User Guide

PAMS

System Module DB6

NHB–3

Technical Documentation

Original 26/97

Page 4–15

– PSL+ will switch power on when the battery is connected. After

that the MCU will detect if power key is pressed or charger con-

nected. If not the power will be switched off.

All devices are powered up at the same time by the PSL+. It supplies the reset

to the ASIC at power up. The ASIC starts the clocks to the DSP and the MCU.

After about 20us the ASIC releases the resets to MCU, RFI and DSP. MCU

and RFI reset is released after 256 13 MHz clock cycles. DSP reset release

time from DSP clock activation can be selected from 0 to 255 13MHz clock

cycles. In our case it is 255. UIM reset release time is according to DSC1900

UIM specifications.

To turn off power for the phone, the user presses the PWR key. The MCU de-

tects this. The MCU cuts off any ongoing call, exits all tasks, acts inoperative to

the user and leaves the PSL+ watchdog without resets. After power–down

delay, the PSL+ cuts off the supply from all circuitry.

If charging is on the phone stays on but it looks to the user like it is powered off

(lights are off and the display is blank) except the charging indicator stays on.

Watchdog System Diagram

ASIC

DSP

MCU

PSL

XPWROFF

reset

POWER

reset