recent
documents, visit www.u
-blox.com.
Copyrig
ht © u-blox AG.

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Contents
Document Information................................................................................................................................ 2
Contents .......................................................................................................................................................... 3
1Hardware description ........................................................................................................................... 5
1.1 Overview........................................................................................................................................................5
1.2 Configuration ...............................................................................................................................................5
1.3 Connecting power .......................................................................................................................................5
1.3.1 VCC_IO: IO Supply Voltage................................................................................................................6
1.3.2 V_BCKP: Backup supply voltage......................................................................................................6
1.3.3 VCC_RF: Output voltage RF .............................................................................................................7
1.3.4 V_ANT: Antenna supply (MAX-M8W).............................................................................................7
1.4 Interfaces......................................................................................................................................................7
1.4.1 UART .....................................................................................................................................................7
1.4.2 Display Data Channel (DDC) .............................................................................................................7
1.4.3 TX_READY............................................................................................................................................7
1.5 I/O pins...........................................................................................................................................................7
1.5.1 RESET_N: Reset input .......................................................................................................................8
1.5.2 EXTINT: External interrupt ...............................................................................................................8
1.5.3 SAFEBOOT_N ......................................................................................................................................8
1.5.4 TIMEPULSE..........................................................................................................................................8
1.5.5 LNA_EN: LNA enable..........................................................................................................................8
1.5.6 ANT_DET: Open Circuit Detection (MAX-M8) ..............................................................................9
1.6 Electromagnetic interference on I/O lines .............................................................................................9
2Design ..................................................................................................................................................... 10
2.1 Pin description...........................................................................................................................................10
2.1.1 Pin name changes.............................................................................................................................10
2.2 Minimal design...........................................................................................................................................11
2.3 Layout: Footprint and paste mask........................................................................................................11
2.4 Antenna and Antenna supervision........................................................................................................12
2.4.1 Antenna design with passive antenna.........................................................................................12
2.4.2 Antenna design with active antenna............................................................................................13
2.4.3 Antenna design with active antenna using antenna supervisor (MAX-M8W) ....................14
2.4.4 Status reporting ...............................................................................................................................14
2.4.5 Power and short detection antenna supervisor (MAX-M8W) .................................................15
2.4.6 Power, short and open detection Antenna Supervisor (MAX-M8W) .....................................16
3Migration to u-blox 8 / M8 modules.............................................................................................. 18
3.1 Migrating u-blox 7 designs to a u-blox 8 / M8 modules....................................................................18
3.2 Hardware migration from MAX-6 to MAX-8 / M8...............................................................................18
3.3 Software migration...................................................................................................................................19
4Product handling................................................................................................................................. 20
4.1 Packaging, shipping, storage and moisture preconditioning ..........................................................20

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4.2 Soldering .....................................................................................................................................................20
4.3 EOS/ESD/EMI precautions......................................................................................................................23
4.4 Applications with cellular modules........................................................................................................26
Appendix ....................................................................................................................................................... 28
AGlossary ................................................................................................................................................. 28
BRecommended components ........................................................................................................... 28
Related documents ................................................................................................................................... 30
Revision history .......................................................................................................................................... 30
Contact.......................................................................................................................................................... 31

