LT1508 LINER [Linear Technology], LT1508 Datasheet
LT1508
Related parts for LT1508
LT1508 Summary of contents
Page 1
... 0.7V R – – SET – LIM C Power Factor and PWM U GND1 PK V LIM 3 5 – + – RUN + S OSC 16V R 15 SET 55% DELAY 200ns 16V BLANKING LT1508 CC 17 GTDR1 1 GND2 2 GTDR2 20 1508 BD 1 ...
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... Line current dead zone is minimized with low bias voltage at the current input to the multiplier. The LT1508 provides many protection features including peak current limiting and overvoltage protection. Implemented with a very high speed process, the LT1508 can be operated at frequencies as high as 300kHz. U RATINGS ...
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... SET OVP = 7.5V 0mA Load, 18V < – 200mA Load, 11.5V V 15V 0V, 50mA Load (Sinking) CC 200mA Load (Sinking) 10mA Load 10nF from GTDR to GND 1nF from GTDR to GND LT1508 = 100 0V SENSE OUT MIN TYP MAX 1 4 – 25 – 250 80 110 3 7 ...
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... LT1508 ELECTRICAL C HARA TERISTICS 18V 15k to GND 1nF to GND SET SET outputs, unless otherwise noted. PARAMETER Soft Start Current SS1 Current (PFC) SS2 Current (PWM) Comparators in PWM Section I Input Current LIM Current Limit Comparator (CL) Threshold GTDR2 Switching Off Threshold at V ...
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... LOAD CAPACITANCE (nF) GTDR1 Maximum Duty Cycle vs R and C SET SET 1.00 0.99 0.98 0.97 0.96 0.95 0.94 0.93 R SET R 0.92 SET R SET 0.91 R SET 0.90 200 600 1000 1400 1800 C CAPACITANCE (pF) SET LT1508 Multiplier Current OUT OUT VA = 6.5V OUT OUT OUT VA OUT VA OUT VA OUT VA OUT VA 0 OUT 0 250 500 1508 G05 ...
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... LT1508 W U TYPICAL PERFORMANCE CHARACTERISTICS R Voltage vs Current SET 120 100 –20 –40 –60 –80 –100 0 –0.2 –0.4 –0.6 R CURRENT (mA) SET PIN FUNCTIONS (For application help with the PFC portion of this chip, see the LT1248 data sheet) PFC SECTION GTDR1 (Pin 1): The PFC MOSFET gate driver is a fast totem pole output which is clamped at 15V ...
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... During this ramp up, PFC reference voltage is equal to SS1 voltage. After SS1 rises past 7.5V, reference voltage remains at 7.5V. V (Pin 17): This is the supply for the chip. The LT1508 CC has two fast gate drivers required to fast charge high power MOSFET gate capacitances. Good supply bypass- ing is required consisting ...
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... F (5V)(500 H)(100k) = (382V)(0. OUT – If the current amplifier gain at 100kHz is less than 4.4, CA there will be no subharmonic oscillation. The open-loop + gain of the current loop is given by: LT1508 1508 • F02 CA(OUT) 60 (382V)(0. (j)(2 f)(500 H)(5V) 45 The current error amp, with 20k ...
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... Note that of (I OUT. M(MAX) = 15k. a 100kHz switching frequency with R (100kHz)(15k) = 1nF. For added protection the LT1508 provides a second independent current limit comparator. When the input voltage to the comparator ( 5.5V OUT below 0V, GTDR1 pin quickly goes low turning off the PFC power switch ...
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... Because of the slow loop response necessary for power factor correction, output overshoot can occur following a sudden load reduction or removal. To protect downstream components, the LT1508 provides an overvoltage com- parator which senses the output voltage and quickly reduces the line current demand. Referring back to Figure ...
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... SS2 low disabling the PWM section if the PFC output voltage falls below approximately 62% of its preset value (240V with nominal 382V output). Start-Up and Supply Voltage The LT1508 draws only 250 A before the chip starts at 16V trickle start, a 91k resistor from the power CC ...
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... O PWM Comparators The LT1508 includes two comparators in the PWM section which implement voltage mode PWM control. The V control voltage pin sets duty factor. An additional current limit comparator turns GTDR2 off in the event the I voltage exceeds 1.1V. On-chip blanking avoids reset due to leading edge noise ...
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... U U APPLICATIONS INFORMATION W U LT1508 13 ...
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... LT1508 U U APPLICATIONS INFORMATION An LT1431 reference/amplifier coupled to a low cost optoisolator closes the loop from secondary side to pri- mary side. Efficiency versus power and line voltage is shown in Figure 10. The PFC preregulator alone has efficiency numbers between 90% and 97% over line and load. ...
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... MIN 0.005 0.125 (0.127) (3.175) MIN MIN 0.100 0.010 (2.540 0.254) LT1508 1.040* (26.416) MAX 0.065 (1.651) TYP 0.018 0.003 (0 ...
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... LT1508 PACKAGE DESCRIPTION 0.291 – 0.299** (7.391 – 7.595) 0.010 – 0.029 (0.254 – 0.737) 0.009 – 0.013 NOTE 1 (0.229 – 0.330) 0.016 – 0.050 (0.406 – 1.270) NOTE: 1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS. ...