Micropower Cost Fixed Adjustable DC-to-DC Converter ADP1109 SENSE
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FEATURES Operates Supply Voltages Fixed Adjustable Output Minimum External Components Required Ground Current: Oscillator Frequency: Logic Shutdown 8-Lead SO-8 Packages APPLICATIONS Cellular Telephones Single-Cell Converters Laptop Palmtop Computers Pagers Cameras Battery Backup Supplies Portable Instruments Laser Diode Drivers Hand-Held Inventory Computers
Micropower Cost Fixed Adjustable DC-to-DC Converter ADP1109
SENSE 250k COMPARATOR 1.25V REFERENCE 120kHz OSCILLATOR DRIVER
ADP1109-3.3: 152k ADP1109-5: ADP1109-12:
SHUTDOWN
Fixed Output
ADP1109
COMPARATOR 1.25V REFERENCE 120kHz OSCILLATOR DRIVER
GENERAL DESCRIPTION
ADP1109 versatile step-up switching regulator. device requires only minimal external components operate complete switching regulator. ADP1109-5 deliver from input ADP1109-12 deliver from input. device also features logic controlled shutdown capability that, when logic applied, will shut down oscillator. operating frequency allows small surface mount components. gated oscillator capability eliminates need frequency compensation.
SHUTDOWN
Adjustable Output
TYPICAL APPLICATION
SENSE
ADP1109-12
VOUT 60mA
SHUTDOWN SHUTDOWN/PROGRAM
Flash Memory Generator
REV.
Information furnished Analog Devices believed accurate reliable. However, responsibility assumed Analog Devices use, infringements patents other rights third parties which result from use. license granted implication otherwise under patent patent rights Analog Devices. Technology Way, P.O. 9106, Norwood, 02062-9106, U.S.A. Tel: 781/329-4700 World Wide Site: http://www.analog.com Fax: 781/326-8703 Analog Devices, Inc., 1998
ADP1109-SPECIFICATIONS
unless otherwise noted)
Symbol 1.20 1.25 VOUT 3.13 4.75 11.45 3.30 5.00 12.00 fOSC VCESAT 1.30 3.46 5.25 12.55 Units
Parameter QUIESCENT CURRENT INPUT VOLTAGE COMPARATOR TRIP POINT VOLTAGE COMPARATOR HYSTERESIS OUTPUT VOLTAGE ADP1109-3.3 ADP1109-5 ADP1109-12 OUTPUT VOLTAGE RIPPLE
Conditions Switch
ADP1109 ADP1109-3.3 ADP1109-5 ADP1109-12 +25°C Full Load +25°C +25°C
OSCILLATOR FREQUENCY DUTY CYCLE SWITCH-ON TIME SWITCH SATURATION VOLTAGE ADP1109-3.3 ADP1109-5 ADP1109-12 SWITCH LEAKAGE CURRENT SHUTDOWN HIGH SHUTDOWN SHUTDOWN INPUT CURRENT SHUTDOWN INPUT CURRENT
VSHUTDOWN VSHUTDOWN
NOTES limits temperature extremes guaranteed correlation using standard quality control methods. Specifications subject change without notice.
CTX15-1
1N5818 300mA INPUT 50mA INPUT
CTX15-1
1N5818 +12V 40mA INPUT 10mA INPUT
CTX15-1
1N5818 300mA INPUT 50mA INPUT
SENSE
SENSE
SENSE
ADP1109-12
SHUTDOWN SHUTDOWN
ADP1109-5
ADP1109-12
Figure Converter
Figure Converter
Figure Converter With Shutdown
REV.
ADP1109
ABSOLUTE MAXIMUM RATINGS* CONFIGURATIONS 8-Lead Plastic (N-8)
Supply Voltage, VOUT -0.4 Voltage -0.4 Shutdown Voltage Switch Current Maximum Power Dissipation Operating Temperature Range +70°C Storage Temperature Range -65°C +150°C Lead Temperature (Soldering, sec) +300°C
*This stress rating only; operation beyond these limits cause device permanently damaged.
FB(SENSE)*
SHUTDOWN VIEW (Not Scale)
ADP1109A
ORDERING GUIDE
CONNECT *FIXED VERSIONS
Model ADP1109AN ADP1109AR ADP1109AN-3.3 ADP1109AR-3.3 ADP1109AN-5 ADP1109AR-5 ADP1109AN-12 ADP1109AR-12
Output Voltage
Package Description Plastic Small Outline Plastic Small Outline Plastic Small Outline Plastic Small Outline
Package Options SO-8 SO-8 SO-8 SO-8
8-Lead SOIC (SO-8)
FB(SENSE)*
ADP1109A SHUTDOWN VIEW (Not Scale)
CONNECT *FIXED VERSIONS
FUNCTION DESCRIPTIONS
Mnemonic SHUTDOWN FB(SENSE)
Function Input Supply Voltage. Connection. Collector Node Power Transistor. Ground. When logic applied this pin, oscillator shut down. ADP1109A (Adjustable), this goes directly comparator input. ADP1109-3.3, ADP1109-5 ADP1109-12, this connected through internal resistor that sets output voltage.
