LT1946 Ver la hoja de datos (PDF) - Linear Technology

Número de pieza

componentes Descripción

Fabricante

LT1946

1.2MHz Boost DC/DC Converter with 1.5A Switch and Soft-Start

Linear Technology 

LT1946

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.

FB (Pin 2): Feedback Pin. Reference voltage is 1.250V.

Connect resistive divider tap here. Minimize trace area at

FB. Set VOUT according to VOUT = 1.250(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): Ground. Tie directly to local ground plane.

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.

Exposed Pad (MS8E, Pin 9): Ground. Must be soldered to

PCB.

BLOCK DIAGRA

SS

8

4µA

VIN

6

1.250V

REFERENCE

VOUT

R1 (EXTERNAL)

FB

R2 (EXTERNAL)

0.5V

+

A1

–

+

A3

–

SHUTDOWN

3

2

SHDN

FB

VC COMP

1

7

120k

90pF

–

COMPARATOR

A2

+

R

Q

S

Σ

RAMP

GENERATOR

÷3 1.2MHz

OSCILLATOR

SW

5

DRIVER

Q1

0.01Ω

4

9

GND

GND

(MSE8 ONLY)

1946 BD

Figure 2. Block Diagram

1946fb

4

Share Link: