Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - DC/DC voltage regulator Converter, Boost, Converter/amplifier, SEPIC MSOP 10

LT1618

sn1618 1618fas

APPLICATIO S

FEATURES

DESCRIPTIO

TYPICAL APPLICATIO

The LT

1618 step-up DC/DC converter combines a tradi-

tional voltage feedback loop and a unique current feedback

loop to operate as a constant-current, constant-voltage

source. This fixed frequency, current mode switcher oper-

ates from a wide input voltage range of 1.6V to 18V, and

the high switching frequency of 1.4MHz permits the use of

tiny, low profile inductors and capacitors. The current

sense voltage is set at 50mV and can be adjusted using the

ADJ

pin.

Available in the 10-Pin (3mm × 3mm) Exposed Pad DFN

and 10-pin MSOP packages, the LT1618 provides a com-

plete solution for constant-current applications.

■

LED Backlight Drivers

■

USB Powered Boost/SEPIC Converters

■

Input Current Limited Boost/SEPIC Converters

■

Battery Chargers

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

■

Accurate Input/Output Current Control: ±5% Over

Temperature

■

Accurate Output Voltage Control: ±1%

■

Wide V

Range: 1.6V to 18V

■

1.4MHz Switching Frequency

■

High Output Voltage: Up to 35V

■

Low V

CESAT

Switch: 200mV at 1A

■

Available in (3mm × 3mm × 0.8mm) 10-Pin DFN and

10-Pin MSOP Packages

Constant-Current/

Constant-Voltage 1.4MHz

Step-Up DC/DC Converter

Efficiency Curve

USB to 12V Boost Converter

(with Selectable 100mA/500mA Input Current Limit)

LOAD CURRENT (mA)

EFFICIENCY (%)

1618 TA01b

100

20 60

120

140

160

OFF

SHDN

ADJ

OUT

12V

ISN

ISP

LT1618

909k

107k

4.7µF

10nF

4.7µF

1618 TA01a

10µH

GND

5104

C1: TAIYO YUDEN JMK212BJ475

C2: TAIYO YUDEN EMK316BJ475

D1: ON SEMICONDUCTOR MBR0520

L1: SUMIDA CR43-100

0.1Ω

13k

20k

3.3V

100mA

500mA

3.3V

Summary of content (16 pages)

