Power and Lighting Tools Forum - Recent Threads

LM5118 / Vin:12~60V Vout:28V Iout:4A

Ryuji Asaka — Thu, 13 Jun 2013 14:21:06 GMT

Hello,

I simulated LM5118 by below conditions by WEBENCH.

But webench couldn't simulate due to "Can't find suitable FET for the design".

Vin(min) 12V

Vin(max) 60V

Vout 28V

Iout 4A

I thoght that LM5118 is only one device for this solution due to LM5118 is back boost with wide Vin range.

Can't operate LM5118 above condition ?

If yes, please kindly let me know the refference design. and why webench can't simulate.

If no, could you pleaes kindly let me know other device which can operate this condition, if there is.

Best Regards,

Ryuji Asaka

Question on the Soft-Start Cap Value for TPS40170 Controller

Harold Taylor — Thu, 06 Jun 2013 15:55:40 GMT

I did a WebBench design for the TPS40170 Controller with 21 to 52 VDC in and Vout = 5V at 0 to 3.5A. The WebBench design generated a soft-start capacitor (Css) of 3900 pF (connected to the SS pin, pin 5 to GND).

However, according to the design equations in the datasheet, this will give a startup time of approximately 0.35 mS (Tss = Css*0.09, where Css is expressed in nF and Tss is expressed in mSec).

The recommended startup time is 4 mS.

My output capacitor is 220 uF.

The 0.35mS startup time results in a load startup current (assuming a linear ramp) of I = CV/t = 0.00022*5.0/0.00035 = 3.14 amps.

However, if the startup time is set for 4 mS (using a 0.047 uF cap for Css instead of 3900 pF), then the load startup current is I = CV/t = 0.00022*5/0.004 = 275 mA. This is far better than 3.14 amps!

Can someone please verify this for me? I will be happy to share my WebBench design details as well as the design I worked through using the equations in the datasheet.

I can be reached at htaylor@comverge.com

Harold Taylor

LM3414HV off current (6uA) too high for application. HELP!! ;)

David Hillstrom — Fri, 10 May 2013 19:23:29 GMT

I have a little problem with a circuit that I have inherited. I have included a .zip with two jpg's that outline the problem precisely. But it boils down to the fact that when the LM3414HV is "shut down" with a low on the DIM pin, the thing still draws about 6uA through the LEDs, which is way too much for my application. I am not really a power guy, and more of a control designer, so I am a little lost on this one, and I need to get a prototype out reasonably soon. I am open to workarounds or different topologies, as this is going to be a high volume product, with 6 to 12 circuits per unit, and unit volumes around 100K/yr by 2015.

HELP!!! ;)

(feel free to contact me.)

thanks,

-Dave

LM3670-ADJ Potential Error - 2.5V Max output voltage in WB model

Tyler Pate — Fri, 17 May 2013 17:31:38 GMT

Greetings,

Our customer pointed out a potential error in the LM3670. In the Webench interface it looks like the max output voltage is 2.5 where the datasheet and product page suggest the output voltage can be up to 3.3V. Is this the case for the adjustable version? It is not necessarily clear in the datasheet. For the adjustable version the datasheet only specs out feedback networks up to 2.5V.

Can you help clarify this?

Thanks, Tyler Pate

LM25085 webench and excel configurator mismatch

andreas kay — Tue, 07 May 2013 07:38:54 GMT

Dear all,

I created a simulation with "low O/P ripple" (minimum ripple solution solution).

The webench suggest me to use a 10nF cap for Cac .

The excel LM25085 quik start sheet suggest me to use 100nF. This is what also the datasheet tells.

2nd point. I propose to advise the user to take care about the gate resistor. Depending on the used FET, the gate charge current is to high for the LM25085.

with regard Andreas

lm3150 dc dc converter

David Legris Tremblay — Wed, 03 Apr 2013 19:58:52 GMT

Hi,

i used the Webench Designer to create a dc dc converter which would convert 36V to 19V 4A. Here is my image of what is the design that it gave to me. I also sent you an image of what the final board looks like (the inductor is on the other side of the board). My problem is that i have a really big oscillation on every wires of my board. I first thought it was because of my inductor. I bought another board with an EMI shield but it changed nothing so now i really dont see how to fix this. I have really big oscillations of 20 Volts peak to peak. If someone wants a clarification or does understand what is happening please answer me fast :)

WEBENCH for HTML5?

greenja — Thu, 09 May 2013 16:02:03 GMT

Hello,

I really think it is time for WEBENCH to be converted to HTML5. Please have your software development group get this done, or bring in some HTML5 developers.

