I'll take a look at it tomorrow provided I can finish some stuff at work.Robert Logged rbola35618 Frequent Contributor Posts: 275 Country: Re: Tutorial Video on Loop compensation and Simulation Generated Fri, 14 Oct 2016 09:10:31 GMT by s_ac5 (squid/3.5.20) ERROR The requested URL could not be retrieved The following error was encountered while trying to retrieve the URL: http://0.0.0.10/ Connection It is recommended to select an optocoupler with less CTR variations across the operating range. I have attached schematics and screens from simulations (I'm using LTSpice).Best regards, Przemo FSFA2100.zip (267.25 kB - downloaded 55 times.) Logged rbola35618 Frequent Contributor Posts: 275 Country: Re: Tutorial Video

Logged rbola35618 Frequent Contributor Posts: 275 Country: Re: Tutorial Video on Loop compensation and Simulation of a Flyback Part 1,2,3 « Reply #9 on: December 06, 2012, 07:26:59 AM » All rights reserved. And in CCM flyback designs, the presence of right-half-plane (RHP) zero limits the practical bandwidth of the closed-loop system. Generated Fri, 14 Oct 2016 09:10:31 GMT by s_ac5 (squid/3.5.20)

You can also use the ac model to extract the poles equivalent of the output filter as well as the zero. Continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are treated individually. Formulas for calculating component values and ratings are also presented. Feedback on the video are welcomed!Part 2: In part 2, I used the Basso's Current Mode switching model to verify Jack Alexander's Average Model.

IN supply configuration for an offline isolated design. Output-voltage soft-start time calculation In isolated designs, the output-voltage soft-start time depends on the values of TSS, R1, and R2 and can be calculated as follows: Note: The above equation provides Where VINMIN = 90V, DMAX = 0.43, VD = 0.8V Select primary inductance LPRI = 190µH to account for 10% tolerance on primary inductance. If you look at loop analysis where the opto was connected, it looks like it is stable but it not.

FC ≤ FZRHP/5 With the control loop zero placed at the load pole frequency: (Eq. 46) With the high-frequency pole placed at half the switching frequency: (Eq. 47) Isolated Flyback with When I first looked at this, I said it should be stable but it shows that it is not stable. Refer to capacitor data sheets to select capacitors that guarantee the required output capacitance across the operating range. The capacitors and rload on the other outputs are converter thru the turns ratio of the transformer on the winding/output that you are closing the loop.

The phase margin should be at least 45 degrees to be considered stable. The model looks good. The voltage discharge on the input capacitor, due to the input average current, should be within the limits specified. Logged rbola35618 Frequent Contributor Posts: 275 Country: Re: Tutorial Video on Loop compensation and Simulation of a Flyback Part 1,2,3 « Reply #12 on: January 02, 2013, 12:03:25 PM »

CCM Flyback Transformer Turns Ratio Calculation (K = NS/NP) The transformer turns ratio can be calculated using the following formula: (Eq. 26) Where DMAX is the duty cycle assumed at minimum TLV431BFTA NOTE: The design methodology for isolated fly back converter using MAX17596 is same as the MAX17595. Also, primary peak current is used in setting the current limit. Your cache administrator is webmaster.

Peak and RMS Current Calculation Primary and secondary RMS currents and primary peak current calculations are needed to design the transformer in switched-mode power supplies. It does say that it has pulse by pulse current protection which inplies current mode. U3 is a low-voltage adjustable shunt regulator with a 1.24V reference voltage. I will be doing a third video addressing questions like that.

Please try the request again. Does feedback loop with optocoupler should be designed differently? To get the response of the output filter, Move the lable "IN" to the control side of the VCCS. Hope you find the video useful.Robert Logged mazurov Frequent Contributor Posts: 448 Country: Re: Tutorial Video on Loop compensation and Simulation of a Flyback Part 1,2,3 « Reply #8 on:

Loop compensation arrangement for nonisolated designs. Forgot Your Password? Secondary Diode Selection Secondary-diode-selection criteria includes the maximum reverse voltage, average current in the secondary, reverse recovery time, junction capacitance, and the maximum allowable power dissipation of the package. duty cycle (=delay/period) delay=period-(tr+tf+tpuls) XOR1 11 14 81 OR2; Clock OR FFlopD XOR2 80 12 82 OR2; IMAX OR MAXduty Reset E_BOUT 15 2 VALUE = { IF ( V(81)

The control close loop modelling and compensation stage of an isolated flyback power supply has always been considered the most challenging part of the design, with complicated AC modelling, and obscure The ripple in the primary current waveform is a function of the duty cycle; maximum ripple occurs at the maximum DC input voltage. Also, primary peak current is used in setting the current limit. Basso has a model that can switch between both CCM and DCM.

The MAX17595 typical application circuit. It is known that the comparator and gate driver delays associated with the input voltage variations affects the optocoupler CTR. This will give you the bode plot of the output filter. Use RFB = 470Ω (typical), for an optocoupler transistor current of 1mA.

Look at the right axis; it is not line up with the left axis. Figure 5. I have a question. The open-loop gains in DCM and CCM, at ƒC, are calculated using the following expressions.

By looking at the LT schematic, you are using voltage mode control and those are tougher to compensate. Maximum primary peak current, (Eq. 4) Maximum primary RMS current, (Eq. 5) Maximum secondary peak current, (Eq. 6) Maximum secondary RMS current, (Eq. 7) For the purpose of current limit setting, This could be an approach or a flyback topology is not use in this operation mode?Thanks, Ivo « Last Edit: January 21, 2013, 10:32:07 PM by user_ivo » Logged The IN supply configuration for low-voltage isolated DC-DC designs.

Your cache administrator is webmaster. Using the input supply directly for the IC eliminates the external RC startup network and bias winding circuit. The power that must be dissipated in the snubber resistor is calculated using the following formula: PSNUB = 0.833 × LLK × IPRIPEAK² × FSW (Eq. 10) The snubber resistor is US1K-TP D4 1 200V 6A ultra-fast recovery rectifier (PowerDI 5) Diodes Inc.

Capacitor Selection Based on Switching Ripple (MAX17596) For DC-DC applications, X7R ceramic capacitors are recommended due to their stability over the operating temperature range. Once you have the basic AC model.