Use Equation 4 to calculate TXH0137D-Q1 on-chip power dissipation P_D:

where

• N is the number of channels active together
• V_OLi is the OUT_i pin voltage for the load current I_Li.

For reliability of TXH0137D-Q1 and the system, the on-chip power dissipation must be lower than or equal to the maximum allowable power dissipation (P_D(MAX)). Equation 5 shows how P_D(MAX) is calculated.

where

• T_J(MAX) is the target maximum junction temperature
• T_A is the operating ambient temperature
• θ_JA is the package junction to ambient thermal resistance

It is recommended to limit the TXH0137D-Q1 IC’s die junction temperature to less than 125°C. The IC junction temperature is directly proportional to the on-chip power dissipation.