Specifications
XT55 Hardware Interface Description
Confidential / Preliminary
s
mo b i l e
XT55_hd_v00.02 Page 90 of 116 17.03.2004
Function Signal name IO Signal form and level Comments
GSM_EPP2 O
GSM_EPN2 O
V
O
max = 3.7Vpp
See also Table 32.
The audio output is
balanced and can directly
operate an earpiece.
If unused keep pins open.
GSM_EPP1 O
GSM_EPN1 O
V
O
max = 3.7Vpp
See also Table 32.
Balanced audio output.
Can be used to directly
operate an earpiece.
If unused keep pins open.
GSM_MICP1 I
GSM_MICN1 I
R
I
# 50kW differential
V
I
max = 1.03Vpp
See also Table 33.
Balanced microphone
input. To be decoupled
with 2 capacitors (C
K
=
100nF), if connected to a
microphone or another
device.
If unused keep pins open.
GSM_MICP2 I
Analog audio
interfaces
GSM_MICN2 I
R
I
= 2kW differential
V
I
max = 1.03Vpp
See also Table 33.
Balanced microphone
input. Can be used to
directly feed an active
microphone.
If used for another signal
source, e.g. op amp, to be
decoupled with capacitors.
If unused keep pins open.
Antenna
power
GPS_VANT I Max. 8V DC
Max. 25 mA
Power supply for active
antenna; in case of 3V
antenna can be connected
to GPS_VCC_RF
Internal
antenna
power
GPS_VCC_RF O Typ.: 3.0V ±5% DC
Max: 25 mA
Regulates 3V output for
feeding a 3V active GPS
antenna
GPS power GPS_VCC I Typ.: 3.3V ±5% DC
Max: 100 mA
Typ. 80 mA (without
feeding GPS_VCC_RF)
50 mV ripple
Digital Input /
Output
GPS_GPIO0 I/O CMOS 3.3V DC level See Chapter 4.5
Digital Input /
Output
GPS_GPIO1 I/O CMOS 3.3V DC level See Chapter 4.5
Digital Input /
Output
GPS_GPIO3 I/O CMOS 3.3V DC level See Chapter 4.5
Digital Input /
Output
GPS_GPIO4 I/O CMOS 3.3V DC level Output for Trickle Power
mode. Connect externally
to GPS_RFPC1. Usable as
LED control output, see
Chapter 4.7
Digital Input /
Output
GPS_GPIO5 I/O CMOS 3.3V DC level See Chapter 4.5
Digital Input /
Output
GPS_GPIO6 I/O CMOS 3.3V DC level See Chapter 4.5
Digital Input /
Output
GPS_GPIO7 I/O CMOS 3.3V DC level See Chapter 4.5
Digital Input /
Output
GPS_GPIO8 I/O CMOS 3.3V DC level Output for Trickle Power
mode. Connect externally
to GPS_RFPC0. Usable as
LED control output, see
Chapter 4.7
Digital Input /
Output
GPS_GPIO9 I/O CMOS 3.3V DC level The pin provides 1 pulse
per second output
(T-MARK), see Chapter 4.7
Explanation of signal names:
P = positive, N = negative