LT3580 LINER [Linear Technology], LT3580 Datasheet
LT3580
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LT3580 Summary of contents
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... Additional features such as frequency foldback and soft- start are integrated. The LT3580 is available in tiny 3mm × 3mm 8-lead DFN and 8-lead MSOP packages. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. ...
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... For more information on tape and reel specifi cations, go to: 2 (Note 1) SYNC Voltage ............................................ –0.3V to 5.5V Operating Junction Temperature Range LT3580E (Notes 2, 5) .........................–40°C to 125°C LT3580I (Notes 2, 5) ..........................–40°C to 125°C Storage Temperature Range ...................–65°C to 150°C 8 SYNC 7 SS ...
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... Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT3580E is guaranteed to meet performance specifi cations from 0°C to 125°C junction temperature. 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 LT3580I is guaranteed over the full – ...
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... LT3580 TYPICAL PERFORMANCE CHARACTERISTICS Switch Current Limit at 1MHz 2.5 2.0 1.5 1.0 0 DUTY CYCLE (%) 3580 G01 Switch Current Limit at Minimum Duty Cycle 3.0 2.5 2.0 1.5 1.0 0.5 0 – 100 TEMPERATURE (°C) 3580 G04 Oscillator Frequency 2 35.7k T 2.5 2.3 2.1 1.9 1.7 1.5 1 75k T 1.1 – 100 TEMPERATURE (°C) 3580 G07 4 Switch Saturation Voltage ...
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... Drive this pin to less than 0.4V to revert to the internal free running clock. See the Applications Information section for more information. Exposed Pad (Pin 9): Ground. Must be soldered directly to local ground plane. LT3580 T = 25°C unless otherwise specifi Active/Lockout Threshold 1 ...
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... LT3580 BLOCK DIAGRAM SHDN 7 – 5 DISCHARGE + 1.3V DETECT UVLO SR2 1.215V 3 REFERENCE + 14.6k A1 – 14.6k A2 – 275k VC SOFT- START I COMPARATOR LIMIT – ∑ RAMP GENERATOR ÷N FREQUENCY ADJUSTABLE FOLDBACK OSCILLATOR SYNC BLOCK SYNC ...
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... FB pin is pulled up to the internal bias voltage of 1.215V by the R connected from V to FB. Comparator A2 becomes OUT inactive and comparator A1 performs the inverting ampli- fi cation from FB to VC. When the LT3580 inverting > V • ...
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... Current Limit and Thermal Shutdown Operation The LT3580 has a current limit circuit not shown in the Block Diagram. The switch current is consistently moni- tored and not allowed to exceed the maximum switch current at a given duty cycle (see the Electrical Charac- teristics table) ...
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... OUT D CESAT The LT3580 can be used in confi gurations where the duty cycle is higher than DC , but it must be operated in MAX the discontinuous conduction mode so that the effective duty cycle is reduced. Inductor Selection ) General Guidelines : The high frequency operation of the FB LT3580 allows for the use of small surface mount inductors ...
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... I exceeds the switch current limit capability OUT of the LT3580. Avoiding Subharmonic Oscillations : The LT3580’s internal slope compensation circuit will prevent subharmonic oscil- lations that can occur when the duty cycle is greater than 50%, provided that the inductance exceeds a minimum value. In applications that operate with duty cycles greater ...
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... ESR with greater output ripple. Ceramic capacitors also make a good choice for the input decoupling capacitor, which should be placed as closely as possible to the LT3580. A 2.2μF to 4.7μF input capacitor is suffi cient for most applications. Table 2 shows a list of several ceramic capacitor manufac- turers. Consult the manufacturers for detailed information on their entire selection of ceramic parts ...
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... APPLICATIONS INFORMATION Compensation—Theory Like all other current mode switching regulators, the LT3580 needs to be compensated for stable and effi cient operation. Two feedback loops are used in the LT3580— a fast current loop which does not require compensation, and a slower voltage loop which does. Standard bode plot analysis can be used to understand and adjust the voltage feedback loop ...
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... The operating frequency of the LT3580 can be synchro- nized to an external clock source. To synchronize to the external source, simply provide a digital clock signal into the SYNC pin. The LT3580 will operate at the SYNC clock 0 frequency. The LT3580 will revert to the internal free-run- –20 ning oscillator clock after SYNC is driven low for a few – ...
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... Figure 6. Chip States vs SHDN Voltage Confi gurable Undervoltage Lockout Figure 7 shows how to confi gure an undervoltage lock- out (UVLO) for the LT3580. Typically, UVLO is used in situations where the input supply is current-limited, has a relatively high source resistance, or ramps up/down slowly. A switching regulator draws constant power from the source, so source current increases as source voltage drops ...
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... Thermal Considerations For the LT3580 to deliver its full output power impera- is ≤10k ±1%. tive that a good thermal path be provided to dissipate the can be deter- UVLO1 heat generated within the package ...
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... BAC P = 84mW BDC P = 35mW INP Total LT3580 power dissipation (P Thermal resistance for the LT3580 is infl uenced by the pres- ence of internal, topside or backside planes. To calculate die temperature, use the appropriate thermal resistance number and add in worst-case ambient temperature θ • P ...
