lt3689-5 Linear Technology Corporation, lt3689-5 Datasheet
lt3689-5
Related parts for lt3689-5
lt3689-5 Summary of contents
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... Linear Technology Corporation. All other trademarks are the property of their respective owners. OUT BST 0.1μF 12μH 3.3V SW 700mA 10pF DA 316k FB RT 22μF SYNC 20.5k 100k f = 700kHz SW 3689 TA01 LT3689/LT3689-5 700mA Step-Down ® operation maintains high effi ciency at Effi ciency 90 1000 V = 12V 3.3V 80 OUT f = 700kHz 12μ 25° ...
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... LT3689/LT3689-5 ABSOLUTE MAXIMUM RATINGS V , EN/UVLO Voltage (Note 2) .................................60V IN BST Voltage ..............................................................60V BST Above SW Voltage .............................................30V OUT, WDE Voltage .....................................................30V FB, RT, SYNC, W/T, WDI, RST, WDO Voltage ............... Voltage .....................................................3V WDT POR PIN CONFIGURATION TOP VIEW WDO WDT 3 C POR SYNC ...
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... Fixed Undervoltage Lockout IN V Overvoltage Lockout IN Quiescent Current from V IN Quiescent Current from OUT LT3689-5 Quiescent Current from V LT3689-5 Quiescent Current from OUT LT3689 FB Voltage LT3689-5 Output Voltage LT3689 FB Pin Bias Current LT3689 FB Voltage Line Regulation LT3689-5 Output Voltage Line Regulation f ...
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... However, external pull-up resistors may be used when faster rise times are required or for V Note 7: Polarity specifi cation for all currents into pins is positive. All voltages are referenced to GND unless otherwise specifi ed. Note 8: For the LT3689-5, V Effi ciency 3.3V OUT ...
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... SYNC = 3. 0.1 0.2 0.3 0.4 0.5 0.7 LOAD CURRENT (A) Switch Current Limit vs Temperature 2.0 SYNC = LOW 1.5 SYNC = HIGH 1.0 0.5 0 100 –50 – 100 TEMPERATURE (°C) LT3689/LT3689-5 Maximum Load Current, 5V 1.4 TYPICAL 1.2 1.0 0.8 MINIMUM 0.6 0 25° 12μ 1MHz 0 125 150 (V) IN 3689 G05 Maximum Output Current, 3.3V 1 ...
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... LT3689/LT3689-5 TYPICAL PERFORMANCE CHARACTERISTICS BST Pin Current 125° –50° 25° 400 600 800 1000 0 200 SWITCH CURRENT (mA) 3689 G13 Switching Frequency 25° 0.8 1.2 1.6 2 0.4 FREQUENCY (MHz) 3689 G16 ...
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... I L 0.2A/DIV V SW 5V/DIV 5μs/DIV V = 12V, FRONT PAGE APPLICATION 6mA LOAD 0.730 0.725 0.720 0.715 3689 G28 0.710 LT3689/LT3689-5 Boost Diode Forward Voltage 900 800 T = –50°C A 700 600 T = 150°C A 500 400 300 200 100 ...
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... LT3689/LT3689-5 TYPICAL PERFORMANCE CHARACTERISTICS Transient Duration vs POR Comparator Overdrive 800 700 600 500 RESET OCCURS ABOVE THE CURVE 400 300 200 100 0 0.10 1.00 10.00 100.00 POR COMPARATOR OVERDRIVE VOLTAGE AS PERCENTAGE OF RESET THRESHOLD, V (%) RST 3689 G30 Reset Timeout Period 8.2nF POR MURATA: GRM2195C1H822FA01 ...
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... FB: The LT3689 regulates the feedback pin to 0.800V. Con- nect the feedback resistor divider tap to this pin. For the fi xed LT3689-5 output, this pin can be used to connect a phase lead capacitor between the OUT pin and FB pin to optimize transient response. ...
