Mobile Phones Download

In Nokia phones repairing we know " PUSL ", each of active components like IC ( Integrated Circuit ) and ASIC always have the PUSL circuit.
So..., what is PUSL..?? and how it works..??
Ok.., let's me to explain it.., ( simple explanation )

What is PUSL..?? and function for..??
PUSL ( Power Up System Logic ), this system is located at Energy Management ( EM ) and has function as Power Up.

How does it Work..???
When the battery inserted to phone, PUSL is ready or Standby but have not given any commands to the circuit, at this condition Pwronx circuit is high which has a voltage value of 1.8 - 3.7Volt. When pwronx circuit connected to ground ( switch on/off pressed ) at least 200mS, this can be called as Power Up.
In this case PUSL will provide voltage command as follows :

• PURX (Power Up Reset X) 1.8V. This voltage is given to RAP IC ( Processor ) and has function to RESET or voltage command to RAP became active.

• RSTX ( Resetx ) 3.7V. In Nokia BB5 phones, RSTX will be given to Energy Management 2 ( Tahvo / Betty IC ) and has function to enable / activate Energy Management 2.

• SleepX 1.8V. This voltage comes from RAP ( Procesor IC ) to Retu ( EM 1 ) and has function to Set phone mode status. Phone have 2 mode status, when power up / booting we called " Active Mode ", and we called " Sleep Mode " when Sleepx voltage below 1.8V.

When phone powered up / booting, PURX must have accurate voltage 1.8V. We often found PURX voltage below 1.8V..,like 1.1 V, this is not caused by RETU ( EM 1 ) problem, but caused by Sleepx voltage from RAP is not accurate 1.8V. So we can assume that Sleepx may affet PURX.
So If you faces problem that PURX voltage is below 1.8V you need to check RAP IC so Sleepx have accurated voltage `1.8V.

Ok maybe enough for this time.., simple explanation about PUSL.

hopefully can help you for repairing mobilr phones analysis.