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LM25143-Q1: Standby mode : dual phase single out

Shinji Tsuji
Genius 14269 points
Part Number: LM25143-Q1


Hi team,

Could you please advise how to configure LM25143-Q1 in standby mode?

I configure dual phase single 3.3V output in regular operating mode and plan to switch to standby mode

when my system need to save power. 

I understand dual phase mode doesn't support standby mode, so I think I need to switch to single phase mode and disable channel 2. 

Please see below 2 settings I plan to switch on the fly during operation. 

When I configure Standby mode as below, the device doesn't start up. Then I disconnect COMP2 pin from COMP1 pin,

then the device start up and operate as standby mode. 

Question1 : Is it necessary to disconnect COMP2 pin from COMP1 pin to enable standby mode?

Question 2: Is there any issue if I switch Regular mode and Standby mode on the fly? 

Regular mode(Dual phase single out) configuration 

MODE : connect to VDDA

DEMB : VDDA

FB1 : VDDA (3.3V)

FB2 : AGND

EN1/EN2 : Enabled

COMP1/2 : connected each other

Standby mode (single phase single out) configuration

MODE : AGND direct or through 10kohm

DEMB : GND

FB1 : VDDA(3.3V)

FB2 : AGND

EN2 : AGND (disabled)

COMP1 : AGND through comp components

COMP2 : connect to COMP1 ( or OPEN) 

regards,

  • 0
    TI__Guru* 75882 points

    Hi Shinji-san,

    MODE is only checked at startup, not changeable on the fly.

    See below as an alternative with MODE tied low. This schematic actually shows the EVM changes to make a 2-phase design (in this case Vout is 13.8V).

    Regards,

    Tim

  • 0 in reply to Timothy Hegarty
    TI__Genius 14269 points

    Hi Tim-san,

    If you connect MODE to AGND, then the device will act as single phase dual out correct?

    Does this schematic mean, disconnecting FB2 loop and insert Channel 1 FB loop to COMP2 through buffer amp, correct?

    Does internal error amp channel2 affect the operation? 

    Could you advise how to enter standby mode? 

    regards,

  • 0 in reply to Shinji Tsuji
    TI__Guru* 75882 points

    MODE to GND configures the IC as a dual-output, where the controller can enter ultra-low quiescent current mode for optimized light-load efficiency. Then we "force" it to operate in 2-phase single-ouotput mode by allowing COMP1 to drive COMP2.