LINEAR TECHNOLOGY LT1303-5 Technical data

FEATURES

■

5V at 200mA from a 2V Input

■

Supply Voltage As Low As 1.8V

■

Up to 88% Efficiency

■

120µA Quiescent Current

■

Low-Battery Detector

■

Low V

■

Uses Inexpensive Surface Mount Inductors

■

8-Lead PDIP or SO Package

Switch: 170mV at 1A Typ

CESAT

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APPLICATIONS

■

EL Panel Drivers

■

2-Cell and 3-Cell to 5V Conversion

■

Palmtop Computers

■

Portable Instruments

■

Bar-Code Scanners

■

PDAs

■

Wireless Systems

LT1303/LT1303-5

Micropower High Efficiency

DC/DC Converters with

Low-Battery Detector

Adjustable and Fixed 5V

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DESCRIPTION

The LT®1303/LT1303-5 are micropower step-up high
efficiency DC/DC converters using Burst ModeTM opera­tion. They are ideal for use in small, low-voltage battery­operated systems. The LT1303-5 accepts an input voltage
between 1.8V and 5V and converts it to a regulated 5V. The
LT1303 is an adjustable version that can supply an output
voltage up to 25V. Quiescent current is only 120µA from
the battery and the shutdown pin further reduces current
to 10µA. The low-battery detector provides an open-
collector output that goes low when the input voltage
drops below a preset level. The on-chip NPN power switch
has a low 170mV saturation voltage at a switch current
of 1A. The LT1303/LT1303-5 are available in 8-lead PDIP
or SO packages, easing board space requirements.

For higher output current, please see the LT1305 or
LT1302.

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

Burst Mode is a trademark of Linear Technology Corporation.

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TYPICAL APPLICATION

L1

22µH

316k

+

2 CELLS

L1 = SUMDIA CD54-220

100µF

1%

412k
1%

SHUTDOWN

V

IN

LT1303-5

GND PGND

Figure 1. 2-Cell to 5V DC/DC Converter with Low-Battery Detect

1N5817

SW

SENSELBI

LBOSHDN

100µF

100k

+

, 5V

V

OUT

200mA

LOW BATTERY
GOES LOW AT 

= 2.2V

V

BAT

LT1303 TA02

90

80

70

60

EFFICIENCY (%)

50

40

30

0.1

5V Output Efficiency



VIN = 4V

VIN = 2.5V

VIN = 3V

1 10010 1000

LOAD CURRENT (mA)

VIN = 2V

LT1303 TA01

1

LT1303/LT1303-5

WW

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ABSOLUTE MAXIMUM RATINGS

V

Voltage .............................................................. 10V

IN

SW1 Voltage ............................................................ 25V

Sense Voltage (LT1303-5) ....................................... 20V

FB Voltage (LT1303)................................................ 10V

Shutdown Voltage ................................................... 10V

LBO Voltage............................................................. 10V

LBI Voltage .............................................................. 10V

Maximum Power Dissipation ............................. 500mW

Operating Temperature Range ..................... 0°C to 70°C

Storage Temperature Range ................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec)..................300°C

LECTRICAL C CHARA TERIST

E

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

I

Q

VINInput Voltage Range 1.8 1.55 V

DC Maximum Duty Cycle ● 75 86 95 %
t

ON

V

CESAT

V

SHDNH

V

SHDNL

I

SHDN

The
temperature range.

Quiescent Current V

Feedback Voltage LT1303 ● 1.22 1.24 1.26 V
Output Sense Voltage LT1303-5 ● 4.8 5.0 5.2 V
Comparator Hysteresis LT1303 (Note 1) ● 6 12.5 mV
Output Hysteresis LT1303-5 (Note 1) ● 22 50 mV
Feedback Pin Bias Current LT1303, VFB = 1V ● 720 nA
Oscillator Frequency Current Limit Not Asserted 120 155 185 kHz
Oscillator TC 0.2 %/°C

Switch On Time Current Limit Not Asserted 5.6 µs
Output Line Regulation 1.8V < VIN < 6V ● 0.06 0.15 %/V
Switch Saturation Voltage ISW = 700mA ● 130 200 mV
Switch Leakage Current VSW = 5V, Switch Off ● 0.1 10 µA
Peak Switch Current VIN = 2V ● 0.75 1.0 1.25 A

LBI Trip Voltage ● 1.21 1.24 1.27 V
LBI Input Bias Current V
LBO Output Low I
LBO Leakage Current V
Shutdown Pin High ● 1.8 V
Shutdown Pin Low 0.5 V
Shutdown Pin Bias Current V

● denotes specifications which apply over the 0°C to 70°C operating

SHDN

V

SHDN

VIN = 5V 0.65 0.9 1.15 A

LBI

LOAD

LBI

SHDN

V

SHDN

V

SHDN

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PACKAGE/ORDER INFORMATION

TOP VIEW

GND

1

LBO

2

SHDN

3

FB (SENSE)*

Consult factory for Industrial and Military grade parts.

ICS

TA = 25°C, VIN = 2.0V, unless otherwise noted.

