ZHCSJB5B September 2019 – December 2019 DRV8904-Q1 , DRV8906-Q1 , DRV8908-Q1 , DRV8910-Q1 , DRV8912-Q1
UNLESS OTHERWISE NOTED, this document contains 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 144 and Figure 145 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 146 and Figure 145 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.