LT1172 Linear Technology Corporation, LT1172 Datasheet
LT1172
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LT1172 Summary of contents
Page 1
... This manual contains a comprehensive discussion of both the LT1070 and the external components used with it, as well as complete formulas for calculating the values of these components. The manual can also be used for the LT1170/LT1171/LT1172 by factoring in the higher TM frequency. A CAD design program called SwitcherCAD is also available ...
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... NC PACKAGE S8 PACKAGE 8-LEAD PDIP 8-LEAD PLASTIC not connect Pin 4 of the LT1172 DIP external circuitry. This pin may be active in future revisions 100 C, = 100 C/W (N) JMAX 100 C, = 120 C/W to 150 C/W JMAX JA depending on board layout (S) * will vary from ...
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... NC PACKAGE 8-LEAD CERDIP * Do not connect Pin 4 of the LT1172 DIP external circuitry. This pin may be active in future revisions 150 C, = 100 C/W JMAX JA ELECTRICAL CHARACTERISTICS perature range, otherwise specifications are at T SYMBOL PARAMETER V Reference Voltage REF ...
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... IN (t)(f) buck and inverting mode R = Inductor DC resistance I = 10A for LT1170, 5A for LT1171, and 2.5A for LT1172 Output catch diode forward voltage 0 100kHz switching frequency Maximum input voltage can be increased by increasing R or Vf. External current limiting such as that shown in AN19, Figure 39, will provide protection up to the full supply voltage rating ...
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... W U TYPICAL PERFOR A CE CHARACTERISTICS Switch Current Limit vs Duty Cycle – 125 DIVIDE VERTICAL SCALE BY TWO FOR LT1171, BY FOUR FOR LT1172 100 DUTY CYCLE (%) 1170/1/2 G01 Line Regulation 150 ...
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... LT1 170/LT1 171/LT1172 W U TYPICAL PERFOR A CE CHARACTERISTICS Shutdown Mode Supply Current 200 180 160 140 T = 150 C 120 J 100 80 60 – 125 100 V PIN VOLTAGE (mV) C 1170/1/2 G10 Idle Supply Current vs Temperature 0.6V ...
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... LOGIC DRIVER ANTI- SAT COMP V C SHUTDOWN CURRENT CIRCUIT AMP GAIN 6 0.15V (LT1170 AND LT1171 ONLY) LT1 170/LT1 171/LT1172 Normal/Flyback Mode Threshold on Feedback Pin –24 –22 –20 –18 FEEDBACK PIN VOLTAGE –16 (AT THRESHOLD) –14 –12 FEEDBACK PIN CURRENT –10 (AT THRESHOLD) – 8 – ...
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... Thermal Considerations When Using the MiniDIP and SW Packages The low supply current and high switch efficiency of the LT1172 allow used without a heat sink in most applications when the TO-220 or TO-3 package is se- lected. These packages are rated at 50 C/W and 35 C/W respectively. The miniDIPs, however, are rated at 100 C/W in ceramic (J) and 130 C/W in plastic (N) ...
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... I R switch dissipation under current limit conditions. The fourth approach is to clamp the V than its internal clamp level of 2V. The LT1172 switch current limit is zero at approximately 1V on the the V pin. Peak switch current can be C externally clamped between these two levels with a diode. ...
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... LT1 170/LT1 171/LT1172 U OPERATIO With 150kHz 1.5V, and R3 = 2k, offset voltage shift is 3.8mV. This is not particularly bother- some, but note that high offsets could result if R3 were reduced to a much lower value. Also, the synchronizing Synchronizing with Bipolar Transistor V IN ...
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... TANTALUM OUTPUT FILTER. Driving High Voltage FET (for Off-Line Applications, See AN25 10V TO LT1170 20V GND (Note that maximum output currents are divided by 2 for LT1171 for LT1172.) LCD Contrast Supply 5V* L1 BAT 3V TO 20V ...
