Datasheet LTC3649 (Analog Devices) - 8
| Fabricante | Analog Devices |
| Descripción | 60V, 4A Synchronous Step-Down Regulator with Rail-to-Rail Programmable Output |
| Páginas / Página | 26 / 8 — FUNCTIONAL DIAGRAM. OPERATION. Main Control Loop |
| Formato / tamaño de archivo | PDF / 1.7 Mb |
| Idioma del documento | Inglés |
FUNCTIONAL DIAGRAM. OPERATION. Main Control Loop
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LTC3649
FUNCTIONAL DIAGRAM
BOOST VIN INTVCC EXTVCC 1/50k PEAK CURRENT REVERSE VIN COMPARATOR COMPARATOR – LDO + 0A 50µA ISET + + VOUT – – + 1/40k IMON ITH SW – BUCK LOGIC INTV AND CC PGDFB 2V + 2V VINREG + GATE DRIVE – PGOOD PGOOD LOGIC MODE/SYNC CLK RT OSC RUN SGND PGND 3649 FD
OPERATION
The LTC3649 is a current mode monolithic step-down
Main Control Loop
regulator. The accurate 50µA bias current on the ISET pin In normal operation, the internal top power MOSFET is allows the user to program the output voltage in a unity- turned on at the beginning of a clock pulse. The inductor gain buffer fashion with just one external resistor from the current is allowed to ramp up to a peak level. Once that ISET pin to GND (RSET). The output voltage is set such that: level is reached, the top power switch is turned off and VOUT = 50µA • RSET the bottom switch is turned on until the next clock cycle. The LTC3649 operates through a wide V The peak inductor current is determined by sensing the IN range, and its frequency can be programmed to a wide range with the R voltage drop across the SW and VIN nodes of the top power T resistor. To suit a variety of applications, the MODE/SYNC MOSFET. The voltage on the ITH pin sets the comparator pin allows the user to trade off output ripple for efficiency. threshold corresponding to inductor peak current. The error amplifier, EA, adjusts this ITH voltage by comparing the VOUT voltage with the voltage on ISET. If the load current increases, it causes a drop in VOUT relative to VISET. This causes the ITH voltage to rise until the average inductor current matches that of the load current. 3649fb 8 For more information www.linear.com/LTC3649 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
FUNCTIONAL DIAGRAM
BOOST VIN INTVCC EXTVCC 1/50k PEAK CURRENT REVERSE VIN COMPARATOR COMPARATOR – LDO + 0A 50µA ISET + + VOUT – – + 1/40k IMON ITH SW – BUCK LOGIC INTV AND CC PGDFB 2V + 2V VINREG + GATE DRIVE – PGOOD PGOOD LOGIC MODE/SYNC CLK RT OSC RUN SGND PGND 3649 FD
OPERATION
The LTC3649 is a current mode monolithic step-down
Main Control Loop
regulator. The accurate 50µA bias current on the ISET pin In normal operation, the internal top power MOSFET is allows the user to program the output voltage in a unity- turned on at the beginning of a clock pulse. The inductor gain buffer fashion with just one external resistor from the current is allowed to ramp up to a peak level. Once that ISET pin to GND (RSET). The output voltage is set such that: level is reached, the top power switch is turned off and VOUT = 50µA • RSET the bottom switch is turned on until the next clock cycle. The LTC3649 operates through a wide V The peak inductor current is determined by sensing the IN range, and its frequency can be programmed to a wide range with the R voltage drop across the SW and VIN nodes of the top power T resistor. To suit a variety of applications, the MODE/SYNC MOSFET. The voltage on the ITH pin sets the comparator pin allows the user to trade off output ripple for efficiency. threshold corresponding to inductor peak current. The error amplifier, EA, adjusts this ITH voltage by comparing the VOUT voltage with the voltage on ISET. If the load current increases, it causes a drop in VOUT relative to VISET. This causes the ITH voltage to rise until the average inductor current matches that of the load current. 3649fb 8 For more information www.linear.com/LTC3649 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts