Tool/software:
Hi team,
My customer wants to check the worst case of power consumption. Could you check the below caluculation?
1.Key Specifications:
Maximum Output Current (IMAX):
35mA per channel when VCC ≥ 3.3V
Number of channels: 36
Output Voltage Drop:Fixed at 0.6V per channel (typical for LED driver)
VCC = 5V
2.Operating Conditions:
Maximum ambient temperature: 85°C
All channels operating simultaneously
3.Maximum Power Consumption Calculation:
Power Dissipation in LED Outputs
Per channel: Voltage drop × Maximum current
0.6V × 35mA = 21mW/channel
All 36 channels: 21mW × 36 = 756mW
Device Core Power Consumption
Supply current in normal operation: Maximum 10mA
Power at VCC = 5V: 5V × 10mA = 50mW
Total Maximum Power Dissipation
LED outputs + Device core
756mW + 50mW = 806mW (0.806W)
4.Thermal Design Considerations:
Thermal Resistance:
Junction-to-ambient (RθJA): 35.7°C/W
Maximum Temperature Rise:
806mW × 35.7°C/W = 28.8°C
5.Maximum Temperature Check:
Maximum ambient temperature: 85°C
Temperature rise: 28.8°C
Junction temperature: 85°C + 28.8°C = 113.8°C
Thermal shutdown temperature (TSD): 160°C
6.Thermal margins:
Margin to thermal shutdown: 160°C - 113.8°C = 46.2°C
Regards,
Shoo
