LT1241 Linear Technology Corporation, LT1241 Datasheet
LT1241
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LT1241 Summary of contents
Page 1
... They are improved plug compatible versions of the industry standard UC1842 series. These devices have both improved speed and lower quiescent current. The LT1241 series is optimized for off-line and DC/DC converter applications. They con- tain a temperature-compensated reference, high gain er- ...
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... LT1241 Series BSOLUTE Supply Voltage ........................................................ 25V Output Current ....................................................... 1A* Output Energy (Capacitive Load per Cycle) ...............5 J Analog Inputs (Pins 2, 3) ............................... – 0 Error Amplifier Output Sink Current...................... 10mA Power Dissipation ................................ 1W A Operating Junction Temperature Range LT124XC ............................................. 100 C LT124XI......................................... – 100 C LT124XM........................................ – 125 C Storage Temperature Range ................. – ...
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... 1.0nF 1mA = Note 2: Low duty cycle pulse techniques are used during test to maintain junction temperature close to ambient. = 10k 3.3nF LT1241 Series MIN TYP MAX 5 5.6 0.2 1.1 2.85 3.00 3.15 0.90 1.00 1.10 70 – 100 100 1.5 0.25 ...
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... LT1241 Series W U TYPICAL PERFOR A Undervoltage Lockout – LT1241 11 10 START-UP THRESHOLD 9 8 MINIMUM OPERATING VOLTAGE 7 6 –50 – 100 125 TEMPERATURE ( C) LT1241 • TPC01 Start-Up Current 200 START-UP THRESHOLD 150 LT1241 LT1242/4 LT1243/5 100 (V) CC LT1241 • TPC04 Supply Current vs ...
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... ERROR AMP OUTPUT VOLTAGE (V) LT1241 • TPC12 Low Level Output Saturation Voltage During Undervoltage Lockout 4.0 3.5 3.0 2 – 2.0 1 125 C 1.0 J 0.5 0 200 0 5 OUTPUT SINK CURRENT (mA) 75 100 125 LT1241 • TPC11 T = – LT1241 • TPC17 = LT1241 • TPC15 5 ...
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... LT1241 • TPC19 Output Rise and Fall Time TIME 50ns/DIV V = 15V LT1241 • TPC22 1nF HARA TERISTICS C Output Deadtime vs Oscillator Frequency – LT1241, LT1243,LT1245 75 70 10nF 5nF 2nF 65 500pF 100 OSCILLATOR FREQUENCY (kHz) LT1241 • TPC20 Output Cross-Conduction Current TIME 50ns/DIV ...
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... LT1245 8.4V 7.6V Oscillator The LT1241 series devices are fixed frequency current mode pulse width modulators. The oscillator frequency and the oscillator discharge current are both trimmed and tightly specified to minimize the variations in frequency and deadtime. The oscillator frequency is set by choosing ...
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... W U appear in the Typical frequency for LT1241, LT1244 and LT1245. The oscillator of LT1241 series devices will run at frequencies up to 1MHz, allowing 500kHz output switching frequencies for all devices. Error Amplifier The LT1241 series of devices contain a fully compensated ...
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... To reduce the maximum current sense threshold to less than 1V the error amplifier output should be clamped to less than 4.4V. Blanking A unique feature of the LT1241 series devices is the built- in blanking circuit at the output of the current sense comparator. A common problem with current mode PWM circuits is erratic operation due to noise at the current sense input ...
Page 10
... In these cases a Schottky clamp diode is recommended from the output to ground. Reference The internal reference of the LT1241 series devices REF bandgap reference, trimmed to within 1% initial toler- ance. The reference is used to power the majority of internal logic and the oscillator circuitry. The oscillator charging current is supplied from the reference ...
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... CLAMP WHERE (MAX) CLAMP ( R S LT1241 Series Soft Start 5V REF 5.6V 1V 1mA 2R – 1.5V – UV LOCKOUT V CC OUTPUT 7 PULL-DOWN T OUTPUT 18V GND 5 BLANKING + 1.5V – I SENSE 1. –ln 1 – C SOFT START 3 • CLAMP LT1241 • TA03 LT1241 • TA02 ...
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... V CC R11 MPT2N60 3 D4 BAT 85 R12 1k 1/10W R17 R18 R16 1/4W 1/4W 1/ 1/2 TURN MUR420 AIRCORE C15 C16 30T 12T 3.3 F 3.3 F 50V 50V 30T CTX210433 13T 100 H 20V 1.5A R15 750 1W RTN C13 4700pF 1kV Y-CAP LT1241 • TA06 ...
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... LT1241 Series UV LOCKOUT OUTPUT 7 PULL-DOWN OUTPUT 18V GND 5 BLANKING + 1.5V – I SENSE 3 LT1241 • TA04 MAX 6 5 0.220 – 0.310 (5.588 – 7.874 0.200 (5.080) MAX 0.015 – 0.060 (0.381 – 1.524) 0.125 3.175 MIN 0.100 0.010 (2.540 0.254) J8 0694 ...
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... LT1241 Series PACKAGE DESCRIPTIO 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) +0.025 0.325 –0.015 +0.635 8.255 –0.381 *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm Dimensions in inches (millimeters) unless otherwise noted. ...
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... Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.228 – 0.244 (5.791 – 6.197) 0.053 – 0.069 (1.346 – 1.752) 0 – 8 TYP 0.014 – 0.019 (0.355 – 0.483) LT1241 Series 0.189 – 0.197* (4.801 – 5.004 0.150 – 0.157** (3.810 – 3.988) ...
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... Boost Regulator Steps Down from Up to 25V Using 4.7 H Inductors Complete Solution for Universal Off-Line Switching Power Supplies UV LOCKOUT V CC OUTPUT 7 PULL-DOWN OUTPUT 18V GND 5 + 1.5V – I SENSE 3 LT1241 • TA05 1241fa LT/TP 0297 5K REV A • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1992 ...