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LTC3541-3 - High Efficiency Buck + VLDO Regulator

Datasheet

Documentation

Features

High Efficiency 500mA Buck Plus 300mA VLDO Regulator
Auto Start-Up Powers VLDO/Linear Regulator Output Prior to Buck Output
Independent 500mA High Efficiency Buck (VIN: 2.7V to 5.5V)
300mA VLDO Regulator with 30mA Standalone Mode
No External Schottky Diodes Required
Fixed Buck Output Voltage: 1.8V
VLDO Input Voltage Range (LVIN: 1.675V to 5.5V)
Fixed VLDO Output Voltage: 1.575V
Selectable Fixed Frequency, Pulse-Skip Operation or Burst Mode Operation
Short-Circuit Protected
Current Mode Operation for Excellent Line and Load Transient Response
Shutdown Current: <3μA
Constant Frequency Operation: 2.25MHz
Low Dropout Buck Operation: 100% Duty Cycle
Small, Thermally Enhanced, 10-Lead (3mm × 3mm) DFN Package

Typical Application

Description

The LTC3541-3 combines a synchronous buck DC/ DC converter with a very low dropout linear regulator (VLDOTM regulator) and internal feedback resistor networks to provide two output voltages from a single input voltage with minimum external components. When configured for dual output operation, the LTC3541-3’s auto start-up feature will bring the 1.575V VLDO/linear regulator output into regulation in a controlled manner prior to enabling the 1.8V buck output without the need for external pin control. The 300mA VLDO/linear regulator output will source only 30mA until the buck output achieves regulation. The input voltage range is ideally suited for applications powered from a Li-Ion battery and 5V or 3.3V rails.

The synchronous buck converter provides a high efficiency output, typically 90%. It can provide up to 500mA of output current while switching at 2.25MHz, allowing the use of small surface mount inductors and capacitors. A mode select pin allows Burst Mode operation to be enabled for higher efficiency at light load currents, or disabled for lower noise, constant frequency operation.

The VLDO regulator provides a low noise, low voltage output capable of providing up to 300mA of output current using only a 2.2μF ceramic capacitor. The input supply voltage of the VLDO regulator (LVIN) may come from the buck regulator or a separate supply.

Options	Vout Switcher (V)	Vout VLDO	Auto Start Up Sequencing
LTC3541	Adj down to 0.8V	Adj down to 0.4V	Switcher, then VLDO
LTC3541-1	Adj down to 0.8V	Adj down to 0.4V	VLDO, then switcher
LTC3541-2	1.875V fixed	1.5V fixed	Switcher, then VLDO
LTC3541-3	1.8V fixed	1.575 fixed	VLDO, then switcher

Packaging

3x3 DFN-10

Order Info

Package Variations and Pricing

Part Number	Package	Pins	Temp	Price (1-99)	Price (1k)^*
LTC3541EDD#PBF	DFN	10	E	$2.70	$1.89
LTC3541EDD#TRPBF	DFN	10	E		$1.95
LTC3541EDD-1#PBF	DFN	10	E	$2.70	$1.89
LTC3541EDD-1#TRPBF	DFN	10	E		$1.95
LTC3541EDD-2#PBF	DFN	10	E	$2.70	$1.89
LTC3541EDD-2#TRPBF	DFN	10	E		$1.95
LTC3541EDD-3#PBF	DFN	10	E	$2.70	$1.89
LTC3541EDD-3#TRPBF	DFN	10	E		$1.95

^* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.