Datasheet

ManualsBrandsLinear Technology ManualsDC / DC Adjustable Switching RegulatorsStep-Up Switching Regulator IC Converter TSOT-23- 34V

LT1615/LT1615-1

sn16151 16151fas

Micropower Step-Up

DC/DC Converters

in ThinSOT

The LT

1615/LT1615-1 are micropower step-up DC/DC

converters in a 5-lead low profile (1mm) ThinSOT pack-

age. The LT1615 is designed for higher power systems

with a 350mA current limit and an input voltage range of

1.2V to 15V, whereas the LT1615-1 is intended for lower

power and single-cell applications with a 100mA current

limit and an extended input voltage range of 1V to 15V.

Otherwise, the two devices are functionally equivalent.

Both devices feature a quiescent current of only 20µA at no

load, which further reduces to 0.5µA in shutdown. A

current limited, fixed off-time control scheme conserves

operating current, resulting in high efficiency over a broad

range of load current. The 36V switch allows high voltage

outputs up to 34V to be easily generated in a simple boost

topology without the use of costly transformers. The

LT1615’s low off-time of 400ns permits the use of tiny, low

profile inductors and capacitors to minimize footprint and

cost in space-conscious portable applications.

■

Low Quiescent Current:

A in Active Mode

A in Shutdown Mode

■

Operates with V

as Low as 1V

■

Low V

CESAT

Switch: 250mV at 300mA

■

Uses Small Surface Mount Components

■

High Output Voltage: Up to 34V

■

Low Profile (1mm) ThinSOT

Package

■

LCD Bias

■

Handheld Computers

■

Battery Backup

■

Digital Cameras

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

1-Cell Li-Ion to 20V Converter for LCD Bias

LT1615

2.5V TO 4.2V

10µH

SHDN

130k

1µF

20V

12mA

C1: TAIYO YUDEN LMK316BJ475

C2: TAIYO YUDEN TMK316BJ105

D1: MOTOROLA MBR0530

L1: MURATA LQH3C100K24

1615/-1 TA01

GND

4.7µF

Efficiency

LOAD CURRENT (mA)

0.1 0.3

EFFICIENCY (%)

1 3 10 30

1615/-1 TA01a

= 4.2V

= 2.5V

= 3.3V

APPLICATIO S

FEATURES

TYPICAL APPLICATIO

DESCRIPTIO

ThinSOT is a trademark of Linear Technology Corporation.

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Summary of content (8 pages)

PAGE 1
LT1615/LT1615-1 Micropower Step-Up DC/DC Converters in ThinSOT U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ The LT®1615/LT1615-1 are micropower step-up DC/DC converters in a 5-lead low profile (1mm) ThinSOT package. The LT1615 is designed for higher power systems with a 350mA current limit and an input voltage range of 1.2V to 15V, whereas the LT1615-1 is intended for lower power and single-cell applications with a 100mA current limit and an extended input voltage range of 1V to 15V.
PAGE 2
LT1615/LT1615-1 U W W W ABSOLUTE AXI U RATI GS U W U PACKAGE/ORDER I FOR ATIO (Note 1) VIN, SHDN Voltage ................................................... 15V SW Voltage .............................................................. 36V FB Voltage .................................................................VIN Current into FB Pin ................................................. 1mA Junction Temperature ........................................... 125°C Operating Temperature Range (Note 2) ..
PAGE 3
LT1615/LT1615-1 U W TYPICAL PERFOR A CE CHARACTERISTICS Switch Saturation Voltage (VCESAT) Feedback Pin Voltage and Bias Current 0.60 Quiescent Current 1.25 50 25 40 23 VFB = 1.23V NOT SWITCHING FEEDBACK VOLTAGE (V) 1.24 0.45 ISWITCH = 500mA 0.40 0.35 0.30 ISWITCH = 300mA 0.25 0.20 VOLTAGE 1.23 30 CURRENT 1.22 20 1.21 10 BIAS CURRENT (nA) SWITCH VOLTAGE (V) 0.50 QUIESCENT CURRENT (µA) 0.55 21 VIN = 12V 19 VIN = 1.2V 17 0.15 –25 0 25 50 TEMPERATURE (°C) 75 1.
PAGE 4
LT1615/LT1615-1 W BLOCK DIAGRA D1 L1 VOUT VIN C1 5 VIN R5 40k 4 SHDN 1 C2 SW R6 40k + A1 ENABLE VOUT – R1 (EXTERNAL) R2 (EXTERNAL) FB 3 Q1 Q2 X10 400ns ONE-SHOT Q3 DRIVER R3 30k RESET + R4 140k 0.12Ω A2 – 42mV* 2 GND 1615/-1 BD * 12mV FOR LT1615-1 Figure 1. LT1615 Block Diagram U OPERATIO The LT1615 uses a constant off-time control scheme to provide high efficiencies over a wide range of output current.
PAGE 5
LT1615/LT1615-1 U U W U APPLICATIO S I FOR ATIO Choosing an Inductor Several recommended inductors that work well with the LT1615 and LT1615-1 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.
PAGE 6
LT1615/LT1615-1 U W U U APPLICATIO S I FOR ATIO input voltages greater than 5V), the current limit overshoot can be quite high. Although it is internally current limited to 350mA, the power switch of the LT1615 can handle larger currents without problem, but the overall efficiency will suffer. Best results will be obtained when IPEAK is kept below 700mA for the LT1615 and below 400mA for the LT1615-1.
PAGE 7
LT1615/LT1615-1 U TYPICAL APPLICATIO S 2-Cell to 3.3V Converter Efficiency 2-Cell to 3.3V Boost Converter L1 4.7µH 90 D1 5 1 VIN SW 3.3V 60mA FB SHDN C2 22µF 3 GND C1 4.7µF VIN = 3V 80 1M LT1615 4 85 4.7pF EFFICIENCY (%) VIN 1.5V TO 3V 604k 2 75 VIN = 1.5V 70 65 60 C1: TAIYO YUDEN LMK316BJ475 C2: TAIYO YUDEN JMK325BJ226 L1: MURATA LQH3C4R7M24 D1: MOTOROLA MBR0520 (408) 573-4150 (408) 573-4150 (814) 237-1431 (800) 441-2447 1615/-1 TA03 55 50 0.
PAGE 8
LT1615/LT1615-1 U TYPICAL APPLICATIO S ±20V Dual Output Converter with Output Disconnect D3 –20V 4mA C3 1µF D2 C4 1µF C5 1µF L1 10µH VIN 1.5V TO 5V 5 D1 20V 4mA 1 VIN 4.7pF SW D4 2M C2 1µF LT1615 4 FB SHDN 3 GND C1 4.