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... LT3689/LT3689-5 BLOCK DIAGRAM INTERNAL 0.8V REF EN/UVLO SYNC SOFT-START V OUT OUT LT3689-5 ERROR AMP ONLY R1 525k FB R2 100k WDE WDI W/T + 80mV FB – – 3. – + SLOPE COMP OSCILLATOR – TRANSITION WATCHDOG DETECT TIMER ADJUSTABLE RESET PULSE GENERATOR 22μ ...
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... WATCHDOG WINDOW MODE LOWER BOUNDARY PERIOD WDL V = OUTPUT VOLTAGE RESET THRESHOLD UV V OUT RST RST POWER-ON RESET TIMING t WDU WATCHDOG TIMING (W/T = HIGH), TIMEOUT MODE t t RST WDU WATCHDOG TIMING (W/T = LOW), WINDOW MODE GOES BELOW V OUT UV LT3689/LT3689-5 t RST t RST 3689 TD 3689fa 11 ...
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... LT3689/LT3689-5 OPERATION The LT3689 is a constant-frequency, current mode step- down regulator with a watchdog and a reset timer that allows microprocessor supervisory functions. Operation can be best understood by referring to the Block Diagram. Keeping the EN/UVLO pin at ground completely shuts off the part drawing minimal current from the V ...
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... The inductor current ramps value exceeding the load current and the output ripple increases. The part then remains off until the output voltage dips below the programmed value before it begins switching again. LT3689/LT3689-5 ) for a given application can be SW(MAX ...
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... LT3689/LT3689-5 APPLICATIONS INFORMATION Maximum Operating Voltage The maximum input voltage for LT3689 applications depends on switching frequency, the absolute maximum ratings of the V and BST pins, and by the minimum IN duty cycle (DC ). The LT3689 can operate from input MIN voltages up to 36V, and safely withstand input transient voltages up to 60V ...
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... I > 125°C, LIM(DA) J INDUCTANCE RANGE URL PART SERIES CDRH4D28 CDRH5D28 A916CY D585LC WE-TPC(M) WE-PD2(M) LT3689/LT3689 high output currents LIM(DA) . This will result in higher inductor ripple will increase as the output voltage collapses ( ) OUT D = 1.2A − • 0.25µs L SIZE (μ ...
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... LT3689/LT3689-5 APPLICATIONS INFORMATION Choose an inductor using the previous inductor selection equation to guarantee 700mA of output current. If using a smaller inductor, check the DA current limit equation to verify that the DA circuitry will not lower the switching frequency. When the switch is off, the potential across the inductor is the output voltage plus the catch diode drop ...
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... The ESR should be specifi the supplier and should be 0.1Ω or less. Such a capacitor will be larger than a ceramic capacitor and will have a larger capacitance because the LT3689/LT3689-5 capacitor must be large to achieve low ESR. Table 3 lists several capacitor vendors. Table 3. Capacitor Vendors ...
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... LT3689/LT3689-5 APPLICATIONS INFORMATION Table 4. Diode Vendors V R PART NUMBER (V) On Semiconductor MBRM120E 20 MBRM140 40 Diodes Inc. B120 20 B130 30 B140 40 B0540W 40 B140HB 40 Ceramic Capacitors Ceramic capacitors are small, robust and have very low ESR. However, ceramic capacitors can cause problems when used with the LT3689 due to their piezoelectric nature. When in Burst Mode operation, the LT3689’ ...
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... Because the LT3689 delivers power to the for good transient output with single, low current pulses, the output ripple is OUT kept below 15mV for a typical application. The LT3689-5 has a slightly higher output ripple of 25mV. This higher ripple can be reduced by using a larger output capacitor. In addition typically 50μ ...
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... LT3689/LT3689-5 APPLICATIONS INFORMATION BST and OUT Pin Considerations Capacitor C3 and the internal boost Schottky diode (see the Block Diagram) are used to generate a boost voltage that is higher than the input voltage. In most cases, a 0.1μF capacitor will work well. Figure 6 shows three ways to ar- range the boost circuit. The BST pin must be more than 2.3V above the SW pin for best effi ...
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... I VIN 0.2A/DIV 3689 F08 20μs/DIV V = 12V f = 2MHz 1μF CERAMIC + 100μF ELECTROLYTIC OUT IN Figure 8. Internal Soft-Start LT3689/LT3689 higher load OUT TO START: EN/UVLO TIED START: EN/UVLO HIGH THRESHOLD = 4.85V 10 100 1000 LOAD (mA) 3589 F07b f = 800KHz 25°C ...
