LM61460-Q1: TINA simulation and WEBENCH result do not match

Brian Han1

Part Number: LM61460-Q1
Other Parts Discussed in Thread: LM61460

Hello,

I wanted to double check my LM61460 circuit with both TINA and WEBENCH tools before I finish my board schematic.

I first got the values from WEBENCH using my conditions and transferred the same values to TINA and ran couple of simulation with both tools, but one of the case's result doesn't match.

As in the attachment, from 13.5V to 5V is good for both WEBENCH and TINA results.

But for the case 20V to 13.5V, the simulated voltage output only goes upto 10V max. I ran the transient analysis with calculate operating point option. TINA version is 9.3.200.277

Thank You

LM61460_13.5V-5V_schCHANGE.TSC

LM61460_20V-13.5V_schCHANGE.TSC

over 5 years ago

0 Daniel Li14 over 5 years ago

TI__Mastermind 27470 points

haven you change the load resistor, I saw the load resistor for 5V s 1.25ohm, and you not change the load resistor, for 13.5V, it should be 4ohm.

Thanks

Daniel Li

0 Brian Han1 over 5 years ago in reply to Daniel Li14

Intellectual 530 points

Hello Daniel,

Thanks for pointing out the resistor! now the Vout is properly set to 13.5V.

Just one more question.

When I make the resistor change, the Vout is 13.5V but it seems it's taking little too long, around 5.7ms, until it reaches the 13.5V

It only takes less than 1ms for the 13.5V to 5V circuit, but this is taking more than 5x the duration.

Is this the way it is?

Best regards,

Brian

0 Daniel Li14 over 5 years ago in reply to Brian Han1

TI__Mastermind 27470 points

from Spec, 5ms softstart time is typical value. can you help double check the time of 5V output. Sometime, simulation model can set a intial value for the circuit to make it more quick to go the stablize.

Thanks

0 Brian Han1 over 5 years ago in reply to Daniel Li14

Intellectual 530 points

Hi,

My model is based on the steady state example snvmbx5.tsc from the LM61460Q1 product page. And I did found out there are some initial voltages set with the capacitors, but even when I set the initial values to 0, the delay was still very short.

I will check for the other variables in the model.

Also, are there available LM61460 EVM gerber files that I can refer to?

Best regards

Brian

0 Marshall_Beck over 5 years ago in reply to Brian Han1

TI__Mastermind 35210 points

Appears soft-start time is within range of datasheet specification (Tss)? Please correct me if I am mistaken.

Here are the gerbers:

Power management

Power management forum

LM61460-Q1: TINA simulation and WEBENCH result do not match