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LT1109A

Micropower

DC/DC Converter

Flash Memory VPP Generator

Adjustable and Fixed 5V, 12V

ITY

Output Voltage

OUT

2V/DIV

SHUTDOWN

5V/DIV

500µs/DIV

1109A TA03

12V

Output Current

OUTPUT CURRENT (mA)

OUTPUT VOLTAGE (V)

13.0

12.5

12.0

11.5

11.0

10.5

10.0

100 150 200

1109A TA02

250 300

= 4.5V

= 5V

■

Uses Off-the-Shelf Inductors

■

Low Cost

■

8-Pin DIP or SO Package

■

Fixed 5V or 12V Output or Adjustable Version

■

Only Four External Components Required

■

360µA Standby Current

■

Logic-Controlled Shutdown

■

Flash Memory VPP

Generators

■

5V to 12V Converters

■

3.3V to 12V Converters

■

Disk Drives

■

PC Plug-In Cards

■

Peripherals

■

Battery-Powered Equipment

The LT1109A is a simple step-up DC/DC converter. The 8-

pin DIP or SOIC devices require only four external compo-

nents to construct a complete DC/DC converter. Current

drain is just 360µA at no load, making the device ideal for

cost-sensitive applications where standby current must

be kept to a minimum.

The LT1109A-12 can deliver 12V at over 150mA from a 5V

supply, enough power to program four flash memory

chips simultaneously. The LT1109A-5 can deliver 5V at up

to 110mA from a 2V input. The devices feature a shutdown

pin that turns off the oscillator when taken low. The gated-

oscillator design requires no frequency compensation

components. High frequency 120kHz operation permits

the use of small surface mount inductors and capacitors.

ESCRIPTIO

All Surface Mount

Flash Memory VPP

Generator

SENSE

PGND GND

LT1109ACS8-12

SHUTDOWN

MBRS130T3

47µF

20V

OUT

12V

L1*

33µH

COILTRONICS CTX33-2

SUMIDA CD54-330LC

1 = PROGRAM

0 = SHUTDOWN

22µF

10V

1109A TA01

Summary of content (8 pages)

PAGE 1
LT1109A Micropower DC/DC Converter Flash Memory VPP Generator Adjustable and Fixed 5V, 12V U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ Uses Off-the-Shelf Inductors Low Cost 8-Pin DIP or SO Package Fixed 5V or 12V Output or Adjustable Version Only Four External Components Required 360µA Standby Current Logic-Controlled Shutdown The LT1109A is a simple step-up DC/DC converter. The 8pin DIP or SOIC devices require only four external components to construct a complete DC/DC converter.
PAGE 2
LT1109A W W W AXI U U ABSOLUTE RATI GS (Voltages Referred to GND Pin) Supply Voltage (VIN) ................................ – 0.4V to 20V SW Pin Voltage ........................................ – 0.4V to 50V Feedback Pin Voltage (LT1109A) ........................... 5.5V Shutdown Pin Voltage ........................................... 5.5V Switch Current .......................................................... 2A Maximum Power Dissipation ............................
PAGE 3
LT1109A U W TYPICAL PERFOR A CE CHARACTERISTICS Efficiency Oscillator Frequency VIN = 5V VOUT = 12V LOAD = 120mA L = 29µH 75 80 75 DUTY CYCLE (%) 140 FREQUENCY (kHz) 85 EFFICIENCY (%) Duty Cycle 80 160 90 120 100 80 70 4.2 4.4 4.6 4.8 5.0 5.2 5.4 INPUT VOLTAGE (V) 5.6 –25 0 25 50 TEMPERATURE (°C) 75 Switch Saturation Voltage 50 –50 100 –25 0 25 50 TEMPERATURE (°C) 75 100 1109A G03 Switch Saturation Voltage Switch On Time 8 0.7 1.4 ISW = 650mA VIN = 3V 0.
PAGE 4
LT1109A U W TYPICAL PERFOR A CE CHARACTERISTICS Minimum/Maximum Oscillator Frequency vs tON LT1109A-12 Output Voltage 160 12.3 OSCILLATOR FREQUENCY (kHz) 150 OUTPUT VOLTAGE (V) 12.2 12.1 12.0 11.9 11.8 0°C ≤ TA ≤ 70°C 140 130 TA= 25°C 120 110 100 90 11.7 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 80 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 tON (µs) 125 1109A G10 1109A G09 W BLOCK DIAGRA S LT1109A-5, LT1109A-12 VIN LT1109A (Adjustable) SENSE VIN SW FB SW R2 250k 1.25V REF 1.
PAGE 5
LT1109A U OPERATIO The LT1109A is a micropower step-up DC/DC converter. It uses Burst ModeTM operation to achieve micropower operation yet still deliver more than 2W of output power from a 5V supply. Circuit operation can be best understood by referring to the LT1109A block diagram. With SHUTDOWN high, comparator A1 compares the feedback (FB) pin voltage with the 1.25V reference signal. When FB Burst ModeTM is a trademark of Linear Technology Corporation U W U UO APPLICATI drops below 1.
PAGE 6
LT1109A UO TYPICAL APPLICATI S 3.3V Powered Flash Memory VPP Generator VIN 3.
PAGE 7
LT1109A UO TYPICAL APPLICATI S 2V to 5V Converter MBRS130T3 10µH* VIN 2V 5V 110mA + 22µF 1 3 SW 8 SENSE VIN LT1109A-12 7 SHUTDOWN GND PGND 4 5 + 33µF** 10V SHUTDOWN * COILTRONICS CTX10-1 SUMIDA CD54-100LC ** AVX TPS SERIES 1109A TA06 5V to 12V Converter with Shutdown to 0V at Output 2k VIN 5V 10µH* MBRS130T3 + 2N4403 22µF 1 VIN 3 SW 8 SENSE VOUT 12V 110mA LT1109A-12 7 SHUTDOWN GND PGND 4 5 + 47µF** 20V + 1µF SHUTDOWN * COILTRONICS CTX33-2 SUMIDA CD54-330LC 1109A TA07 ** AVX T
PAGE 8
LT1109A U PACKAGE DESCRIPTIO Dimensions are 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) +0.025 0.325 –0.015 8.255 +0.635 –0.381 0.130 ± 0.005 (3.302 ± 0.127) 8 7 6 5 0.065 (1.651) TYP 0.009 – 0.015 (0.229 – 0.381) ( 0.400 (10.160) MAX 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 3 4 0.018 ± 0.003 (0.