Nokia 7250, 7250i Service Manual
CCS Technical Documentation
System Module and User Interface
Company confidential
NHL-4J/
Issue 2 06/03
Nokia Corporation.
Page 3
External Accessory Regulator................................................................................. 32
External Audio ...........................................................................................................32
External Microphone Connection ........................................................................... 32External Earphone Connections .............................................................................. 33
Internal Audio ............................................................................................................34
IHF Speaker & Stereo Audio Amplifier ................................................................. 34Internal Microphone................................................................................................ 34Internal Speaker....................................................................................................... 34IHF Speaker & Stereo Audio Amplifier ................................................................. 35
Memory Block ...........................................................................................................36
Security.................................................................................................................... 36
Clock distribution ......................................................................................................36
Audio Control.......................................................................................................... 37Accessory identification and Power Supply............................................................ 37Backup Battery........................................................................................................ 38
RF Module Introduction............................................................................................... 39
RF Frequency Plan ....................................................................................................40DC characteristics ......................................................................................................41
Regulators................................................................................................................ 41Typical current consumption................................................................................... 42Power Distribution .................................................................................................. 43
RF characteristics......................................................................................................... 44
Channel Numbers and Frequencies......................................................................... 44Main RF characteristics........................................................................................... 44Transmitter characteristics ...................................................................................... 44Receiver characteristics........................................................................................... 45RF Block Diagram .................................................................................................. 45RF Block Diagram NHL-4J/NHL-4JX ................................................................... 46
Frequency Synthesizers .............................................................................................47Receiver .....................................................................................................................47Transmitter .................................................................................................................47
Front End................................................................................................................. 47Power Amplifier...................................................................................................... 48RF ASIC Helga ....................................................................................................... 49AFC function........................................................................................................... 49 Antenna .................................................................................................................. 49
User Interface Modules................................................................................................ 50
UI Board TK8 ............................................................................................................50
Keyboard ................................................................................................................. 50Display .................................................................................................................... 51LCD & Keypad Illumination................................................................................... 52Internal Speaker....................................................................................................... 52Buzzer...................................................................................................................... 52Internal Microphone................................................................................................ 52
IR Module ..................................................................................................................53Vibra ..........................................................................................................................53