Tuesday, 24 November 2009

Analysis of Short Flows in Nokia BB5

This analysis is applied to Nokia BB5 mobile phones that use RF (AHNE), using the processor RAPGSM v1.1, not RAP3G.
RAPGSM v1.1 is included in the CMOS processor (MOSFET) which is a series combination of Field Effect Transistor (FET), Vdd (drain) as a positive voltage, Vss (source) as a negative.
RAPGSM need two types of voltage, namely :
  1. Microprocessor Voltage, Vcore = 1,4 V
  2. Data Signal Processor Voltage, VIO = 1,8 V
In RAPGSM have a 19 foot VddCore obtain positive voltage 1,4 V (drain) of the TAHVO, and 19 feet VssCore negative voltage (source) to ground, and 11 feet that obtain VddIO voltage 1,8 V.
Approximately 50 feet from the input voltage (Vdd/Vss) for the RAP, the common short-circuit on its feet. Therefore, most likely caused by this RAPGSM. However, if we want to do a more precise measurement, it is very difficult if only done by injecting a voltage or a heat feeling.
Why? because in RAPGSM IC's module, on input Vdd/Vss, there is a protection diode works as switching when short. So, when RAP short, not hot. However, the heat occurs at a regulator, which is RETU or TAHVO.
Therefore, we could either make a conclusion. So, if RETU heat, it doesn't mean that experienced short RETU.
Therefore, the proper way to do an analysis is to perform elimination. Elimination is to decide the voltage on one of the suspected components, and then compare it back to the power supply.
To be continued ....