TPS7A7002: inputs and output within spec but not able to run in webench

John Chou62

Intellectual 2080 points

Part Number: TPS7A7002

customer with following requirement

LDO，Vin=6v;Vout=0.5v~2v;Iout=2A

we're looking at the part "TPS7A7002"

however, when i'm trying to run simulations on webench, it failed "says the junction temp too high"

but the input and output V/I are within the range.

please kindly comment if customer can use this part for the requirement

Thanks

over 7 years ago

0 kai klaas69 over 7 years ago

Guru 140200 points

Hi John,

2V input to output differential voltage multiplied by 2A load current gives 4W heat the package must dissipate. Junction to ambient thermal resistance is 46.4°C/W. So, the chip would heat up 186K over ambient temperature...

Kai

0 Jason Song over 7 years ago in reply to kai klaas69

TI__Mastermind 23361 points

Hi John,

Like Kai mentioned, the power dissipation of this device just cannot handle the power generated due to voltage drop (difference between Vin and Vout) multiplied by the load current.

For Vin = 6V, Vout = 2V, Iout =2A, the power is around 8W.
For Vin = 6V, Vout = 0.5V, Iout =2A, the power is around 11W.

Junction to ambient thermal resistance is 46.4°C/W. You need to advise the customer to consider lowering the Vin.

Regards,
Jason Song

0 John Chou62 over 7 years ago in reply to Jason Song

TI__Intellectual 2080 points

Thanks for the explanation

is there a recommended part?

with such Vin/Vout parameters?

Thanks

0 Jason Song over 7 years ago in reply to John Chou62

TI__Mastermind 23361 points

Hi John,

The lowest junction to ambient thermal resistance listed as LDO is around 23°C/W. Most LDO's operating junction temperature is lower than 150C. At this power range, you should probably consider using buck converters.

Here you can find more information on TI's buck converters.
www.ti.com/.../overview.html

Regards,
Jason Song

Power management

Power management forum

TPS7A7002: inputs and output within spec but not able to run in webench