Nokia 7088 Troubleshooting Manual page 7

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regulator is enabled. Then, VERG_MSMP, VERG_MSMA & VERG_TCXO regulators
are enabled in sequence after MSMC. There is a 120us (4 Sleep Clocks) delays
between each regulator's turning-on. The RESET_N signal (from PM6610 pin
"PON_RESET_N" to MSM6025 pin "RESIN_N" in schematic) holds low for another
20ms and is sent to MSM. Resets are generated for the MSM's internal MCU and its
internal DSP, and MSM sends TCXO_ON signal to PM ("TCXO_EN" pin) to enable
TCXO. After RESET_N goes high, MSM holds PS_HOLD at low state for 200ms and
then drives PS_HOLD to high state. This will keep all regulators at on state in order
to complete this power on sequence. PHONE_ON key can be released after
PS_HOLD goes high.
The RESOUT_N from MSM is used to reset flash memory during power up and to
put the flash memory in power down during sleep mode. All base band regulators are
switched on when the PM is powered on. The MSM's internal watchdog runs and
resets during normal operation. If the watchdog expires, it will generate a reset signal
to reset to MSM status. Then, MSM drives RESOUT_N low to reset flash memory.
MSM can generate (software control MSM GPIO8) BACKEND_RST_N signal to
reset backend IC.
Backend IC can generate LCD_RST_N to reset LCD. Backend IC can generate
CAM_RST signal to reset camera module.
Figure 3 represents the PM start-up sequence from reset to power-on.
(PHONE_N)
(RESET_N)
Issue 1 12/2006 © 2006 Nokia Corporation
Figure 3: Power-on & off sequence and timing
Baseband Description and Troubleshooting
Company Confidential
7088 (Flower)
Page 7