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LT1109A Micropower DC/DC Converter Flash Memory VPP Generator Adjustable and Fixed 5V, 12V FEATURES
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DESCRIPTIO
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 360A 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. Current drain is just 360A 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 gatedoscillator design requires no frequency compensation components. High frequency 120kHz operation permits the use of small surface mount inductors and capacitors.
APPLICATI
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S
Flash Memory VPP Generators 5V to 12V Converters 3.3V to 12V Converters Disk Drives PC Plug-In Cards Peripherals Battery-Powered Equipment
TYPICAL APPLICATI
All Surface Mount Flash Memory VPP Generator
L1* 33H MBRS130T3 3 SW VIN SENSE
Output Current
13.0 12V 12.5
OUTPUT VOLTAGE (V)
+VIN 5V C1 22F 10V
1
8
VOUT 12V C2 47F 20V
12.0 11.5 11.0 10.5
VIN = 5V
+
7
LT1109ACS8-12 SHUTDOWN PGND GND 4 5
+
VIN = 4.5V
SHUTDOWN 5V/DIV 500s/DIV
1109A TA03
**
* COILTRONICS CTX33-2 SUMIDA CD54-330LC ** 1 = PROGRAM 0 = SHUTDOWN
10.0
1109A TA01
0
50
250 100 150 200 OUTPUT CURRENT (mA)
300
1109A TA02
U
Output Voltage
VOUT 2V/DIV
UO
UO
1
LT1109A ABSOLUTE AXI U RATI GS
Switch Current .......................................................... 2A Maximum Power Dissipation ............................ 300mW Operating Temperature Range .................... 0C to 70C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C (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
PACKAGE/ORDER I FOR ATIO
TOP VIEW VIN 1 NC 2 SW 3 PGND 4 8 7 6 5 FB (SENSE)* SHUTDOWN NC GND
ORDER PART NUMBER LT1109ACN8 LT1109ACN8-5 LT1109ACN8-12
N8 PACKAGE 8-LEAD PLASTIC DIP *FIXED VERSIONS
TJMAX = 90C, JA = 130C/W
ELECTRICAL CHARACTERISTICS
SYMBOL IQ VIN VOUT PARAMETER Quiescent Current Input Voltage Comparator Trip Point Voltage Output Sense Voltage Comparator Hysteresis Output Voltage Ripple fOSC tON DC VCESAT Oscillator Frequency
TA = 25C, VIN = 3V, unless otherwise noted.
MIN
q q
CONDITIONS Switch Off LT1109A LT1109A-5; 2V VIN 5V LT1109A-12; 2V VIN 12V LT1109A LT1109A-5 LT1109A-12
Switch On Time
q
Duty Cycle Switch Saturation Voltage Switch Leakage Current
Full Load VIN = 3V, ISW = 650mA VIN = 5V, ISW = 1A VSW = 12V
VIH VIL IIH IL
SHUTDOWN Pin High SHUTDOWN Pin Low SHUTDOWN Pin Input Current SHUTDOWN Pin Input Current VSHUTDOWN 2.0V 0V VSHUTDOWN 0.8V
The q denotes specifications which apply over the full operating temperature range.
