Specifications

TC35 / TC37 Hardware Interface Description
TC35_37_HD_02_V03.10 - Released Page 52 of 92 21.12.2001
Function Signal
Name
Pin
No.
I/O Signal Level Comment
Ignition /IGT 15 I IDLE/ TALK/ Power-Down mode:
V
out
= 2.3V
R
out
≈ 220k"
V
low,max
= 0.45V @ I
out
= 10µA
t
low
≥ 100ms (see Chapter 3.3!)
Signal: falling edge and hold for t
low
Usage is mandatory
Open drain/collector
driver is required to
pull down this pin to
power on the GSM
Engine
Signal is low active.
DSR0 16 O
/RING0 17 O
RxD0 18 O
TxD0 19 I
CTS0 20 O
RTS0 21 I
DTR0 22 I
RS232
DCD0 23 O
IDLE/ TALK mode:
Output:
R
out
≈ 1k"
V
out,low,max
= 0.2V @ I = 0.1mA
V
out,high,min
= 2.25V @ I = -0.1mA
V
out,high,max
= 2.76V
Input:
R
i
≥ 1M" (1k" serial resistor)
V
in,low,min
= -0.3V, V
i,l,max
= 0.5V
V
in,high,min
= 1.95V, V
i,h,max
=3.3V
Power Down mode:
Signals are not defined.
Be aware of backward supply effects at
the inputs and outputs.
Application interface
to control GSM engine
using AT commands
If unused keep output
pins open and con-
nect input pins to VDD
via 10k".
When a voice call
comes in RING0 goes
active low for 1s and
inactive high for an-
other 4s (alternating).
An incoming data call
also causes RING0 to
go active low, but
without changing to
inactive high. See
Chapter 3.8.2.3 for
more details.
DCD0 and DTR0 lines
are connected via
internal clamp diodes
to 2.65V and GND