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TPS7B82-Q1: SSOP package dissipation

Part Number: TPS7B82-Q1

Hi, 

I would like to check with you if TPS7B8250-Q1 in SSOP package will be able to dissipate some pulses of load current. 

Load profile here is to supply an RF module which consume around 300mA during 100us every 1ms. 

The ambient temperature is Ta= 105°C

Vin = 16V

 Vout=5V

Iout = 300mA

Duration = 100us

Période = 1ms

 

Rest of the time, the module RF is turned off, where Iout of the LDO is below 10mA. 

Can you please confirm if this is ok for TPS7B8250-Q1?

Thanks!, 

Mohamed

 

 

  • Hi Mohamed,

    The power dissipation during the short pulse is (16-5)*0.3 or 3.3W of power. The TJA for the SSOP package is only 63.9C/W so the device will likely thermally shut down during the pulse.The junction temperature (TJ)  will rise to TJ=TA+(VIN-VOUT)*ILOAD*TJA. Where TA is the ambient PCB temperature. As shown in the following application note, the TJA is not an ideal layout so you can lower this number with a good layout. 

    If you can't change the package or lower VIN, one trick is to use a series resistor in line with VIN to help spread the heat. For example, a 20Ohm 2W resistor in series with VIN would dissipate about 1.8W during the pulse making the thermal situation for the LDO much more manageable. 

    Does this help to answer your question?