Datasheet

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LT1301

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12V at 120mA from 5V or 3.3V Supply

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Supply Voltage as Low as 1.8V

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Better High Current Efficiency Than CMOS

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Up to 89% Efficiency

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120µA Quiescent Current

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Shutdown to 10µA

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Programmable 5V or 12V Output

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Low V

CESAT

Switch: 170mV at 1A Typical

■

LIM

Pin Programs Peak Switch Current

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Uses Inexpensive Surface Mount Inductors

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8-Lead DIP or SOIC Package

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Flash Memory V

Generator

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Palmtop Computers

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Portable Instruments

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Bar-Code Scanners

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Personal Digital Assistants

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PCMCIA Cards

The LT1301 is a micropower step-up DC/DC converter that

utilizes Burst Mode™ operation. The device can deliver 5V

or 12V from a two-cell battery input. It features program-

mable 5V or 12V output via a logic-controlled input, no-

load quiescent current of 120µA and a shutdown pin which

reduces supply current to 10µA. The on-chip power switch

has a low 170mV saturation voltage at a switch current of

1A, a four-fold reduction over prior designs. A 155kHz

internal oscillator allows the use of extremely small sur-

face mount inductors and capacitors. Operation is guaran-

teed at 1.8V input. This allows more energy to be extracted

from the battery, increasing operating life. The I

LIM

pin can

be used for soft start or to program peak switch current

with a single resistor allowing the use of even smaller

inductors in lighter load applications. The LT1301 is

available in an 8-lead SOIC package, minimizing board

space requirements. For a selectable 3.3V/5V step-up

converter, please see the LT1300. For higher output

power, see the LT1302.

DESCRIPTION

FEATURES

TYPICAL APPLICATIONS N

Micropower High Efficiency

5V/12V Step-Up DC/DC

Converter for Flash Memory

APPLICATIONS

LT1300 F2

Figure 1. 3.3V/5V to 12V Step-Up Converter

1ms/DIV

= 5V, V

OUT

= 12V

LOAD = 100Ω

Output Voltage

12V

OUT

2V/DIV

LT1301 TAO1

Efficiency

LOAD CURRENT (mA)

10 100 300

LT1301 TA2

EFFICIENCY (%)

= 5V

= 3.3V

L1 = COILCRAFT DO3316-333

OR SUMIDA CD73-330KC

D1 = 1N5817 OR MOTOROLA

MBRS130LT3

C1 = AVX TPSD476M016R0100

OR SANYO OS-CON 165A47M

C2 = AVX TPSD336M020R0100

OR SANYO OS-CON 205A33M

SHUTDOWN

10V/DIV

Burst Mode is a trademark of Linear Technology Corporation.

C2

33µF

20V



12V

OUTPUT

L1

33µH

C1

47µF

LIM

PGND

GND

SENSE

LT1301

SELECT

LT1301 F1

5V

OR

3.3V

SHDN

SHUTDOWN

N/C

0.1µF*



*REQUIRED FOR 5V OUTPUT

Summary of content (12 pages)

