MOBILE COMMUNICATIONS DIVISION
CUSTOMER SERVICES
Version 1.0 22/11/2006
Created by Konrad Szombara
Page 74 of 103
6.5.1 POWER ON SEQUENCE
When the user presses the power key, KEYON pin of AD6537B is pulled low; all
the LDOs required for system boot will be turned on at the same time. Then
AD6537B pull low the KEYROW4 pin of AD6527B by KEYOUT pin, and system
monitors this pin for 2 seconds to make sure the key event is not a key mis-
pressing. After 2 seconds, PWRON pin of AD6527B will trigger DBBON pin of
AD6537B and system is booted up successfully, AD6527B also turns RF block /
key LEDs / LCD backlight on at the same time, then boot procedure is completed.
User Press Power Key
KEYON
KEYOUT
KEYROW4
PWRON
DBBON
CLKON
RF Block ON / Key LED ON / LCD Backlight ON / System ON
LDOs
AD6527B
AD6537B
VCORE / VMEM /
VEXT / VTCXO
ON
> 2 seconds