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1Hardware description
1.1 Overview
u-blox MAX-8 / MAX-M8 modules are standard precision GNSS positioning modules featuring the high
performance u-blox 8 / M8 positioning engine. Available in the industry standard MAX form factor in
a leadless chip carrier (LCC) package, they are easy to integrate and combine exceptional positioning
performance with highly flexible power, design, and connectivity options. SMT pads allow fully
automated assembly with standard pick & place and reflow-soldering equipment for cost-efficient,
high-volume production enabling short time-to-market.
☞For product features see the MAX-8 Data Sheet [1] and MAX-M8 Data Sheet [2].
☞To determine which u-blox product best meets your needs, see the product selector tables on the
u-blox website www.u-blox.com.
1.2 Configuration
The configuration settings can be modified using UBX protocol configuration messages; see the u-
blox 8 /
u-blox M8 Receiver Description Including Protocol Specification [3]. The modified settings
remain effective until power-down or reset. If these settings have been stored in BBR (Battery Backed
RAM), then the modified configuration will be retained, as long as the backup battery supply (V_BCKP)
is not interrupted.
⚠eFuse is One-Time-Programmable; it cannot be changed if it has been programmed once.
In order to save backup current, a u-blox MAX-8C / MAX-M8C module configured in “single crystal“
mode can have the single-crystal feature turned off by means of a SW command. Hot start
performance will be degraded (no time information at startup).
Use the string in Table 1 to turn-off the single-crystal feature. This is recommended for low power
applications, especially if time will be delivered by GSM or uC.
eFuse String
turn-off single-crystal feature B5 62 06 41 09 00 01 01 92 81 E6 39 93 2B EE 30 31
Table 1: String to turn off single-crystal feature
1.3 Connecting power
u-blox MAX-8 / MAX-M8 positioning modules have up to three power supply pins: VCC, VCC_IO, and
V_BCKP.
VCC: Main supply voltage
The VCC pin provides the main supply voltage. During operation, the current drawn by the module can
vary by some orders of magnitude, especially if enabling low-power operation modes. For this reason,
it is important that the supply circuitry be able to support the peak power for a short time (see the
MAX-8 Data Sheet [1] and MAX-M8 Data Sheet [2] for specification).
☞When switching from backup mode to normal operation or at start-up, u-blox MAX-8 / MAX-M8
modules must charge the internal capacitors in the core domain. In certain situations, this can
result in a significant current draw. For low-power applications using Power Save and backup
modes, it is important that the power supply or low ESR capacitors at the module input can deliver
this current/charge.
☞Use a proper GND concept. Do not use any resistors or coils in the power line.

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1.3.1 VCC_IO: IO Supply Voltage
VCC_IO from the host system supplies the digital I/Os. The wide range of VCC_IO allows seamless
interfacing to standard logic voltage levels independent of the VCC voltage level. In many applications,
VCC_IO is simply connected to the main supply voltage.
☞Without a VCC_IO supply, the system will remain in reset state.
1.3.2 V_BCKP: Backup supply voltage
If there is a power failure on the module supply (VCC_IO), the real-time clock (RTC) and battery backed
RAM (BBR) are supplied through the V_BCKP pin. Thus orbit information and time can be maintained
and will allow a hot or warm start. If no backup battery is connected, the module performs a cold start
at every power up if not aiding data are sent to the receiver
☞Avoid high resistance on the V_BCKP line: During the switch from main supply to backup supply,
a short current adjustment peak can cause high voltage drop on the pin with possible
malfunctions.
☞If no backup supply voltage is available, connect the V_BCKP pin to VCC_IO.
☞As long as power is supplied to the u-blox 8 / M8 modules through the VCC_IO pin, the backup
battery is disconnected from the RTC and the BBR to avoid unnecessary battery drain (see Figure
1). In this case, VCC_IO supplies power to the RTC and BBR.
Figure 1: Backup battery and voltage (for exact pin orientation, see the MAX-8 Data Sheet [1] and MAX-M8 Data Sheet [2])
Single Crystal feature on MAX-8C / MAX-M8C
On MAX-8C / MAX-M8C, the reference frequency for the RTC clock will be internally derived from the
main clock frequency (26 MHz) when in Backup Mode (does not have a 32 kHz oscillator). This feature
is called “single crystal” operation. In the event of a power failure, the backup battery at V_BCKP will
supply the 26 MHz crystal oscillator, as needed to maintain the time. This makes MAX-8C / MAX-M8C
a more cost efficient solution at the expense of a higher backup current, as compared to other MAX-
8 / MAX-M8 variants that use an ordinary RTC crystal. Therefore, the capacity of the backup battery
at V_BCKP must be increased if Hardware Backup Mode is needed (See the
MAX-8 Data Sheet [1] and
MAX-M8 Data Sheet [2] for specification).
If the battery used cannot provide the increased current consumption for the needed time on MAX-
8C / MAX-M8C, the “single crystal” feature can be permanently disabled. Then the backup current
will be same as on MAX-8 / MAX-M8 modules without “single crystal” feature. But the time
information is not maintained during off time. So the customer either aides the time at every startup
to the receiver or the hot and warm start performance will be degraded because of missing time
information.
Send this string to disable the “single crystal” feature: “B5 62 41 09 00 01 01 92 81 E6 39 93 2B EE
30 31”.

