Datasheet LTC3854 (Analog Devices) - 7
| Fabricante | Analog Devices |
| Descripción | Small Footprint, Wide VIN Range Synchronous Step-Down DC/DC Controller |
| Páginas / Página | 28 / 7 — PIN FUNCTIONS. FB (Pin 1):. GND (Pin 7):. ITH (Pin 2):. BG (Pin 8):. … |
| Formato / tamaño de archivo | PDF / 547 Kb |
| Idioma del documento | Inglés |
PIN FUNCTIONS. FB (Pin 1):. GND (Pin 7):. ITH (Pin 2):. BG (Pin 8):. RUN/SS (Pin 3):. INTVCC (Pin 9):. BOOST (Pin 4):. VIN (Pin 10):
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Versión de texto del documento
LTC3854
PIN FUNCTIONS FB (Pin 1):
Error Amplifier Feedback Input. This pin receives
GND (Pin 7):
Small Signal and Power Ground. This is the remotely-sensed feedback voltage from an external the high current ground for the gate driver. The internal resistor divider across the output. signal ground is Kelvin connected to this pin for noise
ITH (Pin 2):
Error Amplifier Output and Switching Regulator suppression. Compensation Point. The current comparator trip point
BG (Pin 8):
High Current Gate Drive for Bottom (Synchro- increases with this control voltage. nous) N-channel MOSFET. The voltage swing at this pin is
RUN/SS (Pin 3):
Run Control, Soft-Start. If the voltage from ground to INTVCC. on this pin is held below 0.4V, the part is in shutdown. If
INTVCC (Pin 9):
Output of the Internal 5V Low Dropout the pin is released the capacitance to ground at this pin Regulator. The driver and control circuits are powered sets the soft-start ramp rate. An internal 1.25µA soft-start from this voltage. Must be decoupled to power ground current is always charging this pin. with a minimum of 2.2µF low ESR ceramic capacitor (X5R
BOOST (Pin 4):
Bootstrapped Supply to the Top Side Float- or better). ing Driver. A low ESR capacitor is connected between the
VIN (Pin 10):
Main Supply Pin. A bypass capacitor should BOOST and SW pins and an external Schottky diode is tied be tied between this pin and the signal ground pin. between the BOOST and INTVCC pins. The voltage swing
SENSE– (Pin 11):
The (–) Input to the Differential Current on the BOOST pin is INTVCC to (VIN + INTVCC). Comparator.
TG (Pin 5):
High Current Gate Drive for Top N-channel
SENSE+ (Pin 12):
The (+) Input to the Differential Current MOSFET. This is the output of floating driver with a volt- Comparator. The ITH pin voltage and controlled offsets age swing equal to INTVCC superimposed on the switch between the SENSE– and SENSE+ pins in conjunction with node voltage. RSENSE (or RDCR) set the peak current trip threshold.
SW (Pin 6):
Switch Node Connection to Inductor. The volt-
SGND (Exposed Pad Pin 13):
The exposed pad must be age swing on this pin is from a Schottky diode (external) soldered to PCB ground for electrical contact and rated forward voltage (when this diode is added across the N- thermal performance. channel synchronous MOSFET) below ground to VIN. 3854fb 7 Document Outline Features Description Applications 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 Related Parts
PIN FUNCTIONS FB (Pin 1):
Error Amplifier Feedback Input. This pin receives
GND (Pin 7):
Small Signal and Power Ground. This is the remotely-sensed feedback voltage from an external the high current ground for the gate driver. The internal resistor divider across the output. signal ground is Kelvin connected to this pin for noise
ITH (Pin 2):
Error Amplifier Output and Switching Regulator suppression. Compensation Point. The current comparator trip point
BG (Pin 8):
High Current Gate Drive for Bottom (Synchro- increases with this control voltage. nous) N-channel MOSFET. The voltage swing at this pin is
RUN/SS (Pin 3):
Run Control, Soft-Start. If the voltage from ground to INTVCC. on this pin is held below 0.4V, the part is in shutdown. If
INTVCC (Pin 9):
Output of the Internal 5V Low Dropout the pin is released the capacitance to ground at this pin Regulator. The driver and control circuits are powered sets the soft-start ramp rate. An internal 1.25µA soft-start from this voltage. Must be decoupled to power ground current is always charging this pin. with a minimum of 2.2µF low ESR ceramic capacitor (X5R
BOOST (Pin 4):
Bootstrapped Supply to the Top Side Float- or better). ing Driver. A low ESR capacitor is connected between the
VIN (Pin 10):
Main Supply Pin. A bypass capacitor should BOOST and SW pins and an external Schottky diode is tied be tied between this pin and the signal ground pin. between the BOOST and INTVCC pins. The voltage swing
SENSE– (Pin 11):
The (–) Input to the Differential Current on the BOOST pin is INTVCC to (VIN + INTVCC). Comparator.
TG (Pin 5):
High Current Gate Drive for Top N-channel
SENSE+ (Pin 12):
The (+) Input to the Differential Current MOSFET. This is the output of floating driver with a volt- Comparator. The ITH pin voltage and controlled offsets age swing equal to INTVCC superimposed on the switch between the SENSE– and SENSE+ pins in conjunction with node voltage. RSENSE (or RDCR) set the peak current trip threshold.
SW (Pin 6):
Switch Node Connection to Inductor. The volt-
SGND (Exposed Pad Pin 13):
The exposed pad must be age swing on this pin is from a Schottky diode (external) soldered to PCB ground for electrical contact and rated forward voltage (when this diode is added across the N- thermal performance. channel synchronous MOSFET) below ground to VIN. 3854fb 7 Document Outline Features Description Applications 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 Related Parts