TPS7A8001: Output voltage is oscillated when the input voltage is slowly dropped

Ryuji

Guru 20090 points

Part Number: TPS7A8001

Hello,

In the customer, the output voltage is oscillated at the middle voltage when the input voltage is slowly dropped.(3.3V to 1.0V/10ms)

Vin =3.3V, Vout =1.5V, Iout=95mA
The oscillation is occured when Vin is 1.9V and Vout is 1.2V
EN pin is connected to Vin

The phenomenon does not occur if the load is increased or the input voltage falls fast.

Could you please let me know this operation reason?
Is there a possibility that this behavior will damage the device?

I can send the waveform and schematics if you contacted to the following e-mail address.

asaka-r@clv.macnica.co.jp

Best Regards,
Ryuji

over 6 years ago

0 JCHK over 6 years ago

TI__Mastermind 43610 points

HI Ryuji-san,

I think you are approaching the UVLO:

The minimum recommended operating VIN range is as follows:

I think you are slowly approaching the UVLO which may be causing the oscillation. This mode of operation should not be damaging the device.

Regards,

0 Ryuji over 6 years ago in reply to JCHK

Guru 20090 points

Hello John san,

Thank you for the reply.
Yes, the input voltage is under the UVLO.
However, there is no noise that will exceed hysteresis.

I think that the UVLO is not operated correctly.

Best Regards,
Ryuji

0 JCHK over 6 years ago in reply to Ryuji

TI__Mastermind 43610 points

HI Ryuji-san,

Can you send labeled oscilloscope plots as to what you are seeing? When VIn is below the recommended operating range, we can not guarantee behavior.

Regards,

0 Ryuji over 6 years ago in reply to JCHK

Guru 20090 points

Hi John san,

Thank you. I sent the waveform and schematics to you.

Best Regards,
Ryuji

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TPS7A8001: Output voltage is oscillated when the input voltage is slowly dropped