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⚠This string has to be sent once in production and will permanently turn off the single crystal
feature on MAX-8C / MAX-M8C. The hot start and warm start performance will be degraded if time
information is not provided to the receiver at every startup.
1.3.3 VCC_RF: Output voltage RF
The VCC_RF pin can be used to supply an active antenna or an external LNA. For more information,
see section 2.4.
1.3.4 V_ANT: Antenna supply (MAX-M8W)
At V_ANT pin an antenna supply voltage can be connected which will be provided at RF_IN to supply
an active antenna. For more information see section 2.4.3
.
☞If not used, connect the V_ANT pin to GND.
1.4 Interfaces
1.4.1 UART
u-blox MAX-8 / MAX-M8 positioning modules include a Universal Asynchronous Receiver Transmitter
(UART) serial interface RXD/TXD that supports configurable baud rates. The UART output and input
levels are 0 V to VCC_IO. An interface based on RS232 standard levels (+/- 12 V) can be implemented
using level shifters such as Maxim MAX3232. Hardware handshake signals and synchronous
operation are not supported.
1.4.2 Display Data Channel (DDC)
An I2C compatible Display Data Channel (DDC) interface is available with u-blox MAX-8 / MAX-M8
modules for serial communication with an external host CPU. The interface only supports operation
in slave mode (master mode is not supported). The DDC protocol and electrical interface are fully
compatible with the Fast-Mode of the I2C industry standard. DDC pins SDA and SCL have internal
pull-up resistors to VCC_IO.
For more information about the DDC implementation, see the
u-blox 8 / u-blox M8 Receiver
Description Including Protocol Specification
[3]. For bandwidth information, see the MAX-8 Data
Sheet
[1] and MAX-M8 Data Sheet [2]. For timing, parameters consult the I2C-bus specification [6].
☞The u-blox MAX-8 / MAX-M8 DDC interface supports serial communication with u-blox cellular
modules. See the specification of the applicable cellular module to confirm compatibility.
1.4.3 TX_READY
The TX_READY function is used to indicate when the receiver has data to transmit. A listener can wait
on the TX_READY signal instead of polling the DDC or SPI interfaces. The UBX-CFG-PRT message lets
you configure the polarity and the number of bytes in the buffer before the TX READY signal goes
active. The TX_READY function can be mapped to TXD (PIO 06). The TX_READY function is disabled
by default.
☞The TX_READY functionality can be enabled and configured by AT commands sent to the u-blox
cellular module supporting the feature. For more information, see the
GPS Implementation and
Aiding Features in u-blox wireless modules
[7].
1.5 I/O pins
All I/O pins make use of internal pull-ups. Thus, there is no need to connect unused pins to VCC_IO.

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1.5.1 RESET_N: Reset input
Driving RESET_N low activates a hardware reset of the system. Use this pin only to reset the module.
Do not use RESET_N to turn the module on and off, since the reset state increases power
consumption. In u-blox MAX-8 / MAX-M8 modules, RESET_N is an input only.
1.5.2 EXTINT: External interrupt
EXTINT is an external interrupt pin with fixed input voltage thresholds with respect to VCC_IO (see
the
MAX-8 Data Sheet [1] and MAX-M8 Data Sheet [2] for more information). It can be used for wake-
up functions in Power Save Mode on all u-blox 8 / M8 modules and for aiding. Leave open if unused;
the functions are disabled by default.
If the EXTINT is not used for an external interrupt function, it can be used for some other purpose, e.g.
as an output pin for the TX_READY feature to indicate that the receiver has data to transmit.
Power Control
The power control feature allows overriding the automatic active/inactive cycle of Power Save Mode.
The state of the receiver can be controlled through the EXTINT pin. The receiver can also be forced
OFF using EXTINT when Power Save Mode is not active.
Frequency aiding
The EXTINT pin can be used to supply time or frequency aiding data to the receiver.
For time aiding, hardware time synchronization can be achieved by connecting an accurate time pulse
to the EXTINT pin.
Frequency aiding can be implemented by connecting a periodic rectangular signal with a frequency up
to 500 kHz and arbitrary duty cycle (low/high phase duration must not be shorter than 50 ns) to the
EXTINT pin. Provide the applied frequency value to the receiver using UBX messages.
1.5.3 SAFEBOOT_N
The SAFEBOOT_N pin is for future service, updates and reconfiguration.
1.5.4 TIMEPULSE
A configurable time pulse signal is available with all u-blox 8 / u-blox M8 modules. By default, the time
pulse signal is configured to 1 pulse per second. For more information, see the
u-blox 8 / u-blox M8
Receiver Description Including Protocol Specification
[3].
1.5.5 LNA_EN: LNA enable
On MAX-M8Q, MAX-M8C, MAX-8C and MAX-8Q modules, in Power Save Mode, the system can turn
on/off an optional external LNA using the LNA_EN signal in order to optimize power consumption.
Signals: "high" = Turn ON LNA, "low" = Turn OFF LNA
Antenna Short circuit detection (ANT_OK) (MAX-M8W)
MAX-M8W module includes internal short circuit antenna detection. For more information, see
section 2.4.5.
"high" = antenna is ok (e.g. no short); "low" = antenna not ok (e.g. short)
Antenna supervision is configurable using message UBX-CFG-ANT.
☞Refer to the u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification [3] for
information about further settings.

