Module spare parts UFC760BE1142 3BHE0Q4573R1142

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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.
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UFC760BE1142 3BHE0Q4573R1142

Feature Description (continued) The LM3481 can be synchronized to an external clock. The external clock must be connected between the FA/SYNC/SD pin and ground, as shown in Figure 26. The frequency adjust resistor may remain connected while synchronizing a signal, therefore if there is a loss of signal, the switching frequency will be set by the frequency adjust resistor. It is also necessary to have the width of the synchronization pulse wider than the duty cycle of the converter and to have the synchronization pulse width ≥ 300 ns. The FA/SYNC/SD pin also functions as a shutdown pin. If a high signal (refer to the Electrical Characteristics section for definition of high signal) appears on the FA/SYNC/SD pin, the LM3481 stops switching and goes into a low current mode. The total supply current of the IC reduces to 5 µA, typically, under these conditions. Figure 27 and Figure 28 show an implementation of a shutdown function when operating in frequency adjust mode and synchronization mode, respectively. In frequency adjust mode, connecting the FA/SYNC/SD pin to ground forces the clock to run at a certain frequency. Pulling this pin high shuts down the IC. In frequency adjust or synchronization mode, a high signal for more than 30 µs shuts down the IC. Figure 25. Frequency Adjust Figure 26. Frequency Synchronization Figure 27. Shutdown Operation in Frequency Adjust Mode UVLO VIN R7 R8 IUVLO VUVLOSEN - + + - 2 R7 = ß ® © ß ® © -1 VEN 1.43V R8 x R8 = ß ® © ß ® © 1 + 1.43V ± VSH IUVLO VEN ± 1.43V x 1.43V FA/SYNC/SD 40 k: DR 30 Ps LM3481 17 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) Figure 28. Shutdown Operation in Synchronization Mode 7.3.5 Undervoltage Lockout (UVLO) Pin The UVLO pin provides user programmable enable and shutdown thresholds. The UVLO pin is compared to an internal reference of 1.43 V (typical), and a resistor divider programs the enable threshold, VEN. When the IC is enabled, a 5-μA current is sourced out of the UVLO pin, which effectively causes a hysteresis, and the UVLO shutdown threshold, VSH, is now lower than the enable threshold. Setting these thresholds requires two resistors connected from the VIN pin to the UVLO pin and from the UVLO pin to GND (see Figure 29). Select the desired enable, VEN, and UVLO shutdown, VSH, thre