CAUTION (electrostatic discharge) sensitive device. Electrostatic charges high 4000 readily accumulate human body test equipment discharge without detection. Although ADP1109 features proprietary protection circuitry, permanent damage occur devices subjected high energy electrostatic discharges. Therefore, proper precautions recommended avoid performance degradation loss functionality.
WARNING!
SENSITIVE DEVICE
REV.
ADP1109 -Typical Performance Characteristics
123.5 OSCILLATOR FREQUENCY 123.0 122.5 122.0 121.5 121.0 120.5 120.0 119.5 119.0 118.5 INPUT VOLTAGE SWITCH CURRENT INPUT VOLTAGE VCESAT QUIESCENT CURRENT DUTY CYCLE
Figure Oscillator Frequency Input Voltage
Figure Switch Saturation Voltage Switch Current
Figure Quiescent Current Input Voltage
OSCILLATOR FREQUENCY
TEMPERATURE
SWITCH-ON TIME TEMPERATURE
TEMPERATURE
Figure Oscillator Frequency Temperature
Figure Switch-On Time Temperature
Figure Duty Cycle Temperature
0.39 0.38 QUIESCENT CURRENT TEMPERATURE 0.37 VCE(SAT) 0.36 0.35 0.34 0.33 0.32 0.31
TEMPERATURE
Figure Switch Saturation Voltage Temperature
Figure Quiescent Current Temperature
REV.
ADP1109
APPLICATION INFORMATION
THEORY OPERATION
ADP1109 flexible, power switch-mode power supply (SMPS) controller step-up dc/dc converter applications. This device uses gated-oscillator technique provide very high performance with quiescent current. example, more than output power generated from source, while quiescent current only functional block diagram ADP1109 shown page internal 1.25 reference connected input comparator, while other input externally connected (via pin) feedback network connected regulated output. When voltage falls below 1.25 oscillator turns driver amplifier provides base drive internal power switch, switching action raises output voltage. When voltage exceeds 1.25 oscillator shut off. While oscillator off, ADP1109 quiescent current only comparator includes small amount hysteresis, which ensures loop stability without requiring external components frequency compensation. shutdown feature permits oscillator shut off. Holding SHUTDOWN will disable oscillator, ADP1109's quiescent current will remain output voltage ADP1109 with external resistors. Three fixed-voltage models also available: ADP1109-3.3 (+3.3 ADP1109-5 ADP1109-12 (+12 fixed-voltage models identical ADP1109, except that laser-trimmed voltage-setting resistors included chip. fixed-voltage models ADP1109, simply connect SENSE (Pin directly output voltage.
COMPONENT SELECTION General Notes Inductor Selection
ADP1109 designed applications where input voltage fairly stable, such generating from logic supply. ADP1109 does have internal switch current limiting circuit, inductor saturate input voltage high. ADP1111 ADP3000 should considered battery powered similar applications where input voltage varies. minimize Electro-Magnetic Interference (EMI), toroid core type inductor recommended. core inductors lower cost alternative problem.
Calculating Inductor Value
Selecting proper inductor value simple, two-step process: Define operating parameters: minimum input voltage, maximum input voltage, output voltage output current. Calculate inductor value, using equations following section.
Inductor Selection
step-up, boost, converter (Figure inductor must store enough power make difference between input voltage output voltage. inductor power calculated from equation: VOUT -VIN IOUT
where diode forward voltage 1N5818 Schottky). Energy stored inductor only while ADP1109 switch energy stored inductor each switching cycle must must equal greater than:
When ADP1109 internal power switch turns current begins flow inductor. Energy stored inductor core while switch this stored energy then transferred load when switch turns off. specify inductor ADP1109, proper values inductance, saturation current resistance must determined. This process difficult, specific equations provided this data sheet. general terms, however, inductance value must enough store required amount energy (when both input voltage switch time minimum), high enough that inductor will saturate when both switch time their maximum values. inductor must also store enough energy supply load, without saturating. Finally, resistance inductor should low, that excessive power will wasted heating windings. most ADP1109 applications, inductor with saturation current rating resistance <0.4 suitable. Ferrite core inductors that meet these specifications available small, surface-mount packages. Air-core inductors, well chokes, unsuitable because their peak current ratings.
order ADP1109 regulate output voltage. When internal power switch turns current flow inductor increases rate
where Henrys switch equivalent resistance (typically +25°C) resistance inductor. most applications, voltage drop across switch small compared simpler equation used:
Replacing above equation with time ADP1109 (5.5 typical) will define peak current given inductor value input voltage. this point, inductor energy calculated follows: peak
REV.
