
WA_DEV_W228_PTS_002 Rev
001
Page 48 of 108
Product Technical Specification &
Customer Design Guidelines
SIM Interface
The
Subscriber
Identification
Module
can
be
directly
connected
to
the
WISMO228
through
this
dedicated
interface.
This
interface
controls
both
1.8V
and
3V
SIM
cards
and
is
fully
compliant
with
GSM
11.11
recommendations
concerning
SIM
functions.
The
SIM
uses
four
signals,
namely:
•
SIM
‐
VCC:
SIM
power
supply
•
~SIM
‐
RST:
reset
•
SIM
‐
CLK:
clock
•
SIM
‐
IO:
I/O
port
It
is
recommended
to
add
Transient
Voltage
Suppressor
(TVS)
diodes
on
the
signals
connected
to
the
SIM
socket
in
order
to
prevent
any
Electrostatic
Discharge.
TVS
diodes
with
low
capacitance
(less
than
10pF)
have
to
be
connected
on
the
SIM
‐
CLK
and
SIM
‐
IO
signals
to
avoid
any
disturbance
from
the
rising
and
falling
edge
of
the
signals.
TVS
diodes
are
mandatory
for
the
Full
Type
Approval
and
they
must
be
placed
as
close
to
the
SIM
socket
as
possible.
The
recommended
low
capacitance
diode
array
to
use
is
the
DALC208SC6
from
ST
Microelectronics.
Electrical Characteristics
The
following
table
describes
the
electrical
characteristics
of
the
SIM
interface.
Table 12. Electrical Characteristics of the SIM Interface
Parameters
Conditions
Minimum
Typical
Maximum
Unit
SIM-IO VIH
IIH =
±
20µA
0.7xVSIM -
-
V
SIM-IO VIL
IIL = 1mA
-
-
0.4
V
~SIM-RST, SIM-CLK
VOH
Source current = 20µA
0.9xVSIM
-
-
V
SIM-IO VOH
Source current = 20µA
0.8xVSIM
-
-
V
~SIM-RST, SIM-IO, SIM-
CLK
VOL
Sink current =
-200µA
- -
0.4
V
SIM-VCC Output Voltage
SIM-VCC = 2.9V
2.75
2.9
3.0
V
Содержание WISMO228
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