ld7578h Leadtrend Technology, ld7578h Datasheet
ld7578h
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ld7578h Summary of contents
Page 1
... It provides functions of low startup current, green-mode power-saving operation, leading-edge blanking of the current sensing and internal slope compensation. Also, the LD7578H features more protections like OLP (Over Load Protection), OVP (Over Voltage Protection), and OTP (Over Temperature Protection) to prevent the circuit being damaged from the abnormal conditions. ...
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... Protection Mode Part number OLP/OVP LD7578HGS Latch LD7578HGN Latch The LD7578H is ROHS compliance. Pin Descriptions PIN NAME Pulling this pin below 0.95V will shutdown the controller to enter latch mode until the AC power-on recycles. By connecting a NTC between this pin and ground will 1 (-) LATCH achieve OTP protection function ...
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... Block Diagram 32V 16.0V/ 10.0V Internal OSC Green Mode Control Vbias COMP CS 5.0V (-)LATCH Leadtrend Technology Corporation LD7578H-DS-00 February 2010 UVLO Comparator internal bias & Vref VCC OK PG Vref OK OLP OVP OTP PWM Comparator Slope Compensation + Leading Edge Blanking OCP Comparator 0. 85V ...
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... Stresses beyond the ratings specified in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Leadtrend Technology Corporation LD7578H-DS-00 February 2010 4 www.leadtrend.com.tw LD7578H -0 ...
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... Maximum Input Voltage,Vcs_off Maximum Input Voltage,Vcs_min Leading Edge Blanking Time Leading Edge Blanking Time Input impedance Delay to Output Oscillator for Switching Frequency Frequency Green Mode Frequency Leadtrend Technology Corporation LD7578H-DS-00 February 2010 =15.0V) CC CONDITIONS Vcc< UVLO(on), HV=500V Vcc> UVLO(off), HV=500V Vcc=UVLO(off) V =0V,Fsw=65KHz COMP ...
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... Output Low Level Output High Level Rising Time Falling Time OLP (Over Load Protection) OLP Trip Level Delay Time De-latch Vcc Level Leadtrend Technology Corporation LD7578H-DS-00 February 2010 =15.0V) CC CONDITIONS 65KHz Fsw=65KHz (-20°C ~105°C) (VCC=11V-25V) (PDR, Power Down Reset) VCC=15V, Io=20mA ...
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... Temperature (°C) Fig Current Source vs. Temperature (HV=500V, Vcc=0V) 18.0 17.2 16.4 15.6 14.8 14.0 - Temperature (°C) Fig. 3 UVLO (on) vs. Temperature - Temperature (°C) Fig. 5 Frequency vs. Temperature Leadtrend Technology Corporation LD7578H-DS-00 February 2010 0.91 0.89 0.87 0.85 0.83 0.81 80 120 125 -40 12 11.2 10.4 9.6 8 120 125 -40 22.0 21.0 20.0 19.0 18.0 17.0 16.0 15 ...
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... Fig. 7 Frequency vs. Vcc Temperature (°C) Fig. 9 Max Duty vs. Temperature 7.0 6.5 6.0 5.5 5.0 4.5 - Temperature (°C) Fig open loop voltage vs. Temperature CO MP Leadtrend Technology Corporation LD7578H-DS-00 February 2010 100 120 -40 6.0 5.5 5.0 4.5 4.0 3.5 80 ...
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... Temperature (°C) Fig. 13 Latch Pin Turn(On) Level vs. Temperature 104 102 100 -40 - Temperature (°C) Fig. 15 (-)Latch Pin Source Current vs. Temperature Leadtrend Technology Corporation LD7578H-DS-00 February 2010 0.955 0.950 0.945 0.940 0.935 0.93 0.925 0.920 0.915 - 100 120 60 80 ...
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... However, this startup resistor was usually of larger resistance, and it therefore required more power and longer time to start up. To achieve an optimized topology, as shown in figure 13, the LD7578H was built in with high voltage startup circuit to optimize the power saving. During the startup sequence, a high-voltage current ...
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... Voltage Feedback Loop The voltage feedback signal is issued from the TL431 in the secondary side through the photo-coupler to the COMP pin of LD7578H. The input stage of LD7578H, like the UC384X, is incorporated with 2 diodes voltage offset circuit and a voltage divider with 1/3 ratio. Therefore, A pull-high resistor is embedded internally thus can be eliminated on the external circuit ...
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... LD7578H, the internal slope compensation circuit has been implemented to simplify the external circuit design. On/Off Control The LD7578H can be controlled to turn off by pulling COMP pin to lower than 1.2V. The gate output pin of LD7578H will be disabled immediately under such condition. The off mode can be released when the pull-low signal is removed ...
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... Vcc will not recover until AC power turn off . Figure 18 shows its operation. The Vcc of LD7578H will drop down due to AC power turn off. The de-latch level of OVP is determined by internal PDR. Over voltage protection could be released soon as Vcc is below PDR level ...
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... OTP circuit is implemented by sensing the hot-spot of power circuit like power MOSFET or output rectifier. It can be easily achieved by connecting a NTC on the (-)LATCH pin of LD7578H. As the device temperature or ambient temperature rises high enough, the resistance of NTC will decrease, so that the voltage on the (-)LATCH pin will be = μ ...
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... LD7578H has eliminated the parasitic SCR efficiently. Figure 23 shows the equivalent circuit of LD7580’s Hi-V structure. It tells LD7578H is capable to sustain negative voltage and superior than similar products. Even though, a 40KΩ resistor is still recommended to be placed on the Hi-V path dV ⋅ ...
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... Reference Application Circuit --- 10W (5V/2A) Adapter Pin < 0.15W when Pout = 0W & Vin = 264Vac Schematic Leadtrend Technology Corporation LD7578H-DS-00 February 2010 16 www.leadtrend.com.tw LD7578H ...
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... R53 2.49KΩ, 0805, 1% R54 100Ω, 0805 R55 1KΩ, 0805 R56A 2.7KΩ, 1206 R56B N/A NTC1 5Ω, 3A FL1 20mH T1 EI-22 L51 2.7μH Leadtrend Technology Corporation LD7578H-DS-00 February 2010 P/N Original C51 C52 C54 C55 CX1 CY1 D1A D1B D1C D1D D2 D4 ...
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... Package Information SOP-8 Symbols θ Leadtrend Technology Corporation LD7578H-DS-00 February 2010 Dimensions in Millimeters Dimensions in Inch MIN MAX MIN 4.801 5.004 0.189 3.810 3.988 0.150 1.346 1.753 0.053 0.330 0.508 0.013 1.194 1.346 0.047 0.178 0.229 0.007 0.102 ...
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... Important Notice Leadtrend Technology Corp. reserves the right to make changes or corrections to its products at any time without notice. Customers should verify the datasheets are current and complete before placing order. Leadtrend Technology Corporation LD7578H-DS-00 February 2010 Dimension in Millimeters Dimensions in Inches Min Max Min 9 ...
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... Revision History Rev. Date Change Notice 00 2/22/2010 Original Specification Leadtrend Technology Corporation LD7578H-DS-00 February 2010 20 www.leadtrend.com.tw LD7578H ...