TLV703: TLV70318 startup waveform

Frank Xiao

Genius 12055 points

Part Number: TLV703

Hi team,

My customer is using the TLV70318 now. Input 3v3, output 1v8. As you can see, the Output startup waveform slew rate has two period has two slew rate. It seems the device trigger OCP or OTP during the startup period. Or OCP threshold is different during different startup period. i have let them share the details to see the current. Do you have some experience about the phenomenon? Thanks.

yellow is the input voltage, purple is output voltage, blue is EN.

stage 1: 0v->1.2v, 8ms, stage 2 1.2v->1.8v 40us

i have used the ic=cdu/at to get the 3mA during stage1, 300mA during stage 2.

Thanks.

over 3 years ago

0 JCHK over 3 years ago

TI__Mastermind 43610 points

Hi Frank,

Do you see the same thing if you reduce the amount of capacitance at the output?

Thanks,

0 Frank Xiao over 3 years ago in reply to JCHK

TI__Genius 12055 points

HI Cumming,

i have calculated the current to the Cout. ic=cdu/at to get the 3mA during stage1, 300mA during stage 2. So the Cout may not be the root cause. Thanks.

0 JCHK over 3 years ago in reply to Frank Xiao

TI__Mastermind 43610 points

Hi Frank,

I just noticed you were slewing the enable pin very slowly. Between 0.4 and 0.9V the operation of the LDO is undefined.

I think this is causing the strange startup you are seeing.

Power management

Power management forum

TLV703: TLV70318 startup waveform