1

LTC1844 Series

1844ia

150mA, Micropower,

Low Noise, VLDO

Linear Regulator

May 2003

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Very Low Dropout:

90mV at 150mA

30mV at 50mA (LTC1844-3.3)

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Wide Input Voltage Range: 1.6V to 6.5V

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Low 35

µA Supply Current, Even in Dropout

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Low Noise: 30

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±1.75% Voltage Accuracy Over Temperature,

Voltage and Current Ranges

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Fast Transient Response

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10nA Supply Current in Shutdown

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Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 2.8V, 3.3V

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Adjustable Output Voltage: 1.25V to 6V

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Output Current Limit

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Reverse-Battery and Reverse-Current Protection

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No Protection Diodes Needed

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Stable with 1

µF Output Capacitor

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Stable with Ceramic Capacitors

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Short-Circuit and Thermal Overload Protection

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Low Profile (1mm) SOT-23 Package

Fixed Voltage Low Noise, VLDO Linear Regulator

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Bluetooth/802.11 Cards

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PDAs and Notebook Computers

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Portable Instruments and Battery-Powered Systems

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Cellular Phones

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

The LTC

dropout) linear regulators designed for low power/portable

applications. These regulators can operate from input

voltages as low as 1.6V. Typical output noise is only

30

90mV at the maximum load current of 150mA, reducing to

30mV at 50mA.

The internal P-channel MOSFET pass transistor requires

no base current, allowing the device to draw only 35

µA

during normal operation, independent of the dropout

voltage and load current. The quiescent current falls to a

negligible 10nA during shutdown.

Other features include high output voltage accuracy,

excellent transient response, stablity with ultralow ESR

ceramic capacitors as small as 1

µF, reverse-battery and

reverse-current protection, short-circuit and thermal

overload protection and output current limiting.

The LTC1844 regulators are available in a low profile

(1mm) SOT-23 (ThinSOT

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

Final Electrical Specifications

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-

tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

IN

SHDN

1844 TA01

1

µF

LTC1844-3.3

OUT

3.3V

3.3V TO 6.5V

BYP

GND

0.1

µF

1

µF

OFF ON

5

4

2

3

1

VLDO and ThinSOT are trademarks of Linear Technology Corporation.

LTC1844-3.3 Dropout Voltage vs Load Current

0

0

20

40

60

80

120

100

25

50

75

100

1844 TA02

125

150