The site is great and the tools are very useful. The problem is TI is not keeping up with designers that are using mobile platforms.

Thanks,

Webench vs Switcher Pro / TPS54331

Tsukui Yusuke — Mon, 15 Apr 2013 23:58:25 GMT

Hi.

Please let me know about webench and switcher pro.

The values of A differ by the simulation result of Webench and　Switcher　Pro.

Although a part　 is a near value, do the values of phase margin differ so far?

Which should phase margin believe?

I attach the result of webench and switcher pro which were outputted.

(Please visit the site to view this file)

yusuke

where are the Boost converters in SwitcherPro?

tomassetti — Wed, 19 Nov 2008 21:48:21 GMT

A couple of observations:

There are no SWIFT boost converters represented. TPS61xxx or TPS63xxx. When will we see these

The design wizard is not so wizardly when it recommends buck converters for obvious boost requirements (try entering a Vin of 2.5-3V and a Vout at 5V at .05A).

Any ideas when these will be addressed in switcherpro?

thanks.

Steve Tomassetti

AFAE TI

Webench Generated Schematic

Pravas Mohanty — Sat, 03 Nov 2012 05:56:07 GMT

WEBENCH is asking for the voltage and current at output(s). It asks for input voltage max and min. Why does it not ask for input current from the user?”

LM3150 simulation failures in Webench

Aaron Walsh — Mon, 25 Feb 2013 17:23:19 GMT

Dear forum members,

I am trying to use Webench to simulate a 24Vdc to 12Vdc converter using the LM3150 but without success.

The Startup simulation shows the output voltage rising to just 0.4V and then falling back to 0V within 700uS, never reaching 12V.

The Load Transient simulation from 0.01 - 6.00 amps produces unuseable results.

I would also like to simulate a zero load condition.

Any help would be greatly appreciated.

Aaron

Configuration for LM3150

Vin Min = 23V

Vin Max = 25V

Vout = 12V

Iout = 6A

Amb. Temp =40

TPS54526 / inimum inductance in WEBENCH

S.Satoshi — Wed, 13 Mar 2013 14:45:15 GMT

Hi,

I would like to choose the inductor of 1.0uH this value is recommended in Table 1 in datahseet, but it can not be chosen in WEBENCH simulation. I believe it should be chosen. Is my understanding correct?

Best Regards,

Sonoki / Japan Disty

TPS40170 in Webench

Jamaal_Charles — Thu, 21 Feb 2013 23:43:20 GMT

Hello,

I'm trying to design a circuit with the TPS40170. I used Webench with my requirements, 22-36Vin, 13Vout. Most of the time it will only draw 2A, but it will have occasional pulses at 13A for 50ms. If I put the load at 13A for worst case, the TPS40170 doesn't show up as an option. I thought the TPS40170 is capable of 20A, is that correct? If so, why would it not show up in Webench as an option? If I lower the load to 10A, it does show up. Is this the right device for my requirements, or should I use something else. The reason I wanted to use the TPS40170 is that it seems to be a good device for the rest of my loads.

Thanks,

Question on the application note U-161--Powering a 35W DC metal helide high intensity discharge(HID) lamp using ucc3305 controller

bee leung — Tue, 19 Feb 2013 06:53:17 GMT

Dear all,

I am interested in the application note U161 of the title"Powering a 35W DC metal helide high intensity discharge(HID) lamp using ucc3305 controller".
I want to ask if i want to construct the ballast, is it just follow to the schematic of the figure.2 as shown in the note ?

http://www.ti.com/litv/pdf/slua078a

thank you.

bee

TPS40305 DC-DC buck webench design suggestion

Uzi Saltoon — Mon, 11 Feb 2013 15:59:48 GMT

Hi ,

I'd like to ask your help with a question about the webench design,

I asked for Vin 4.45 to 19.6, I out=2.1A, Vout 3.75V

It suggest to use the TPS40305 which has max D.C of 85%

The design shows using D.C of 85.3% (when Vin is min)

How can it be?

Is the D.C on the DS include losses? i.e can I use the formula Vout_min=Vin_min*D.C? or need to take into consideration also some losses..?

Attached copy of the design.

