RoyalTek REB-3300 - Manual (Page 13)

REB-3300 Operational Manual
antenna(or antenna connector) has to be a controlled impedance line
(Microstrip at 50 ).
V_ANT_IN
This pin is reserved an external DC power supply for active antenna.
If using 3.0V active antenna, pin 19 has to be connected to pin 20.
If using 3.3V or 12V active antenna ,this pin has to be connected to 3.3V or 5V
power supply.
VCC_RF
This pin provides DC voltage 3.0 for active antenna.
Reset
This pin provides an active-low reset input to the board. It causes the board to
reset and start searching for satellites. If not utilized, it may be left open.
PPS
This pin provides one pulse-per-second output from the board, which is
synchronized to GPS time. This is not available in Trickle Power mode.
Backup battery (V_BAT)
This is the battery backup input that powers the SRAM and RTC when main
power is removed. Typical current draw is 10uA.
Without an external backup battery or super cap, the TMP will execute a cold
start after every power on. To achieve the faster start-up offered by a hot or
warm start, either a battery backup must be connected or a super cap installed.
To maximize battery lifetime, the battery voltage should not exceed the supply
voltage and should be between 2.5V and 3.6V.
With the super cap (B1) installed, and after at least ten minutes of continuous
operation, the data retention is about seven hours.
Note that even though all other components are rated at –40 to +85 deg C , a
typical super cap is specified over a temperature range of –25 to +70 deg C and
a typical rechargeable Lithium battery is over –20 to +70 deg C.
GPIO Functions
Several I/Os are connected to the digital interface connector for custom
applications.
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