1307B 查看數據表（PDF） - Linear Technology

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1307B

Single Cell Micropower 600kHz PWM DC/DC Converters

Linear Technology 

LT1307/LT1307B

PI FU CTIO S

VC (Pin 1): Compensation Pin for Error Amplifier. Con-

nect a series RC from this pin to ground. Typical values

are 100kΩ and 680pF. Minimize trace area at VC.

FB (Pin 2): Feedback Pin. Reference voltage is 1.22V.

Connect resistor divider tap here. Minimize trace area at

FB. Set VOUT according to: VOUT = 1.22V(1 + R1/R2).

SHDN (Pin 3): Shutdown. Ground this pin to turn off

switcher. Must be tied to VIN (or higher voltage) to enable

switcher. Do not float the SHDN pin.

GND (Pin 4): Ground. Connect directly to local ground

plane.

SW (Pin 5): Switch Pin. Connect inductor/diode here.

Minimize trace area at this pin to keep EMI down.

VIN (Pin 6): Supply Pin. Must have 1µF ceramic bypass

capacitor right at the pin, connected directly to ground.

LBI (Pin 7): Low-Battery Detector Input. 200mV refer-

ence. Voltage on LBI must stay between ground and

700mV.

LBO (Pin 8): Low-Battery Detector Output. Open collec-

tor, can sink 10µA. A 1MΩ pull-up is recommended.

BLOCK DIAGRA

VIN

6

R5

40k

VOUT

R1

(EXTERNAL)

FB

Q1

FB

2

R2

(EXTERNAL)

VIN

R6

40k

+

gm

–

ERROR

AMPLIFIER

Q2

×10

R3

30k

R4

140k

RAMP

GENERATOR

VC

1

+

*

BIAS –

A1

SHUTDOWN

SHDN

3

LBI

7+

LBO

ENABLE

8

200mV

–

A4

COMPARATOR

–

FF

+

Σ

+

+

A2

R

Q

S

DRIVER

SW

5

Q3

600kHz

OSCILLATOR

A=3

0.15Ω

*HYSTERESIS IN LT1307 ONLY

4

GND

1307 F02

Figure 2. LT1307/LT1307B Block Diagram

1307fa

7

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