lt3430-1 Linear Technology Corporation, lt3430-1 Datasheet
lt3430-1
Related parts for lt3430-1
lt3430-1 Summary of contents
Page 1
... SYNC pin can be externally synchronized with a logic level input from 228kHz to 700kHz for the LT3430 or from 125kHz to 250kHz for the LT3430-1. The LT3430/LT3430-1 are available in a thermally enhanced 16-pin TSSOP package. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. ...
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... LT3430/LT3430-1 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Voltage (V ) .................................................. 60V IN BOOST Pin Above SW (Note 11) .............................. 35V BOOST Pin Voltage ................................................. 68V SYNC Voltage ............................................................. 7V ⎯ S ⎯ H ⎯ D ⎯ N Voltage ............................................................ 6V BIAS Pin Voltage ..................................................... 30V FB Pin Voltage/Current .................................. 3.5V/2mA Operating Junction Temperature Range LT3430EFE (Notes 8, 10) .................. –40°C to 125°C LT3430IFE (Notes 8, 10) .................. – ...
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... ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are Open Circuit, unless otherwise noted. PARAMETER Maximum Switch Duty Cycle (LT3430-1) Switch Frequency (LT3430) Switch Frequency (LT3430-1) f Line Regulation SW f Shifting Threshold SW Minimum Input Voltage Minimum Boost Voltage Boost Current (Note 5) ...
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... LT3430/LT3430-1 TYPICAL PERFORMANCE CHARACTERISTICS Switch Peak Current Limit 25° TYPICAL 4 GUARANTEED MINIMUM DUTY CYCLE (%) 3430 G01 Lockout and Shutdown Threshold 2.4 LOCKOUT 2.0 1.6 1.2 0.8 START-UP 0.4 SHUTDOWN 0 –50 – 100 JUNCTION TEMPERATURE (°C) 3430 G04 Error Amplifi er Transconductance ...
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... G13 Switch Minimum ON Time vs Temperature 600 500 400 300 200 100 0 75 100 125 –50 –25 3430 G16 LT3430/LT3430-1 BOOST Pin Current 90 = 25° 25° SWITCH CURRENT (A) 3430 G11 T = 125°C ...
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... It is directly logic compatible and can be driven with any signal between 10% and 90% duty cycle. The synchronizing range is 125kHz to 250kHz for the LT3430-1 and 228kHz to 700kHz for the LT3430. See Synchronizing in Applications Information for details. ⎯ S ⎯ H ⎯ D ⎯ N (Pin 15): The ⎯ S ⎯ H ⎯ D ⎯ N pin is used to turn off the regulator and to reduce input drain current to a few mi- croamperes ...
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... Most of the circuitry of the LT3430/LT3430-1 operates from an internal 2.9V bias line. The bias regulator normally draws power from the regulator input pin, but if the BIAS pin is connected to an external voltage equal to or higher fl ...
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... The suggested value for the LT3430 output divider resistor (see Figure 2) from FB to ground (R2 less, and a formula for R1 is shown below. For the LT3430-1, choose the resistors so that the Thevinin resistance of the divider at the feedback pin is 7.5kΩ. The output voltage error caused by ignoring the input bias current on the FB pin is less than 0 ...
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... Choosing the Inductor For most applications, the output inductor will fall into the range of 5µH to 47µH (10µH to 100µH for LT3430-1). Lower values are chosen to reduce physical size of the inductor. Higher values allow more output current because they reduce peak current seen by the LT3430/LT3430-1 switch, which has a 3A limit ...
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... If maximum load current is 1A, for instance induc- tor may not survive a continuous 4A overload condition. Dead shorts will actually be more gentle on the inductor /L because the LT3430/LT3430-1 have frequency and current IN limit foldback. Table 2 VENDOR/ PART NO. ...
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... Maximum Output Load Current Maximum load current for a buck converter is limited by the maximum switch current rating (I for the LT3430/LT3430-1 is 3A. Unlike most current mode converters, the LT3430/LT3430-1 maximum switch current limit does not fall off at high duty cycles. Most current mode converters suffer a drop off of peak switch current for duty cycles above 50% ...
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... If a higher output load current is required, the inductor value must be increased OUT(MAX) criteria, use the I the LT3430/LT3430-1 are designed to operate well in both modes of operation, allowing a large range of inductor values to be used – ...
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... LT3430 applications is 0.05Ω to 0.2Ω. A typical output capacitor is an AVX type TPS, 100µF at 10V, with a guaranteed ESR less than 0.1Ω (The LT3430-1 will typically use two of these capacitors in parallel). This is a “D” size surface mount solid tantalum capacitor. TPS capacitors are specially constructed and tested for low ESR, so they give the lowest ESR for a given volume ...
