lt3150 Linear Technology Corporation, lt3150 Datasheet
lt3150
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lt3150 Summary of contents
Page 1
... Selection of the N-channel MOSFET R 300mV for low V The LT3150 includes a fixed frequency boost regulator that generates gate drive for the N-channel MOSFET. The internally compensated current mode PWM architecture combined with the 1.4MHz switching frequency permits the use of tiny, low cost capacitors and inductors. The LT3150’ ...
Page 2
... Current Flows into Pin SHDN1 V = 0V, Current Flows into Pin SHDN1 10V V 20V IN2 FB2 = V , Current Flows out of Pin FB2 ORDER PART NUMBER 16 FB1 15 GND LT3150CGN 14 SHDN1 13 I POS 12 I NEG GN PART 11 GATE NC MARKING 10 9 COMP 3150 = 40 C ...
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... POS Current Flows Into Pin Current Flows Out of Pin Note 3: Switch current limit is guaranteed by design and/or correlation to static test. and power Note 4: The V of the external MOSFET must be greater than A GS(th) 3V – OUT LT3150 = MIN TYP MAX UNITS 2 – ...
Page 4
... LT3150 W U TYPICAL PERFOR A CE CHARACTERISTICS Boost Switching Regulator Switch V vs Switch Current CESAT 700 600 500 400 300 200 100 0 0 100 200 300 400 500 600 SWITCH CURRENT (mA) 3150 G01 Switch Current Limit vs Duty Cycle 1000 900 ...
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... Current Limit Threshold Voltage Line Regulation vs Temperature 0 – 0.1 – 0.2 – 0.3 – 0.4 – 0.5 175 –75 – 50 – 100 TEMPERATURE ( C) LT3150 Linear Regulator Controller Gain and Phase vs Frequency 200 150 PHASE 100 GAIN 10k 100k 1M 150 175 FREQUENCY (Hz) 3150 G10 – ...
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... LT3150 W U TYPICAL PERFOR A CE CHARACTERISTICS SHDN2 Source Current vs Temperature –10 – 11 – 12 – 13 – 14 – 15 – 16 – 17 – 18 – 19 – 20 –75 – 50 – TEMPERATURE ( C) SHDN2 High Clamp Voltage vs Temperature 2.1 2.0 1.9 1.8 1.7 1.6 1.5 –75 – 50 – TEMPERATURE ( CTIO S SW (Pin 1): Boost Converter Switch Pin. Connect induc- tor/diode here ...
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... Connect resistive divider tap here. Minimize trace area at FB1. Set 1.23V(1 + R1/R2). OUT trademark of Linear Technology Corporation. SENSE LT3150 and I pins. A 50mV POS NEG to defeat current limit. An alternative pin. This action disables the current supply voltage and terminates ...
Page 8
... LT3150 W BLOCK DIAGRA IN1 IN1 R5 R6 40k 40k V IN2 R1 (EXTERNAL) FB1 Q1 Q2 FB1 16 x10 R2 R3 (EXTERNAL) 30k R4 GND 140k SW1 NORMALLY SHDN2 OPEN SW2 NORMALLY CLOSED V IN2 START-UP 5 GND V 6 OUT R7 (EXTERNAL) FB2 FB2 8 R8 ...
Page 9
... W U The LT3150 controller unique, easy-to-use device that drives an external N-channel MOSFET as a source follower and realizes an extremely low dropout, ultrafast transient response regulator. The circuit achieves supe- ...
Page 10
... Input supply disturbances do not propagate through to the output. The feedback loop for a regulator circuit is completed by providing an error signal to the FB2 pin. A resistor divider network senses the output voltage and sets the regulated DC bias point. In general, the LT3150 stage regulator feedback loop permits a loop crossover frequency m on the order of 1MHz while maintaining good phase and gain margins ...
Page 11
... Schottky diode D1 clamps the amplifier’s output and prevents Q5 from pulling down the COMP node. In addition, Schottky diode D2 turns off pull-down transistor Q4 normally on and LT3150 LT3150 supply voltage as long as an IN2 . Pulling the REF turns off the 15 A pull-up current ...
Page 12
... BOOST REGULATOR COMPONENT SELECTION Diode Linear Technology recommends the use of a Schottky diode with the LT3150. For input supply voltages less than 2V, the Motorola MBR0520 or equivalent is a good choice due to its small size, low cost and low forward voltage. The average diode current equals the V 12mA typically ...
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... LINEAR REGULATOR COMPONENT SELECTION Output Capacitors The LT3150 linear regulator is stable with a wide range of output capacitors (assuming the feedback loop is prop- erly frequency compensated). However, using multiple, low value, very low ESR ceramic capacitors ( 4 parallel optimizes the load transient response of an LT3150 feedback loop ...
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... APPLICATIO S I FOR ATIO Figures 1 and 2 show voltage coefficient and temperature coefficient comparisons between Y5V and X5R material. With the critical pole in the LT3150 feedback loop being set by the absolute value of the output capacitor obvious why Linear Technology strongly recommends the use of ceramic capacitors with X5R or X7R dielectric material ...
Page 15
... Frequency compensation is accomplished with a passive network tied from the LT3150’s COMP pin to ground. The LT3150 generally employs a Type-2 frequency compensa- tion method. The “Type-2” method uses two poles and one zero ...
Page 16
... LT3150 U U APPLICATIO S I FOR ATIO P1 = 1/(2 • • R • C1) O AVOL = g • R • REF OUT Z1 = 1/(2 • • R1 • C1 (Q1)/(2 • • AV1 = g I LOAD(MIN) FREQUENCY (Hz) MANY HIGH ORDER POLES AND ZEROS PAST UNITY-GAIN (Q1) REF • ...
Page 17
... R3 100k * A(t)/1.11V t = SHUTDOWN LATCH-OFF TIME Current Limit with Foldback Limiting Example SET R5 << 3150 TA05 OUT V SHDN2 IN1 C1* 3150 TA07 SHDN2 C2* 3150 TA09 LT3150 Using No R Current Limit SENSE D1 MBR0520L SHDN2 I V POS IN1 NEG Q1 GATE ...
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... GND I 5.1 NEG Si4410 GND GATE FB2 COMP 1.5k 6800pF 50pF C : PANASONIC SP SERIES EEFUE0E221R 20% IN C1: AVX TAJA475M020R 20V 20% L1: MURATA LQH32CN100K11 OR SUMIDA CDRH3D16100 2.5V to 1.8V, 1.7A Low Dropout Linear Regulator MBR0520L L1 6.65k LT3150 IN2 FB1 V IN1 SHDN2 SHDN1 1.37k 1% SWGND I POS GND I 5.1 NEG Si4410 ...
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... TYP .015 .004 45 .053 – .068 (0.38 0.10) (1.351 – 1.727) 0 – 8 TYP .008 – .012 (0.203 – 0.305) LT3150 .189 – .196* (4.801 – 4.978) .009 (0.229 REF .150 – .157** (3.810 – 3.988) ...
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... Synchronous Step-Down OUT DC/DC Converter LTC3412 2.5A(I ), 4MHz, Synchronous Step-Down OUT DC/DC Converter Linear Technology Corporation 20 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 SENSE MBR0520L LT3150 V SW IN2 SHDN1 FB1 V IN1 SHDN2 SHDN1 SWGND I POS 0. GND I NEG ...