LMR14203: How to output negative voltage

Liu Yang

Expert 5945 points

Part Number: LMR14203

Dear

My Japan customer has a question about LMR14203XMKE/NOPB. The question is below:

Please tell me how to output negative power.

1. Is the GND terminal good for connection to GND of VIN?

2. About /SHDN control, when turning off should connect /SHDN to GND or negative voltage level?

3. Do you have reference circuit diagram?

Pls help me

Tom.Liu

over 5 years ago

0 David Baba over 5 years ago

TI__Mastermind 28660 points

Hello Liu,

Vout goes to Gnd. Please review the link below, you will find this most helpful and covers the topics of Shutdown (in section 7,1 ).

www.ti.com/.../snva856.pdf

Hope this helps?

0 Liu Yang over 5 years ago in reply to David Baba

TI__Expert 5945 points

Hi David,

Thank you for your reply and I have another question.

There is a description that "be sure that the EN input of the buck can withstand the full input voltage rating of the regulator (from datasheet Absolute Maximum Ratings section)" in section 7,1. And in datasheet's "Absolute Maximum Ratings" section, /SHDN is "-0.3V to (VIN+0.3V) <45V" which is in condition of GND=0V. If Vout goes to Gnd, what is the Absolute Maximum Ratings of /SHDN?

BR

Tom.Liu

0 David Baba over 5 years ago in reply to Liu Yang

TI__Mastermind 28660 points

Hello Tom,

The Abs max stays exactly the same. The Abs max rating for Vin to Gnd of the Device (Pin 5 to Pin 2 and if SHDN is tied to Vin, Pin Pin 4 to Pin 2) must not be greater than the Abs max rating. The device will see Vin+Vout. Say you have 24V in and -ve12V out these pins will see 24V+12V = 36V.

Hope this helps?

0 Liu Yang over 5 years ago in reply to David Baba

TI__Expert 5945 points

Hi David,

Thank you for your reply and your answer is very helpful.

BR

Tom.Liu

Power management

Power management forum

LMR14203: How to output negative voltage