LM3424-Q1: problem in using driver

nisha11 23

Part Number: LM3424-Q1

I AM USING DRIVER IN BUCK MODE WITH INPUT VOLTAGE 24V. IN OUTPUT I AM USING LED ARRAY (3 ROWS WITH EACH ROW HAVING 5 LEDS). AS SOON AS I SWITCHED ON POWER SUPPLY, LED ARRAY ALSO GET 6V WHICH CAUSES IT TO BE IN ON STATE (THOUGH VERY SMALL BRIGHTNESS). AND I HAVE NOT GIVEN ANY SIGNAL TO ENABLE PIN OF THE DRIVER. I AM USING BUCK CIRCUIT GIVEN IN DATA SHEET AS EXAMPLE.ITS MY REQUIREMENT THAT LED ARRAY MUST STAY OFF UNTIL UNLESS ENABLE SIGNAL IS PROVIDE.

ALSO IN BUCK CIRCUIT EXAMPLE L1 IS USED TWICE. IS IT REQUIRED OR IT’S A PRINTING MISTAKE.

KINDLY HELP ME

over 4 years ago

0 Tuan Tran74 over 4 years ago

TI__Genius 17690 points

Hello,

Are you pulling the EN pin to ground during this power up or is it floating? It needs to be pulled to ground. There should not be any voltage on the LED unless there is some leakage path with the components that you are using and you will need to trouble shoot where that leakage is coming from.

Thanks Tuan

0 Tuan Tran74 over 4 years ago in reply to Tuan Tran74

TI__Genius 17690 points

Hello,

There is a typo there on L1...That should be two separate inductors.

Thanks Tuan

0 nisha11 23 over 4 years ago in reply to Tuan Tran74

Prodigy 40 points

en pin is grounded.

can u suggest which components are providing leakage path?

0 nisha11 23 over 4 years ago in reply to Tuan Tran74

Prodigy 40 points

EN pin is grounded.

can u suggest which components are providing leakage path?

0 Tuan Tran74 over 4 years ago in reply to nisha11 23

TI__Genius 17690 points

Hello,

Can you give me your full schematic along with part list. I would also like to have the following scope capture with the capture on rising edge of VIN.

CH1: VIN CH2: Vout CH3: EN CH4: Gate

Thanks Tuan