LM2622 600kHz/1.3MHz Step-up DC/DC Converter LM2622 step-up DC/DC
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LM2622 600kHz/1.3MHz Step-up DC/DC Converter
LM2622 600kHz/1.3MHz Step-up DC/DC Converter
LM2622 step-up DC/DC converter with 1.6A, internal switch selectable operating frequency. With ability convert 3.3V multiple outputs -8V, 23V, LM2622 ideal part biasing displays. LM2622 operated switching frequencies 600kHz 1.3MHz allowing easy filtering noise. external compensation gives user flexibility setting frequency compensation, which makes possible small, ceramic capacitors output. LM2622 available profile 8-lead MSOP package.
Features
1.6A, 0.2, internal switch Operating voltage 2.0V 600kHz/1.3MHz selectable frequency operation Over temperature protection 8-Lead MSOP package
Applications
Bias Supplies
Typical Application Circuit
DS101273-1
Operation
2000 National Semiconductor Corporation
DS101273
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LM2622
Connection Diagram
View
DS101273-4
8-Lead Plastic MSOP Package Number MUA08A
Ordering Information
Order Number LM2622MM-ADJ LM2622MMX-ADJ Package Type MSOP-8 MSOP-8 Package Drawing MUA08A MUA08A Supplied 1000 Units, Tape Reel 3500 Units, Tape Reel S18B S18B Package
Description
Name SHDN FSLCT Function Compensation network connection. Connected output voltage error amplifier. Output voltage feedback input. Shutdown control input, active low. Analog power ground. Power switch input. Switch connected between pin. Analog power input. Switching frequency select input. 1.3MHz. Ground 600kHz. Connect ground.
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LM2622
Block Diagram
DS101273-3
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LM2622
Absolute Maximum Ratings (Note
Military/Aerospace specified devices required, please contact National Semiconductor Sales Office/ Distributors availability specifications. Voltage Voltage Voltage SHDN Voltage FSLCT Maximum Junction Temperature Power Dissipation(Note Lead Temperature Vapor Phase sec.) 150°C Internally Limited 300°C 215°C
Infrared sec.) Susceptibility (Note Human Body Model (Note Machine Model
220°C
200V
Operating Conditions
Operating Junction Temperature Range (Note Storage Temperature Supply Voltage -40°C +125°C -65°C +150°C
Electrical Characteristics
Specifications standard type face 25°C those with boldface type apply over full Operating Temperature Range -40°C +125°C)Unless otherwise specified. =2.0V unless otherwise specified. Symbol ICL(Note VO/ILOAD %VFB/VIN DMAX ISHDN RDSON ThSHDN Parameter Quiescent Current Feedback Voltage Switch Current Limit Load Regulation Feedback Voltage Line Regulation Bias Current (Note Input Voltage Range Error Transconductance Error Voltage Gain Maximum Duty Cycle Switching Frequency Shutdown Current Switch Leakage Current Switch RDSON SHDN Threshold Threshold Threshold FSLCT Ground FSLCT VSHDN VSHDN 2.7V, Output High Output 1.25 0.01 -0.5 0.01 1.92 1.82 2.7V (Note 3.3V 2.0V 12.0V Conditions (Not Switching) VSHDN 1.2285 (Note (Note 1.26 1.65 0.013 (Note 1.2915 Units mV/A µmho
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LM2622
Electrical Characteristics
(Continued)
Specifications standard type face 25°C those with boldface type apply over full Operating Temperature Range -40°C +125°C)Unless otherwise specified. =2.0V unless otherwise specified. Symbol Parameter Thermal Resistance Conditions Junction Ambient(Note Junction Ambient(Note Junction Ambient(Note Junction Ambient(Note Junction Ambient(Note (Note (Note (Note Units °C/W
