Module spare parts UFC721BE101 3BHE021889R0101

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Product Description

Product Description
Focus on DCS, PLC, robot control system and large servo system.
Main products: various modules / cards, controllers, touch screens, servo drivers.
Advantages: supply of imported original products, professional production parts,
Fast delivery, accurate delivery time,
The main brands include ABB Bailey, Ge / fuanc, Foxboro, Invensys Triconex, Bently, A-B Rockwell, Emerson, ovation, Motorola, xyvom, Honeywell, Rexroth, KUKA, Ni, Deif, Yokogawa, Woodward, Ryan, Schneider, Yaskawa, Moog, prosoft and other brands

UFC721BE101 3BHE021889R0101

To prevent the subharmonic oscillations, a compensation ramp is added to the control signal, as shown in Figure 21. With the compensation ramp, ΔVsamp1 and the convergence criteria are expressed by, (11) (12) The compensation ramp has been added internally in the LM3481. The slope of this compensation ramp has been selected to satisfy most applications, and it's value depends on the switching frequency. This slope can be calculated using the formula: MC = VSL x fS (13) In Equation 13, VSL is the amplitude of the internal compensation ramp and fS is the controller's switching frequency. Limits for VSL have been specified in the Electrical Characteristics section. To provide the user additional flexibility, a patented scheme has been implemented inside the IC to increase the slope of the compensation ramp externally, if the need arises. Adding a single external resistor, RSL(as shown in Figure 23) increases the amplitude of the compensation ramp as shown in Figure 22. Figure 22. Additional Slope Compensation Added Using External Resistor RSL Where, ΔVSL = K x RSL (14) K = 40 µA typically and changes slightly as the switching frequency changes. Figure 24 shows the effect the current K has on ΔVSLand different values of RSL as the switching frequency changes. A more general equation for the slope compensation ramp, MC, is shown below to include ΔVSL caused by the resistor RSL. MC = (VSL + ΔVSL) x fS (15) RFA = fS 22 x 103 - 5.74 LM3481 DR ISEN RSEN VIN L1 D1 Q1 COUT VOUT RSL + CSEN 15 LM3481, LM3481-Q1 SNVS346F –NOVEMBER 2007–REVISED NOVEMBER 2014 Product Folder Links: LM3481 LM3481-Q1 Copyright © 2007–2014, Texas Instruments Incorporated Submit Documentation Feedback Feature Description (continued) It is good design practice to only add as much slope compensation as needed to avoid subharmonic oscillation. Additional slope compensation minimizes the influence of the sensed current in the control loop. With very large slope compensation the control loop characteristics are similar to a voltage mode regulator which compares the error voltage to a saw tooth waveform rather than the inductor current. Figure 23. Increasing the Slope of the Compensation Ramp Figure 24. ΔVSL vs RSL 7.3.4 Frequency Adjust, Synchronization, and Shutdown The switching frequency of the LM3481 can be adjusted between 100 kHz and 1 MHz using a single external resistor. This resistor must be connected between the FA/SYNC/SD pin and ground, as shown in Figure 25. Refer to the Typical Characteristics to determine the value of the resistor required for a desired switching frequency. Equation 16 can also be used to estimate the frequency adjust resistor. Where fS is in kHz and RFA