LT3581 LINER [Linear Technology], LT3581 Datasheet
LT3581
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LT3581 Summary of contents
Page 1
... The LT3581 is ideal for many local power supply designs. It can be easily configured in Boost, SEPIC, Inverting or Flyback configurations, and is capable of generating 12V at 830mA, or –12V at 625mA from a 5V input. In addition, the LT3581’s slave switch allows the part to be configured in high voltage, high power charge pump topologies that are very efficient and require fewer components than traditional circuits. The LT3581’ ...
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... FAULT Voltage ............................................ –0.3V to 40V FAULT Current .....................................................±500µA CLKOUT Voltage .......................................... –0. CLKOUT Current ......................................................1mA Operating Junction Temperature Range LT3581E (Notes 2, 4) ......................... –40°C to 125°C LT3581I (Notes 2, 4) .......................... –40°C to 125°C Storage Temperature Range .................. –65°C to 150°C 14 SYNC 13 SS ...
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... OSC Free-Running or Synchronizing SYNC At All Duty Cycles At All Duty Cycles, SW2/SW1 = 78% (Note 3) SW1 & SW2 Tied Together 2.75A SW1 SW2 SW1 SW2 LT3581 , unless otherwise noted. (Note 2). IN FAULT IN MIN TYP MAX 2.3 2.5 l 22.1 23.5 25 1.195 1.215 1 ...
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... Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT3581E is guaranteed to meet performance specifications from 0°C to 125°C. Specifications over the –40°C to 125°C junction temperature range are assured by design, characterization and correlation with statistical process controls ...
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... TEMPERATURE (°C) Frequency Foldback 1 1/2 1/3 1/4 1/5 1/6 INVERTING BOOSTING CONFIGURATIONS CONFIGURATIONS 0 0 0.2 0.4 0.6 0.8 1.0 FB VOLTAGE (V) LT3581 T = 25°C, unless otherwise noted. A Current Sharing Between SW1 and SW2 When Tied Together 100 SW1 + SW2 CURRENT (A) 3581 G02 CLKOUT Duty Cycle ...
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... LT3581 Typical perForMance characTerisTics Gate Current vs SS Voltage 1000 900 800 700 600 500 400 300 200 100 0 0 0.25 0.50 0.75 1.00 1.25 SS VOLTAGE (V) 3581 G10 SHDN Pin Current 32 28 25° 125°C 4 –40° 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 SHDN VOLTAGE (V) 3581 G13 CLKOUT Rise Time at 1MHz ...
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... CLKOUT (Pin 10/Pin 12): Clock Output Pin. Use this pin to synchronize one or more other compatible switching regulator ICs to the LT3581. The clock that this pin outputs runs at the same frequency as the internal oscillator of the part or as the SYNC pin. CLKOUT may also be used onverter temperature monitor since the CLKOUT pin’ ...
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... LDO SHDN + – 1.33V UVLO V IN 1.215V REFERENCE + 14.6k A1 – 14.6k A2 – **SW OVERVOLTAGE PROTECTION IS NOT GUARANTEED TO PROTECT THE LT3581 DURING SW OVERVOLTAGE EVENTS OUT1 R FAULT FAULT 22V 933µA DIE TEMP MIN V 165°C 750mV IN STARTUP AND FAULT – LOGIC + DRIVER ...
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... INTERNALLY BY LT3581 • SWITCHER DISABLED • CLKOUT DISABLED SS > 1.8V AND NO FAULT1 CONDITIONS STILL DETECTED POST FAULT DELAY • SS SLOWLY DISCHARGES FAULT1 SS < 50mV LOCAL FAULT OVER • INTERNAL FAULT PIN PULLDOWN FAULT1 RELEASED BY LT3581 • SS CONTINUES DISCHARGING TO GND FAULT PIN > 1.0V 3581 SD 3581f ...
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... The SHDN pin has 30mV of hysteresis to protect against glitches and slow ramping. Undervoltage Lockout (UVLO) The SHDN pin can also be used to create a configurable UVLO. The UVLO function sets the turn on/off of the LT3581 at a desired input voltage (V ). Figure 3 shows how a INUVLO ...
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... In this manner, the error amplifier sets the correct peak current level to maintain output regulation. As long as the part is not in fault (see Operation – Fault section) and the SS pin exceeds 1.8V, the LT3581 drives its CLKOUT pin at the frequency set by the RT pin or the SYNC pin. The CLKOUT pin can be used to synchronize other compatible switching regulator ICs (including additional LT3581s) with the LT3581. Additionally, CLKOUT’ ...
