LITTI
LITTI is the mixed signal ASIC used in the GSMCost 4.0 engine. The main functionality is: Voltage regulation,
battery charge control, audio codec, A/D conversion, various drivers, Real Time Clock (RTC), system logic, and
digital interfaces.
Modes of operation
BB4.1 has five different functional modes:
• No supply: In NO_SUPPLY mode, the phone has no supply voltage.
• Acting Dead: If the phone is off when the charger is connected, the phone is powered on but enters a state
called ”Acting Dead”. To the user, the phone acts as if it was switched off.
• Active: In the Active mode the phone is in normal operation, scanning for channels, listening to a base
station, transmitting and processing information.
• Sleep: In sleep mode VCTCXO is shut down and 32 kHz sleep clock oscillator is used as reference clock for
the base band.
• Charging: Charging can be performed in any operating mode.
Audio function description
Audio
The basic audio structure and communication between HW-audio modules and the audio ASIC's is illustrated
in the block diagram below.
RM-305; RM-306
System module
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COMPANY CONFIDENTIAL
Issue 2
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