ISO5451-Q1: VCC1 maximum consumption current

Hi Jie,

The maximum power dissipation of our gate drivers is limited by the junction temperature.

• The application must ensure that the power dissipation will keep the junction temperature under the recommended operating temperature which for ISO5451-Q1 is 125C
• The maximum operating junction will depend on the VCC power dissipation from the primary(low voltage side), but is much lower when compared to the power dissipation on the secondary
• The secondary power dissipation depends on many factors including VDD-VEE voltage, operating switching frequency, external gate resistors used, and the switch being used. Power dissipation calculations are explained in page 28, section 10.2.2.9 Determining the Maximum Available, Dynamic Output Power, POD-max of the ISO5451 datasheet (link here).
• Once the power dissipation is calculated you must use one of the equations one of the thermal resistance values found in the thermal information table in section 7.4 (link here) and one of the equations in the Semiconductor and IC Package Thermal Metrics app note (link here).
  • For initial calculations you use RthethaJA, but PSIJT and PSIJB are more accurate for calculating final system values.

Let me know if there's any additional questions.

Best regards,

Andy Robles