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SE873 Family Product User Guide
Reference Designs
1VV0301216
Rev.4
Page 49 of 69
2018-08-24
Along with power and ground, the minimum signals required to operate the module properly are:
one RF input and four digital lines.
The RF input can be connected directly to a passive GNSS antenna.
C5 is used to block DC voltage from entering the module. The active-antenna reference design
shows a DC power feed for its LNA. The inductor L1 is chosen to be self-resonant at the GPS L1
frequency (1.57542 GHz) to minimize loading on the RF trace. Capacitor C6 is also chosen to be
self-resonant at the GPS L1 frequency such that it is close to an RF short at that frequency.
V_ANT is the supply voltage for the external active antenna.
TX is a standard serial output - usually a UART with a default bit rate of 9600 bps, 8 data bits, 1
stop bit, and no parity. As is the case with all UART data, the idle state is logic one. This is a 1.8
volt logic level signal. Note that it can be configured for I
2
C or SPI interface.
RX is a standard serial input - usually a UART with a default bit rate of 9600 bps, 8 data bits, 1
stop bit and no parity. As is the case with all UART data, the idle state is logic one. This is a 1.8
volt logic level signal, but is tolerant to 3.6 volts. Note that it can be configured for I
2
C or SPI
interface.
SYSTEM-ON is an output indicating the power state of the module. If the module is in the RUN
state, the logic level will be high, otherwise the logic level will be low. This is a 1.8 volt signal.
ON-OFF is an input to control the power state of the module. After power-up, the module will enter
the RUN state if it is high, or the HIBERNATE state if it is low. SYSTEM- ON will then indicate
the system’s state.
Note:
ON-OFF must not be tied to V18 or the module will not be able to exit a commanded
HIBERNATE state.
Resistor R1 as shown pulls GPIO6 high, which specifies the serial port configuration to be serial
UART. See section
8.5 Serial I/O Ports - Configuration and
The power supply shown is a minimal design for power requirements. The power supply must
have tight voltage regulation under varying line and load conditions to prevent falsely tripping the
internal voltage supervisor within the module.
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