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... LT3689/LT3689-5 APPLICATIONS INFORMATION Synchronization To select low ripple Burst Mode operation, tie the SYNC pin below 0.3V (this can be ground or a logic output). Synchro- nizing the LT3689 oscillator to an external frequency can be done by connecting a square wave (with positive and negative pulse width >80ns) to the SYNC pin. The square wave amplitude should have valleys that are below 0 ...
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... Typical Transient vs LT3689/LT3689-5 POR Comparator Overdrive in the Typical Performance Characteristics section). This prevents spurious resets caused by output voltage transients such as load steps or short brownout conditions without sacrifi ...
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... LT3689/LT3689-5 APPLICATIONS INFORMATION In both watchdog modes, when WDO is asserted, the reset timer is enabled. Any WDI pulses that appear while the reset timer is running are ignored. When the reset timer expires, the WDO is allowed to go high again. Therefore input is applied to the WDI pin, then the watchdog circuitry produces a train of pulses on the WDO pin ...
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... WDT V IN and t WDU WDL Figure 14. Diode D4 Prevents a Shorted Input from Discharging a Backup Battery Tied to the Output; It Also Protects the Circuit from a Reversed Input. The LT3689 Runs Only When the Input is Present LT3689/LT3689 3689 F13 10μs/DIV OUT V BST ...
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... LT3689/LT3689-5 APPLICATIONS INFORMATION the LT3689’s output. If the V pin is allowed to fl oat and IN the EN/UVLO pin is held high (either by a logic signal or because it is tied then the LT3689’s internal circuitry IN will pull its quiescent current through its SW pin. This is fi ...
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... BST WINDOW TIMEOUT WDE WDI SW LT3689 WDO RST WDT RT C SYNC POR GND = 182ms C5 WDU 68nF f = 1MHz 157ms RST LT3689/LT3689-5 , 700kHz switching frequency. At 700mA OUT C2 L1 0.1μF 12μH C4 5.6pF D1 R1 536k 5V 700mA C3 R2 10μF 102k R T 12.7k 3689 TA02 3689fa 27 ...
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... RT C SYNC POR GND = 182ms C5 68nF f = 700kHz 157ms RST 5V, 2MHz Step-Down Converter 1μF V EN/UVLO IN OUT W/T BST WDE WDI SW LT3689-5 WDO RST WDT RT C SYNC POR GND = 182ms C5 68nF f = 2MHz 157ms RST C2 L1 0.1μF 12μH C4 10pF D1 R1 316k 3 ...
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... MAX SEATING PLANE 0.17 – 0.27 (.007 – .011) 0.50 TYP (.0197) BSC LT3689/LT3689-5 8 0.35 REF 1.651 0.102 0.12 REF (.065 .004) DETAIL “B” CORNER TAIL IS PART OF DETAIL “B” THE LEADFRAME FEATURE. FOR REFERENCE ONLY 9 NO MEASUREMENT PURPOSE ...
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... LT3689/LT3689-5 PACKAGE DESCRIPTION 3.50 0.05 1.45 0.05 (4 SIDES) 2.10 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 0.10 PIN 1 TOP MARK (NOTE 6) NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WEED-2) 2. DRAWING NOT TO SCALE 3. 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 ...
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... DESCRIPTION A 04/10 Added LT3689-5 Fixed Output Voltage Option 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 representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...
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... LT3689/LT3689-5 TYPICAL APPLICATION 1.8V Step-Down Converter with System Reset Generated by L1: WE-PD2: 7447745047 D1: MBRM140 C1, C2, C3: X7R OR X5R RELATED PARTS PART NUMBER DESCRIPTION LT1766 60V, 1. 200kHz, High Effi ciency Step-Down DC/DC OUT Converter LT1936 36V, 1. 500kHz High Effi ciency Step-Down DC/DC OUT Converter LT1976/LT1977 60V, 1. 200kHz/500kHz, High Effi ...