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... IN AN19, FIGURE 39, SHOULD BE ADDED WITH C1 REDUCED TO 200pF. * REQUIRED IF INPUT LEADS 2" ** PULSE ENGINEERING 92114 COILTRONICS 50-2-52 + C3* 100 F OPTIONAL INPUT FILTER –20V 12 (Note that maximum output currents are divided by 2 for LT1171 for LT1172.) † L1 OPTIONAL C3 OUTPUT FILTER D1 V OUT 12V ...
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... COILTRONICS CTX300 SUMIDA 6345-020 OR COILTRONICS 110092-1 *** † A MODIFICATION WILL ALLOW OPERATION DOWN TO 4.5V. CONSULT FACTORY. LT1 170/LT1 171/LT1172 REQUIRED IF INPUT LEADS 2" PULSE ENGINEERING 92114, COILTRONICS 50-2-52 TO AVOID STARTUP PROBLEMS FOR INPUT VOLTAGES BELOW 10V, CONNECT ANODE AND IN REMOVE R5. C1 MAY BE REDUCED FOR LOWER OUTPUT CURRENTS ...
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... LT1 170/LT1 171/LT1172 U TYPICAL APPLICATIO 2 C5* 100 F + C4* 470 –15V * REQUIRED IF INPUT LEADS 2" 14 Positive Buck Converter * REQUIRED IF INPUT LEADS 2" ** PULSE ENGINEERING 92114 COILTRONICS 50-2- LT1170 R1 3.74k FB V GND 1.24k 470 Negative Boost Regulator ...
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... DIODE LIM LT1432 V MODE OUT * R2 IS MADE FROM PC BOARD GND COPPER TRACES. ** MAXIMUM CURRENT IS DETERMINED BY THE CHOICE OF LT1070 FAMILY. SEE APPLICATION SECTION. LT1 170/LT1 171/LT1172 OUT 5V 2000 F R1 3.74k R2 1.24k 1170/1/2 TA16 OPTIONAL ...
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... LT1 170/LT1 171/LT1172 PACKAGE DESCRIPTIO CORNER LEADS OPTION .045 – .068 (1.143 – 1.650) FULL LEAD OPTION .300 BSC (7.62 BSC) .008 – .018 (0.203 – 0.457) NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS .320 – .350 (19.30 – 19.69) (8.13 – 8.89) .420 – .480 (10.67 – ...
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... TYP .080 .420 .350 .205 .565 .320 .090 .042 RECOMMENDED SOLDER PAD LAYOUT FOR THICKER SOLDER PASTE APPLICATIONS LT1 170/LT1 171/LT1172 .400* (10.160) MAX .255 .015* (6.477 0.381) .020 MIN N8 0502 .165 – ...
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... LT1 170/LT1 171/LT1172 PACKAGE DESCRIPTIO .010 – .020 45 (0.254 – 0.508) .008 – .010 0 – 8 TYP (0.203 – 0.254) .016 – .050 (0.406 – 1.270) NOTE: INCHES 1. DIMENSIONS IN (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) ...
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... SEATING PLANE 0.152 – 0.202 (3.861 – 5.131) 0.260 – 0.320 (6.60 – 8.13) LT1 170/LT1 171/LT1172 0.165 – 0.180 (4.191 – 4.572) 0.045 – 0.055 (1.143 – 1.397) 0.620 (15.75) TYP 0.700 – 0.728 (17.78 – ...
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... LT1 170/LT1 171/LT1172 U TYPICAL APPLICATIO V IN 28V LT1170 GND + C5* 100 F * REQUIRED IF INPUT LEADS 2" RELATED PARTS PART NUMBER DESCRIPTION LT1070/LT1071/LT1072 5A/2.5A/1.25A High Efficiency Switching Regulators LT1074/LT1076 5.5A/2A Step-Down Switching Regulators LT1082 1A, High Voltage, High Efficiency Switching Regulator LT1268/LT1268B 7.5A, 150kHz Switching Regulators LT1269/LT1271 ...