Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - DC/DC voltage regulator Converter/amplifier DFN 12

LTC3441

3441fa

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Regulated Output with Input Above, Below or Equal

to the Output

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Single Inductor, No Schottky Diodes

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High Efficiency: Up to 95%

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25μA Quiescent Current in Burst Mode

Operation

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Up to 1.2A Continuous Output Current from a Single

Lithium-Ion

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True Output Disconnect in Shutdown

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2.4V to 5.5V Input Range

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2.4V to 5.25V Output Range

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1MHz Fixed Frequency Operation

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Synchronizable Oscillator

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Selectable Burst Mode or Fixed Frequency Operation

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<1μA Quiescent Current in Shutdown

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Small, Thermally Enhanced 12-Lead (4mm × 3mm)

DFN package

High Current Micropower

Synchronous Buck-Boost

DC/DC Converter

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Handheld Computers

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Handheld Instruments

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MP3 Players

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Digital Cameras

Burst Mode is a registered trademark of Linear Technology Corporation.

Efficiency vs V

The LTC

3441 is a high efficiency, fixed frequency, buck-

boost DC/DC converter that operates efficiently from input

voltages above, below or equal to the output voltage. The

topology incorporated in the IC provides a continuous trans-

fer function through all operating modes, making the prod-

uct ideal for single lithium ion or multicell applications where

the output voltage is within the battery voltage range.

The device includes two 0.10Ω N-channel MOSFET

switches and two 0.11Ω P-channel switches. External

Schottky diodes are optional, and can be used for a

moderate efficiency improvement. The operating frequency

is internally set to 1MHz and can be synchronized up to

1.7MHz. Quiescent current is only 25μA in Burst Mode

operation, maximizing battery life in portable applications.

Burst Mode operation is user controlled and can be

enabled by driving the MODE/SYNC pin high. If the MODE/

SYNC pin is driven low or with a clock, then fixed fre-

quency switching is enabled.

Other features include a 1μA shutdown, soft-start control,

thermal shutdown and current limit. The LTC3441 is

available in a thermally enhanced 12-lead (4mm × 3mm)

DFN package.

(V)

2.5

EFFICIENCY (%)

3.5

4 4.5

3441 TA02

100

5.5

OUT

= 200mA

OUT

= 1A

OUT

= 3.3V

SW1

SHDN/SS

MODE/SYNC

PGND

SW2

OUT

GND

PGND

LTC3441

10μF

*1 = Burst Mode OPERATION

0 = FIXED FREQUENCY

: TAIYO YUDEN JMK212BJ106MG

OUT

: TAIYO YUDEN JMK325BJ226MM

L1: TOKO A916CY-4R7M

2.5V TO 4.2V

Li-Ion

15k

340k

OUT

22μF

OUT

3.3V

200k

1.5nF

3441 TA01

4.7μH

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

Li-Ion to 3.3V at 1A Buck-Boost Converter

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

Summary of content (16 pages)

