Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsPMICsPMIC - DC/DC voltage regulator Boost PDIP 8

LT1303/LT1303-5

Micropower High Efficiency

DC/DC Converters with

Low-Battery Detector

Adjustable and Fixed 5V

FEATURES

■

5V at 200mA from a 2V Input

■

Supply Voltage As Low As 1.8V

■

Up to 88% Efficiency

■

120

A Quiescent Current

■

Low-Battery Detector

■

Low V

CESAT

Switch: 170mV at 1A Typ

■

Uses Inexpensive Surface Mount Inductors

■

8-Lead PDIP or SO Package

DESCRIPTION

■

EL Panel Drivers

■

2-Cell and 3-Cell to 5V Conversion

■

Palmtop Computers

■

Portable Instruments

■

Bar-Code Scanners

■

PDAs

■

Wireless Systems

APPLICATIONS

TYPICAL APPLICATION

The LT

1303/LT1303-5 are micropower step-up high

efficiency DC/DC converters using Burst Mode

opera-

tion. They are ideal for use in small, low-voltage battery-

operated 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.

LOAD CURRENT (mA)

0.1

EFFICIENCY (%)

1 10010 1000

LT1303 TA01

= 2V

= 4V



= 2.5V

= 3V

5V Output Efficiency

GND PGND

SENSELBI

LBOSHDN

LT1303-5

100k

100µF

SHUTDOWN

412k

100µF

2 CELLS

316k

L1

22µH

1N5817

OUT

, 5V

200mA

LOW BATTERY

GOES LOW AT 

BAT

= 2.2V

L1 = SUMDIA CD54-220

LT1303 TA02

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

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

Burst Mode is a trademark of Linear Technology Corporation.

Summary of content (12 pages)

