LT1765/LT1765-1.8/LT1765-2.5/

LT1765-3.3/LT1765-5

1

1765fd

TYPICAL APPLICATION

DESCRIPTION

Monolithic 3A, 1.25MHz

Step-Down Switching Regulator

regulator. A high efficiency 3A, 0.09Ω switch is included

on the die together with all the control circuitry required

to construct a high frequency, current mode switching

regulator. Current mode control provides fast transient

response and excellent loop stability.

New design techniques achieve high efficiency at high

switching frequencies over a wide operating voltage

range. A low dropout internal regulator maintains con-

sistent performance over a wide range of inputs from

24V systems to Li-Ion batteries. An operating supply

current of 1mA improves efficiency, especially at lower

output currents. Shutdown reduces quiescent current to

15μA. Maximum switch current remains constant at all

duty cycles. Synchronization allows an external logic level

signal to increase the internal oscillator into the range of

1.6MHz to 2MHz.

Full cycle-by-cycle current control and thermal shutdown

are provided. High frequency operation allows the reduc-

tion of input and output filtering components and permits

the use of chip inductors.

L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.

*Patent Pending

5V to 3.3V Step-Down Converter

FEATURES

APPLICATIONS

TSSOP or 8-Lead SO Package

All Duty Cycles*

Enhanced TSSOP Packages

BOOST

LT1765-3.3

OUTPUT

3.3V

2.5A

INPUT

5V

1765 TA01

0.18μF

2.2nF

UPS120

4.7μF

CERAMIC

2.2μF

CERAMIC

CMDSH-3

1.5μH

FB

SHDN

ON

OFF

GND

SYNC

Efficiency vs Load Current

SWITCH CURRENT (A)

0

80

85

2.0

1765 • TAO1a

75

70

0.5

1.0

1.5

90