PAGE 1
LTC3441 High Current Micropower Synchronous Buck-Boost DC/DC Converter U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO The LTC®3441 is a high efficiency, fixed frequency, buckboost DC/DC converter that operates efficiently from input voltages above, below or equal to the output voltage.
PAGE 2
LTC3441 W W W AXI U U ABSOLUTE RATI GS U U W PACKAGE/ORDER I FOR ATIO (Note 1) VIN, VOUT Voltage........................................ – 0.3V to 6V SW1, SW2 Voltage DC ...........................................................– 0.3V to 6V Pulsed < 100ns ...................................... – 0.3V to 7V SHDN/SS, MODE/SYNC Voltage ................. – 0.3V to 6V Operating Temperature Range (Note 2) .. – 40°C to 85°C Maximum Junction Temperature (Note 4) ...........
PAGE 3
LTC3441 ELECTRICAL CHARACTERISTICS Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC3441E is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls.
PAGE 4
LTC3441 U W TYPICAL PERFOR A CE CHARACTERISTICS Switch Pins Before Entering Boost Mode Active Quiescent Current 630 620 Feedback Voltage 1.241 VIN = VOUT = 3.6V 610 SW2 2V/DIV VIN = 3V VOUT = 3.3V IOUT = 500mA 50ns/DIV 1.231 FEEDBACK VOLTAGE (V) VIN + VOUT CURRENT (μA) SW1 2V/DIV 600 1.226 590 1.221 580 570 1.216 560 1.211 550 1.206 540 3441 G05 VIN = VOUT = 3.6V 1.236 1.201 530 520 –55 –25 5 35 65 TEMPERATURE (°C) 95 125 1.
PAGE 5
LTC3441 U W TYPICAL PERFOR A CE CHARACTERISTICS NMOS RDS(ON) PMOS RDS(ON) 0.15 VIN = VOUT = 3.6V SWITCHES B AND C 0.14 VIN = VOUT = 3.6V SWITCHES A AND D 0.13 PMOS RDS(ON) (Ω) NMOS RDS(ON) (Ω) 0.13 Minimum Start Voltage 2.30 MINIMUM START VOLTAGE (V) 0.15 0.11 0.09 0.12 0.11 0.10 0.09 0.08 0.07 0.07 0.05 –55 0.05 –50 2.25 2.20 2.15 0.06 –25 5 35 65 TEMPERATURE (°C) 95 125 –25 35 65 5 TEMPERATURE (°C) 3441 G14 95 125 2.
PAGE 6
LTC3441 W BLOCK DIAGRA SW1 + 10 5 SW2 SW D SW A VIN SW B GATE DRIVERS AND ANTICROSS CONDUCTION VOUT ISENSE AMP – 3.2A PGND AVERAGE CURRENT LIMIT THERMAL SHUTDOWN SUPPLY CURRENT LIMIT – + UVLO + 1.22V – FB 12 CLAMP + – 2.4V + R1 PWM COMPARATORS – VCC INTERNAL PWM LOGIC AND OUTPUT PHASING ERROR AMP + – 4A 8 REVERSE CURRENT LIMIT + gm = 1 k 100 VOUT 2.4V TO 5.25V –0.8A SW C – 9 PVIN 4 + VIN 2.4V TO 5.
PAGE 7
LTC3441 U OPERATIO The LTC3441 provides high efficiency, low noise power for applications such as portable instrumentation. The LTC proprietary topology allows input voltages above, below or equal to the output voltage by properly phasing the output switches. The error amp output voltage on the VC pin determines the output duty cycle of the switches. Since the VC pin is a filtered signal, it provides rejection of frequencies from well below the switching frequency.
PAGE 8
LTC3441 U OPERATIO Buck Region (VIN > VOUT) Switch D is always on and switch C is always off during this mode. When the internal control voltage, VCI, is above voltage V1, output A begins to switch. During the off time of switch A, synchronous switch B turns on for the remainder of the time. Switches A and B will alternate similar to a typical synchronous buck regulator.
PAGE 9
LTC3441 U OPERATIO When transitioning from Burst Mode operation to fixed frequency, the system exhibits a transient since the modes of operation have changed. For most systems this transient is acceptable, but the application may have stringent input current and/or output voltage requirements that dictate a broad-band voltage loop to minimize the transient. Lowering the DC gain of the loop will facilitate the task (5M from FB to VC) at the expense of DC load regulation.
