UM220-IV M0 User Manual
10
4.2
Avoid Power Connection
The module input ports of UM220-IV M0 include: RXD and GPIO. When the module is not
powered on, if there is data input in the above ports, it will form a series of power on the
module VCC. When the series voltage is higher than 1.6V, it may cause a failure of starting
up when the module is powered on.
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 power connection. Or to connect a
1KΩ resistor in series to RX, a 33Ω or 1K
Ω
resistor to TX, and a 4.7KΩ resistor to other
necessary PIO in the Pin.
4.3
Antenna
If UM220-IV M0 uses a +3V active antenna,
it is recommended to use the VCC_RF pin
output to power the antenna through a feed inductor.
UM220 -IV M0
RF_IN
VCC_RF
Figure 4-1 UM220-IV M0 Active A3V Solution
If the UM220-IV M0 uses an active antenna other than +3V, the bias voltage V_BIAS
required by the antenna is supplied to the antenna through a feed inductor.
V_BIAS
UM220 -IV M0
RF_IN
VCC_RF
Figure 4-2 UM220-IV M0 Active Antenna (Other than +3V) Solution
If UM220-IV M0 uses a passive antenna, and the antenna is directly connected to
RF_IN pin, the VCC_RF can be suspended. It should be noted that the use of passive
antennas may cause a decrease in GNSS performance compared to active antennas.
