• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 569 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Query reg CSD17313Q2Q1

Deepak Holla1
Prodigy 110 points
Other Parts Discussed in Thread: TPS2410, LM5010

Hi TI,

We are planning on using the part CSD17313Q2Q1 in one of our upcoming designs.

Given below are the tentative design details:

Planned Scheme: Active OR-ing (i.e. tying the Drains of both N-FETs together and providing independent power supplies at the Source terminals)
Voltage at Source of 1st FET: 12V
Voltage at Source of 2nd FET: 5V
Load Current: 1A
Since we do not have separate Gate driving signal we are planning to connect the Source signal to Gate terminal.(effectively shorting Gate and Source terminals)

We have below mentioned queries:

1. Will this Active OR-ing circuit work ?
2. Ideally in this circuit Vgs would be zero hence N-FET will not turn ON, what are the changes we need to incorporate in the Gate driving side in order to turn ON N-FET?
3. Would the drop across the circuit be Current X Rds(on) or would there be any additional drop since the two FETs are connected ?
4. If this is not a suitable method please suggest the best alternate method for Active OR-ing two supplies using FETs.

A speedy response will be appreciated.

Regards,
Deepak Holla
Project Lead
L&T Technology Services
TC3, Tower A, 7th Floor
Manapakkam
Chennai-600 089.

  • 0
    TI__Mastermind 18200 points

    Deepak, 

    I spoke with our applications engineer Magai Gari and got the following response: 

    "I’m afraid his circuit will not work.

     

    Connect gate to source will not turn on the FETs. Current will flow through FET’s body diode. This way it’s no different than using discrete diodes, except that discrete diodes have a better performance than FETs’ intrinsic body diodes. Thus power loss will NOT equal to current2 x Rdson. Instead, it’s going to be current x FET’s body diode forward voltage drop. I would suggest using a TI ORing controller in the circuit, such as LM5010 or TPS2410.

    http://www.ti.com/product/lm5050-1

    http://www.ti.com/product/tps2410/description"