PAGE 10
LTC3441 U W U U APPLICATIO S I FOR ATIO COMPONENT SELECTION 1 SHDN/SS FB 12 2 GND VC 11 3 PGND VIN 10 4 SW1 PVIN 9 5 SW2 VOUT 8 6 PGND MODE 7 handle the peak inductor current without saturating. Molded chokes or chip inductors usually do not have enough core to support the peak inductor currents in the 1A to 2A region. To minimize radiated noise, use a toroid, pot core or shielded bobbin inductor. See Table 1 for suggested components and Table 2 for a list of component suppliers.
PAGE 11
LTC3441 U W U U APPLICATIO S I FOR ATIO Input Capacitor Selection Since the VIN pin is the supply voltage for the IC it is recommended to place at least a 4.7μF, low ESR bypass capacitor. Table 2. Capacitor Vendor Information SUPPLIER PHONE FAX WEB SITE input voltages, VIN bypassing becomes more critical; therefore, a ceramic bypass capacitor as close to the VIN and GND pins as possible is also required.
PAGE 12
LTC3441 U W U U APPLICATIO S I FOR ATIO The unity-gain frequency of the error amplifier with the Type I compensation is given by: VOUT + 1.22V ERROR AMP 1 fUG = Hz 2 • π • R1 • CP1 R1 FB – 12 CP1 VC Most applications demand an improved transient response to allow a smaller output filter capacitor. To achieve a higher bandwidth, Type III compensation is required. Two zeros are required to compensate for the double-pole response. 11 R2 3441 F07 Figure 7.
PAGE 13
LTC3441 U TYPICAL APPLICATIO S Li-Ion to 3.3V at 1.2A Converter L1 4.7μH 4 9 2.8V TO 4.2V * C1 10μF SW2 5 8 VOUT 12 LTC3441 VIN FB 1 11 VC SHDN/SS 7 2 MODE/SYNC GND 3 6 PGND PGND 10 D2 PVIN *1 = Burst Mode OPERATION 0 = FIXED FREQUENCY R1 340k VOUT 3.3V 1.2A C2 22μF R3 15k C4 1.5nF R2 200k C1: TAIYO YUDEN JMK212BJ106MG C2: TAIYO YUDEN JMK325BJ226MM D1, D2: ON SEMICONDUCTOR MBRM120LT3 L1: TOKO A916CY-3R3M 3441 TA03a Efficiency 100 90 80 EFFICIENCY (%) Li-Ion SW1 D1 4.
PAGE 14
LTC3441 U TYPICAL APPLICATIO S Li-Ion to 5V at 600mA Boost Converter with Output Disconnect L1 4.7μH 4 SW1 9 2.5V TO 4.2V Li-Ion 0.047μF C1 10μF * SW2 5 R1 619k VOUT 12 LTC3441 FB 1 11 VC SHDN/SS 7 2 MODE/SYNC GND 3 6 PGND PGND VIN *1 = Burst Mode OPERATION 0 = FIXED FREQUENCY VOUT 5V 600mA 8 PVIN 10 1M D1 COUT 22μF R3 15k C4 1.5nF C1: TAIYO YUDEN JMK212BJ106MG C2: TAIYO YUDEN JMK325BJ226MM D1: MBRM120LT3 L1: TOKO A916CY-4R7M R2 200k 3441 TA04a Efficiency 100 VIN = 4.
PAGE 15
LTC3441 U PACKAGE DESCRIPTIO DE/UE Package 12-Lead Plastic DFN (4mm × 3mm) (Reference LTC DWG # 05-08-1695) 0.70 ±0.05 3.60 ±0.05 2.20 ±0.05 3.30 ±0.05 1.70 ± 0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.50 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 4.00 ±0.10 (2 SIDES) 7 R = 0.115 TYP 0.40 ± 0.10 12 R = 0.05 TYP PIN 1 TOP MARK (NOTE 6) 0.200 REF 3.00 ±0.10 (2 SIDES) 0.75 ±0.05 3.30 ±0.10 1.70 ± 0.10 6 0.25 ± 0.05 PIN 1 NOTCH R = 0.
PAGE 16
LTC3441 U TYPICAL APPLICATIO PCMCIA Powered GSM Modem L1 10μH 4 9 RS 0.05Ω VIN 2.5V TO 5.5V 1A MAX SW2 5 R1 392k 8 VOUT 12 LTC3441 FB 1 11 VC SHDN/SS 7 2 MODE/SYNC GND 3 6 PGND PGND 10 C1 10μF SW1 PVIN R6 24k + 1N914 1/2 LT1490A VIN VOUT 3.6V 2A (PULSED) COUT 2200μF – C4 10nF R5 24k R2 200k 3441 TA05 + R4 1k 1/2 LT1490A – 2N3906 C1: TAIYO YUDEN JMK212BJ106MG C2: SANYO MV-AX SERIES L1: TOKO A916CY-4R7M ICURRENTLIMIT = 1.