PAGE 1
LT1303/LT1303-5 Micropower High Efficiency DC/DC Converters with Low-Battery Detector Adjustable and Fixed 5V U DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ 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.
PAGE 2
LT1303/LT1303-5 W U U W W W VIN Voltage .............................................................. 10V SW1 Voltage ............................................................ 25V Sense Voltage (LT1303-5) ....................................... 20V FB Voltage (LT1303) ................................................ 10V Shutdown Voltage ................................................... 10V LBO Voltage ............................................................. 10V LBI Voltage ..................
PAGE 3
LT1303/LT1303-5 U W TYPICAL PERFORMANCE CHARACTERISTICS VCESAT vs Switch Current 225 190 200 180 175 170 150 125 100 900 160 150 140 75 130 50 120 25 110 0 0.1 1.0 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 SWITCH CURRENT (A) 1000 ISW = 700mA RESISTANCE (kΩ) 200 VCESAT (mV) VCESAT (mV) 250 800 700 600 500 400 100 –50 –25 25 50 0 TEMPERATURE (°C) LT1303 G01 75 300 –50 100 LT1303-5 Sense Voltage 1.250 1.245 5.08 1.245 1.220 5.06 1.240 5.04 1.
PAGE 4
LT1303/LT1303-5 U W TYPICAL PERFORMANCE CHARACTERISTICS Oscillator Frequency Switch On-Time FREQUENCY (kHz) 7 ON-TIME (µs) 6 5 4 Maximum Duty Cycle 200 100 190 95 180 90 170 85 DUTY CYCLE (%) 8 160 150 140 130 2 –50 –25 0 25 50 TEMPERATURE (°C) 75 100 60 55 100 –50 50 –50 –25 25 50 0 TEMPERATURE (°C) 75 Quiescent Current SWITCH OFF VIN = 2V 160 150 140 130 120 400 100 75 L = 33µH VL = 3V 1100 SWITCH CURRENT (mA) 180 25 50 0 TEMPERATURE (°C) Switch Current Limit 1200
PAGE 5
LT1303/LT1303-5 U U U PIN FUNCTIONS GND (Pin 1): Signal Ground. Tie to PGND under the package. LBI (Pin 5): Low-Battery Comparator Input. When voltage on this pin below 1.24V, LBO is low. LBO (Pin 2): Open-Collector Output of Low-Battery Comparator. Can sink 100µA. Disabled when device is in shutdown. 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. Pull high to shut down the device.
PAGE 6
LT1303/LT1303-5 W BLOCK DIAGRA S FB 6 VIN 7 18mV CURRENT COMPARATOR R1 474k HYSTERETIC COMPARATOR – OFF – A3 DRIVER OSCILLATOR C1 R2 156k R1 3Ω C2 REFERENCE 1.24V SW + 4 Q2 1× Q1 160× + – C3 + GND 1 LBI 5 SHUTDOWN 3 LBO 2 8 Figure 3. LT1303-5 Block Diagram PGND LT1303 BD02 U OPERATION Operation of the LT1303 is best understood by referring to the Block Diagram in Figure 2.
PAGE 7
LT1303/LT1303-5 U OPERATION to about 2µs. Response time of C2, which determines minimum on-time, is approximately 300ns. Low Battery Detector hysteresis built in, but hysteresis can be added by connecting a high-value resistor from LBI to LBO as shown in Figure 5. The internal reference can be accessed via the comparator as shown in Figure 6. The low battery detector is enabled when SHDN is low and disabled when SHDN is high. The comparator has no VBAT VIN 100k 5V LT1303 LBO 2N3906 R1 1.
PAGE 8
LT1303/LT1303-5 U W U U APPLICATIONS INFORMATION Capacitor Selection LT1303 F08 Figure 8. This Inductor Saturates at IL≈1A. A Poor Choice Input and output capacitors should have low ESR for best efficiency. Recommended capacitors include AVX TPS series, Sprague 595D series, and Sanyo OS-CON. The output capacitor’s ESR determines the high frequency ripple amplitude. A 100µF capacitor is the minimum recommended for a 5V output. Higher output voltages can use lower capacitance values.
PAGE 9
LT1303/LT1303-5 U TYPICAL APPLICATIONS Setting Output Voltage on LT1303 1N5817 L1 VIN VIN SW VOUT + R2 LT1303 100µF + FB GND PGND 100µF R1 ( ) VOUT = 1.24V 1 + R2 R1 1303 TA03 5V Step-Up Converter with Reference Output 100k 2N3906 VIN LBO + LBI + 2.2µF * SUMIDA CD54-220MC 33k SW GND OUTPUT 5V SENSE LT1303-5 100µF VREF OUTPUT 1.24V 1N5817 22µH* INPUT 1.8V TO 4.
PAGE 10
LT1303/LT1303-5 U TYPICAL APPLICATIONS 4-, 5-Cell to 5V Converter with Output Disconnect 510Ω MBRS130T3 10µH* VIN 2V TO 8V ZTX788B VIN SW VOUT 5V 100mA SENSE + LT1303-5 33µF + + SHDN GND 33µF PGND 220µF** SHUTDOWN *SUMIDA CD54-100MC **AVX TPS 220µF/10V LT1303TA05 3-Cell to 3.3V Boost/Linear Converter with Output Disconnect MBRS130T3 10µH* VIN 2V TO 6V Si9433 100k VIN SHUTDOWN SW SHDN 100Ω LB0 + LT1303 + 33µF 33µF LBI GND PGND VOUT 3.3V/200mA 1.
PAGE 11
LT1303/LT1303-5 U TYPICAL APPLICATIONS EL Panel Driver T1** 1:15 VIN 1.5V TO 8V 10Ω 4,5 •6 • 10 MUR160 C1* 50pF 1,2 1N5818 4.7µF 160V 3.3M + VIN 47µF 0.1µF CERAMIC SW 3.3M 1k 1/2W 3.
PAGE 12
LT1303/LT1303-5 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. N8 Package 8-Lead Plastic DIP 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) ( +0.025 0.325 –0.015 8.255 +0.635 –0.381 ) 0.400* (10.160) MAX 0.130 ± 0.005 (3.302 ± 0.127) 0.045 – 0.065 (1.143 – 1.651) 0.065 (1.651) TYP 8 7 6 5 1 2 3 4 0.255 ± 0.015* (6.477 ± 0.381) 0.125 (3.175) MIN 0.005 (0.127) MIN 0.015 (0.380) MIN N8 0695 0.018 ± 0.003 (0.457 ± 0.076) 0.100 ± 0.010 (2.