LTC3549 Series

250mA Low VINBuck Regulator in 2mm × 3mm DFN

Catalog

250mA Low VINBuck Regulator in 2mm × 3mm DFN

Part	Synchronous Rectifier	Voltage - Output (Max) [Max]	Package / Case	Number of Outputs	Operating Temperature [Max]	Operating Temperature [Min]	Output Type	Voltage - Input (Max) [Max]	Supplier Device Package	Frequency - Switching	Current - Output	Topology	Voltage - Input (Min) [Min]	Function	Mounting Type	Voltage - Output (Min/Fixed)	Output Configuration
Analog Devices LTC3549EDCB#TRMPBF		5.5 V	6-WFDFN Exposed Pad	1	85 °C	-40 °C	Adjustable	5.5 V	6-DFN (2x3)	2.25 MHz	250 mA	Buck	1.6 V	Step-Down	Surface Mount	0.611 V	Positive

Catalog

250mA Low VINBuck Regulator in 2mm × 3mm DFN

Key Features

• 1.6V to 5.5V Input Voltage Range

• Internal Soft-Start

• Low Ripple Burst Mode®OperationOutput Ripple: <20mVP-PIQ: 50µA

• Output Ripple: <20mVP-P

• IQ: 50µA

• 2.25MHz Constant-Frequency Operation

• High Efﬁ ciency: Up to 93%

• 250mA Output Current (VIN= 1.8V, VOUT= 1.2V)

• 450mA Peak Inductor Current

• No Schottky Diode Required

• Low Dropout Operation: 100% Duty Cycle

• 0.611V Reference Voltage

• Stable with Ceramic Capacitors

• Shutdown Mode Draws <1µA Supply Current

• Current Mode Operation for Excellent Line and Load Transient Response

• Overtemperature Protection

• Available in a Low Proﬁ le (0.75mm) 6-Lead (2mm × 3mm) DFN Package

Description

The LTC3549 is a high efficiency, monolithic synchronous buck regulator using a constant-frequency, current mode architecture. The output voltage is adjusted via an external resistor divider.A fixed switching frequency of 2.25MHz is supported. This switching frequency allows the use of small surface mount inductors and capacitors, including ceramics.Supply current during Burst Mode operation is only 50µA dropping to < 1µA in shutdown. The 1.6V to 5.5V input voltage range makes the LTC3549 ideally suited for single cell Li-Ion, Li-Metal and 2-cell alkaline, NiCd or NiMH battery-powered applications. 100% duty cycle capability provides low dropout operation, extending battery life in portable systems. Burst Mode operation can be user-enabled, increasing efficiency at light loads, further extending battery life.The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Internal soft-start offers controlled output voltage rise time at startup without the need for external components.Applications2 AA-Cell ApplicationsCellular PhonesDigital CamerasMP3 Players