Vctcxo

Vctcxo From Pwm
Power distribution diagram

Pressing power key

Pressing power key

t1 < 1 ms t2 1 - 6 ms, VCXO settled t3 62 ms, PURX delay generated by CCONT

After PWR-key has been pushed, CCONT gives PURX reset to MAD4 and turns on VR1, VBB and VR6 regulators (if battery voltage has exceeded 3.0 V). VR1 supplies VCTCXO, VBB supplies MAD, and VR6 supplies digital parts of CAFE. After the initial delay, t2, VCTCXO starts to give a proper 19.2MHz clock to CAFE, which further divides it to 9.83MHz for MAD4. CAFE will output the 9.83MHz clock only after the PURX reset has been removed. After delay, t3, CCONT releases PURX and MAD4 can take control of the operation of the phone.

After MAD4s reset is released MCU-SW detects that the PWR-key is still pushed and shows the user that the phone is powering up by turning on the LCD and the lights. MCU-SW then powers up the RF receiver part.

V5V-regulator (for RF) default value is off in power-up, and can be controlled on via serial bus when needed.

Power up when charger connected Normal battery voltage

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