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... R FAULT the events that accompany the detection of an output short on the LT3581. V OUT 10V/DIV cut IN OUT V FAULT 5V/DIV V CLKOUT 2V/DIV I L 2A/DIV Figure 4. Output Short Circuit Protection of the LT3581 resistor (typically 100k). Figure 4 shows 3581 F04 5µs/DIV 3581f ...
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... Figure 5. This topology allows for positive output volt- ages that are higher than the input voltage. An external PMOS (optional) driven by the GATE pin of the LT3581 can achieve input or output disconnect during a fault event. A single feedback resistor sets the output voltage. For output voltages higher than 40V, see the Charge Pump Aided Regulators section ...
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... Given Are Typical Values for a 700kHz, Wide Input Range (3V to 16V) SEPIC Converter with 5V Out The LT3581 can also be configured as a SEPIC as shown in Figure 6. This topology allows for positive output voltages that are lower, equal, or higher than the input voltage. Out- ...
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... Values and Voltages Given Are Typical Values for a 2MHz –12V Inverting Topology Using Coupled Inductors Due to its unique FB pin, the LT3581 can work in a Dual Inductor Inverting configuration as in Figure 7. Changing the connections of L2 and the Schottky diode in the SEPIC topology results in generating negative output voltages ...
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... D1 C OUT 3581 F09 AND L2 GROUND DIRECTLY TO LT3581 EXPOSED PAD PIN 17 ADVISED IN AND L2 GROUND WITH GND EXCEPT AT THE EXPOSED PAD. IN GROUNDS DIRECTLY TO LT3581 EXPOSED PAD PIN 17 ADVISED OUT GROUND WITH GND EXCEPT AT THE EXPOSED PAD. OUT , and OUT1 ’ ...
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... OUT TO NOT COMBINE C GROUND WITH GND EXCEPT AT THE EXPOSED PAD. OUT C: RETURN D1 GROUND DIRECTLY TO LT3581 EXPOSED PAD PIN 17 ADVISED TO NOT COMBINE D1 GROUND WITH GND EXCEPT AT THE EXPOSED PAD. L1, L2: MOST COUPLED INDUCTOR MANUFACTURERS USE CROSS PINOUT FOR IMPROVED PERFORMANCE. Figure 10. Suggested Component Placement for Dual Inductor Inverting Topology (MSOP Shown, DFN Similar, Not to Scale ...
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... To get a temperature J diode charge, and other capacitive loss terms increase proportionally with frequency. Oscillator Timing Resistor (R The operating frequency of the LT3581 can be set by the internal free-running oscillator. When the SYNC pin is driven low (< 0.4V), the frequency of operation is set by a resistor J from the R capacitor resides inside the IC ...
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... The SYNC pin of the slave LT3581 is driven T by the CLKOUT pin of the master LT3581. Note that the RT pin of the slave LT3581 must have a resistor tied to ground. It takes a few clock cycles for the CLKOUT signal to begin oscillating, and it’s preferable for all LT3581s to have the same internal free-running frequency ...
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... High V Charge Pump Topology OUT The LT3581 can be used in a charge-pump topology as shown in Figure 12, multiplying the output of an inductive boost converter. The master switch (SW1) can be used to drive the inductive boost converter (first stage of charge pump), while the slave switch (SW2) can be used to drive one or more other charge pump stages ...
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... PMOS in series with V IN PMOS being driven by the GATE pin of the LT3581. Since the GATE pin pull-down current is linearly proportional to the SS voltage, and the SS charge up time is relatively slow, the GATE pin pull-down current will increase gradually, thereby turning on the external PMOS slowly ...
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... INDUCTOR SELECTION General Guidelines: The high frequency operation of the LT3581 allows for the use of small surface mount inductors. % For high efficiency, choose inductors with high frequency core material, such as ferrite, to reduce core losses. Also to improve efficiency, choose inductors with more volume for a given inductance ...
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... Negative values of L put load current, I capability of the LT3581. Avoiding Sub-Harmonic Oscillations The LT3581’s internal slope compensation circuit will prevent sub-harmonic oscillations that can occur when the duty cycle is greater than 50%, provided that the inductance exceeds a certain minimum value. In applica- ...
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... An external PMOS, controlled by the LT3581’s GATE pin, can be used to facilitate input or output disconnect. The GATE pin turns on the PMOS gradually during start-up (see Soft-Start of External PMOS in the Operation section), and turns the PMOS off when the LT3581 is in shutdown or in fault. of the chip as well as to the IN ...
