Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - DC/DC voltage regulator Boost DFN 8

LTC3539/LTC3539-2

35392fb

For more information www.linear.com/3539/3539-2

Typical applicaTion

FeaTures

applicaTions

DescripTion

2A, 1MHz/2MHz

Synchronous Step-Up

DC/DC Converters

The LT C

3539/LTC3539-2 are synchronous, 2A step-up

DC/DC converters with output disconnect. Synchronous

rectification enables high efficiency in the low profile

2mm × 3mm DFN package. Battery life is extended with

a 700mV start-up voltage and operation down to 500mV

once started.

A switching frequency of 1MHz (LTC3539) or 2MHz

(LTC3539-2) minimizes solution footprint by allowing the

use of tiny, low profile inductors and ceramic capacitors.

The current mode PWM design is internally compensated,

reducing external parts count. The LTC3539/LTC3539-2

feature a pin-enabled automatic Burst Mode operation at

light load conditions. Anti-ring circuitry reduces EMI by

damping the inductor in discontinuous mode. Additional

features include a low shutdown current of under 1µA and

thermal overload protection.

The LTC3539/LTC3539-2 are offered in a 2mm × 3mm ×

0.75mm DFN package.

Wide V

, High Power 3.3V Regulator

Delivers 3.3V at 900mA From 2 Alkaline/NiMH Cells

Delivers 5V at 900mA From a Lithium-Polymer

Battery

Start-Up Voltage: 700mV

1.5V to 5.25V V

OUT

Range

Up to 94% Efficiency

> V

OUT

Operation

±1.5% Feedback Voltage Tolerance

1MHz (LTC3539) or 2MHz (LTC3539-2) Fixed

Frequency Operation

Output Disconnect

Selectable Burst Mode

or PWM Operation

10µA Quiescent Current

Logic Controlled Shutdown: <1µA

Requires Only 6 External Components

Low Profile (2mm × 3mm × 0.75mm) DFN Package

Medical Instruments

Portable Bar Code Scanners

Noise Canceling Headphones

Portable GPS Navigation

Handheld PCs

L, LT , LT C , LT M and Burst Mode are registered trademarks and ThinSOT is a trademark of

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

LOAD

AVERAGE (mA)

0.1 1 10 100 1000

0.1

100

1000

EFFICIENCY (%)

POWER LOSS (mW)

100

3539 TA01b

POWER LOSS

EFFICIENCY

= 2.4V

OUT

= 3.3V

FREQUENCY = 1MHz

FREQUENCY = 2MHz

Efficiency and Power Loss vs Load Current

3539 TA01a

LTC3539

2.2µF

OUT

3.3V

600mA

1.8V TO 3.6V

4.7µH

OUT

MODE

SHDN FB

PGND

GND

562k

22µF

× 2

33pF

BURSTPWM

ONOFF

Summary of content (14 pages)