2
U
U
W
WW
U
W
TOP VIEW VIN 1 NC 2 SW 3 PGND 4 8 FB (SENSE)* 7 SHUTDOWN 6 NC 5 GND
ORDER PART NUMBER LT1109ACS8 LT1109ACS8-5 LT1109ACS8-12
S8 PART MARKING 1109A 1109A5 1109A1
S8 PACKAGE 8-LEAD PLASTIC SO *FIXED VERSIONS
TJMAX = 90C, JA = 150C/W
TYP 360
MAX 500 9 1.30 5.25 12.55 12.5 50 120 135 155 6.9 7.4 77 0.65 1.00 10 0.8 10 20
UNITS A V V V V mV mV mV kHz kHz s s % V V A V V A A
2 1.20 4.75 11.52 1.25 5.00 12.00 8 25 60 105 95 4.1 3.8 60 120 5.5 68 0.5 0.7 1 2.0
q q q q q q q
q q
q q q q
LT1109A
TYPICAL PERFOR A CE CHARACTERISTICS
Efficiency
90 VIN = 5V VOUT = 12V LOAD = 120mA L = 29H
FREQUENCY (kHz)
85
EFFICIENCY (%)
120
DUTY CYCLE (%) 0 25 50 TEMPERATURE (C) 75 100
80
75
70 4.2
4.4 4.6
4.8 5.0 5.2 5.4 INPUT VOLTAGE (V)
Switch Saturation Voltage
1.4 VIN = 3V 1.2 1.0
VCESAT (V)
VIN = 2V
0.5
VCESAT (V)
SWITCH ON TIME (s)
0.8 0.6 0.4 0.2 0 0
0.2
0.4
0.6
0.8
1.0
1.2
ISWITCH (A)
1109A G04
Quiescent Current
500 450 QUIESCENT CURRENT (A) 400 350 300 250 200 -50 QUIESCENT CURRENT (A) 500
-25
UW
5.6
1109A G01
Oscillator Frequency
160
80 75 70 65 60 55
Duty Cycle
140
100
80
5.8
60 -50
-25
50 -50
-25
0 25 50 TEMPERATURE (C)
75
100
1109A G03
1109A G02
Switch Saturation Voltage
0.7 ISW = 650mA 0.6
Switch On Time
8
7
VIN = 5V
0.4 0.3 0.2 0.1 0 -50
6
5
4
1.4
1.6
-25
0 25 50 TEMPERATURE (C)
75
100
1109A G05
3 -50
-25
0 25 50 TEMPERATURE (C)
75
100
1109A G06
Quiescent Current
TA = 25C 450
400
350
300
250 0 25 50 TEMPERATURE (C) 75 100
1109A G07
0
2
4
6 8 10 12 14 16 18 20 INPUT VOLTAGE (V)
1109A G08
3
LT1109A
TYPICAL PERFOR A CE CHARACTERISTICS
LT1109A-12 Output Voltage
12.3 12.2 OSCILLATOR FREQUENCY (kHz)
OUTPUT VOLTAGE (V)
12.1 12.0 11.9 11.8 11.7 -50 -25
50 25 75 0 TEMPERATURE (C)
BLOCK DIAGRA S
LT1109A-5, LT1109A-12 LT1109A (Adjustable)
VIN
SENSE R2 250k
1.25V REF
+
COMP A1
-
R1*
GND
SHUTDOWN *LT1109A-5: R1 = 83k LT1109A-12: R1 = 29k
4
UW
Minimum/Maximum Oscillator Frequency vs tON
160 150 140 130 120 110 100 90 80 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 tON (s)
1109A G10
0C TA 70C
TA= 25C
100
125
1109A G09
W
SW
VIN
FB
SW
1.25V REF 120kHz OSC DRIVER Q1
+
COMP A1
-
120kHz OSC DRIVER
Q1
PGND
GND
SHUTDOWN
PGND
1109A BD
LT1109A
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
APPLICATI
S I FOR ATIO
Inductor Selection A DC/DC converter operates by storing energy as magnetic flux in an inductor core, and then switching this energy into the load. To operate as an efficient energy transfer element, the inductor must fulfill three requirements: inductance value, saturation current and DC resistance. A fourth requirement is physical size. The inductors recommended with the LT1109A circuits are small, surface-mountable and are designed for switch-mode applications. Avoid using RF chokes or air core units since they have very low peak current ratings. The LT1109A works best in situations where the input voltage does not vary much since the device has no internal switch current limit function. For situations where the input voltage varies, such as battery inputs, the LT1107 or LT1111 is suggested instead. Capacitor Selection The output capacitor should be chosen on the basis of its equivalent series resistance (ESR) and capacitance value. Low ESR tantalum surface-mountable capacitors such as those made by AVX are well-suited for DC/DC converter applications. Inexpensive aluminum electrolytics may have excessive ESR, resulting in high output ripple. These should be avoided. Diode Selection Speed, forward drop, and leakage current are the three main considerations in selecting a diode for LT1109A converters. General purpose rectifiers such as the 1N4001
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U
UO
U
drops below 1.25V, A1 switches on the 120kHz oscillator. The driver amplifier boosts the signal level to drive the output NPN power switch. When the FB voltage is sufficient to trip A1, the oscillator is turned off. A low signal on the shutdown pin gates off the oscillator, overriding A1. With SHUTDOWN low, quiescent current remains at 360A.
