LT1303 データシートの表示（PDF） - Linear Technology

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LT1303

Micropower High Efficiency DC/DC Converters with Low-Battery Detector Adjustable and Fixed 5V

Linear Technology 

LT1303/LT1303-5

PIN FUNCTIONS

GND (Pin 1): Signal Ground. Tie to PGND under the

package.

LBO (Pin 2): Open-Collector Output of Low-Battery Com-

parator. Can sink 100µA. Disabled when device is in

shutdown.

SHDN (Pin 3): Shutdown. Pull high to shut down the

device. Ground for normal operation.

FB/Sense (Pin 4): On 1303 (adjustable) this pin connects

to the main comparator C1 input. On LT1303-5 this pin

connects to the resistor string that sets output voltage

at 5V.

LBI (Pin 5): Low-Battery Comparator Input. When voltage

on this pin below 1.24V, LBO is low.

VIN (Pin 6): Supply Pin. Must be bypassed with a large

value electrolytic to ground. Keep bypass within 0.2" of the

device.

SW (Pin 7): Switch Pin. Connect inductor and diode here.

Keep layout short and direct to minimize radio frequency

interference.

PGND (Pin 8): Power ground. Tie to signal ground (pin1)

under the package. Bypass capacitor from VIN should be

tied directly to PGND within 0.2" of the device.

BLOCK DIAGRA S

VIN +

C1

6 VIN

L1

D1

7 SW

+

C2

CURRENT

COMPARATOR

18mV

C2

R1

HYSTERETIC

COMPARATOR

FB

4

–

OFF

R2

REFERENCE

1.24V

C1

+

OSCILLATOR

A3

DRIVER

R1

3Ω

Q2

1×

Q1

160×

–

C3

+

GND

LBI

1

5

LBO

2

SHUTDOWN

3

PGND

8

LT1303 BD01

Figure 2. LT1303 Block Digram

5

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