lt3570 Linear Technology Corporation, lt3570 Datasheet
lt3570
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lt3570 Summary of contents
Page 1
... LDO controller. Each converter is designed with a 1.5A current limit and an input range from 2.5V to 36V, making the LT3570 ideal for a wide variety of applications. Switching frequencies up to 2MHz are programmed with an external timing resistor and the oscillator can be synchronized to an external clock ...
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... LT3570IUF#PBF LT3570IUF#TRPBF LT3570EFE#PBF LT3570EFE#TRPBF LT3570IFE#PBF LT3570IFE#TRPBF Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container. Consult LTC Marketing for information on non-standard lead based fi nish parts. For more information on lead free part marking, go to: For more information on tape and reel specifi ...
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... 7.87k 2.5V to 40V VIN1,2,3 C1 800mV (Note 6) FB1,2 C1 800mV (Note 6) FB3 V = 500mV SS1 600mV FB1 FB1,2 (Note (Note 7) SW1 SW1 = 40V SHDN1 LT3570 = 12V unless otherwise noted. MIN TYP MAX l 2.1 2.5 l 2.1 2.5 0 1.5 3.2 4.5 65 150 3.5 4.5 3.5 4.5 700 950 0 1.5 2.3 3.1 0.3 1.4 l 1.1 1.25 1 ...
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... Specifi cations over the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LT3570I is guaranteed over the full –40°C to 125°C operating junction temperature range. Note 3: V supplies power for the part ...
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... TEMPERATURE (° 125° 25° –40° 100 3570 G10 LT3570 V Quiescent Current IN3 vs Temperature 900 800 700 600 500 400 300 200 100 0 –50 – 125 150 TEMPERATURE (°C) ...
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... LT3570 TYPICAL PERFORMANCE CHARACTERISTICS SW2 Current Limit vs Duty Cycle 3.0 2.5 2.0 1.5 1.0 0 DUTY CYCLE (%) BOOST Pin Current vs Switch Current 25° –40° 0.2 0.4 CURRENT (A) 6 350 300 250 200 150 100 T = 125° 25°C ...
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... Input Voltage for the Buck Regulator. IN2 This pin also supplies the current to the internal circuitry of the LT3570. This pin must be locally bypassed with a capacitor. SW2 (Pin 3/Pin15): Switch Node. This pin connects to the emitter of an internal NPN power switch. Connect a ...
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... LT3570 BLOCK DIAGRAM 8 3570fa ...
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... NPN LDO regula- tor. Operation can be best understood by referring to the Block Diagram. If all of the SHDN pins are held low, the LT3570 is shut down and draws zero quiescent current. When any of the pins exceed 1.4V the internal bias circuits turn on. Each regulator will only begin regulating when its corresponding SHDN pin is pulled high ...
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... The LT3570 limits its switch cur- rent in order to protect itself and the system from overload faults. Therefore, the maximum output current that the LT3570 will deliver depends on the switch current limit, DCR HEIGHT (Ω) (mm) the inductor value and the input and output voltages ...
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... Then use these equations to check that the LT3570 will be able to deliver the required output current. Note again that these equations assume that the inductor current is continu- ous. Discontinuous operation occurs when I than Δ ...
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... Table 2 lists several capacitor vendors. Buck Input Capacitor Selection Bypass the input of the LT3570 circuit with a 10μF or higher ceramic capacitor of X7R or X5R type. A lower value or a less expensive Y5V type will work if there is additional bypassing provided by bulk electrolytic capaci- tors the input source impedance is low ...
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... OUT2 Considering that the maximum load current is ~1.5A, RMS ripple current will always be less than 0.75A. The high frequency of the LT3570 reduces the energy storage requirements of the input capacitor, so that the capacitance required is often less than 10μF . The combi- nation of small size and low impedance (low equivalent series resistance or ESR) of ceramic capacitors makes them the preferred choice ...
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... The LT3570 uses current mode control to regulate the output. This simplifi es loop compensation. In particular, the LT3570 does not depend on the ESR of the output capaci- tor for stability so you are free to use ceramic capacitors to achieve low output ripple and small circuit size. ...
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... SS is less than approximately 100mV. I 500mA/DIV V 3570 F03a I OUT 500mA/DIV V OUT 200μs/DIV Figure 3c. Transient Response Well Damped LT3570 and ms. In the event OUT OUT 3570 F03b 200μs/DIV Figure 3b. Transient Response is Better 3570 F03c 3570fa 15 ...
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... If the current through the inductor exceeds the current limit of the LT3570, the switch is prevented from turning on for 10μs allowing the inductor current to decrease. The 10μs off-time limits the average current that can be delivered to the load ...
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... QFN package which shows the topside metal from the DC1106A demonstration board. Thermal Considerations To deliver the power that the LT3570 is capable of imperative that a good thermal path be provided to dissipate the heat generated within the package. This can be accomplished by taking advantage of the large ther- mal pad on the underside of the IC ...
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... GND T R9 20.0k “Dying Gasp” System C10 0.1μ BIAS IN1 IN2 IN3 SHDN1 BOOST C8 SHDN2 100nF SHDN3 SW2 D2 SW1 FB2 SS2 V C2 LT3570 R8 FB1 51k SS1 1nF R7 20k NPN_DRV C6 1nF FB3 R SYNC GND T R9 44. OUT2 10μH ...
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... TYP 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 LT3570 BOTTOM VIEW—EXPOSED PAD R = 0.115 TYP 23 24 0.40 ± 0. 2.45 ± 0.10 ...
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... PDA Core BIAS IN1 IN2 IN3 SHDN1 SHDN1 BOOST SHDN2 SHDN2 SHDN3 SHDN3 SW2 L1 D1 12μH SW1 FB2 SS2 191k LT3570 FB1 R2 SS1 10. 25k NPN_DRV C6 1nF C4 10nF FB3 R SYNC GND T R9 20k COMMENTS 3V to 25V Input, V MSOP Package V IN ...