User Guide

NHL-10
System Module and User Interface CCS Technical Documentation
ISSUE 2 01/2004 COMPANY CONFIDENTIAL 9
Copyright © 2003 Nokia. All Rights Reserved.
• The RESET mode is a synonym for the start-up sequence and contains
in fact several modes. In this mode regulators and oscillators are
enabled and after they have stabilized, the system reset is released and
the PWR_ON mode entered.
• In the PWR_ON mode the SW is running and controlling the system.
• The SLEEP mode is entered from the PWR_ON mode when the sys-
tem’s activity is low (SLEEPX controlled by SW).
• FLASHING mode is for production SW download.
Voltage limits
In the following table the voltage limits of the system are listed. These are also controlling sys-
tem states.
The master reset threshold controls the internal reset of the UEMK. If the battery voltage is
above V
MSTR
, the UEMK’s charging control logic is alive. Also, the RTC is active and supplied
from the main battery. Above V
MSTR
, the UEMK allows the system to be powered on although
this may not succeed due to voltage drops during start-up. The SW can also consider battery
voltage too low for operation and power down the system.
Clocking Scheme
A 26 MHz VCXO is used as system clock generator in GSM. During the system start-up, UEMK
RC-oscillators generate timing for state machines. All clock signals of the engine are illustrated
in the following figure.
Bluetooth uses a 26 MHz clock.
Table 1: Voltage limits
Parameter Description Value
V
MSTR+
Master reset threshold (rising) 2.1 V (typ.)
V
MSTR-
Master reset threshold (falling) 1.9 V (typ.)
V
COFF+
Hardware cutoff (rising) 3.1 V (typ.)
V
COFF-
Hardware cutoff (falling) 2.8 V (typ.)
V_BU
COFF+
Back-up battery cutoff (rising) 2.1 V (typ.)
V_BU
COFF-
Back-up battery cutoff (falling) 2.0 V (typ.)
SW
COFF
SW cutoff limit (> regulator
drop-out limit) MIN!
3.3 V SW changeable