MAX-M5Q - Hardware Integration Manual
FTX-HW-13008
Objective Specification
Hardware description
Page 11 of 40
2.4
Configuration
2.4.1
Configuration MAX-M5Q
2.4.1.1
UART MAX-M5Q
UART Port 0 is normally used for GNSS data reports and receiver control. To configure serial data rates from
4,800 baud to 921,600 baud, use the command:
$PMTK251,<baud>*<checksum><CR><LF>
Ensure that the message payload fits in selected baud rate. Default baud rate is 115,200 baud; protocol is
NMEA. RX signal is pulled up internally and can be left floating (not connected) when not used.
Use caution when implementing MAX-M5Q configuration since forward compatibility is not
guaranteed.
2.5
Connecting power
The MAX-M5Q has three power supply pins:
VCC, V_BCKP
and
VCC_IO.
2.5.1
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 datasheet for specification).
When switching from backup mode to normal operation or at startup, MAX-M5Q 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. For ground plane design
see section 4.1.2
2.5.2
V_BCKP: Backup Supply Voltage
In case of a power failure on the module supply,
V_BCKP
supplies power to the real-time clock (RTC) and
battery backed RAM (BBR). Use of valid time and the GPS/GNSS orbit data at startup will improve the GPS/GNSS
performance, i.e. enables hot and warm starts. If no backup battery is connected, the module performs a cold
start at power up.
If no backup supply voltage is available, connect the
V_BCKP
pin to
VCC
.
V_BCKP
provides supply all the time to backup memory & RTC. Since there is no internal switch to
provide backup supply via
VCC_IO
, the
V_BCKP
current will increase while navigating. That will drain
the backup battery faster.
2.5.3
VCC_IO
For compatibility (migration path for MAX-7 and MAX-8), Pin 7 (Reserved) must be connected to
VDD
.
2.5.4
VCC_RF: Output Voltage RF section
The
VCC_RF
pin can supply an active antenna or external LNA. For more information, see section 4.2.2.