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... The rise and fall times of these pulses are very fast. The input capacitor is required to reduce the volt- age ripple this causes at the input of LT3430/LT3430-1 and force the switching current into a tight local loop, thereby minimizing EMI. The RMS ripple current can be ...
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... LT3430-1 a 1.5µF boost capacitor is recommended. SHUTDOWN FUNCTION AND UNDERVOLTAGE LOCKOUT Figure 4 shows how to add undervoltage lockout (UVLO) to the LT3430/LT3430-1. Typically, UVLO is used in situ- ations where the input supply is current limited, or has a relatively high source resistance. A switching regulator draws constant power from the source, so source cur- rent increases as source voltage drops ...
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... Application Note 19 has more details on the theory . of slope compensation. The LT3430-1 synchronizing range is from 125kHz to 250kHz (slope compensation loss oc- curs above 133kHz). At power-up, when V Figure 2, Q2), the sync function is disabled. This allows the frequency foldback to operate in the shorted output condition ...
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... At switch off, this parasitic inductance produces a fl yback spike across the LT3430/ LT3430-1 switch. When operating at higher currents and input voltages, with poor layout, this spike can generate voltages across the LT3430/LT3430-1 that may exceed its absolute maximum rating ...
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... FB components should be kept as far away as C possible from the switch and boost nodes. The LT3430/ LT3430-1 pinout has been designed to aid in this. The ground for these components should be separated from the switch current path. Failure will result in poor stability or subharmonic like oscillation. ...
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... Switch loss OUT OUT = + EFF V IN (Note: Switching losses are less for the LT3430-1 oper- ating at only 100kHz) Boost current loss OUT OUT = P BOOST V IN Quiescent current loss ...
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... IN losses. In general, the maximum and minimum V should be checked with maximum typical load current for calculation of the LT3430/LT3430-1 die temperature more accurate die temperature is required, a measure- ment of the SYNC pin resistance (to GND) can be used. The SYNC pin resistance can be measured by forcing a voltage no greater than 0 ...
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... DROOP Input Voltage vs Operating Frequency Considerations The absolute maximum input supply voltage for the LT3430/ LT3430-1 is specifi 60V. This is based solely on internal semiconductor junction breakdown effects. Due to internal power dissipation, the actual maximum V a particular application may be less than this. ...
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... In systems with a primary and backup supply, for example, a battery powered device with a wall adapter input, the ) can be F output of the LT3430/LT3430-1 can be held up by the pin to ground C backup supply with the LT3430/LT3430-1 input discon- nected. In this condition, the SW pin will source current ...
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... APPLICATIONS INFORMATION LT3430/LT3430-1 will consume their quiescent operating current of 1.5mA. The V pin will also source current to IN any other components connected to the input line. If this load is greater than 10mA or the input could be shorted to ground, a series Schottky diode must be added, as shown in Figure 12. With these safeguards, the output can be held at voltages up to the V absolute maximum rating ...
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... The circuit in Figure positive-to-negative topology using a grounded inductor. It differs from the standard approach in the way the IC chip derives its feedback signal because the LT3430/LT3430-1 accepts only posi- tive feedback signals. The ground pin must be tied to the regulated negative output. A resistor divider to the FB pin then provides the proper feedback voltage for the chip ...
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... L ≥15µH. It increases to about V ) OUT F 2.0 for smaller inductors at lower load currents. Capacitor 1.2 to 2.0 The output capacitor ripple current for the positive-to- negative converter is similar to that for a typical buck regulator— triangular waveform with peak-to-peak LT3430/LT3430 OUT ⎡ ⎛ ( ...
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... Care should be used if diodes rated less than 1A are used, especially if continuous overload conditions must be tolerated. 3.3V, 2A Buck Converter 6 1.5µF BOOST 30BQ060 LT3430 OFF ON SHDN BIAS 14 12 SYNC FB GND V C ...
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... BSC 4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT MILLIMETERS (INCHES) *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE LT3430/LT3430-1 4.90 – 5.10* (.193 – .201) 3.58 (.141) 16 1514 6.40 2.94 (.252) ( ...
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... LT3430/LT3430-1 RELATED PARTS PART NUMBER DESCRIPTION LT1074/LT1074HV 4. 100kHz, High Effi ciency Step-Down DC/DC OUT Converters LT1076/LT1076HV 1. 100kHz, High Effi ciency Step-Down DC/DC OUT Converters LT1676 60V, 440mA (I ), 100kHz, High Effi ciency Step-Down OUT DC/DC Converter LT1765 25V, 2.75A (I ), 1.25MHz, High Effi ciency Step-Down OUT ...