LMZ14201: how to drive EN pin with LM3880

Vincent David

Intellectual 340 points

Part Number: LMZ14201
Other Parts Discussed in Thread: LMZ14202, , LM3880, LMZ14203

Hello

I have a concern I try to command a LMZ14201 and LMZ14202 , following the proposed schematic with the resistor divider

( LM3880 is set with 100 K resistor ballast and works fine without LMZ connection )

LMZ14201 Vin is 12V

test result

1) straight drive EN with a 5 V DC source that work

2) straight drive EN by using the LM3880 I destroy the LM3880 after several ON/OFF Cycles

3) resistor divider ( 9.1K / 20K ) EN by using LM3880 = I do not succeed to drive the LMZ14201 I measure 1.2 V out of the LM3880 after the ballast

Does someone can explain where is the problem ?

Does someone now what is the current level at the EN PIN LMZ14201 / 202 ?

Thanks

David

over 5 years ago

0 Denislav Petkov over 5 years ago

TI__Mastermind 18940 points

Hi Vincent,

Could you please provide a schematic/diagram for the configuration for case 2 and case 3 above?
I just want to make sure I understand your setup before we give you some suggestions.

Cheers,
Denislav

0 Vincent David over 5 years ago in reply to Denislav Petkov

Intellectual 340 points

Hello Denislav

thanks for your answer

I want to connect following blue trace

Can I do that or shall I use another set up to connect the LM3880 flag

Regards

David

0 Denislav Petkov over 5 years ago in reply to Vincent David

TI__Mastermind 18940 points

Hello David,

I have not worked with the LM3880 but it seems like you should be able to use this configuration to enable the module. Was this the setup which caused damage to the LM3880 after several power cycles?

I checked the internal pull-up details on the LMZ device. There is a 6uA pull up current source to VIN along with a 5V clamp on the EN pin. The max operating voltage on the EN is 6.5V.

Cheers,
Denislav

0 Vincent David over 5 years ago in reply to Denislav Petkov

Intellectual 340 points

Hello Denislav

Thanks

I am in process to test this circuit , that a circuit provided in the LMZ14203 TI doc but EN pin looks to be the same as LMZ14201 and 202

I will post the results beginning of next week

Regards

David

0 Denislav Petkov over 5 years ago in reply to Vincent David

TI__Mastermind 18940 points

Sounds good David. Let us know if you need additional help.

I will close this thread for now. If you need additional support, just reply back we will continue from there.

Cheers,
Denislav

0 Vincent David over 5 years ago in reply to Denislav Petkov

Intellectual 340 points

Hello

up to know I have not make the tests as components will be delivered tomorrow

I agree you close the thread I will re open one in two day stop provide results report I think that an important concern due a real problem in TI documentation regarding EN management as the a crucial point

that the same concern with LM3880 , documentation is quite light regarding the subject , schematic are far not enough detailed as there is no application note available

thanks again for your help

Regards

David

Power management

Power management forum

LMZ14201: how to drive EN pin with LM3880