Telit Wireless Solutions GE863-QUAD Manual Do Utilizador

 
 
 
 

 

 

 1vv0300715 Rev. 1 - 19/09/06  

  

Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved 

 

page 15 of 79 

 

4 Power Supply 

The power supply circuitry and board layout are a very important part in the full product design and 
they strongly reflect on the product overall performances, hence read carefully the requirements and 
the guidelines that will follow for a proper design. 

4.1 Power Supply Requirements 

The GE863-QUAD/PY power requirements are: 
•  Nominal 

V 

•  Max 

V 

•  Supply voltage range:  

3.4 V - 4.2 V 

•  Max Peak current consumption (impulsive):  

1.9 A 

•  Max Average current consumption during GPRS transmission (rms): 

500 mA 

•  Max Average current consumption during VOICE/CSD transmission (rms):  

270 mA 

•  Average current during Power Saving:   

≈ 4 mA 

•  Average current during idle (Power Saving disabled) 

≈ 19 mA 

 
The GSM system is made in a way that the RF transmission is not continuous, else it is packed into 
bursts at a base frequency of about 216 Hz, the relative current peaks can be as high as about 2A. 
Therefore the power supply has to be designed in order to withstand with these current peaks without 
big voltage drops; this means that both the electrical design and the board layout must be designed for 
this current flow. 
If the layout of the PCB is not well designed a strong noise floor is generated on the ground and the 
supply; this will reflect on all the audio paths producing an audible annoying noise at 216 Hz; if the 
voltage drop during the peak current absorption is too much, then the device may even shutdown as a 
consequence of the supply voltage drop.