User Guide

PAMS
Technical Documentation
NME–3
Technical Information
Page 61
Issue 1 10/99
Figure 19. Power distribution diagram
BLD
Power Supply
5V
3V
MCU
Memory
SIM
LCD
Keyboard
Audio
8V
8V
Reset strategy is divided up between hard– and software to protect
accidential power down of SIM. As long, ”+5V” is below 4.63V, Reset is
active (active LOW, Net: _RESOUT), and min. 20msec after 4.63V was
reached. After _RESET is high, software has to wait in a loop until Net:
”SUPPLYOK” goes high. This is at the point, where the Voltage supplied
via Cable is over 7,0 Volt. After this happens, HS–Microcontroller can start
the normal program (with SIM–start).
If Voltage supplied via Cable goes below 6.0 Volts, the microcontroller is
interupted via ”SUPPLOWIRQ” (active low), then it must be monitored. If it
is low for a certain time, the system has to be shut down. This shut down
should terminate in the wait loop from the beginning (until SUPPLYOK).
Current Consumption
The handset current consumption dependents on three different parts:
1. digital part
2. backlight diming
3. audio
If only the digital part is active (no call active and BLD is switched offf) the
current consumption is around 40 mA. When BLD is switched on with a
duty cycle of 100% the current consumption is increased to approximately
90 mA. Depending on the BLD duty cycle the current consumption is
varying between 40 mA and 90 mA. If a call is active the current
consumtion can increase up to 100 mA when BLD duty cycle is 100%