Siemens SXG 75 Service Repair Documentation page 22

6.2.4 MSM6250 bootup and mode control
The MSM6250 supports booting from the NAND FLASH memory. The high pull-up (R1700) on the
bootmode input pin is used to indicate to the MSM hardware that FLASH boot-up is required. After
power-on reset, the MSM hardware automatically loads the boot code from NAND flash to an on-
chip boot SRAM, and then releases the ARM to execute from this boot SRAM. By executing the
boot code, the ARM processor transfers the entire phone software to the SDRAM, and then
branches to the SDRAM to execute the phone software and completes the boot-up process.
The MSM6250 runs in "Native" mode. This mode is selected by the Mode 0, Mode 1 and Mode 2
pins (Schematic sheet 17). The pins are left floating (internal pulldown resistors) to select Native
mode. Note that the Mode pins are connected to additional MSM6250 pins. This is a requirement of
the device – the signals are not required for any external functions.
MSM6250 Function
TCXO
USB_XTAL48_IN
USB_XTAL48_OUT
SLEEP_XTAL_IN
SLEEP_XTAL_OUT
RESIN_N
RESOUT_N
RESOUT_N_EBI1
WDOG_EN
MODE[2]
MODE[1]
MODE[0]
BOOT_MODE
MSM6250 clocks and mode control
Technical Documentation
TD_Repair_L3_SXG75_R1.0.pdf
Signal Function
BUFF_TCXO TCXO clock input from PM6650
(48MHz crystal) 48 MHz crystal oscillator input
(48MHz crystal) 48 MHz crystal oscillator
SLEEP_CLK
Low-power sleep crystal oscillator from PM6650
(not used)
PON_RST_N Hardware reset input from PM6650
(not used)
Reset output generated by RESIN_N and by
RESOUT1_N
wdog_reset. Reset to LCD, NAND FLASH
(not used)
(not used)
(not used)
(not used)
pull-up to VREG_MSMP (boot from NAND)
Company Confidential
2006©BenQ
Release 1.0
01/2006
Page 22 of 73