11
Solution:
When the module is not powered on, make sure that the IO port connected to the module
is in a high-resistance state or a low level to avoid leakage power. Another solution is to
connect a 1KΩ resistor in series to the serial port RX, and connect a 33Ω or 1KΩ resistor
in series to TX (There is no need to connect any resistor to the TX of the module with PN
2310408000024). It is also recommended to connect a 4.7KΩ resistor in series to the
Pin of other necessary PIOs.
4.4
Antenna
If the UM220-IV M0 uses an active antenna, the bias voltage V_BIAS is supplied to the
antenna through a feed inductor. It’s recommended to use an independent power as
V_BIAS to supply the antenna.
If the antenna power supply and the module’s main supply VCC use the same power rail,
the ESD, surge and overvoltage from the antenna will have an effect on VCC, which may
cause damage to the module. Therefore, it’s recommended to design an independent
power rail for the antenna to reduce the possibility of damage to the module.
V_BIAS
UM220 -IV M0
RF_IN
VCC_RF
Figure 4-1 UM220-IV M0 Active Antenna Solution
If UM220-IV M0 uses a passive antenna, the antenna can be directly connected to the
RF_IN pin. It should be noted that the use of passive antennas may cause a decrease in
GNSS performance compared to active antennas.
UM220 -IV M0
RF_IN
VCC_RF
Figure 4-2 UM220-IV M0 Passive Antenna Solution