The baseband module includesfourASICs: CHAPS, CCONT, COBBA-GJP and MAD2WD1, which take care ofthe baseband functions of the engine. The baseband is designed to work with the DCT-4 type direct conversion RF.
The baseband is running from a 2.8V power rail (VBB), which is supplied by a power controlling ASIC CCONT. In the CCONT there are 6 individually controlled regulator outputs for RF-section and two outputs for the baseband. In addition, there is one +5V power supply output (V5V). The CCONT contains also a SIM interface, which supports both 3V and 5VSIM-cards. A real time clock function is integrated into the CCONT, which utilizes the same 32kHz clock supply as the sleep clock. The battery charging is controlled by a PWM-signal from the CCONT. The PWM duty cycle is determined by charging software and is fed to the CHAPS charging switch.
The baseband architecture supports a power saving function called "Sleep-mode". In Sleep-mode, the VCTCXO is shut off, which is used as system clock source for both RF and baseband. During the Sleep-mode, the system runs from a 32 kHz crystal. The phone is waken up by a timer running from this 32 kHz clock supply. The sleeping time is determined by some network parameters. The sleep mode is entered when both the MCU and the DSP are in standby mode and the normal VCTCXO clock has been switched off.
The MAD2WD1 is a dual voltage circuit using VBB (2.8V Baseband supply) and VCORE (1. 750V. Core Voltage supply for MAD2WD1 ver. C05).
The interface between the baseband and the RF section is mainly handled by a COBBA ASIC. COBBA provides A/D and D/A conversion ofthe in-phase and quadrature receive and transmit signal paths and also A/D and D/A conversions of received and transmitted audio signals to and from the user interface. The COBBA supplies the analog TXC and AFC signals to RF section according to the MAD2WD1 DSP digital control. Data transmission between the COBBA and the MAD2WD1 is implemented using serial bus for high speed signaling and for PCM coded audio signals. Digital speech processing is handled by the MAD2WD1 ASIC. COBBA is a dual voltage circuit, the digital parts are running from the baseband supply VBB (2.8V) and the analog parts are running from the analog supply VCOBBA (2.8V).
The baseband supports both internal and external microphone inputs and speaker outputs. Source selection and gain control ofthe Input and output signals is done by the COBBA according to control messages from the MAD. Keypad tones, DTMF, and other audio tones are generated and encoded by the MAD and transmitted to the COBBA for decoding.
An UI-Switch N400 is used as HW-driver for: LEDs, Buzzer and Vibra. Buzzer and Vibra (internal) alert control signals are generated by the MAD2WD1 with separate PWM outputs.
IrDa is not supported by the HDa12.
Flashing of the phone is done in either of two ways:
• By Aftersales using the 4-poled 'Test Flash Connection' pos.: X201 and a 'HDa12 Service battery'.
• In Production using the 8-poled 'Production Flash Connection' pos.: X202. (PADs located on the Keyboard side of the PCB).
EMC shielding is implemented using three metal cans: two for the RF and one for the Baseband. Heat generated by the circuitry will be conducted out via the PCB ground planes.
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