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1.5.6 ANT_DET: Open Circuit Detection (MAX-M8)
Antenna open circuit detection (ANT_DET) is not activated by default on the MAX-8 / MAX-M8
modules. ANT_DET can be mapped to PIO13 (EXTINT).
ANT_DET is an input used to report whether an external circuit has detected an external antenna or
not.
"high" = Antenna detected (antenna consumes current); "low" = Antenna not detected (no current
drawn).
Antenna supervision is configurable using message UBX-CFG-ANT.
☞Refer to the u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification [3] for
information about further settings.
1.6 Electromagnetic interference on I/O lines
Any I/O signal line with a length greater than approximately 3 mm can act as an antenna and may pick
up arbitrary RF signals transferring them as noise into the GNSS receiver. This specifically applies to
unshielded lines, in which the corresponding GND layer is remote or missing entirely, and lines close
to the edges of the printed circuit board.
If, for example, a cellular signal radiates into an unshielded high-impedance line, it is possible to
generate noise in the order of volts and not only distort receiver operation but also damage it
permanently.
On the other hand, noise generated at the I/O pins will emit from unshielded I/O lines. Receiver
performance may be degraded when this noise is coupled into the GNSS antenna (see Figure 19).
To avoid interference by improperly shielded lines, it is recommended to use resistors (e.g. R>20 Ω),
ferrite beads (e.g. BLM15HD102SN1) or inductors (e.g. LQG15HS47NJ02) on the I/O lines in series.
These components should be chosen with care because they will affect also the signal rise times.
Figure 2 shows an example of EMI protection measures on the RX/TX line using a ferrite bead. More
information can be found in section 4.3.
Figure 2: EMI Precautions

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2Design
2.1 Pin description
Function PIN No I/O Description Remarks
Power VCC 8 I Supply Voltage Provide clean and stable supply.
GND 1,10,12 I Ground Assure a good GND connection to all GND pins of the module,
preferably with a large ground plane.
V_BCKP 6 I Backup Supply
Voltage
Backup supply voltage input pin. Connect to VCC_IO if not
used.
Antenna RF_IN 11 I GNSS signal
input from
antenna
The connection to the antenna has to be routed on the PCB.
Use a controlled impedance of 50 Ωto connect RF_IN to the
antenna or the antenna connector. DC block inside.
VCC_RF 14 O Output Voltage
RF section
Can be used for active antenna or external LNA supply.
LNA_EN
(MAX-M8C/Q
MAX-8C/Q)
Reserved
(MAX-M8W)
13 O Active Antenna
Control
Ext. LNA control pin in power save mode.
LNA_EN pin voltage level is VCC_IO
- Reserved Leave open
UART TXD 2 O Serial Port UART, leave open if not used, Voltage level referred VCC_IO.
Can be configured as TX Ready indication for the DDC
interface.
RXD 3 I Serial Port UART, leave open if not used, Voltage level referred VCC_IO
System TIMEPULSE 4 O Timepulse
Signal
Leave open if not used, Voltage level referred VCC_IO
PIO13/EXTINT
5 I External
Interrupt
Leave open if not used, Voltage level referred VCC_IO
Can be programmed on MAX-M8W as Open Circuit Detection
(ANT_DET)
SDA 16 I/O DDC Pins DDC Data. Leave open, if not used.
SCL 17 I DDC Pins DDC Clock. Leave open, if not used.
VCC_IO 7 I VCC_IO IO supply voltage. Input must be always supplied. Usually
connect to VCC Pin 8
RESET_N 9 I Reset Reset
V_ANT
(MAX-M8W )
Reserved
(MAX-M8C/Q
MAX-8C/Q)
15 I Antenna Bias
Voltage
Connect to GND (or leave open) if passive antenna is used. If
an active antenna is used, add a 10 Ωresistor in front of
V_ANT input to the Antenna Bias Voltage or VCC_RF
- Reserved Leave open
SAFEBOOT_N 18 I SAFEBOOT_N For future service, leave OPEN
Table 2: Pinout MAX-8 / MAX-M8
2.1.1 Pin name changes
Selected pin names have been updated to agree with a common naming convention across u-blox
modules. The pins have not changed their operation and are the same physical hardware but with
updated names. The table below lists the pins that have changed name along with their old and new
names.
No Previous Name New name
13 ANT_ON LNA_EN
Table 3: Pin name changes

