LTC3780

1

3780fe

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

High Efficiency, Synchronous,

4-Switch Buck-Boost Controller

The LTC

ing regulator controller that operates from input voltages

above, below or equal to the output voltage. The constant

frequency current mode architecture allows a phase-lock-

able frequency of up to 400kHz. With a wide 4V to 30V

(36V maximum) input and output range and seamless

transfers between operating modes, the LTC3780 is ideal

for automotive, telecom and battery-powered systems.

The operating mode of the controller is determined through

the FCB pin. For boost operation, the FCB mode pin can

select among Burst Mode

and forced continuous mode. During buck operation, the

FCB mode pin can select among skip-cycle mode, discon-

tinuous mode and forced continuous mode. Burst Mode

operation and skip-cycle mode provide high efficiency

operation at light loads while forced continuous mode and

discontinuous mode operate at a constant frequency.

Fault protection is provided by an output overvoltage

comparator and internal foldback current limiting. A power

good output pin indicates when the output is within 7.5%

of its designed set point.

High Efficiency Buck-Boost Converter

n

(5mm

× 5mm) 32-Lead QFN Packages

, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology

Corporation. All other trademarks are the property of their respective owners.

Protected by U.S. Patents including 5481178, 6304066, 5929620, 5408150, 6580258,

patent pending on current mode architecture and protection

+

TG2

0.1μF

0.1μF

BOOST2

SW2

BG2

TG1

BOOST1

SW1

BG1

PLLIN

RUN

SS

SGND

FCB

0.010Ω

4.7μF

A

B

D

C

2200pF

1μF

CER

100μF

16V

CER

330μF

16V

ON/OFF

0.1μF

4.7μH

20k

PGOOD

LTC3780

7.5k

1%

3780 TA01

105k

1%

22μF

50V

CER

5V TO 32V

12V

5A

+

0

90

95

100

15

25

3780 TA01b

85

80

510

20

30

35

75

70

8

9

10

7

6

5

4

3

2

1

0

Efficiency and Power Loss