User's Manual

MC55/56 Hardware Interface Description
Confidential / Preliminary
s
MC55/56_hd_v03.00 Page 73 of 104 16.08.2005
5 Electrical, reliability and radio characteristics
5.1 Absolute maximum ratings
Absolute maximum ratings for supply voltage and voltages on digital and analog pins of
MC55/56 are listed in Table 24. Exceeding these values will cause permanent damage to
MC55/56.
Table 24: Absolute maximum ratings
Parameter Min Max Unit
Voltage BATT+ -0.3 4.8 V
Voltage at digital pins -0.3 3.3 V
Voltage at analog pins -0.3 3.0 V
Voltage at digital / analog pins in POWER DOWN mode -0.25 +0.25 V
Voltage at POWER pin 15 V
Voltage at CHARGE pin 15 V
Differential load resistance between EPNx and EPPx 15
Ω
5.2 Operating temperatures
Test conditions were specified in accordance with IEC 60068-2 (still air). The values stated
below are in compliance with GSM recommendation TS 51.010-01.
Table 25: Operating temperatures
Parameter Min Typ Max Unit
Ambient temperature (according to GSM 11.10) -20 25 55 °C
Restricted operation
*)
-25 to -20 55 to 70
***)
°C
Automatic shutdown
MC55/56 board temperature
Battery temperature
-29
-18
>70
**)
>60
°C
°C
Charging temperature (software controlled fast charging) 0 +45 °C
*)
MC55/56 works, but deviations from the GSM specification may occur.
**)
MC55/56 has the automatic shutdown set to 70°C at PCL5 (GSM 900 / GSM 850) GPRS Class
8. This prevents permanent damage to components on the board. Consider the ratio of output
power, supply voltage and operating temperature: To achieve T
amb max
= 70°C and, for example,
GSM 900 / GSM 850 PCL5 the supply voltage must not be higher than 4.2V.
***)
To achieve T
amb max
= 70°C at permanent GPRS class 8 operation (4Tx, 1Rx, GSM 900 /
GSM 850 at PCL5 with a supply voltage 4.2V) it is recommended to integrate MC55/56 in such
a way that a minor heat exchange with the environment can take place. A solution might be the
usage of a small heat sink.