Datasheet LT3470A (Analog Devices) - 7
| Fabricante | Analog Devices |
| Descripción | Micropower Buck Regulator with Integrated Boost and Catch Diodes |
| Páginas / Página | 20 / 7 — PIN FUNCTIONS. SHDN (Pin 8):. BOOST (Pin 3):. BIAS (Pin 2):. NC (Pin 7):. … |
| Revisión | C |
| Formato / tamaño de archivo | PDF / 747 Kb |
| Idioma del documento | Inglés |
PIN FUNCTIONS. SHDN (Pin 8):. BOOST (Pin 3):. BIAS (Pin 2):. NC (Pin 7):. IN (Pin 6):. FB (Pin 1):. GND (Pin 5):. Exposed Pad (Pin 9):
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LT3470A
PIN FUNCTIONS SHDN (Pin 8):
The SHDN pin is used to put the LT3470A
BOOST (Pin 3):
The BOOST pin is used to provide a drive in shutdown mode. Tie to ground to shut down the voltage, which is higher than the input voltage, to the LT3470A. Apply 2V or more for normal operation. If the internal bipolar NPN power switch. shutdown feature is not used, tie this pin to the VIN pin.
BIAS (Pin 2):
The BIAS pin connects to the internal boost
NC (Pin 7):
This pin can be left floating, connected to VIN, Schottky diode and to the internal regulator. Tie to VOUT or tied to GND. when VOUT > 2.5V or to VIN otherwise. When VBIAS > 3V
V
the BIAS pin will supply current to the internal regulator.
IN (Pin 6):
The VIN pin supplies current to the LT3470A’s internal regulator and to the internal power switch. This
FB (Pin 1):
The LT3470A regulates its feedback pin to pin must be locally bypassed. 1.25V. Connect the feedback resistor divider tap to this
GND (Pin 5):
Tie the GND pin to a local ground plane pin. Set the output voltage according to VOUT = 1.25V (1 below the LT3470A and the circuit components. Return + R1/R2) or R1 = R2 (VOUT/1.25 – 1). the feedback divider to this pin.
Exposed Pad (Pin 9):
Ground. Must be soldered to PCB.
SW (Pin 4):
The SW pin is the output of the internal power switch. Connect this pin to the inductor, catch diode and boost capacitor.
BLOCK DIAGRAM
VIN BIAS VIN C1 + – BOOST 500ns ONE SHOT R Qʹ C3 S Q – SW L1 VOUT C2 ENABLE + BURST MODE NC DETECT SHDN VREF 1.25V gm FB GND R2 R1 3470a BD Rev. C For more information www.analog.com 7 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History related parts
PIN FUNCTIONS SHDN (Pin 8):
The SHDN pin is used to put the LT3470A
BOOST (Pin 3):
The BOOST pin is used to provide a drive in shutdown mode. Tie to ground to shut down the voltage, which is higher than the input voltage, to the LT3470A. Apply 2V or more for normal operation. If the internal bipolar NPN power switch. shutdown feature is not used, tie this pin to the VIN pin.
BIAS (Pin 2):
The BIAS pin connects to the internal boost
NC (Pin 7):
This pin can be left floating, connected to VIN, Schottky diode and to the internal regulator. Tie to VOUT or tied to GND. when VOUT > 2.5V or to VIN otherwise. When VBIAS > 3V
V
the BIAS pin will supply current to the internal regulator.
IN (Pin 6):
The VIN pin supplies current to the LT3470A’s internal regulator and to the internal power switch. This
FB (Pin 1):
The LT3470A regulates its feedback pin to pin must be locally bypassed. 1.25V. Connect the feedback resistor divider tap to this
GND (Pin 5):
Tie the GND pin to a local ground plane pin. Set the output voltage according to VOUT = 1.25V (1 below the LT3470A and the circuit components. Return + R1/R2) or R1 = R2 (VOUT/1.25 – 1). the feedback divider to this pin.
Exposed Pad (Pin 9):
Ground. Must be soldered to PCB.
SW (Pin 4):
The SW pin is the output of the internal power switch. Connect this pin to the inductor, catch diode and boost capacitor.
BLOCK DIAGRAM
VIN BIAS VIN C1 + – BOOST 500ns ONE SHOT R Qʹ C3 S Q – SW L1 VOUT C2 ENABLE + BURST MODE NC DETECT SHDN VREF 1.25V gm FB GND R2 R1 3470a BD Rev. C For more information www.analog.com 7 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History related parts