LMR33620: LMR33620 External UVLO Control

Hello

Unfortunately, the EN hysteresis can not be changed on this device.

However, I have attached a schematic of a simple discrete circuit that may

be helpful.

TI also has several power-on-reset devices that may also be of 

interest to you.

Thanks

Hi Kumaran

another solution: LMR33620 has POWER GOOD output, you can use this signal to control a small MOSFET to change the bottom resistor of EN divider.

B R

Andy

Hi Andy,

If we set resistors for VSTART, and reduce the RENB with PG, will it not increase further the VON/VOFF? Pls correct if my understanding is wrong.

-Selva

Hi Andy,

I found another simpler solution with VOUT. Will this work for LMR33620 where we have additional 100mV hysteresis. Pls check and let me know. Thanks.

How to add hysteresis to a DC/DC converter

Other Parts Discussed in Post: TINA-TI , LM73605 A version of this post was also published on Electronic Design . Is enable hysteresis not included in the DC/DC converter you are designing with? Or is…

By ReedKacz over 6 years ago in Technical articles > Power management

-Selva

Hi Selva,

EN hysteresis also can be adjusted by bias EN pin with Vout.  the drawback is output maybe be biased close to EN pin voltage if input stay below V-start for long time, there should be dead load on output to sink the bias current, 

LMR33620 has VCC pin,  you may use VCC instead of Vout to change the hysteresis.

B R

Andy 

HI Andy,

Thanks for your reply. Will I need to consider somewhere the internal device hysteresis of 100mV in the equations. PSPICE sim results are not matching with calculations.

-Selva

Hello

Yes, you will have to include the built-in 100mV when using the Vout or PGOOD method.

Thanks