PAGE 1
LT1301 Micropower High Efficiency 5V/12V Step-Up DC/DC Converter for Flash Memory U DESCRIPTION FEATURES 12V at 120mA from 5V or 3.3V Supply Supply Voltage as Low as 1.
PAGE 2
LT1301 U U W W W SYMBOL PARAMETER IQ Quiescent Current VIN ORDER PART NUMBER TOP VIEW GND 1 8 PGND SEL 2 7 SW SHDN 3 6 VIN SENSE 4 5 ILIM N8 PACKAGE 8-LEAD PLASTIC DIP VSHDNH VSHDNL VSELH VSELL ISHDN Output Referred Comparator Hysteresis Oscillator Frequency Oscillator TC Maximum Duty Cycle Switch On-Time Output Line Regulation Switch Saturation Voltage Switch Leakage Current Peak Switch Current (Internal Trip Point) Shutdown Pin High Shutdown Pin Low Select Pin High Select Pin Low Shutd
PAGE 3
LT1301 U W TYPICAL PERFORMANCE CHARACTERISTICS Total Quiescent Current in Shutdown 5V Output Efficiency 90 80 TA = 25°C VIN = 3.3V 84 ISHDN + IVIN + ISENSE (µA) 86 VIN = 2.
PAGE 4
LT1301 U U U PIN FUNCTIONS GND (Pin 1): Signal Ground. Tie to PGND under the package. for approximately 400mA. A resistor between ILIM and ground sets peak current to some intermediate value . Sel (Pin 2): Output Select. When tied to VIN converter regulates at 12V. When grounded or floating converter regulates at 5V. May be driven under logic control. VIN (Pin 6): Supply Pin. Must be bypassed with a large value electrolytic to ground. Keep bypass within 0.2" of the device. SHDN (Pin 3): Shutdown.
PAGE 5
LT1301 TEST CIRCUITS 5V 2V 100Ω VIN IL SEL 100µF SW fOUT LT1301 SENSE SHDN GND PGND Oscillator Test Circuit LT1301 TC U OPERATION Operation of the LT1301 is best understood by referring to the Block Diagram in Figure 2. When A1’s negative input, related to the Sense pin voltage by the appropriate resistor-divider ratio is higher that the 1.25V reference voltage, A1’s output is low. A2, A3 and the oscillator are turned off, drawing no current.
PAGE 6
LT1301 U W U U APPLICATIONS INFORMATION VOUT 100mV/DIV AC COUPLED VOUT 5V/DIV VSW 10V/DIV IIN 500mA/DIV IL 500mA/DIV VSHDN 10V/DIV 20µs/DIV 200µs/DIV LT1300 F4 Figure 5. Start-Up Response Figure 4. Burst Mode Operation in Action Output Voltage Selection The LT1301 can be selected to 5V or 12V under logic control or fixed at either by tying Select to ground or VIN respectively. It is permissible to tie Select to a voltage higher than VIN as long as it does not exceed 10V.
PAGE 7
LT1301 U W U U APPLICATIONS INFORMATION Table 1. Recommended Inductors VENDOR Coilcraft 5 ILIM PIN Open Open Open Ground 10k Ground Open Open Open Open Open Ground Ground Open Open Open Ground Open Ground switching. Zero load current causes the LT1301 to switch so infrequently that C3 can completely discharge reducing subsequent peak switch current to 400mA. If a load is suddenly applied, output voltage will sag until C3 can be recharged and peak switch current returns to 1A.
PAGE 8
LT1301 U U W U APPLICATIONS INFORMATION Capacitor Selection Diode Selection Low ESR capacitors are required for both input and output of the LT1301. ESR directly affects ripple voltage and efficiency. For surface mount applications AVX TPS series tantalum capacitors are recommended. These have been specially designed for SMPS and have low ESR along with high surge current ratings. For through-hole applications Sanyo OS-CON capacitors offer extremely low ESR in a small size.
PAGE 9
LT1301 U TYPICAL APPLICATIONS N LCD Contrast Supply VIN 1.8V TO 6V CONTRAST VOUT –4V TO –29V 12mA MAXIMUM FROM 1.8V SUPPLY (77% EFFICIENT) 20mA MAXIMUM FROM 3V SUPPLY (83% EFFICIENT) T1 4 7 3 1 22µF 150K 8 2 10 9 NC + + 35V VIN SW SENSE SHDN 1N5819 SHUTDOWN LT1301 100µF NC ILIM SELECT PGND GND 12K T1 = DALE LPE-5047-AO45 (605) 665-9301 12K + 2.2µF PWM IN 0% TO 100% CMOS DRIVE 0V TO 5V LT1300 TA5 Low-Voltage CCFL Power Supply 9 7 22pF 3kV TI 1 VIN 2V - 6V 5 4 1Ω 3 2 0.
PAGE 10
LT1301 U TYPICAL APPLICATIONS N 5V to – 5V Converter L1 33µH 5V 1N965 2 3 1 4 –VOUT 5V 300mA 1N5817 + 33µF 1N4148 + 33µF SW VIN NC 0.1µF NC SHDN SELECT SENSE GND LT1301 OR LT1300 SHUTDOWN 4.99K 1% ILIM PGND 4.
PAGE 11
LT1301 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. N8 Package 8-Lead Plastic DIP 0.300 – 0.320 (7.620 – 8.128) 0.045 – 0.065 (1.143 – 1.651) 8 7 6 5 0.065 (1.651) TYP 0.009 – 0.015 (0.229 – 0.381) ( 0.400 (10.160) MAX 0.130 ± 0.005 (3.302 ± 0.127) +0.025 0.325 –0.015 +0.635 8.255 –0.381 0.250 ± 0.010 (6.350 ± 0.254) 0.045 ± 0.015 (1.143 ± 0.381) ) 0.100 ± 0.010 (2.540 ± 0.254) 0.125 (3.175) MIN 0.020 (0.508) MIN 1 2 4 3 0.018 ± 0.003 (0.
PAGE 12
LT1301 U.S. Area Sales Offices NORTHEAST REGION Linear Technology Corporation One Oxford Valley 2300 E. Lincoln Hwy.,Suite 306 Langhorne, PA 19047 Phone: (215) 757-8578 FAX: (215) 757-5631 SOUTHEAST REGION Linear Technology Corporation 17060 Dallas Parkway Suite 208 Dallas, TX 75248 Phone: (214) 733-3071 FAX: (214) 380-5138 SOUTHWEST REGION Linear Technology Corporation 22141 Ventura Blvd.