Note Absolute maximum ratings limits beyond which damage device occur. Operating Ratings conditions which device intended functional, device parameter specifications guaranteed. guaranteed specifications test conditions, Electrical Characteristics. Note maximum allowable power dissipation function maximum junction temperature, TJ(MAX), junction-to-ambient thermal resistance, ambient temperature, Electrical Characteristics table thermal resistance various layouts. maximum allowable power dissipation ambient temperature calculated using: (MAX) (TJ(MAX) TA)/JA. Exceeding maximum allowable power dissipation will cause excessive temperature, regulator will into thermal shutdown. Note human body model capacitor discharged through 1.5k resistor into each pin. machine model 200pF capacitor discharged directly into each pin. Note susceptibility using human body model 500V Note limits guaranteed room temperature (standard typeface) temperature extremes (bold typeface). room temperature limits 100% production tested. limits temperature extremes guaranteed correlation using standard Statistical Quality Control (SQC) methods. limits used calculate Average Outgoing Quality Level (AOQL). Note Typical numbers 25°C represent most likely norm. Note Duty cycle affects current limit ramp generator. Note Current limit duty cycle. TYPICAL PERFORMANCE section Switch Current Limit Note Bias current flows into pin. Note Junction ambient thermal resistance external heat sink) MSO8 package with minimal trace widths (0.010 inches) from pins circuit. Scenario Power Dissipation section. Note Junction ambient thermal resistance MSO8 package with minimal trace widths (0.010 inches) from pins circuit approximately 0.0191 copper heat sinking. Scenario Power Dissipation section. Note Junction ambient thermal resistance MSO8 package with minimal trace widths (0.010 inches) from pins circuit approximately 0.0465 copper heat sinking. Scenario Power Dissipation section. Note Junction ambient thermal resistance MSO8 package with minimal trace widths (0.010 inches) from pins circuit approximately 0.2523 copper heat sinking. Scenario Power Dissipation section. Note Junction ambient thermal resistance MSO8 package with minimal trace widths (0.010 inches) from pins circuit approximately 0.0098 copper heat sinking layer 0.0760 copper heat sinking bottom layer, with three 0.020 vias connecting planes. Scenario Power Dissipation section.
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LM2622
Typical Performance Characteristics
Efficiency Load Current (VIN 3.3V, kHz) Efficiency Load Current (VIN 3.3V, MHz)
DS101273-26
DS101273-25
Switch Current Limit Temperature (VIN 3.3V, VOUT
Switch Current Limit
DS101273-22 DS101273-20
RDSON (ISW
(600 kHz, switching)
DS101273-27
DS101273-28
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LM2622
Typical Performance Characteristics
(600 kHz, switching)
(Continued)
(1.3 MHz, switching)
DS101273-29
DS101273-21
(1.3 MHz, switching)
shutdown)
DS101273-19
DS101273-18
Frequency (600 kHz)
Frequency (1.3 MHz)
DS101273-23
DS101273-24
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LM2622
Typical Performance Characteristics
Load Transient Response (600 operation)
(Continued) Load Transient Response (1.3 operation)
DS101273-16
DS101273-17
Test circuit shown Figure
Test circuit shown Figure
Operation
DS101273-2
FIGURE Simplified Boost Converter Diagram First Cycle Operation Second Cycle Operation Continuous Conduction Mode LM2622 current-mode, boost regulator. boost regulator steps input voltage higher output voltage. continuous conduction mode (when inductor current never reaches zero steady state), boost regulator operates cycles. first cycle operation, shown Figure (a), transistor closed diode reverse biased. Energy collected inductor load current supplied COUT. second cycle shown Figure (b). During this cycle, transistor open diode forward biased. energy stored inductor transferred load output capacitor.
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ratio these cycles determines output voltage. output voltage defined
where duty cycle switch.