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2.2 Minimal design
This is a minimal setup for a MAX-8 / M8 GNSS receiver:
Figure 3: MAX-8 / MAX-M8 passive antenna design
☞For information on increasing immunity to jammers such as GSM, see section 4.3.
2.3 Layout: Footprint and paste mask
Figure 4 describes the footprint and provides recommendations for the paste mask for MAX-8 / MAX-
M8 LCC modules. These are recommendations only, and not specifications. Note that the copper and
solder masks have the same size and position.
To improve the wetting of the half vias, reduce the amount of solder paste under the module and
increase the volume outside of the module by defining the dimensions of the paste mask to form a T-
shape (or equivalent) extending beyond the copper mask. For the stencil thickness, see section 4.2
.
☞Consider the paste mask outline when defining the minimal distance to the next component. The
exact geometry, distances, stencil thicknesses and solder paste volumes must be adapted to the
specific production processes (e.g. soldering) of the customer.
9.7 mm [382 mil]
10.1 mm [398 mil]
1.0 mm
[39.3 mil]
0.7 mm
[27.6 mil]
0.8 mm
[31.5 mil]
0.65 mm
[26.6 mil]
1.1 mm
[43.3 mil]
0.8 mm
[31.5 mil]
Figure 4: MAX-8 / MAX-M8 footprint
Stencil: 150 µ m
7.9 mm [311 mil]
12.5 mm [492 mil]
9.7 mm [382 mil]
0.7 mm
[27.6 mil]
0.5 mm
[19.7 mil]
0.8 mm
[31.5 mil]
0.6 mm
[23.5 mil]
Figure 5: MAX-8 / MAX-M8 paste mask
☞MAX Form Factor (10.1 x 9.7 x 2.5): Same Pitch as NEO for all pins: 1.1 mm, but 4 pads in each
corner (pin 1, 9, 10 and 18) only 0.7 mm wide instead 0.8 mm

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2.4 Antenna and Antenna supervision
The MAX-8 / MAX-M8 modules are designed for usage with an active antenna, see section 2.4.2
2.4.1 Antenna design with passive antenna
☞A passive antenna can be used, but require an external LNA and SAW for best performance.
A design using a passive antenna requires more attention to the layout of the RF section. Typically, a
passive antenna is located near electronic components; therefore, care should be taken to reduce
electrical noise that may interfere with the antenna performance. Passive antennas do not require a
DC bias voltage and can be directly connected to the RF input pin RF_IN. Sometimes they may also
need a passive matching network to match the impedance to 50 Ω.
Figure 6 shows a minimal setup for a design with a good GNSS patch antenna.
Figure 6: Module design with passive antenna (for exact pin orientation see MAX-8 Data Sheet [1] and MAX-M8 Data Sheet
[2])
☞Use an antenna that has sufficient bandwidth to receive all GNSS constellations. See Appendix.
Figure 7 shows a design using an external LNA and SAW to increase the sensitivity for best
performance with passive antenna.
Figure 7: MAX-8C/Q and M8C/Q modules design with passive antenna and an external LNA and SAW (for exact pin
orientation see the
MAX-8 Data Sheet [1] and MAX-M8 Data Sheet [2])

