USGlobalsat ET-314 - Manual (Page 7)

ET-314
The Specifications are subject to be changed without notice. Copyright © 2007, GlobalSat Technology.
Page 7 of 19
Version 1.2
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 15uA. Without an external backup battery, the module/engine board will
execute a cold star after every turn on. To achieve the faster start-up offered by a hot or warm start,
a battery backup must be connected. The battery voltage should be between 2.0v and 5.0v.
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 –30 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.