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... It is almost impossible to get rid of this noise, once present in the ground plane. The solu- tion is to tie D1’s cathode to the ground pin of the LT3580 before the combined currents are dumped in the ground plane as drawn in Figure 2, Figure 12 and Figure 13. This single layout technique can virtually eliminate high frequency “ ...
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... LT3580 APPLICATIONS INFORMATION GND OUT Figure 9. Suggested Component Placement for Boost Topology (Both DFN and MSOP Packages. Not to Scale). Pin 9 (Exposed Pad) must be soldered directly to the local ground plane for adequate thermal performance. Multiple vias to additional ground planes will improve thermal performance ...
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... LT3580 SYNC SS 10k C1 75k 0.1μF 2.2μF C1: 2.2μF , 25V, X5R, 1206 C2: 10μF , 25V, X5R, 1206 D1: MICROSEMI UPS120 L1: SUMIDA CDR6D23MN-4R2 Figure 14. 1.2MHz 12V Boost Converter LT3580 –V OUT C3 R LOAD + 3580 F12 –V OUT C3 R LOAD + 3580 F13 V OUT ...
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... FB VC SYNC SS 10k C1 121k 0.1μF 2.2μF 4.7nF C1, C2: 2.2μF , 25V, X5R, 1206 D1: MICROSEMI UPS140 L1: SUMIDA CDRH105R-470 C3 L1 1μF D1 4.7μH L2 4.7μ SHDN GND 46.4k LT3580 SYNC SS 10k 22pF 35.7k 0.1μF 1nF V OUT 12V 100μs/DIV IN V OUT 40V 150mA C2 2.2μ ...
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... D1-D4: ON SEMICONDUCTOR MBR0540 D5: MICROSEMI UPS140 L1: SUMIDA CDR6D28MNNP-100 R1, R2: 0.5W L1 10μH 3. SHDN LT3580 C1 GND 4.7μ SYNC SS 4.7μF 10k 45.3k 0.1μF 2.2nF LT3580 D1 V OUT2 95V R2 C5 80mA D2 10Ω 1μ 1μF OUT1 64V R1 40mA D4 C4 10Ω 1μ 1μF C3 1μ ...
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... D2: ON SEMICONDUCTOR MBR0540 T1: TDK LDT565630T-041 I AC COUPLED 1:10 • D1 4.7μH • SHDN GND R 4.22M* LT3580 SYNC SS 10k 100pF 464k 0.47μF 10nF 3580 TA05a Start-Up Waveforms PRIMARY 1A/DIV V OUT 50V/DIV 5V INPUT 2ms/DIV NO LOAD Switching Waveforms V ...
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... R 4.22M* FB LT3580 V OUT FB –350V VC 4.5mA (V SS 2.5mA (V 10k 100pF 0.47μF 10nF 3580 TA06 LT3580 FOR ANY V BETWEEN –50V TO OUT –350V, CHOOSE R ACCORDING OUT 83.3μA FOR 5V INPUT, KEEP MAXIMUM OUTPUT POWER AT 1.58W FOR 3.3V INPUT, KEEP MAXIMUM OUTPUT POWER AT 0.88W = 5V ...
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... Output Load Step V OUT 0.5V/DIV AC COUPLED I L 0.5A/DIV 100μs/DIV 3.3μ SHDN GND 130k LT3580 SYNC SS 10k C1 35.7k 0.1μF 4.7μF 2.2nF C1, C2: 4.7μF , 25V, X5R, 1206 D1: MICROSEMI UPS120 L1: COILCRAFT LPS4018-332ML Effi ciency and Power Loss vs Load Current 95 90 ...
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... Effi ciency and Power Loss vs Load Current 100 200 300 600 400 500 LOAD CURRENT (mA) 3580 TA08b LT3580 V OUT –5V 800mA (V = 12V) IN 620mA ( 450mA (V = 3.3V) 10μF IN 3580 TA08a 1200 1000 800 600 400 200 0 700 ...
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... LT3580 PACKAGE DESCRIPTION 3.5 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) 0.25 ± 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS PIN 1 TOP MARK (NOTE Package 8-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698) 0.675 ±0.05 PACKAGE OUTLINE 0.50 BSC 2.38 ±0.05 (2 SIDES) 3.00 ±0.10 1.65 ± 0.10 (4 SIDES) (2 SIDES) 0.75 ± ...
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... TYP 0.53 ± 0.152 (.021 ± .006) (.043) DETAIL “A” MAX SEATING PLANE 0.22 – 0.38 (.009 – .015) TYP LT3580 BOTTOM VIEW OF EXPOSED PAD OPTION 2.06 ± 0.102 (.081 ± .004) 1 1.83 ± 0.102 (.072 ± .004) 8 0.52 (.0205) 8 ...
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... Inverting Converter Generates –12V from 12V Input C3 L1 1μF 10μ 12V SHDN GND LT3580 SYNC SS C1 45.3k 0.1μF 2.2μF C1: 2.2μF , 25V, X5R, 1206 C2: 10μF , 25V, X5R, 1206 C3: 1μF , 50V, X5R, 0805 D1: CENTRAL SEMI CMMSH1-40 ...