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The LNA_EN pin (LNA enable) can be used to turn on and off an optional external LNA in power save
mode in on/off operation.
The VCC_RF output can be used to supply the LNA with a filtered supply voltage.
☞A standard GNSS LNA has enough bandwidth to amplify GPS/GLONASS/BeiDou signals.
Figure 8: MAX-M8W Module design with passive antenna and an external LNA and SAW (for exact pin orientation see the
MAX-M8 Data Sheet [2])
2.4.2 Antenna design with active antenna
Active antennas have an integrated low-noise amplifier. Active antennas require a power supply that
will contribute to the total budget of GNSS system power consumption, with typically an additional
5 to 20 mA.
If the supply voltage of the MAX-8 / M8 receivers matches the supply voltage of the antenna (e.g. 3.0
V), use the filtered supply voltage available at pin VCC_RF as shown in Figure 9.
Active antenna design using VCC_RF pin to supply the active antenna
Figure 9: MAX-8C/Q and M8C/Q active antenna design, external supply from VCC_RF (for exact pin orientation see the MAX-
8 Data Sheet [1] and MAX-M8 Data Sheet [2])
For the MAX-M8W active antenna design with external supply from VCC_RF, see Figure 11.
In case the VCC_RF voltage does not match with the supply voltage of the active antenna, use a
filtered external supply as shown in Figure 10.

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Active antenna design powered from external supply
Since the external bias voltage is fed into the most sensitive part of the receiver (i.e. the RF input),
this supply should be free of noise. Usually, low frequency analog noise is less critical than digital noise
of spurious frequencies with harmonics up to the GNSS frequency.
Figure 10: MAX-8C/Q and M8C/Q active antenna design, direct external supply (for exact pin orientation see the MAX-8 Data
Sheet [1] and MAX-M8 Data Sheet [2])
☞The circuit shown in Figure 10 works with all u-blox 8 / M8 modules, also with modules without
VCC_RF output.
External supply (MAX-M8W)
For the module design with active antenna with external supply, see Figure 13
2.4.3 Antenna design with active antenna using antenna supervisor (MAX-
M8W)
An active antenna supervisor provides the means to check the antenna for open and short circuits
and to shut off the antenna supply if a short circuit is detected. The Antenna Supervisor is configured
using serial port UBX binary protocol message. Once enabled, the active antenna supervisor produces
status messages, reporting in NMEA and/or UBX binary protocol (see section 2.4.4).
The current active antenna status can be determined by polling the UBX-MON-HW monitor
command. If an antenna is connected, the initial state after power-up is “Active Antenna OK.”
The module firmware supports an active antenna supervisor circuit, which is connected to the pin
EXTINT. For an example of an open circuit detection circuit, see Figure 14. High on EXTINT means
that an external antenna is not connected.
☞Antenna open circuit detection (OCD) is not activated by default on the MAX-8/M8 modules. OCD
can be mapped to PIO13 (EXTINT). To activate the antenna supervisor use the UBX-CFG-ANT
message. For more information about how to implement and configure OCD, see the
u-blox 8 / u-
blox M8 Receiver Description Including Protocol Specification
[3]
☞For recommended parts for the designs that follow, see the Appendix.
2.4.4 Status reporting
At startup, and on every change of the antenna supervisor configuration, the MAX-8/M8 modules will
output an NMEA ($GPTXT) or UBX (INF-NOTICE) message with the internal status of the antenna
supervisor (disabled, short detection only, enabled).

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Abbreviation Description
AC Active Antenna Control enabled
SD Short Circuit Detection Enabled
OD Open Circuit Detection enabled
PDoS Short Circuit Power Down Logic enabled
SR Automatic Recovery from Short state
Table 4: Active Antenna Supervisor Message on startup (UBX binary protocol)
☞To activate the antenna supervisor use the UBX-CFG-ANT message. For further information, see
the
u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification [3].
Similar to the antenna supervisor configuration, the status of the antenna supervisor will be reported
in an NMEA ($GPTXT) or UBX (INF-NOTICE) message at start-up and on every change.
2.4.5 Power and short detection antenna supervisor (MAX-M8W)
If a suitably dimensioned series resistor R_BIAS is placed in front of pin V_ANT, a short circuit can be
detected in the antenna supply. This is detected inside the u-blox MAX-M8W module and the antenna
supply voltage will be immediately shut down. After which, periodic attempts to re-establish antenna
power are made by default.
An internal switch (under control of the receiver) can turn off the supply to the external antenna
whenever it is not needed. This feature helps to reduce power consumption in power save mode.
☞To configure the antenna supervisor, use the UBX-CFG-ANT message. For further information,
see the u-blox 8 /
u-blox M8 Receiver Description Including Protocol Specification [3].
⚠Short circuits on the antenna input without limitation (R_BIAS) of the current can result in
permanent damage to the receiver! Therefore, it is mandatory to implement an R_BIAS in all risk
applications, such as situations where the antenna can be disconnected by the end-user or that
have long antenna cables.
☞If VCC_RF voltage does not match with the antenna supply voltage, use a filtered external supply,
as shown in Figure 13.
Supply from VCC_RF (MAX-M8W)
Figure 11 shows an active antenna supplied from the u-blox MAX-M8W module.
The VCC_RF pin can be connected with V_ANT to supply the antenna. Note that the voltage
specification of the antenna has to match the actual supply voltage of the u-blox module (e.g. 3.0 V).
Figure 11: MAX-M8W module design with active antenna, internal supply from VCC_RF (for exact pin orientation, see the
MAX-M8 Data Sheet [2])

