LMR36520: IBB UVLO

d_zero

Genius 4775 points

Part Number: LMR36520

Hi All,

is it possible to add UVLO on IBB only with two resistors ? ( we don't need to drive the EN pin form MCU)

Vin=24V

Vout=-9V

UVLO 11.25V (no hysteresis needed)

Br,

over 3 years ago

0 Gui He over 3 years ago

TI__Mastermind 27276 points

Hi D

You can refer to this.

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/981546/lm5145-uvlo-function-with-ibb-configuration?tisearch=e2e-sitesearch&keymatch=UVLO%2520IBB#

Best regards.

0 d_zero over 3 years ago in reply to Gui He

Genius 4775 points

Hi Gui,

yes i saw this post before, but we don't need to EN to be driven from eg. MCU, but only need the UVLO function , is it possible to avoid the level shifter?

Best Regards,

David.

+1 Gui He over 3 years ago in reply to d_zero

TI__Mastermind 27276 points

Hi D

For IBB work condition. the GND pin for chip is not at the same voltage level as power ground. Before start up, Vo=0V, GND=0V; after start up, Vo=-9V, GND=-9V.

For start up UVLO, you can configure R1 R2 so that when Vin_ ground=11.25V,EN_GND=1.231V;

But when shut down ,since GND=-9V, Vin need to be reach 1.24V for EN_GND to be lower than 1.212V. Not 11.25V that you expected.

Best regards.

Power management

Power management forum

LMR36520: IBB UVLO