data/text/DLP2/888827

LM5041: Feedback loop Compensation

Part Number: LM5041 Hi Every one: I need to clarify LM5041 application circuit compensation design. Application circuit error opamp pole and zero placed below freq. Error op amp zero 1 placed by R35,C36 @ 1.326KHz Error op amp zero 2 placed by R32,C40 @ 22.9KHz Error op amp pole 1 placed by R42,C40 @96.7KHz Error op amp pole 2 placed by R35,C35 @279KHz My question 1) Op amp first zero placed in plant double pole L=60uH, Cout: 932uH F=673Hz? 2)Op amp second zero placed freq where should get? 3) I dint find Cout ESR value. Pole 1 placed in plant zero? I think Pole 2 placed almost in buck switching freq.LM5041..docx 3) How to compensate opto pole by error opamp in this application? 4)Kindly share any document available for compensation design for this application. (Opto coupler feedback with external opamp) 5) R11 and C11 form the opto pole? Kindly reply as soon as possible. Regards, Kubendran

Hellocompany Team, I am expecting your valuable reply. Regards, Kubendran

Hellocompany Team, We are facing loop compensation and buck switching node voltage oscillation issue with respect to LM 5041 application circuit design. Always i seen LM5041 related query response very delayed. Kindly reply previous query. Regards, Kubendran

Hi Kubendran, Sorry for the delay, the office that supports this controller was on public holiday, I have assigned an AE to this post. Regards Peter

Hi Peter, When will i expect the reply. Regards, Kubendran

Hellocompany team, No reply? Regards, Kubendran

Hi Kubendran, My mistake, there was a mistake in the email address for the AE in the system and this post did not appear on his list. I am checking if the AE assigned can support if not I will assign a new AE to help. I should have an update tomorrow. Regards Peter

Hi Kubendran, Unfortunate, I didn't find any document for the compensation design of this application. In this application, the designer used much complex two stage network with two LM6132 op amps and a LM4041 reference. I guess this circuit demonstrates the flexibility that can be used in electronic circuit design. I think it can be designed simpler with only one amplifier LM6132 and one reference LM4041. Since in this application, there is no internal error amplifier used, so it relies on the designer to add the error amplifier. It is targeted at isolated designs the error amp is usually on the secondary side driving an opto-coupler through the isolation barrier to the control pin. The schematic in page 14 of the LM5041 datasheet shows such a scheme. U4A is the error amplifier. C35, R35, C36, R42, C40 and R32 make up the type III compensation network. Regards, Teng

Hi Sir, Please read carefully my previous query. What you are said error op amp R and C value corresponding pole and zero frequency already calculated. My question how you are placed compensator pole,zero and opto coupler pole to the plant response. If i consider plant is double pole that value not matched with actually what you are used in compensator pole and zero. Actually current mode plant having one pole and one zero. In this way also checked compensator value did not matched. Kindly look this one serious and give best solution.I am facing converter output oscillating issue. Regards, Kubendran

Hi Kubendaran, Did you made a measurement of the gain, phase or if you have done a load transient test and measured the response of the output voltage waveform to see if the response with well damped or under damped. I don't think we can get a final value through calculation, actually it is complected and difficult to establish the signal model. My suggestion is: please adjust the compensation according the measured transient performance. Regards, Teng

Hi Sir, I will share the waveform to your mail. Please reply. Regards, Kubendran.