SPRS975H August 2016 – February 2020 DRA780 , DRA781 , DRA782 , DRA783 , DRA785 , DRA786 , DRA787 , DRA788
Refer to the PDF data sheet for device specific package drawings
Lumped methodology consists of grouping all of the power pins on both the PMIC (voltage source) and processor (current sink) devices. Then the PMIC source is set to an expected Use Case voltage level and the processor load has its Use Case current sink value set as well. Now the lumped/effective resistance for the power rail trace/plane routes can be determine based upon the actual layout’s power rail etch wide, shape, length, via count and placement Figure 7-5 illustrates the pin-grouping/lumped concept.
The lumped methodology consists of importing the PCB layout database (from Cadence Allegro tool or any other layout design tool) into the static IR drop modeling and simulation tool of preference for the PCB designer. This is followed by applying the correct PCB stack-up information (thickness, material properties) of the PCB dielectric and metallization layers. The material properties of dielectric consist of permittivity (Dk) and loss tangent (Df).
For the conductor layers, the correct conductivity needs to be programmed into the simulation tool. This is followed by pin-grouping of the power and ground nets, and applying appropriate voltage/current sources. The current and voltage information can be obtained from the power and voltage specifications of the device under different operating conditions / Use Cases.