LT1576IS8-5SYNC Linear Technology, LT1576IS8-5SYNC Datasheet

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... There is an optional function of shutdown or synchronization. Standard surface mount external parts can be used including the inductor and capacitors. , LTC and LT are registered trademarks of Linear Technology Corporation 1N914 L1** ...

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... ORDER PART NUMBER LT1576CS8 LT1576CS8-SYNC TOP VIEW LT1576IS8 SHDN OR LT1576IS8-SYNC 8 SYNC* LT1576CS8 SENSE LT1576CS8-5 SYNC C BIAS 5 LT1576IS8-5 LT1576IS8-5 SYNC S8 PACKAGE S8 PART MARKING 1576 1576SN 1576I 576ISN + 5V, switch open, unless otherwise noted. IN MIN TYP MAX 1.195 1.21 1.225 1.18 1.24 4.94 5.0 5 ...

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ELECTRICAL CHARACTERISTICS range, otherwise specifications are PARAMETER Minimum Switch Duty Cycle (Note 10) Switch Frequency Switch Frequency Line Regulation Frequency Shifting Threshold on FB Pin Minimum Input Voltage (Note 3) Minimum Boost Voltage (Note 4) Boost ...

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LT1576/LT1576 TYPICAL PERFORMANCE CHARACTERISTICS Switch Drop 0.5 125 C 0 0.3 –20 C 0.2 0 0.50 0.75 1.00 1.25 1.50 0.25 SWITCH CURRENT (A) 1576 G01 Shutdown Pin Bias Current 4 AT 2.44V STANDBY ...

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W U TYPICAL PERFORMANCE CHARACTERISTICS Shutdown Supply Current 100 25V 10V 0.1 0.2 0.3 0.4 SHUTDOWN VOLTAGE (V) 1576 G10 Switching Frequency 240 220 200 180 160 –50 –25 ...

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LT1576/LT1576 TYPICAL PERFORMANCE CHARACTERISTICS BOOST Pin Current 0.50 0.25 SWITCH CURRENT ( PIN FUNCTIONS V (Pin 1): The switch pin is the emitter of the on-chip SW ...

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PIN FUNCTIONS This pin sits at about 1V for very light loads and 2V at maximum load. It can be driven to ground to shut off the regulator, but if driven high, current must be limited to ...

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LT1576/LT1576-5 W BLOCK DIAGRAM INPUT 2.9V BIAS INTERNAL BIAS REGULATOR V CC SLOPE COMP 200kHz SYNC OSCILLATOR SHUTDOWN COMPARATOR – + 0.4V SHDN 3 – LOCKOUT COMPARATOR 2.44V U U APPLICATIONS INFORMATION FEEDBACK PIN FUNCTIONS The feedback (FB) ...

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U U APPLICATIONS INFORMATION Table 1 OUTPUT R1 VOLTAGE R2 (NEAREST 1%) ( 4.99 7.32 3.3 4.99 8.66 5 4.99 15.8 6 4.99 19.6 8 4.99 28.0 10 4.99 36.5 12 4.99 44.2 15 4.99 ...

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LT1576/LT1576 APPLICATIONS INFORMATION The internal circuitry which forces reduced switching frequency also causes current to flow out of the feedback pin when output voltage is low. The equivalent circuitry is shown in Figure completely off ...

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U U APPLICATIONS INFORMATION OUT(MAX Discontinuous mode 2 V OUT Example: with 5V, and V OUT 200 OUT MAX 2 5 ...

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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 Output Capacitor Ripple Current (RMS OUT IN I RIPPLE RMS Ceramic Capacitors Higher value, lower cost ceramic capacitors are now becoming available in smaller case sizes. These are ...

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LT1576/LT1576 APPLICATIONS INFORMATION This formula will not yield values higher than 1A with maximum load current of 1.25A unless the ratio of input to output voltage exceeds 5:1. The only reason to consider a larger diode is the ...

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U U APPLICATIONS INFORMATION INPUT SHDN Threshold voltage for lockout is about 2.44V. A 3.5 A bias current flows out of the pin at threshold. This internally generated current is used to force a ...

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LT1576/LT1576 APPLICATIONS INFORMATION SWITCH NODE CONSIDERATIONS For maximum efficiency, switch rise and fall times are made as short as possible. To prevent radiation and high frequency resonance problems, proper layout of the com- ponents connected to the switch ...

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U U APPLICATIONS INFORMATION including the switch, catch diode, and input capacitor is the only one containing nanosecond rise and fall times. If you follow this path on the PC layout, you will see that it is irreducibly short. If ...

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LT1576/LT1576 APPLICATIONS INFORMATION guarantee power sharing. The actual value of the capacitor in microfarads is not particularly important because at 200kHz, any value above essentially resistive. RMS ripple current rating is the critical parameter. Actual ...

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U U APPLICATIONS INFORMATION At power-up, when V is being clamped by the FB pin (see C Figure 2, Q2), the sync function is disabled. This allows the frequency foldback to operate in the shorted output con- dition. During normal ...

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LT1576/LT1576 APPLICATIONS INFORMATION the output. Gain is set by the 1.5A/V transconductance of the LT1576 power section and the effective complex impedance from output to ground. Gain rolls off smoothly above the 160Hz pole frequency set by the ...

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U U APPLICATIONS INFORMATION Analog experts will note that around 7kHz, phase dips close to the zero phase margin line. This is typical of switching regulators, especially those that operate over a wide range of loads. This region of low ...

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LT1576/LT1576 APPLICATIONS INFORMATION How Do I Test Loop Stability? The “standard” compensation for LT1576 is a 100pF capacitor for C , with While this compensation C C will work for most applications, the “optimum” ...

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U U APPLICATIONS INFORMATION The output of the regulator contains both the desired low frequency transient information and a reasonable amount of high frequency (200kHz) ripple. The ripple makes it difficult to observe the small transient two-pole, 100kHz ...

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LT1576/LT1576 APPLICATIONS INFORMATION with large inductors. Output ripple voltage for the positive- to-negative converter will be much higher than a buck converter. Ripple current in the output capacitor will also be much higher. The following equations can be ...

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U U APPLICATIONS INFORMATION inductor is therefore typically based on ensuring that peak switch current rating is not exceeded. This gives the lowest value of inductance that can be used, but in some cases (lower output load currents) it may ...

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LT1576/LT1576 APPLICATIONS INFORMATION Ripple Current in the Input and Output Capacitors Positive-to-negative converters have high ripple current in both the input and output capacitors. For long capacitor lifetime, the RMS value of this current must be less than ...

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... FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 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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... High Efficiency Step-Down Converter LT1676/LT1776 High Efficiency Step-Down Switching Regulators LT1777 Low Noise Step-Down Switching Regulator 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 losses. C4 provides a low impedance path to maintain an equal voltage swing in L1B, improving regulation flyback converter, during switch on time, all the converter’ ...