12
Pin 5:
RXD1 - First Serial Asynchronous Input. RS-232 compatible with
maximum input voltage range -25 < V < 25. This input may be
directly connected to standard 3 to 5Vdc CMOS logic. The
minimum low signal voltage requirement is 0.8V, and the maximum
high signal voltage requirement is 2.4V. Maximum load impedance
is 4.7K ohms. This input may be used to receive serial
initialization/configuration data, as specified in Section 4.1.
Pin 6:
POWER DOWN - External Power Down Input. Inactive if not
connected or less than 0.5V. Active if greater than 2.7V. Typical
switch point is 2.0V @ 0.34 mA. Input impedance is 15K Ohms.
Activation of this input powers the internal regulators off and drops
the supply current below 20mA in the -LVx version and below 1mA in the
-HVx version. The computer will be reset when power is restored.
Pin 7:
VAUX - Auxiliary External Backup Battery Charge circuit. If used,
a 4VDC to 35VDC @ 4mA power source is required to supply a trickle
charge to the battery. During normal operation a trickle charge is
supplied to the battery from an internal regulator. On-board
rechargeable battery capacity is 7 mA hour.
Pin 8:
GND - Power and Signal Ground
Pin 9:
Vin - Connected to Pin 10 (VER 11 and above).
Pin 10: Vin - Reg3.6V to +6V, 200 mA (maximum) in the -LVx versions.
Typical operating current is 120 mA plus antenna power. Transients and
overvoltages are protected by an internal 6.8V transient zener diode and
a positive temperature coefficient thermistor. With voltages greater than
6.8Vdc the thermistor will power the unit off until proper supply voltages
are returned. Antenna supply is derived from Vin after passing through a
50mA current limiter. The CMOS/TTL output buffers are powered by Vin,
therefore a 3.6Vdc supply will create 3.6V logic output levels.
In the -HVS version, Vin can be an unregulated 6.0Vdc to 40Vdc. This
voltage drives a switching regulator with a nominal 4.4Vdc output, which
powers the antenna connector current limiter, the internal linear
regulators, and the CMOS output buffers.
Pin 11: NC - This pin is floating on GPS 25LP but reserved for future.
Pin 12: NMEA - NMEA 0183, Version 1.5 electrical specification compatible serial
output. This output is CMOS compatible with a no load voltage swing of
0.2Vdc to 0.9xVCC. This output normally provides ASCII sentences
formatted per “NMEA 0183, Version 2.0”. User selectable baud rates of
300, 600, 1200, 2400, 4800, 9600 and 19200 are available, with 4800 as
the default. The data output on this pin is identical to the data output on
pin 4.