PAGE 1
LTC3539/LTC3539-2 2A, 1MHz/2MHz Synchronous Step-Up DC/DC Converters Features n n n n n n n n n n n n n n Description Delivers 3.3V at 900mA From 2 Alkaline/NiMH Cells Delivers 5V at 900mA From a Lithium-Polymer Battery VIN Start-Up Voltage: 700mV 1.5V to 5.25V VOUT Range Up to 94% Efficiency VIN > VOUT Operation ±1.
PAGE 2
LTC3539/LTC3539-2 Absolute Maximum Ratings Pin Configuration (Note 1) VIN Voltage.................................................... –0.3V to 6V SW Voltage DC............................................................. –0.3V to 6V Pulsed <100ns.......................................... –0.3V to 7V SHDN, FB, MODE Voltage............................. –0.3V to 6V VOUT.............................................................. –0.3V to 6V Operating Temperature (Notes 2, 5)..........
PAGE 3
LTC3539/LTC3539-2 Electrical Characteristics The l denotes the specifications which apply over the specified temperature range of –40°C to 85°C, otherwise specifications are at TA = 25°C. VIN = 1.2V, VOUT = 3.3V, unless otherwise noted. PARAMETER CONDITIONS Maximum Duty Cycle VFB = 1.15V l Minimum Duty Cycle VFB = 1.3V l Switching Frequency LTC3539 LTC3539-2 l l MODE Input High Voltage MIN TYP 87 90 MAX % 0 0.7 1.8 1 2 1.3 2.4 0.88 VMODE = 1.
PAGE 4
LTC3539/LTC3539-2 Typical Performance Characteristics 200 1000 90 30 1 20 VIN = 2.4V VIN = 3.6V VIN = 4.2V 10 0 0.1 1 0.1 1000 10 100 LOAD CURRENT (mA) 140 80 400 20 200 1 2 50 45 0.75 0.85 0.95 VIN (V) 1.05 45 LEAVE BURST 30 25 20 15 fSW = 2MHz COUT = 44µF 90 50 0.8 0.9 1 1.1 1.2 VIN (V) 1.3 1.4 fSW = 2MHz 20 ENTER BURST LOAD CURRENT (mA) fSW = 1MHz 40 10 0 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 VIN (V) 3539 G07c LEAVE BURST 20 fSW = 2MHz 15 ENTER BURST 0.
PAGE 5
LTC3539/LTC3539-2 Typical Performance Characteristics RDS(ON) vs VOUT RDS(ON) Change vs Temperature RDS(ON) (Ω) 0.20 NORMALIZED RDS(ON) (Ω) 0.25 PMOS 0.15 0.10 NMOS 0.05 0.50 1.2 0.25 1.1 1.0 0.9 0.8 0 1.5 2.0 2.5 3.0 3.5 4.0 VOUT (V) 4.5 5.0 1mA LOAD 0.70 0.65 NO LOAD 0 25 50 TEMPERATURE (°C) 75 –0.50 –10 10 30 50 TEMPERATURE (°C) 70 90 –1.
PAGE 6
LTC3539/LTC3539-2 Pin Functions SW (Pin 1): Switch Pin. Connect inductor between SW and VIN. Keep PCB trace lengths as short and wide as possible to reduce EMI. If the inductor current falls to zero, or SHDN is low, an internal anti-ring resistor is connected from SW to VIN to minimize EMI. Connect resistor divider tap to this pin. The output voltage can be adjusted from 1.5V to 5.25V by: VOUT = 1.20V • [1 + (R2/R1)] MODE (Pin 7): Burst Mode Pin.
PAGE 7
LTC3539/LTC3539-2 Operation DETAILED DESCRIPTION The LTC3539 is a high power synchronous boost converter in an 8-lead 2mm × 3mm DFN package. With the ability to start up and operate from inputs of 700mV, the device features fixed frequency, current mode PWM control for exceptional line and load regulation. The current mode architecture with adaptive slope compensation provides excellent transient load response, requiring minimal output filtering.
PAGE 8
LTC3539/LTC3539-2 Operation Zero Current Comparator: The zero current comparator monitors the inductor current to the output and shuts off the synchronous rectifier once this current reduces to approximately 40mA. This prevents the inductor current from reversing in polarity, improving efficiency at light loads. Synchronous Rectifier: The P-channel MOSFET synchronous rectifier is disabled when VOUT is much less than VIN.
PAGE 9
LTC3539/LTC3539-2 Applications Information VIN > VOUT Operation COMPONENT SELECTION The LTC3539 will maintain output voltage regulation even when the input voltage is above the desired output. Note that the efficiency and the maximum output current capability are reduced. Refer to Typical Performance Characteristics. Inductor Selection Short-Circuit Protection The LTC3539 output disconnect feature allows an output short circuit while maintaining a maximum internally set current limit.
PAGE 10
LTC3539/LTC3539-2 Applications Information An output capacitor of up to 100µF is required at lower output voltages. Even with VOUT greater than 3V, larger values up to 100µF may be used to obtain extremely low output voltage ripple and improve transient response. X5R and X7R dielectric materials are preferred for their ability to maintain capacitance over wide voltage and temperature ranges. Y5V types should not be used. Table 1. Representative Inductors VENDOR PART/STYLE Coilcraft (847) 639-6400 www.
PAGE 11
LTC3539/LTC3539-2 Typical Applications 1 Cell to 1.8V 2.2µH VIN 1V TO 1.6V 2.2µF SW VIN LTC3539 PWM BURST MODE VOUT 1M OFF ON SHDN 33pF FB GND PGND 22µF* ×2 1.91M *AT HIGH LOAD CURRENTS, A TANTALUM CAPACITOR WILL IMPROVE PERFORMANCE. VOUT 1.8V 500mA 3539 TA02 1 Cell to 3.3V 2.2µH VIN 0.9V TO 1.6V 2.2µF VIN SW LTC3539 PWM BURST MODE VOUT 1M OFF ON SHDN 33pF FB GND PGND VOUT 3.3V 350mA 22µF ×2 562k 3539 TA03 Li-Ion Cell to 5V 2.2µH VIN 3V TO 4.5V 2.
PAGE 12
LTC3539/LTC3539-2 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. DCB Package 8-Lead Plastic DFN (2mm × 3mm) (Reference LTC DWG # 05-08-1718 Rev A) 0.70 ±0.05 1.35 ±0.05 3.50 ±0.05 1.65 ±0.05 2.10 ±0.05 PACKAGE OUTLINE 0.25 ±0.05 0.45 BSC 1.35 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED R = 0.115 TYP R = 0.05 5 TYP 2.00 ±0.10 (2 SIDES) 0.40 ±0.10 8 1.35 ±0.10 1.65 ±0.10 3.
PAGE 13
LTC3539/LTC3539-2 Revision History (Revision history begins at Rev B) REV DATE DESCRIPTION B 02/13 Improved feedback voltage tolerance spec PAGE NUMBER Clarified Burst Mode operation 1, 2 8 35392fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use.
PAGE 14
LTC3539/LTC3539-2 Related Parts PART NUMBER DESCRIPTION COMMENTS LTC3400/ LTC3400B 600mA ISW, 1.2MHz, Synchronous Step-Up DC/DC Converters 92% Efficiency VIN: 0.85V to 5V, VOUT(MAX) = 5V, IQ = 19µA/300µA, ISD <1µA, ThinSOT™ Package LTC3401 1A ISW, 3MHz, Synchronous Step-Up DC/DC Converter 97% Efficiency VIN: 0.5V to 5V, VOUT(MAX) = 6V, IQ = 38µA, ISD <1µA, 10-Lead MS Package LTC3402 2A ISW, 3MHz, Synchronous Step-Up DC/DC Converter 97% Efficiency VIN: 0.