TPS62002: Phantom power delivery

steven rose

Part Number: TPS62002
Other Parts Discussed in Thread: TPS61202, TPS61200

I have an application of this part we have been using as a modular piece for a couple years now. We moved this to a new product and after we turn on the device by applying voltage to the EN pin and then turn it back off by switching EN to GND Vout maintains .475 V. Applying VIN to EN after this does not resume normal operation. VIN, PS, UVLO, maintain at battery level of 3.45V. Vaux goes from 5V when on the first time to 2.85V and maintains that. The FB pin maintains VOUT since they are tied directly together.
Any thoughts on what is going on would be fantastic

over 4 years ago

0 Varun John over 4 years ago

TI__Mastermind 21580 points

Hi Steven,

Thanks for reaching out to us. I would need a bit more information from you.

Can you share your schematic for TPS62002?

Does the VOUT reach the target of 1V on the initial turn on?

How much load current does your application have? Do you happen to have any scope shots of the 1^st turn on & off plus the 2^nd turn on?

Best regards,

Varun

0 steven rose over 4 years ago in reply to Varun John

Prodigy 10 points

so I just now realize i put in the wrong part number... it is TPS61202 Im not sure if that can be changed.

I attached a picture of the regulator part of the schematic. We have it setup for a tps61200 but R6 and R7 are DNL and R1 is converted to a 0 ohm for tps61202/1. VOUT does reach 5V on the initial turn on. Our load is nominally ~60 mA with an additional ~250 mA transient load every second and lasts no more than 2ms. I will collect pictures from the scope.

0 steven rose over 4 years ago in reply to Varun John

Prodigy 10 points

https://imgur.com/a/Bcjejcw
Here is a link to the scope shots.

Yellow(1) is VOUT on C3
Dark Blue(4) is EN on R3
Light Blue(2) is VAUX on C4
Magenta(3) is VIN on C1

0 Jasper Li over 4 years ago in reply to steven rose

TI__Mastermind 46905 points

Hi Steven,

was the device damaged? or it can resume to operate after fully powering off the IC and enabling it again.

0 steven rose over 4 years ago in reply to Jasper Li

Prodigy 10 points

No if i remove VIN and allow it to dissipate charge it works perfectly fine again.

Side Note: I did try it with an older setup with the TPS61200 setup for 5V and it caused the feed back sense to malfunction which made the chip output to 6.34V. Once again removing VIN allowed for return of normal operation.

+1 Jasper Li over 4 years ago in reply to steven rose

TI__Mastermind 46905 points

Hi Steven,

I guess such strange behavior is caused by high frequency noise in the EN pin.

could you help to provide clean EN signal and check again?

0 steven rose over 4 years ago in reply to Jasper Li

Prodigy 10 points

This appears to solved the issue after adding a 10 uF and .01uF cap between EN and VIN it completely killed the noise. After a day of testing we have not seen the issue.

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TPS62002: Phantom power delivery