Panasonic EB-X70 Service Manual

Also see for EBX70 - CELL PHONE: Operating instructions Operating instructions Technical information Service manual

TECHNICAL DESCRIPTIONIssue 1 Section 4 PMCD030901C8Revision 0 – 18 – Service Manual4.6. SYREN4.6.1 IntroductionSYREN U120 contains the interace circuits to the audio, RF and auxiliary analogue functions. It is configured using the TSPon CALYPSO+ and interfaces with the DSP in CALYPSO+ via the voice and I & Q interfaces.Figure 4.9: SYREN Device U1204.6.2 Power Amplifier Ramp (APC)The purpose of the Automatic Power Control is to generate an envelope signal to control the power ramping up, rampingdown and power level of the radio burst.It includes a DAC and RAM in which the shape of the envelope (ramp-up and ramp-down) are stored digitally. The envelopesignal is converted to analogue by a 10-bit DAC. RF requirements determine the co-efficient of the ramp shape.Timing of the APC is generated internally and is dependent on real time signals from TSP and the content of two registerswhich control the relative position of the envelope signal versus the modulated I & Q.4.6.3 AudioSYREN provides the analogue interface for the digital audio samples processed by the DSP in CALYPSO+. A 16mm 8 Ωspeaker mounted on the back of the handset is used both for playing ring tones and for desktop handsfree (DTHF) functions.The personal handsfree (PHF) headset connects directly to the HSO (earpiece) and HSMIC (microphone) pins of the SYRENdevice. Bias for the microphone is provided by HSMICBIAS from SYREN. Detection of PHF connection is made by aninterrupt on IO(2) of CALYPSO+. A small delay is applied before HSOVMID bias voltage is activated to minimise noise heardin the headset when HSO is enabled. This voltage controls transistor TR402 which delays the bias at the headset connector.Melodies and simple ring tones are produced by Melody Generator U301 which outputs these to both the DTHF speaker andto AUX1 of SYREN. The audio feed to SYREN allows ring tones and melodies to be played at a lower level through the PHFheadset. U301 is controlled via the CALYPSO+ microwire interface with an interrupt signal to indicate when its FIFO buffersare empty.4.6.4 LED DriverSYREN contains an open collector type output for the Charge LED control. The default state is ON to enable indication ofcharging in the case of a deeply discharged battery.10694-1U100CALYPSOU120SYRENDSPAPCVOICEBAND I/FU301MELODYGENERATORSIDETONEMICROPHONERECEIVERDTHF SPEAKERPERSONALHANDSFREE(PHF)PARAMP APC (U605)MICBIASHSMICBIASHSVMIDHSOTR402nPHF±DETnPHF±DET