PAGE 1
LT1618 Constant-Current/ Constant-Voltage 1.4MHz Step-Up DC/DC Converter U FEATURES DESCRIPTIO ■ The LT®1618 step-up DC/DC converter combines a traditional voltage feedback loop and a unique current feedback loop to operate as a constant-current, constant-voltage source. This fixed frequency, current mode switcher operates from a wide input voltage range of 1.6V to 18V, and the high switching frequency of 1.4MHz permits the use of tiny, low profile inductors and capacitors.
PAGE 2
LT1618 U W W W ABSOLUTE AXI U RATI GS (Note 1) VIN, SHDN Voltage ................................................... 18V SW Voltage .............................................................. 36V ISP, ISN Voltage ...................................................... 36V IADJ Voltage ............................................................... 6V FB Voltage .............................................................. 1.5V VC Voltage ............................................................
PAGE 3
LT1618 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 1.6V, VSHDN = 1.6V, unless otherwise noted. PARAMETER CONDITIONS Switch VCESAT Switch Leakage Current SHDN Pin Current VSHDN = 1.6V MIN TYP MAX UNITS ISW = 1A (Note 4) 200 260 mV Switch Off, VSW = 5V 0.01 5 µA 5 20 µA 0.
PAGE 4
LT1618 U W TYPICAL PERFOR A CE CHARACTERISTICS Switching Frequency Frequency Foldback 1.8 1.6 1.7 1.4 SHDN Pin Current 50 1.6 1.5 VIN = 18V 1.4 VIN = 1.6V 1.3 1.2 45 1.2 SHDN PIN CURRENT (µA) SWITCHING FREQUENCY (MHz) SWITCHING FREQUENCY (MHz) TJ = 25°C 1.0 0.8 0.6 0.4 0.2 1.1 1.0 – 50 – 25 100 125 35 30 TJ = 25°C 25 20 TJ = 125°C 15 10 5 0 75 25 50 0 TEMPERATURE (°C) TJ = – 50°C 40 0 0 0.2 0.8 0.4 0.6 1.0 FEEDBACK PIN VOLTAGE (V) 1618 G07 1.
PAGE 5
LT1618 W BLOCK DIAGRA D1 L1 RSENSE VIN VOUT C1 SHDN VIN 9 C2 SW 7 8 Q1 DRIVER + 0.02Ω A1 ×25 ×5 – + 1.4MHz OSCILLATOR + S 3 – 2 ISN 4 IADJ Σ + Q R ISP + A3 – 5 A2 – – + R1 1 FB 1.263V R2 10 VC GND RC CC Figure 1. LT1618 Block Diagram U OPERATIO The LT1618 uses a constant frequency, current mode control scheme to provide excellent line and load regulation. Operation can be best understood by referring to the Block Diagram in Figure 1.
PAGE 6
LT1618 U W U U APPLICATIONS INFORMATION Inductor Selection Several inductors that work well with the LT1618 are listed in Table 1, although there are many other manufacturers and devices that can be used. Consult each manufacturer for more detailed information and for their entire selection of related parts. Many different sizes and shapes are available. Ferrite core inductors should be used to obtain the best efficiency, as core losses at 1.
PAGE 7
LT1618 U W U U APPLICATIONS INFORMATION Setting Output Voltage To set the output voltage, select the values of R1 and R2 (see Figure 1) according to the following equation. ⎛V ⎞ R1 = R2 ⎜ OUT – 1⎟ ⎝ 1.263 ⎠ For current source applications, use the FB pin for overvoltage protection. Pick R1 and R2 so that the output voltage will not go too high if the load is disconnected or if the load current drops below the preset value.
PAGE 8
LT1618 U U W U APPLICATIONS INFORMATION When sensing input current, the sense resistor should be placed in front of the inductor (between the decoupling capacitor and the inductor) as shown in the circuits in the Typical Applications section. This will regulate the average inductor current and maintain a consistent inductor ripple current, which will, in turn, maintain a well regulated input current.
PAGE 9
LT1618 U TYPICAL APPLICATIO S 4.5W Direct Broadcast Satellite (DBS) Power Supply with Short-Circuit Protection 0.068Ω 3 2 7 ISN SW 9 FB VIN 4 5 R3 10k Q1 FMMT717 ZETEX R1 100k 1 C3 3.3µF SHDN IADJ GND C1 4.7µF L2 33µH ISP LT1618 8 L3 2.2µH D1 ADD 5V 3.3V VC 10 RC 2k R5 24.9k R2 10k D2 MURS110 13.5V/18.5V C4 3.
PAGE 10
LT1618 U TYPICAL APPLICATIONS 2-Cell White LED Driver L1 4.7µH VIN 1.6V TO 3V C1 4.7µF 9 10kHz TO 50kHz PWM BRIGHTNESS ADJUST D1 8 7 VIN SW SHDN ISP 4 2 R1 2M LT1618 IADJ 1 FB VC GND 5 20mA 3 ISN R3 5.1k 2.49Ω 10 C2 1µF C3 0.1µF R2 160k CC 0.1µF C1: TAIYO YUDEN JMK212BJ475 C2: TAIYO YUDEN EMK316BJ105 D1: ON SEMICONDUCTOR MBR0520 L1: SUMIDA CLQ4D10-4R7 (408) 573-4150 (408) 573-4150 (800) 282-9855 (847) 956-0666 1618 • TA03 2-Cell Luxeon LED Driver L1 10µH VIN 1.
PAGE 11
LT1618 U TYPICAL APPLICATIONS Li Ion White LED Driver L1 10µH VIN 2.7V TO 5V C1 4.7µF 9 10kHz TO 50kHz PWM BRIGHTNESS ADJUST D1 8 7 VIN SW SHDN ISP ISN R3 5.1k LT1618 4 IADJ GND 2.49Ω 20mA 3 2 R1 2M 1 FB VC 5 10 C2 1µF C3 0.1µF R2 100k CC 0.1µF C1: TAIYO YUDEN JMK212BJ475 C2: TAIYO YUDEN TMK316BJ105 D1: ON SEMICONDUCTOR MBR0530 L1: SUMIDA CLQ4D10-100 (408) 573-4150 (408) 573-4150 (800) 282-9855 (847) 956-0666 1618 • TA04 White LED Driver for 20 LEDs L1 10µH VIN 2.7V TO 5V C1 4.
PAGE 12
LT1618 U TYPICAL APPLICATIONS USB to 5V SEPIC Converter VIN 5V C1 4.7µF 3 C3 0.47µF L1 10µH 0.1Ω VOUT 5V 2 7 ISN SW 3.3V OFF ON 0V 9 L2 10µH ISP 20k 4 3.
PAGE 13
LT1618 U TYPICAL APPLICATIO S 12V Boost Converter with 500mA Input Current Limit IL1 L1 10µH 0.1Ω 3 8 9 VOUT 12V 2 7 ISN SW VIN = 5V 1 FB 5 C2 4.7µF R2 107k SHDN 4 85 R1 909k LT1618 VIN Efficiency 90 ISP IADJ GND C1 4.7µF D1 VC 10 2k EFFICIENCY (%) VIN 1.8V TO 5V 80 VIN = 3.
PAGE 14
LT1618 U PACKAGE DESCRIPTIO DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698) 0.675 ±0.05 3.50 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.38 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3.00 ±0.10 (4 SIDES) R = 0.115 TYP 0.38 ± 0.10 6 10 5 1 1.65 ± 0.10 (2 SIDES) PIN 1 TOP MARK (SEE NOTE 6) 0.200 REF (DD10) DFN 1103 0.25 ± 0.05 0.50 BSC 0.75 ±0.05 0.00 – 0.05 2.38 ±0.10 (2 SIDES) BOTTOM VIEW—EXPOSED PAD NOTE: 1.
PAGE 15
LT1618 U PACKAGE DESCRIPTIO MS Package 10-Lead Plastic MSOP (Reference LTC DWG # 05-08-1661) 0.889 ± 0.127 (.035 ± .005) 5.23 (.206) MIN 3.20 – 3.45 (.126 – .136) 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 0.50 0.305 ± 0.038 (.0197) (.0120 ± .0015) BSC TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 0.497 ± 0.076 (.0196 ± .003) REF 10 9 8 7 6 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 4.90 ± 0.152 (.193 ± .006) DETAIL “A” 0° – 6° TYP GAUGE PLANE 1 2 3 4 5 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 0.86 (.
PAGE 16
LT1618 U TYPICAL APPLICATIONS Li-Ion Buck-Boost Mode Luxeon LED Driver Buck Mode Luxeon LED Driver D2 350mA 0.15Ω L1 3.3µH VIN 3.2V TO 5V 2 9 C1 4.7µF D2 D1 D1 3 7 ISP SW L1 47µH 2 7 ISN SW 100k ISN LT1618 8 700mA 0.07Ω VIN 16V 1 FB VIN C2 4.7µF SHDN 10k IADJ GND 4 C1 4.