LT1946A Ver la hoja de datos (PDF) - Linear Technology

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LT1946A

2.7MHz Boost DC/DC Converter with 1.5A Switch and Soft-Start

Linear Technology 

LT1946A

PI FU CTIO S

VC (Pin 1): Error Amplifier Output Pin. Tie external com-

pensation network to this pin or use the internal compen-

sation network by shorting the VC pin to the COMP pin.

External compensation consists of placing a resistor and

capacitor in series from VC to GND. Typical capacitor

range is from 90pF to 270pF. Typical resistor range is from

25k to 120k.

FB (Pin 2): Feedback Pin. Reference voltage is 1.25V.

Connect resistive divider tap here. Minimize trace area at

FB. Set VOUT according to VOUT = 1.25 • (1+R1/R2).

SHDN (Pin 3): Shutdown Pin. Tie to 2.4V or more to enable

device. Ground to shut down. Do not float this pin.

GND (Pin 4, Exposed Pad): Ground. Tie both Pin 4 and

the exposed pad directly to local ground plane. The

ground metal to the exposed pad should be wide for better

heat dissipation. Multiple vias (local ground plane ↔

ground backplane) placed close to the exposed pad can

further aid in reducing thermal resistance.

SW (Pin 5): Switch Pin. This is the collector of the internal

NPN power switch. Minimize the metal trace area con-

nected to this pin to minimize EMI.

VIN (Pin 6): Input Supply Pin. Must be locally bypassed.

COMP (Pin 7): Internal Compensation Pin. Provides an

internal compensation network. Tie directly to the VC pin

for internal compensation. Tie to GND if not used.

SS (Pin 8): Soft-Start Pin. Place a soft-start capacitor

here. Upon start-up, 4µA of current charges the capacitor

to 1.5V. Use a larger capacitor for slower start-up. Leave

floating if not in use.

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sn1946a 1946afs

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