TPS61096EVM-787: Quiescent current

Julien Campos

Part Number: TPS61096EVM-787

Dear Madam, Dear Sir,

We are doing tests to measure the quiescent current of the TPS61096EVM-787.

We use an input voltage supply of 3.3V and without load at the output of the boost, the current of the supply is 6.4 μA.

See the set-up below:

Thus, we have: Iq=6.4 μA (input current) (ILIM = HIGH and without boot-up)
But in the datasheet, we can read that Iq=1.2μA (and 2.5μA maximum)

Even taking into account the Iq from Vout (200 nA at 20V, so roughly 1.2 uA to add on the input), We still dont reach that value of 6.4 uA.

Why is that so?

Also, a question regarding Vosns pin, apparently it does sampling on the output voltage to feed the FB pin, hence to reduce the quiescent current compared to a DC/DC architecture where the resistor divided is always connected to the output. My question is: what is the frequency of that sampling?

Thank you per advance.

Julien

over 6 years ago

0 Minqiu Xie over 6 years ago

TI__Mastermind 21565 points

Hi Julien:

Sorry, I'm out of office today. Please forgive me that I may reply later tomorrow. Thank you!

0 Minqiu Xie over 6 years ago in reply to Minqiu Xie

TI__Mastermind 21565 points

Hi Julien:

Thanks for your kind patience.

The Iq may not the same with what you think before. It should be tested without switch. We have an application note, you could check it for the details: http://www.ti.com/lit/an/slyt412/slyt412.pdf If you have further question after read the note, please let me know.

The converter detect the output voltage, in analogy way. May I know what the sample frequency you mentioned. Thank you!

0 Julien Campos over 6 years ago in reply to Minqiu Xie

Prodigy 50 points

Thank you Minqiu for the precision, this AN is very helpful.

Should I understand that we have no possibility to really measure this Iq for this specific evaluation board? Because looking at the datasheet of the evaluation board, there is no possibility of deactivating the switching operation while maintaining the device enabled, cause there are no pins having such functions.

Regards,

Julien

0 Minqiu Xie over 6 years ago in reply to Julien Campos

TI__Mastermind 21565 points

Hi Julien:

You could use another power supply to make the Vout little higher than your target. The converter will enter into PFM mode. And if the Vout keep higher than the trigger value, it won't switch.

And there is another application introduce how to measure the efficiency more precise with light load: http://www.ti.com/lit/an/slva236a/slva236a.pdf

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TPS61096EVM-787: Quiescent current