User Guide

RH-30/RH-31 Company Confidential

System Module Nokia Customer Care

Power up with PWR key

When the Power on key is pressed the UEM enters the power up sequence as described in

the previous paragraph. Pressing the power key causes the PWRONX pin on the UEM to

be grounded. The UEM PWRONX signal is not part of the keypad matrix. The power key is

only connected to the UEM. This means that when pressing the power key an interrupt is

generated to the UPP that starts the MCU.

The MCU then reads the UEM interrupt register and notice that it is a PWRONX interrupt.

The MCU now reads the status of the PWRONX signal using the UEM control bus, CBUS.

If the PWRONX signal stays low for a certain time the MCU accepts this as a valid power

on state and continues with the SW initialization of the baseband. If the power on key

does not indicate a valid power on situation, the MCU powers off the baseband.

Power up when charger is connected

In order to be able to detect and start charging in a case where the main battery is fully

discharged (empty) and hence UEM has no supply (NO_SUPPLY or BACKUP mode of

UEM) charging is controlled by START-UP CHARGING circuitry.

Whenever VBAT level is detected to be below master reset threshold (VMSTR-) charging

is controlled by START_UP charge circuitry. Connecting a charger forces VCHAR input to

rise above charger detection threshold, VCHDET+.

By detection start-up charging is started. UEM generates 100mA constant output cur-

rent from the connected charger’s output voltage. As battery charges its voltage rises,

and when VBAT voltage level higher than master reset threshold limit (VMSTR+) is

detected START_UP charge is terminated.

Monitoring the VBAT voltage level is done by charge control block (CHACON). MSTRX=‘1’

output reset signal (internal to UEM) is given to UEM’s RESET block when VBAT>VMSTR+

and UEM enters into reset sequence described in section Power Up and Reset.

If VBAT is detected to fall below VMSTR- during start-up charging, charging is cancelled.

It will restart if new rising edge on VCHAR input is detected (VCHAR rising above VCH-

DET+).

Power up when battery is connected

Baseband can be powered up by connecting battery with sufficient voltage. Battery volt-

age has to be over UEM internal comparator threshold level, Vcoff+. Battery low limit is

specified in Table 2. Battery Voltage Range. When battery voltage is detected, UEM

enters to reset sequence as described in section Power Up and Reset

Phone can be powered up to LOCAL mode by setting BSI resistor 560Ω. This causes MCU

to wake up directly when battery voltage is supplied.