Forum posts

low frequence ripple TOP249

artem999 — Mon, 22 Nov 2010 12:58:55 -0800

Hi PI-Spock!

During experiments I have found out that if to short the resistor R9 that low-frequency noise stops. Probably something is no perfectly in order with feedback. The picture is applied.

Best Regards, Artem

The 7th Guangzhou Int'l Water Heater Exhibition 2012

Trista7 — Tue, 17 Apr 2012 21:51:46 -0700

The 7th Guangzhou Int'l Water Heater Exhibition 2012

Date:August 21-23,2012 Venue: China Import & Export Fair PazhouComplex

On August 13,2011, GWHE was crowned with success at the China Import & Export Fair Pazhou Complex. There are total 137 exhibitors, about 500 booths. Thanks to all the exhibitors and visitors to support GWHE, especially the famous enterprises, like MEDIA, Msrite, SHIM CHEN,M.UNIVERSE, Himin, Aigete, Linuo Ritter, Chigao ,Solartech and so on.

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buck DC/DC solution

sharwan1 — Wed, 07 Jul 2010 23:43:47 -0700

i need to do DC/DC from 120Vdc to 12Vdc.
The solutions that the PI design offer me are with flyback,
and i need solution with BUCK .
can you tell me how to choose buck in the software.

best regards.
sharon.

Very high bias voltage

bbmilo — Mon, 30 Jan 2012 20:06:40 -0800

Hi,

The bias voltage of my design with TOP267E 14V 2.5A single output, is 15V at no load. It increases to 27V at half load which sends the power supply into auto-restart mode.
PI Expert file is as attached.

The power supply manage to supply full load 2.5A with V pin grounded.

Read in the forums that added a small series resistor could help. But for my case it's too much voltage to drop. I'd rather find out the cause of the problem and fix it there.

Is it just down to the coupling of the transformer?
Please give suggestion to solve this problem and to improve design.

Thanks,

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Help on LNK306 ...

narbeh_rob — Sat, 06 Mar 2010 00:24:16 -0800

HI, I need some help

I design a power supply with LNK306 and at its input I use normal 2 watt resistor (instead of fusible one) sometimes its blow up.... I change the resistor with higher one (86 ohm and 150 ohm) but it sometime still blow up.... now i have some questions

1) Can I remove the input resistor completely (as the data sheet says it is optional)?

2) Can I use normal 10 ohm, 2 W resistors with some normal glass type fuse serial with it ?

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TOP 247Y circuit

alex.62mold — Mon, 08 Nov 2010 11:53:41 -0800

Hello Sirs,
I build my first flyback smps,using TOP 247 and Myrra 74050 transformer-ETD34
5V/12V output,and already I have a problem : without load the output voltage
increases from 8 to 10 V,(maybe more but I didn't wait)first quick,than slower and slower.With a low load -a lamp 6V/0.5A- the output voltage is 2.45V and
current 0.32A,constant.For the first experiment I used the primary/basic
feedback circuit (R=15 ohm).All the components are cold,there isn't any warming trend.I honestly don't know what to do,please give an advice.
Regards,Alex

Switching Noise

azkhan — Wed, 05 Oct 2011 13:56:54 -0700

Hi,
I developed the attached Power Supply using PI SW. I see very high switching noise (approx 100 mV peak to peak) in my bread board. Can you review the schematics and make recommendations. My laod is 200 mA at 3.3V.
Thanks,
Asif Khan
SMK Manufacturing,
1055 Tierra Del Rey #H
Chula Vista, CA91910
619-216-6431

problem on TOPSwitch

Jime Pan — Wed, 12 Jan 2011 22:32:06 -0800

I read the paper of TOP252-262 TOPSwitch HX family and followed Fig.42 drawing to make a PCB circuit(see attachement).

I made some modification based on the drawing. TOP261YN and TOP261E was chosen insteady of TOP258YN. I want the 24V output and about 10A. So the transformer was redesigned. The data can be seen in attachement. Some resistors are changed, for instanced, R15,R16 and R17. It works. During input power from 60-230V and no-load and light load(1-2A), the output voltage is steady(about 26V). It is OK. But there are a number of problem in it.

1. Noise

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LinkSwitch TN Fusible Resistor Selection

jsitar — Mon, 23 May 2011 10:46:55 -0700

I am having trouble finding a suitable fusible resistor for a design using a LNK302. The recommendation in application note AN-37 is 100-470 Ohm, 0.5W. Though there are companies that make resistors that meet that spec, I haven't been able to find any that both meet the spec and possess a UL1412 rating. UL1412 fusible resistors are required for our safety certification. Are there any suggested sources for UL1412 certified resistors in the 100-470 Ohm range with a 0.5W power rating? Thanks in advance!

about surge strength of capzero product

j-ason — Sun, 09 May 2010 05:43:02 -0700

i want to know how high surge voltage can pass for capzero product? how about 1.5k?