SLVSEC9C September 2019 – February 2020 DRV8904-Q1 , DRV8906-Q1 , DRV8908-Q1 , DRV8910-Q1 , DRV8912-Q1
PRODUCTION DATA.
The variation of thermal parameters such as the RθJA (Junction-to-Ambient Thermal Resistance) and ΨJB (Junction-to-Board Characterization Parameter) is highly dependent on the PCB type, copper thickness and the copper pad area.
Figure 152 and Figure 153 shows the variation of the RθJA (Junction-to-Ambient Thermal Resistance) and ΨJB (Junction-to-Board Characterization Parameter) with copper-pad area for 2-layer PCB. As shown in these curves, the thermal resistance is lower for the higher copper thickness PCB and the higher copper pad-area.
Similarly, Figure 154 and Figure 153 shows the variation of the RθJA and ΨJB with copper-pad area for 4-layer PCB respectively.
NOTE
The thermal parameters (RθJA (Junction-to-Ambient Thermal Resistance) and ΨJB (Junction-to-Board Characterization Parameter)) are calculated considering the ambient temperature of 25°C and with 1.5-W power evenly dissipated between high-side and low-side FET's. The thermal parameters calculated considering the power dissipation at the actual location of the power-FETs rather than an averaged estimation.
The thermal parameters are highly dependent on the external conditions such as altitude, package geometry etc. Refer to Application Report for more details.
Figure 152. 2-Layer PCB Junction-to-Ambient Thermal Resistance (RθJA) vs Copper Area
Figure 154. 4-Layer PCB Junction-to-Ambient Thermal Resistance (RθJA) vs Copper Area
Figure 153. 2-Layer PCB Junction-to-Board Characterization Parameter (ΨJB) vs Copper Area
Figure 155. 4-Layer PCB Junction-to-Board Characterization (ΨJB) Parameter vs Copper Area