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The LNA_EN signal can be used to turn on and off an external active Antenna. This reduces power
consumption in Power Save Mode (Backup mode).
Figure 12: External active antenna control (MAX-8C/Q and M8C/Q)
Figure 13: MAX-M8W module design with external supply, active antenna (for exact pin orientation, see the MAX-M8 Data Sheet
[2])
2.4.6 Power, short and open detection Antenna Supervisor (MAX-M8W)
The open circuit detection (ANT_DET) circuit uses the current flow to detect an open circuit in the
antenna. Calculate the threshold current using Equation 1.

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Figure 14: Schematic of open circuit detection (for exact pin orientation, see the MAX-M8 Data Sheet [2])
RFVcc
Rbias
RR
R
I_
32
2
•






+
=
Equation 1: Calculation of threshold current for open circuit detection
☞Antenna open circuit detection (ANT_DET) is not activated by default. It can be enabled by the
UBX-CFG-ANT message. This configuration must be sent to the receiver at every startup.
To enable the Antenna open circuit detection feature, the following command must be sent to the
receiver at every startup:
“B5 62 06 13 04 00 1F 00 F0 B5 E1 DE”.
"high" = Antenna detected (antenna consumes current); "low" = Antenna not detected (no
current drawn).
For more information about how to implement and configure OCD, see the
u-blox 8 / u-blox M8
Receiver Description Including Protocol Specification
[3].
☞If the antenna supply voltage is not derived from VCC_RF, do not exceed the maximum voltage
rating of ANT_DET.

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3Migration to u-blox 8 / M8 modules
3.1 Migrating u-blox 7 designs to a u-blox 8 / M8 modules
u-blox is committed to ensuring that products in the same form factor are backwards compatible over
several technology generations. Utmost care has been taken to ensure there is no negative impact on
function or performance and to make u-blox 8 / M8 modules as fully compatible as possible with u-
blox 7 versions. If using BeiDou, check the bandwidth of the external RF components and the antenna.
For power consumption information, see the
MAX-8 Data Sheet [1] and MAX-M8 Data Sheet [2].
It is highly advisable that customers consider a design review with the u-blox support team to ensure
the compatibility of key functionalities.
☞Selected pin names have been updated to agree with a common naming convention across u-blox
modules. The pins have not changed their operation and are the same physical hardware but with
updated names.
3.2 Hardware migration from MAX-6 to MAX-8 / M8
Pin MAX-6 MAX-8/M8 Remarks for Migration
Pin Name Typical Assignment Pin Name Typical Assignment
1 GND GND GND GND No difference
2 TxD Serial Port TXD Serial Port No difference
3 RxD Serial Port RXD Serial Port No difference
4 TIMEPULSE Timepulse (1PPS) TIMEPULSE Timepulse (1PPS) No difference
5 EXTINT0 External Interrupt Pin EXTINT External Interrupt Pin No difference
6 V_BCKP Backup Supply
Voltage
V_BCKP Backup Supply Voltage If this was connected to GND on u-
blox 6 module, OK to do the same in
u-blox 8 / M8 .
(MAX-8C / M8C: Higher backup
current, see Single Crystal)
7 VCC_IO IO supply voltage
Input must always be
supplied. Usually
connect to VCC Pin 8
VCC_IO IO supply voltage Input
must always be supplied.
Usually connect to VCC
Pin 8
No difference
8 VCC Module power supply
MAX-6G 1.75 – 2.0V
MAX-6Q/C: 2.7 – 3.6V
VCC Module power supply
MAX-8C/M8C: 1.65 – 3.6V
MAX-8Q/M8Q: 2.7 – 3.6V
9 VRESET connect to pin 8 RESET_N Reset input If pin 9 is connected directly to pin 8,
the RESET function is not available. If
the RESET function shall be used, a
3k3 resistor from pin 9 to pin 8 in
conjunction with an open drain buffer
is required for u-blox 6. For MAX-8 /
M8 modules pin 8 can be connected
to pin 9 or can be left open. Do not
populate the 3k3 resistor.
Behavior of RESET
_N has changed; In
u-blox 7 / 8 / M8, a RESET erases the
time information in the BBR, which
was maintained in u-blox 6. There-
fore, in u-blox 7 / 8 / M8 a RESET will
not result in a hot start, etc.
10 GND GND GND GND No difference

