LTC1147L 查看數據表（PDF） - Linear Technology

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LTC1147L

High Efficiency Step-Down Switching Regulator Controllers

Linear Technology 

LTC1147-3.3

LTC1147-5/LTC1147L

PI FU CTIO S

VIN (Pin 1): Main Supply Pin. Must be closely decoupled

to ground Pin 7.

CT (Pin 2): External capacitor CT from Pin 2 to ground sets

the operating frequency. The actual frequency is also

dependent upon the input voltage.

ITH (Pin 3): Gain Amplifier Decoupling Point. The current

comparator threshold increases with the Pin 3 voltage.

SENSE – (Pin 4): Connects to internal resistive divider

which sets the output voltage. Pin 4 is also the (–) input for

the current comparator.

SENSE + (Pin 5): The (+) input to the current comparator.

A built-in offset between Pins 4 and 5 in conjunction with

RSENSE sets the current trip threshold.

SHDN/VFB (Pin 6): When grounded, the fixed output

versions of the LTC1147 family operate normally. Pulling

Pin 6 high holds the P-channel MOSFET off and puts the

LTC1147 in micropower shutdown mode. Requires CMOS

logic signal with tr, tf < 1µs. Do not leave this pin floating.

On the LTC1147L this pin serves as the feedback pin from

an external resistive divider used to set the output voltage.

GND (Pin 7): Two independent ground lines must be

routed separately to: 1) the (–) terminal of COUT, and 2) the

cathode of the Schottky diode and (–) terminal of CIN.

PDRIVE (Pin 8): High current drive for the P-channel

MOSFET. Voltage swing at this pin is from VIN to ground.

UU

W

FU CTIO AL DIAGRA Pin 6 Connection Shown For LTC1147-3.3 and LTC1147-5; Changes Create LTC1147L.

1 VIN

8 PDRIVE

7 GND

SENSE+

5

SENSE –

4

VFB

6

V

SLEEP

R

Q

S

S

–

VTH2

VTH1

T

+

OFF-TIME

VIN

2

CT

CONTROL

SENSE –

25mV TO 150mV

C

–+

13k

ITH 3

VOS

G

1.25V

SHDN 6

REFERENCE

5pF

100k

LTC1147 • FD

sn1147 1147fds

5

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