LT1375HV Linear Technology, LT1375HV Datasheet

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... Standard surface mount external parts are used, includ- ing the inductor and capacitors. For low input voltage applications with 3.3V output, see LT1507. This is a functionally identical part that can operate with input voltages between 4.5V and 12V. , LTC and LT are registered trademarks of Linear Technology Corporation. D2 1N914 C2 0.1 F ...

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... LT1375/LT1376 ABSOLUTE MAXIMUM Input Voltage LT1375/LT1376 .................................................. 25V LT1375HV/LT1376HV ........................................ 30V BOOST Pin Voltage LT1375/LT1376 .................................................. 35V LT1375HV/LT1376HV ........................................ 40V SHDN Pin Voltage ..................................................... 7V BIAS Pin Voltage ...................................................... 7V FB Pin Voltage (Adjustable Part) ............................ 3.5V FB Pin Current (Adjustable Part) ............................ 1mA U PACKAGE/ORDER INFORMATION TOP VIEW BOOST ...

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... 15V 1.5V, boost open, switch open CONDITIONS All Conditions All Conditions 5V V 25V 30V (LT1375HV/LT1376HV (Notes 2, 8) SHDN (Note 8) SHDN 1V 2. 4.4V SHDN FB ...

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... CONDITIONS V Open Device Shutting Down C V Open LT1375HV/LT1376HV Device Shutting Down C LT1375HV/LT1376HV Device Starting current is the current drawn by the BIAS pin when the bias pin is held at 5V. Total input referred supply current is calculated by summing input supply current ( TOT ...

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W U TYPICAL PERFORMANCE CHARACTERISTICS Shutdown Pin Bias Current 500 CURRENT REQUIRED TO FORCE SHUTDOWN (FLOWS OUT OF PIN). AFTER SHUTDOWN, 400 CURRENT DROPS TO A FEW A 300 200 8 AT 2.38V STANDBY THRESHOLD (CURRENT FLOWS OUT OF PIN) ...

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LT1375/LT1376 W U TYPICAL PERFORMANCE CHARACTERISTICS Maximum Load Current 10V OUT 1. 10V OUT 1. 1.00 0. 0.50 0. ...

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PIN FUNCTIONS BIAS (LT1376 Only): The BIAS pin is used to improve efficiency when operating at higher input voltages and light load current. Connecting this pin to the regulated output voltage forces most of the internal circuitry ...

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LT1375/LT1376 W BLOCK DIAGRAM High switch efficiency is attained by using the BOOST pin to provide a voltage to the switch driver which is higher than the input voltage, allowing switch to be saturated. This boosted voltage is generated with ...

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U U APPLICATIONS INFORMATION LT1375/LT1376 AMPLIFIER Q2 V GND C Please read the following if divider resistors are increased above the suggested values OUT Table 1 OUTPUT R1 VOLTAGE R2 (NEAREST ...

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LT1375/LT1376 U U APPLICATIONS INFORMATION pin when output voltage is low. The equivalent circuitry is shown in Figure completely off during normal operation. If the FB pin falls below 1V, Q1 begins to conduct current and reduces ...

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U U APPLICATIONS INFORMATION Example: with 5V, and V OUT 500 10 • • I OUT MAX The main reason for using such ...

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... INFORMATION 5. After making an initial choice, consider the secondary things like output voltage ripple, second sourcing, etc. Use the experts in the Linear Technology’s applica- tions department if you feel uncertain about the final choice. They have experience with a wide range of inductor types and can tell you about the latest devel- opments in low profile, surface mounting, etc ...

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U U APPLICATIONS INFORMATION discharge surges, such as when the regulator output is dead shorted, do not harm the capacitors. Unlike the input capacitor, RMS ripple current in the output capacitor is normally low enough that ripple cur- rent rating ...

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LT1375/LT1376 U U APPLICATIONS INFORMATION regulator input voltage. Average forward current in normal operation can be calculated from OUT IN OUT I D AVG V IN This formula will not yield values higher than 1A with maximum ...

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U U APPLICATIONS INFORMATION IN INPUT latch low under low source voltage conditions. UVLO prevents the regulator from operating at source voltages where these problems might occur. Threshold voltage for lockout is about 2.38V, ...

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LT1375/LT1376 U U APPLICATIONS INFORMATION (magnetic) radiation is minimized by keeping catch diode, switch pin, and input bypass capacitor leads as short as possible. E field radiation is kept low by minimizing the length and area of all traces connected ...

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U U APPLICATIONS INFORMATION PARASITIC RESONANCE Resonance or “ringing” may sometimes be seen on the switch node (see Figure 7). Very high frequency ringing following switch rise time is caused by switch/diode/input capacitor lead inductance and diode capacitance. Schot- tky ...

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LT1375/LT1376 U U APPLICATIONS INFORMATION practice therefore to simply use the worst-case value and assume that RMS ripple current is one half of load current. At maximum output current of 1.5A for the LT1376, the input bypass capacitor should be ...

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U U APPLICATIONS INFORMATION 8.0 7.5 (A) (B) 7.0 (C) 6.5 6.0 (D) 5.5 5.0 0.001 0.01 0.1 LOAD CURRENT (A) Figure 9. Minimum Input Voltage C2 0.1 F BOOST INPUT LT1376-5 2N3905 + SENSE ...

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LT1375/LT1376 U U APPLICATIONS INFORMATION introduce multiple poles into the feedback loop. The inductor and output capacitor on a conventional step- down converter actually form a resonant tank circuit that can exhibit peaking and a rapid 180 phase shift at ...

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U U APPLICATIONS INFORMATION 77dB at low frequency, rolling off to unity-gain at 20kHz. Phase shows a two-pole characteristic until the ESR of the output capacitor brings it back above 10kHz. Phase mar- gin is about 60 at unity-gain. Analog ...

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LT1375/LT1376 U U APPLICATIONS INFORMATION How Do I Test Loop Stability? The “standard” compensation for LT1376 is a 3.3nF capacitor for C , with While this compensation will C C work for most applications, the “optimum” value ...

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U U APPLICATIONS INFORMATION Keep in mind that this procedure does not take initial component tolerance into account. You should see fairly clean response under all load and line conditions to ensure that component variations will not cause problems. One ...

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LT1375/LT1376 U U APPLICATIONS INFORMATION POSITIVE-TO-NEGATIVE CONVERTER The circuit in Figure classic positive-to-negative topology using a grounded inductor. It differs from the standard approach in the way the IC chip derives its feedback signal, however, because the ...

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U U APPLICATIONS INFORMATION INDUCTOR VALUE Unlike buck converters, positive-to-negative converters cannot use large inductor values to reduce output ripple voltage. At 500kHz, values larger than 25 H make almost no change in output ripple. The graph in Figure 19 ...

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LT1375/LT1376 U U APPLICATIONS INFORMATION of thumb here to make a final decision. If modest ripple is needed and the larger inductor does the trick, go for it. If ripple is noncritical use the smaller inductor. If ripple is extremely ...

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... MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...

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... LTC1174 High Efficiency Step-Down and Inverting DC/DC Converter LT1176 Step-Down Switching Regulator LT1372/LT1377 500kHz and 1MHz High Efficiency 1.5A Switching Regulators Burst Mode is a trademark of Linear Technology Corporation. Linear Technology Corporation 28 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear-tech.com U Dimensions in inches (millimeters) unless otherwise noted. ...