LTC3853

1

3853fc

For more information www.linear.com/LTC3853

TYPICAL APPLICATION

FEATURES

DESCRIPTION

Triple Output,

Multiphase Synchronous

Step-Down Controller

The LTC®3853 is a high performance triple output step-

down switching regulator controller that drives all N-

channel synchronous power MOSFET stages. Power loss

and supply noise are minimized by operating the output

stages out of phase. The part can be configured as a dual

phase controller plus a single phase controller if needed.

Thepartcanalsobeconfiguredtoprovideasingle3-phase

output for even higher output currents.

A wide 4.5V to 24V (28V maximum) input voltage sup-

ply range encompasses most battery chemistries and

intermediate bus voltages. Phase 3 can regulate output

voltages up to 13.5V. A constant-frequency current mode

architecture allows for a phase-lockable frequency up to

750kHz.

Independent TK/SS pins for each output ramps the output

voltagesandcanbeconfiguredforcoincidentorratiometric

tracking. Current foldback limits MOSFET heat dissipation

during short-circuit conditions. The MODE/PLLIN pin

continuous inductor current modes.

High Efficiency Triple 5V/3.3V/1.2V Step-Down Converter

n

Triple, 120° Phased Controllers Reduce Required

Input Capacitance and Power Supply Induced Noise

n

Configurable as a 180° Dual Phase Controller Plus a

Single Phase Controller

n

The Third Phase Can Regulate Up to a 13.5V Output

n

High Efficiency: Up to 92%

n

n

±0.75% 0.8V Output Voltage Accuracy

n

Phase-Lockable Fixed Frequency 250kHz to 750kHz

n

Supports Pre-Biased Outputs

n

Dual N-Channel MOSFET Synchronous Drive

n

n

Adjustable Soft-Start Current Ramping or Tracking

n

Foldback Output Current Limiting

n

Output Overvoltage Protection

n

Dual Power Good Output Voltage Monitors

n

40-Lead 6mm × 6mm QFN Package

L

, LT, LTC, LTM, Linear Technology, Burst Mode, Polyphase and the Linear logo are registered

trademarks of Linear Technology Corporation. All other trademarks are the property of their

respective owners. Protected by U.S. Patents, including 5481178, 5705919, 5929620, 6100678,

6144194, 6177787, 6304066, 6580258.

TG1

TG2

BOOST1,2,3

SW1

SW2

BG1

BG2

LTC3853

MODE/PLLIN

20k

FREQ/PLLFLTR

PGND

PGOOD12

SGND

TK/SS1,2,3

SW3

TG3

BG3

RUN1,2,3

PGOOD3

2.2k

15k

20k

63.4k

0.1µF

4.7µF

10k

500kHz

5V

5A

3.3V

5A

20k

1k

2.2k

1.2V

5A

7V TO 24V

1500pF

100µF

10V

220pF

10nF

22µF

50V

0.1µF

0.1µF

2.2µH

2.2µH

1µH

0.1µF

SW1,2,3

0.1µF

+

100µF

6V

+

100µF

6V

+

10k

105k