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Pin MAX-6 MAX-8/M8 Remarks for Migration
Pin Name Typical Assignment Pin Name Typical Assignment
11 RF_IN Matched RF-Input, DC
block inside.
RF_IN Matched RF-Input, DC
block inside.
No difference
12 GND GND GND GND No difference
13 ANT_ON Active antenna or ext.
LNA control pin in
power save mode.
ANT_ON pin voltage
level: MAX-6 ->
VCC_RF (pull-up)
LNA_EN
Ext. LNA control pin in
power save mode.
LNA_EN pin voltage level:
MAX-M8 -> VCC_IO
(push-pull)
On MAX-6, ANT_ON pin voltage level
is with respect to VCC_RF, on MAX-
8 / M8 to VCC_IO
(only relevant when VCC_IO does not
share the same supply with VCC)
14 VCC_RF Can be used for active
antenna or external
LNA supply.
VCC_RF Can be used for active
antenna or external LNA
supply.
No difference
15 RESERVED Leave open. RESERVED
(MAX-M8W:
V_ANT )
Leave open. No difference
16 SDA DDC Data SDA DDC Data No difference
17 SCL DDC Clock SCL DDC Clock No difference
18 SAFEBOOT_N Leave open. SAFEBOOT_N Leave open. No difference
Table 5: Pin-out comparison MAX-6 vs. MAX-8 / MAX-M8
3.3 Software migration
☞For an overall description of the module software operation, see the u-blox 8 / u-blox M8 Receiver
Description Including Protocol Specification
[3].
☞For migration, see u-blox M8 FW SPG3.01 Migration Guide [8].

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4Product 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
MAX-8 Data Sheet [1] and MAX-
M8 Data Sheet
[2].
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.
4.2 Soldering
Soldering paste
Use of “No Clean” soldering paste is strongly recommended, as it does not require cleaning after the
soldering process has taken place. The paste listed in the example below meets these criteria.
Soldering Paste: OM338 SAC405 / Nr.143714 (Cookson Electronics)
Alloy specification: Sn 95.5/ Ag 4/ Cu 0.5 (95.5% Tin/ 4% Silver/ 0.5% Copper)
Melting Temperature: 217° C
Stencil Thickness: See section 2.3
The final choice of the soldering paste depends on the approved manufacturing procedures.
The paste-mask geometry for applying soldering paste should meet the recommendations.
☞The quality of the solder joints on the connectors (“half vias”) should meet the appropriate IPC
specification.
Reflow soldering
A convection type-soldering oven is highly recommended over the infrared type radiation oven.
Convection heated ovens allow precise control of the temperature and all parts will be heated up
evenly, regardless of material properties, thickness of components and surface color.
Consider the IPC-7530 Guidelines for temperature profiling for mass soldering (reflow and wave)
processes, published 2001.
Preheat phase
Initial heating of component leads and balls. Residual humidity will be dried out. Note that this preheat
phase will not replace prior baking procedures.
•Temperature rise rate: max. 3° C/s. If the temperature rise is too rapid in the preheat phase it may
cause excessive slumping.
•Time: 60 – 120 s. If the preheat is insufficient, rather large solder balls tend to be generated.
Conversely, if performed excessively, fine balls and large balls will be generated in clusters.
•End Temperature: 150 – 200° C. If the temperature is too low, non-melting tends to be caused in
areas containing large heat capacity.
Heating/ Reflow phase
The temperature rises above the liquidus temperature of 217° C. Avoid a sudden rise in temperature
as the slump of the paste could become worse.