LNK623-Design ist in restart until 140V-input

Posted by: littlecb on 08/29/2013

Hello,

my LNK623-Design not works fine, sometimes.

Output is:

24V DC / 130 mA

10V DC / 40 mA

Input is:

85V-265V AC

Normaly the Design runs at 50-65 Volts AC at INPUT-terminals, but sometimes other

produced board dont run stable at 90V AC at input-terminals.

Then the LNK623 ever do startups. If i cut the C504 out of the design it works. But that can't

be a solution.

in the *.jpg-files you con see on ch1 the DS-voltage and on ch2 the ds-current at different

input-voltages.

can you give me a hint, what can i do or test to find the mistake?

best regards

Christian

Files

Trafo_s.pdf (172.85 KB)

Netzteil_s.pdf (114.17 KB)

IMG663_failed_60V-AC-Input_restarts.jpg (337.93 KB)

IMG664_failed_80V-AC-Input_restarts.jpg (346.01 KB)

IMG665_failed_over_140V_it-runs.jpg (349.94 KB)

IMG667_ok_30V-AC-Input.jpg (354.88 KB)

IMG668_ok__60V-AC-Input.jpg (364.73 KB)

IMG670_ok_90V-AC-Input.jpg (368.96 KB)

IMG672_ok_140V-AC-Input.jpg (362.13 KB)

Comments

Who designed the transformer for you? Did you used PI Expert to design it?

Hello & thx for answer.

The transformer is designed by kaschke components. Yes, we used PI-Expert to simulate & optimeze. The original design is designed by a assistant from PI in Dec 2, 2009.

I have simulate/design changed/ all recommendations from PI-Expert realized, but no effekt.

The design stays very hard in restart. But if i changed the LNK623 with lasered-code (1317/0V380E) with (1112/95895B), the design works much better.

(1317/0V380E) no start with Input-Voltage until 265 V AC

(1112/95895B) start with Input-Voltage at ~85 V AC

Have you a explanation for me to this problem?

best regards

Christian

Is it possible you post the whole transformer document? The document created by PI engineer. Is the power supply designed to run at what input voltage ? You mention " Normaly the Design runs at 50-65 Volts AC at INPUT" But also yoou said " Input is: 85V-265V AC"

So please clarity the specs

Hello PI-Worf,

thx for answer. The Power supply is designed to run 85V-265V AC, not at 60V AC. 85V-265V AC is the regular specification. Only without load, i have notice that the design starts often with ~60V AC.

But this is not a specification for our customers. It is only a memo for me in the laboratory.

Thanks in advance

littlecb

... sorry, the range is not 85-265V AC. it is 93-265V AC.

Check your PI expert file transformer and see if the feedback resistors Rupper and Rlower corresponded with your schematic