Specifications

DSH_WISMC04_1v2 WISM 50 pin TCP-IP Data Sheet.doc © 2007-8 EZURiO Ltd
Page 8
4.2 Electrical Specifications
4.2.1 Absolute Maximum ratings
Absolute maximum ratings for supply voltage and voltages on digital and analogue pins of the Module
are listed below. Exceeding these values will cause permanent damage.
Parameter Min Max Unit
Peak current of power supply 550 mA
Voltage at digital pins -0.3 3.3 V
Voltage at VCC_5V pin 3.3 5 V
4.2.2 Recommended Operating Parameters
If a motherboard is being designed for interchangeable use with a Siemens GPRS module and a WISM
then some signal levels may need to meet tighter limits than specified for each individual module.
Consult the Application Note AN014 – WISM and MC55 Design Considerations.
4.2.2.1 Power Supply
Signal Name Pin No Voltage level Comments
Vcc 26, 27, 28, 29, 30 3.3V to 5.0V I
typ
= 250mA.
All Vcc pins should be connected
GND 21, 22, 23, 24, 25,
42
6 Ground terminals to be attached in
parallel
4.2.2.2 Signal Levels for UART Interface
Signal Type Signal level Signal level @ 0mA load Signal level @ 4mA load
Input V
IL
max=0.8V
V
IH
min=2.1V
V
IH
max=3.3V
Output V
OL
max=0.2V
V
OH
min=2.8V
V
OL
max=0.4V
V
OH
min=2.6V
4.2.2.3 RS-232 Interface
Signal Name Pin No I/O Comments
/RXD 15 O This pin must NOT be pulled low by external circuitry.
/TXD 17 I
/RTS 34 I
/CTS 37 O
/DSR 33 O
Direction is programmable – default is Output
/DTR 35 I
Direction is programmable – default is Input
/RING 32 O
Direction is programmable – default is Output
/DCD 39 O
Direction is programmable – default is Output