LM2622
Operation
Compensation
(Continued)
keep current programmed control converter stable above duty cycles 50%, inductor must meet certain criteria. inductor, along with input output voltage, will determine slope current through inductor (see Figure (a)). slope inductor current great, circuit will unstable above duty cycles 50%. 10µH inductor recommended operation, while 4.7µH inductor used operation. duty cycle approaching maximum 85%, necessary increase inductance much LM2622 provides compensation (COMP) customize voltage loop feedback. recommended that series combination used compensation network, shown Figure given application, there exists unique combination that will optimize performance LM2622 circuit terms transient response. series combination introduces pole-zero pair according following equations:
DS101273-5
FIGURE Inductor current. Diode current. LM2622 current mode boost converter. signal flow this control scheme feedback loops, that senses switch current that senses output voltage.
where output impedance error amplifier, 1Meg. most applications, performance optimized choosing values within range 680pF 4.7nF. Refer applications section recommended values specific circuits conditions.
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LM2622
Application Information
DS101273-8
FIGURE Triple Output Bias (600 operation) Triple Output Bias circuit Figure shows LM2622 configured provide outputs -8V, 23V, convenient biasing displays. output regulated, while outputs unregulated. output generated typical boost topology. basic operation boost converter described OPERATION section. output voltage with RFB1 RFB2 output derived from diode inverter. During second cycle, when transistor open, conducts charges minus diode drop ()0.4V using Schottky). When transistor opens first cycle, conducts C1's polarity reversed with respect output producing -8V. output realized with series capacitor charge pumps. consists four stages: first stage includes LM2622 switch; second stage uses third stage includes LM2622 switch; final stage first stage, charges when LM2622 switch closed, which causes conduct when switch open. second stage, voltage across when switch open. However, because referenced output, voltage when referenced ground. third stage, appears across when switch closed. When switch opens, referenced output minus diode drop, which raises voltage with respect ground about 24V. Hence, fourth stage, charged when switch open. From first stage last,
placed across RFB1 pseudo soft-start. compensation network chosen optimally stabilize converter. inductor also affects stability. When operating kHz, 10uH inductor recommended insure converter stable duty cycles greater than 50%. Refer COMPENSATION section more information.
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LM2622
Application Information
(Continued)
there three diode drops that make output voltage closer 3xVDIODE (about 22.8V 0.4V forward drop assumed). TABLE Components Circuits Figure Component COUT1 COUT2 CFB1 CFB2 RFB1 RFB2 10µH 10µF 10µF 3.9nF 0.1µF USED 10µF 4.7µF 0.1µF 40.2k 7.5k 5.1k MBRM140T3 BAT54S BAT54S BAT54S 4.7µH 22µF USED 1.5nF 15nF 560pF 22µF 4.7µF 0.1µF MBRM140T3 BAT54S BAT54S BAT54S
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LM2622
Application Information
(Continued)
Operation
DS101273-31
FIGURE operation Operation
DS101273-30
FIGURE operation
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LM2622
Application Information
Power Dissipation
(Continued)
output power LM2622 limited maximum power dissipation. maximum power dissipation determined formula (Tjmax TA)/JA where Tjmax maximum specidfied junction temperature (125°C), ambient temperature, thermal resistance package. dependant layout board shown below.
DS101273-13
DS101273-11
DS101273-12
DS101273-14
DS101273-15
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LM2622 600kHz/1.3MHz Step-up DC/DC Converter
Physical Dimensions
inches (millimeters) unless otherwise noted
LIFE SUPPORT POLICY NATIONAL'S PRODUCTS AUTHORIZED CRITICAL COMPONENTS LIFE SUPPORT DEVICES SYSTEMS WITHOUT EXPRESS WRITTEN APPROVAL PRESIDENT GENERAL COUNSEL NATIONAL SEMICONDUCTOR CORPORATION. used herein: Life support devices systems devices systems which, intended surgical implant into body, support sustain life, whose failure perform when properly used accordance with instructions provided labeling, reasonably expected result significant injury user.
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critical component component life support device system whose failure perform reasonably expected cause failure life support device system, affect safety effectiveness.
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National does assume responsibility circuitry described, circuit patent licenses implied National reserves right time without notice change said circuitry specifications.
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