Burst ModeTM is a trademark of Linear Technology Corporation
are unsuitable for use in any switching regulator application. Although they are rated at 1A, the switching time of a 1N4001 is in the 10s to 50s range. At best, efficiency will be severely compromised if this diode is used; at worst, the circuit may not work at all. The 1N5818 is an ideal choice for LT1109A circuits. Surface-mountable versions, such as the MBRS130T3, are available as well.
Table 1. Inductor Manufacturers
MANUFACTURER Coiltronics International 984 S.W. 13th Court Pompano Beach, FL 33069 305-781-8900 Sumida Electric Co., Ltd. 637 E. Golf Road, Suite 209 Arlington Heights, IL 60005 708-956-0666
OCTA-PACTM is a trademark of Coiltronics International
PART NUMBERS Surface Mount OCTA-PACTM Series
CD54 CD105 Surface Mount
Table 2. Capacitor Manufacturers
MANUFACTURER AVX Myrtle Beach, SC 29578 803-946-0690 Philips Components 2001 W. Blue Heron Blvd. P.O. Box 10330 Riviera Beach, FL 33404 407-881-3200 Sanyo Video Components 1201 Sanyo Avenue San Diego, CA 92073 619-661-6322 PART NUMBERS TPS Series
49MC Series
OS-CON Series
5
LT1109A
TYPICAL APPLICATI UO S
3.3V Powered Flash Memory VPP Generator
20H* MBRS130T3 12V 60mA 3 SW 8 SENSE
VIN 3.3V
+
22F 1 VIN
LT1109A-12 7 SHUTDOWN GND PGND 4 5
+
33F** 25V
SHUTDOWN * COILTRONICS CTX20-1 SUMIDA CD54-220LC ** AVX TPS SERIES
1109A TA04
2V Powered Flash Memory VPP Generator
10H* MBRS130T3 12V 35mA 3 SW 8 SENSE
VIN 2V
+
22F 1 VIN
LT1109A-12 7 SHUTDOWN GND PGND 4 5
+
33F** 25V
SHUTDOWN * COILTRONICS CTX10-1 SUMIDA CD54-100LC ** AVX TPS SERIES
1109A TA05
6
LT1109A
TYPICAL APPLICATI UO
VIN 5V
S
2V to 5V Converter
10H* MBRS130T3 5V 110mA 3 SW 8 SENSE
VIN 2V
+
22F 1 VIN
LT1109A-12 7 SHUTDOWN GND PGND 4 5
+
33F** 10V
SHUTDOWN * COILTRONICS CTX10-1 SUMIDA CD54-100LC ** AVX TPS SERIES
1109A TA06
5V to 12V Converter with Shutdown to 0V at Output
2k 10H* MBRS130T3 2N4403 22F 1 VIN 3 SW 8 SENSE VOUT 12V 110mA
+
LT1109A-12 7 SHUTDOWN GND PGND 4 5
+
47F** 20V
+
1F
SHUTDOWN * COILTRONICS CTX33-2 SUMIDA CD54-330LC ** AVX TPS SERIES
1109A TA07
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
7
LT1109A PACKAGE DESCRIPTIO U
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) 0.130 0.005 (3.302 0.127) 0.400 (10.160) MAX 8 7 6 5
0.009 - 0.015 (0.229 - 0.381)
0.065 (1.651) TYP 0.125 (3.175) MIN 0.020 (0.508) MIN
0.250 0.010 (6.350 0.254)
(
+0.025 0.325 -0.015 8.255 +0.635 -0.381
)
0.045 0.015 (1.143 0.381) 0.100 0.010 (2.540 0.254)
1
2
3
4
0.018 0.003 (0.457 0.076)
N8 0392
S8 Package 8-Lead Plastic SOIC
0.189 - 0.197 (4.801 - 5.004) 8 0.010 - 0.020 x 45 (0.254 - 0.508) 0.053 - 0.069 (1.346 - 1.752) 0.004 - 0.010 (0.101 - 0.254) 0.228 - 0.244 (5.791 - 6.197) 0.150 - 0.157 (3.810 - 3.988) 7 6 5
0.008 - 0.010 (0.203 - 0.254)
0.016 - 0.050 0.406 - 1.270
0- 8 TYP
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) BSC 1 2 3 4
SO8 0392
8
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977
sn1109A 1109afs LT/GP 0493 10K REV 0
(c) LINEAR TECHNOLOGY CORPORATION 1993

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