(Please visit the site to view this file)

Thanks

Uzi

About LM2588 DC-DC CONVERTER

SATISH JAISWAL — Mon, 28 Jan 2013 10:12:10 GMT

Hello everyone,

I am using LM2588 adj IC for boosting 12V to 60V. In the circuit, when i give power, it is not boosting. it only show zero at input and output.

I want to ask whether the design which TI design tool give, work or not????????????/

thanks

Satish Jaiswal

M.Tech IIT DELHI

High Power LED driver circuit

Alex Saal — Wed, 04 Apr 2012 15:17:58 GMT

I am a mechanical engineer, but I need to put together an LED array. I understand that I need to use a driver to regulate current. I will be using a DC power supply. I have found links to many complicated circuits on the web, but I would like to find a simple and usable circuit that will regulate current properly.

How to calculate switching loss of LM3414HV?

alchemy tan — Tue, 15 Jan 2013 06:26:47 GMT

How to calculate switching loss of LM3414HV?

TPS5410D junction temperature calculation and heat sink requrements

Sesha giri — Thu, 17 Jan 2013 09:58:22 GMT

Hi ,

this is seshagiri. first started with TPS54040 for 5v@0.5A and then moved to TPS5410D for 5v@1A. i started thermal calculations, i approached like this , please let me know my approach is correct?.

Ambient temp=70degC

for junction temperature calculation purpose i used the formula, Tj = TA +(PD*Rth)

as per TPS5410D data sheet Rth = 75 degC/Watt

PD = 5V*0.25A= 1.25W ........ it can withstand upto 5W

as per data sheet it can with stand upto junction temperature 125degC

but as per my calculation Tj=TA+(PD*Rth) = 70 +(1.25*75) = 163.5degC

in this case itis crossing the recommended junction temperature 125degC, but i am using only 1.25W , but it can withstand upto 5W.

please let me know shall i need heat sink for this application.

I awaiting for anyone reply

Thank you very much in advance.

TPS5420

Ye Xu — Fri, 18 Jan 2013 15:34:06 GMT

Hi, I'm doing a 3.3V design with TPS5420 these days. I'm trying to understand the open loop gain of TPS5420 buck circuit. However, with limited info from datasheet, it's difficult for me to figure out a transfer function that could match well with the bode plot shown in WEBENCH. Is there any doc that could explain how to get the transfer function that could match with the bode plot in WEBENCH? That will help a lot for me to understand the stability performance of this chip. Thanks a lot.

Webench LM3401 design has wrong MOSFET symbol

George Biner (Arrow) — Tue, 15 Jan 2013 18:04:36 GMT

Hello: I just shared a design with Howard Chen and Eric Hackett. Customer reports that the design works OK but the FET symbol is Nch when it should be Pch.

Also, cannot optimize design "optimixation data not available for this design' what exactly does that mean and why is that happening? When can we or can't optimize?

EAU 80k/yr, thanks.

George Biner, Arrow LA

12v-60v,0.35A DC-DC converter for LED tubelight

SATISH JAISWAL — Thu, 03 Jan 2013 04:54:37 GMT

Hello everyone, I am a M.Tech student. I want to design a LED tubelight of 21W. So, I want to design a DC-DC LED driver. I am using LM3424 IC for this application.

Is this IC is suitable for this application or not?

WEBENCH(R) Power Architect

eli — Wed, 02 Jan 2013 16:59:32 GMT

As you can see from the attached,for POWER ARCHITECT design I can not get the option to SHARE DESIGN.

Can you advise why I do not have this option?

(Please visit the site to view this file)

TPS62130 Voltage Generation Accuracy

shakti ahuja — Fri, 28 Dec 2012 09:31:07 GMT

I want to generate 5V with +-2% accuracy (i.e. 4.9V - 5.1V). My input voltage range is 5.7V-10V. My output current requirement is 3A. the temperature variation would be from -40 deg C to 70 deg C.

I want to use TPS62130 for the Generation. The webench tool has suggested the value 180K with 0.5% accuracy and 953K with 1% accuracy. My Questions are as follows:-

1. Why is the resistor value of 0.5% accuracy of 180K required whereas the 953K is of 1% accuracy.

2. Will the circuit be able to provide the desired voltage accuracy of 4.9V - 5.1V for 5V if I use feedback resistors of 0.5% accuracy of 180K and 1% for 953K?