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TPS61030: Backup Power Solution Using Supercap with TPS61030

Wendy Wang1
Genius 17100 points
Part Number: TPS61030
Other Parts Discussed in Thread: TPS61022

Hi,

I read a document named Backup Power Solution Using Supercap with TPS61030 for Data Concentrator Circuit

 http://www.ti.com/lit/ug/tidu594/tidu594.pdf

In the document, it says that:"As the real Vout =5V, Vout_re can be set to 4.5V, which is lower than real Vout even considering the voltage drop
caused by load transient. The Vout_re at this condition should be not too low; otherwise the high power dissipation
may occur at the feedback resistor. At the same time, the power save mode of TPS61030 must be enable (SYNC
PIN connect to GND) to stop the TPS61030 from switching. The boost converter only consumes quiescent
current, 20μA typically.
When the Vsys powers off, and becomes lower than 5V, the VLBI will be lower than 510mV. An internal MOSFET
shorts the LBO pin to GND."

My questions: 1. Does Vout_re really exist when it is 4.5V? Does it mean that when Vout_re is lower than the real Vout, TPS61030 will stop switching?

2.When the power save mode of TPS61030 is enable, if Vout_re is higher than real Vout, will TPS61030 starts switching?

  • 0
    TI__Mastermind 46905 points

    Hi Wenziu,

    your understanding is correct. if setting to power save mode, the TPS61030 stop switching if the real VOUT is a little higher than the its setting voltage and start switching again if the real VOUT is lower than setting voltage.

    if your application is for super capacitor application, the latest device TPS61022 is suggested.

  • 0 in reply to Jasper Li
    TI__Genius 17100 points

    Hi Jasper,

    Thank you for your prompt reply.

    Besides, in the document, it says "The Vout_re at this condition should be not too low; otherwise the high power dissipation may occur at the feedback resistor."

    I don't know which resistor does the power dissipation occur at? Does Vout_re always exist when it is lower than the real VOUT?

    I have attached the boost circuit below, so that you can explain it visually.

    Thanks&Best regards,

    Wenxiu

  • 0 in reply to Jasper Li
    TI__Genius 17100 points

    Hi Jasper,

    I have read the datasheet of TPS61022.  Since it does't have a SYNC pin, does the power-save mode of TPS61022 controlled by the FB voltage？When the FB voltage hits the PFM reference voltage, the TPS61022 goes into the power-save mode. When the FB voltage falls below the PFM reference voltage, the device starts switching again and goes out of the power-save mode?

    Thanks&Best regards,

    Wenxiu

  • 0 in reply to Wendy Wang1
    TI__Mastermind 46905 points

    Hi Wenxiu,

    your understanding about the PFM operation is correct.