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... PMOS is Fairchild Semiconductor SG COMPENSATION – ADJUSTMENT < compensate the feedback loop of the LT3581, a series resistor-capacitor network in parallel with an optional ≥ single capacitor should be connected from the V GND. For most applications, choose a series capacitor in the range of 1nF to 10nF with 2.2nF being a good starting value ...
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... COMPENSATION – THEORY Like all other current mode switching regulators, the LT3581 needs to be compensated for stable and efficient operation. Two feedback loops are used in the LT3581: a fast current loop which does not require compensation, and a slower is C voltage loop which does. Standard Bode plot analysis can be used to understand and adjust the voltage feedback loop ...
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... RHP zero Z3 to achieve adequate phase 1 • PL margin • 2 • Figure 17. Bode Plot for Example Boost Converter LT3581 VALUE UNITS COMMENT 14.5 Ω Application Specific 9.4 µF Application Specific 1 mΩ Application Specific 305 kΩ Not Adjustable 1000 pF Adjustable 56 pF Optional/Adjustable 0 ...
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... D1: DIODES INC. PD3S230H-7 L1: VISHAY IHLP1616 BZ-01-OR68 (ONLY 4.1mm 4.5mm 2mm 1.5µH C2 4.7µF SW1 SW2 130k 100k FAULT GATE SHDN CLKOUT RT V LT3581 C 56pF SYNC SS GND 0.1µF D2: VISHAY MSS2P3 L1: SUMIDA CDR6D28MN-IR5 M1: VISHAY SILICONIX SI7123DN V OUT AC-COUPLED 200mV/DIV 1A/DIV V SW 0.5A/DIV V CLKOUT ...
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... OUT1 50V/DIV I 0.5A/DIV V SS 1V/DIV 3581 TA04b Efficiency and Power Loss 12V TOTAL OUTPUT POWER (W) 3581 TA04d LT3581 V OUT2 97V C7 90mA (V = 9V) IN 140mA (V = 12V) 2.2µF IN 180mA (V = 16V OUT1 65V 60mA ( 2.2µF 70mA (V ...
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... 300 600 LOAD CURRENT (mA 2.2µF D1 3.3µH L2 3.3µH SW1 SW2 • LT3581 130k SHDN GATE 100k FAULT CLKOUT 100pF SYNC SS 43.2k GND 0.1µF C1: 3.3µF , 25V, X7R, 1206 C2: 2.2µF , 50V, X7R, 1206 C3: 10µF , 25V, X7R, 1210 ...
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... D2: CENTRAL SEMI CMMSH2-40 D3: DIODES INC. PD3S230H-7 L1, L2: COILCRAFT MSD7342-332MLB M1: 2N7002 Q1: MMBT3904 Wide Input Range SEPIC Can Ride Through V V BAT 10V/DIV V OUT 2V/DIV I L 2A/DIV 1600 3581 TA07b LT3581 C4 2.2µ OUT 3.3V 0.9A (3V < V < 9V) BAT 10k L2 1. 9V) BAT 3.3µH 470pF • ...
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... C4, C5: 10µF , 50V, X7R, 1210 D1 TO D5: DIODES INC. PD3S230H-7 L1: VISHAY IHLP-2525CZ-01-8R2 R1: 2.4k, 2W 700kHz, –5V Inverting Converter Can Accept Input Voltages from 3V to 16V C2 L1 1µF 3.3µ 16V SW1 SW2 LT3581 SHDN GATE C1 100k 22µF FAULT CLKOUT ...
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... D1: DIODES INC. B230LA L1, L2: COILCRAFT MSD7342-332MLB OUT 1.5A (12V ≤ V ≤ 16V) IN 3.3µH • 45.3k C3 22µF 2 100pF 7.87k 1µF 2.2nF 3581 TA10a LT3581 Efficiency 3. 12V 16V 400 800 1200 1600 LOAD CURRENT (mA) ...
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... LT3581 package DescripTion 2.845 0.102 (.112 .004) 5.23 (.206) MIN 0.305 0.038 (.0120 .0015) TYP RECOMMENDED SOLDER PAD LAYOUT DETAIL “A” 0.254 (.010) GAUGE PLANE 0.18 (.007) NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. ...
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... ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE LT3581 R = 0.115 0.40 0.10 TYP ...
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... LT3581 Typical applicaTion 5V to –12V Inverting Converter Switches at 2MHz C2 L1 1µF 3.3µ SW1 SW2 LT3581 SHDN GATE C1 100k 3.3µF FAULT CLKOUT SYNC SS 43.2k GND C1: 3.3µF , 16V, X7R, 1206 C2: 1µF , 25V, X7R, 1206 C3: 4.7µF , 25V, X7R, 1206 D1: DIODES INC. PD3S230H-7 ...