= 0.5V, V
= 1.8V ● 715 µA

= 1V ● 720 nA

= 100µA ● 0.11 0.4 V

= 1.3V, V

= 5V ● 8.0 20 µA
= 2V ● 3.0 µA
= 0V ● 0.1 1 µA

= 5V, V

SEL

= 5V ● 0.1 5 µA

LBO

= 5.5V ● 120 200 µA

SENSE

Note 1: Hysteresis specified is DC. Output ripple may be higher if output
capacitance is insufficient or capacitor ESR is excessive.

4

N8 PACKAGE
8-LEAD PDIP

S8 PACKAGE

8-LEAD PLASTIC SO

*FIXED VERSION

= 100°C, θJA = 130°C/W (N8)

T

JMAX

= 100°C, θJA = 150°C/W (S8)

T

JMAX

PGND

8

SW

7



V

6

IN

LBI

5



● 2.0 V

ORDER PART

NUMBER

LT1303CN8
LT1303CS8
LT1303CN8-5
LT1303CS8-5

S8 PART MARKING

1303
13035

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2

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TEMPERATURE (˚C)

–50



700

800

900

25 75

LT1303 GO3

600

500

–25 0

50 100

400

300

RESISTANCE (kΩ)

1000

TEMPERATURE (°C)

–50

1.200

LBI VOLTAGE (V)

1.210

1.215

1.220

1.225

1.230

1.235

–25

0

25 50

LT1303 G06



75

1.240

1.245

1.250

1.205

100

TEMPERATURE (°C)

–50 –25 25 75

0.60

SWITCH CURRENT (A)

0.70

0.90

1.00

1.10

50

1.50

LT1303 G09

0.80

0 100

1.20

1.30

1.40

VIN = 2V

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TYPICAL PERFORMANCE CHARACTERISTICS

LT1303/LT1303-5

V

vs Switch Current

CESAT

250
225
200
175

150

(mV)

125

CESAT

100

V

75
50
25

0

0.21.0 0.3 0.5 0.7 0.9

0.1
SWITCH CURRENT (A)

LT1303 FB Voltage

1.250

1.245

1.240

1.235

1.230

1.225

1.220

1.215

FEEDBACK VOLTAGE (V)

1.210

1.205

1.200
–50

–25

TEMPERATURE (°C)

0

0.4

0.6

25 50

0.8

LT1303 G01

75

LT1330 G04

1.0

100

V

vs Temperature

CESAT

200

ISW = 700mA

190
180
170

160

(mV)

150

CESAT

140

V

130
120
110
100

–50

–25

5.10

5.08

5.06

5.04

5.02

5.00

4.98

SENSE VOLTAGE (V)

4.96

4.94

4.92

4.90
–50

–25

25 50

0

TEMPERATURE (°C)

25 50

0

TEMPERATURE (°C)

75

LT1303 G02

75

LT1303 G05

LT1303-5 Sense Pin Resistance
to Ground

100

Low Battery Detect Trip PointLT1303-5 Sense Voltage

100

LBI Pin Bias Current

20
18
16
14

12
10

8

BIAS CURRENT (nA)

6
4
2
0

–50

–25

25 50

0

TEMPERATURE (°C)

75

LT1303 G07

100

FB Pin Bias Current

20
18
16
14

12
10

8

BIAS CURRENT (nA)

6
4
2
0

–50

–25

25 50

0

TEMPERATURE (°C)

75

LT1303 G08

100

Switch Current Limit

3

LT1303/LT1303-5

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TYPICAL PERFORMANCE CHARACTERISTICS

Switch On-Time Maximum Duty Cycle

8

7

6

5

ON-TIME (µs)

4

3

2

–50

02550

–25

TEMPERATURE (°C)

75 100

LT1303 G10

Oscillator Frequency

200

190
180
170

160

150
140

FREQUENCY (kHz)

130

120

110
100

–50

–25

TEMPERATURE (°C)

0

25 50

75

LT1303 G11

100

100

95
90
85

80
75
70

DUTY CYCLE (%)

65
60
55
50

–50

–25

TEMPERATURE (°C)

Quiescent Current Quiescent Current Switch Current Limit

200
190
180
170

160
150
140
130

QUIESCENT CURRENT (µA)

120

110

100

SWITCH OFF
V

IN

–50

= 2V

–25

TEMPERATURE (°C)

0

25 50

75

LT1303 G13

100

QUIESCENT CURRENT (µA)

500

400

300

200

100

0

TA = 25°C
SWITCH OFF

0

2

4

INPUT VOLTAGE (V)

6

8

10

LT1303 G14

1200

L = 33µH

= 3V

V

L

1100

1000

900

SWITCH CURRENT (mA)

800

700

2

0

INPUT VOLTAGE (V)

0

25 50

4

100

75

LT1303 G12

6

8

10

LT1303 G15

V

OUT

100mV/DIV

AC COUPLED

200mA

I

LOAD

0mA

4

Transient Response
Figure 1 Circuit

VIN = 2V
V

= 5V

OUT

200µs/DIV

LT1303 G16

Shutdown Pin Response

5V

V

OUT

1V/DIV

V

SHDN

5V/DIV

R

= 100Ω

LOAD

V

= 2V

IN

V

= 5V

OUT

= 100µF

C

OUT

500µs/DIV

LT1303 G17

Low Battery Detector Transient
Response

V

LBO

2V/DIV

+10mV

V

TRIP

V

LBI

V

–10mV

TRIP

R

PULL-UP

= 47k

5µs/DIV

LT1303 G18