ADP1109
previously mentioned, must greater than PL/fOSC that ADP1109 deliver necessary power load. best efficiency, peak current should limited less. Higher switch currents will reduce efficiency because increased saturation voltage switch. High peak current also increases output ripple. general rule, keep peak current possible minimize losses switch, inductor diode. practice, inductor value easily selected using equations above. example, consider supply that will generate from source. inductor power required from Equation (120 each switching cycle, inductor must supply:
Output Voltage Selection
output voltage back ADP1109 resistors (Figure When voltage comparator's inverting input falls below 1.25 oscillator turns "on" output voltage begins rise. output voltage therefore formula: VOUT 1.25 (11)
Resistors provided internally fixed-voltage versions ADP1109. this case, complete dc-dc converter requires only four external components.
Capacitor Selection
optimum performance, ADP1109's output capacitor must carefully selected. Choosing inappropriate capacitor result efficiency and/or high output ripple. Ordinary aluminum electrolytic capacitors inexpensive, often have poor Equivalent Series Resistance (ESR) Equivalent Series Inductance (ESL). aluminum capacitors, specifically designed switch mode converter applications, also available, these better choice than general purpose devices. Even better performance achieved with tantalum capacitors, although their cost higher. Very values achieved using OS-CON capacitors (Sanyo Corporation, Diego, CA). These devices fairly small, available with tape-and-reel packaging, have very ESR.
Diode Selection
required inductor power fairly this example, peak current also low. Assuming peak current starting point, Equation rearranged recommend inductor value: 45.8
Substituting standard inductor value with resistance, will produce peak switch current PEAK
-1.0
Once peak current known, inductor energy calculated from Equation
(10)
inductor energy greater than /fOSC requirement inductor will work this application. substituting other inductor values into same equations, optimum inductor value selected. When selecting inductor, peak current must exceed maximum switch current calculated peak current greater than either input voltage must increased load current decreased.
specifying diode, consideration must given speed, forward voltage drop reverse leakage current. When ADP1109 switch turns off, diode must turn rapidly high efficiency maintained. Schottky rectifiers, well fast signal diodes such 1N4148, appropriate. forward voltage diode represents power that delivered load, must also minimized. Again, Schottky diodes recommended. Leakage current especially important current applications, where leakage significant percentage total quiescent current. most circuits, 1N5818 suitable companion ADP1109. This diode leakage, fast turn-on turn-off times. surface mount version, MBRS130T3, also available. switch currents less, Schottky diode such BAT85 provides leakage less than similar device, BAT54, available SOT-23 package. Even lower leakage, range, obtained with 1N4148 signal diode. General purpose rectifiers, such 1N4001, suitable ADP1109 circuits. These devices, which have turn-on times more, slow switching power supply applications. Using such diode "just started" will result wasted time effort. Even ADP1109 circuit appears function with 1N4001, resulting performance will indicative circuit performance when correct diode used.
REV.
ADP1109
OUTLINE DIMENSIONS
Dimensions shown inches (mm).
8-Lead Plastic (N-8)
0.430 (10.92) 0.348 (8.84)
0.280 (7.11) 0.240 (6.10)
0.210 (5.33) 0.160 (4.06) 0.115 (2.93)
0.060 (1.52) 0.015 (0.38) 0.130 (3.30) SEATING PLANE
0.325 (8.25) 0.300 (7.62) 0.195 (4.95) 0.115 (2.93)
0.022 (0.558) 0.100 0.070 (1.77) 0.014 (0.356) (2.54) 0.045 (1.15)
0.015 (0.381) 0.008 (0.204)
8-Lead SOIC (SO-8)
0.1968 (5.00) 0.1890 (4.80)
0.1574 (4.00) 0.1497 (3.80)
0.2440 (6.20) 0.2284 (5.80)
0.0098 (0.25) 0.0040 (0.10)
0.0688 (1.75) 0.0532 (1.35)
0.0196 (0.50) 0.0099 (0.25)
SEATING PLANE
0.0500 0.0192 (0.49) (1.27) 0.0138 (0.35)
0.0098 (0.25) 0.0075 (0.19)
0.0500 (1.27) 0.0160 (0.41)
REV.
C3251-8-1/98
PRINTED U.S.A.
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