High Efficiency Boost Converter High Power White Driver RT9278 co

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High Efficiency Boost Converter High Power White Driver RT9278 co

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RT9278
High Efficiency Boost Converter High Power White Driver
RT9278 compact, high efficiency, synchronous step-up converter, provides power supply solution products powered either two-cell, three-cell Alkaline/ NiMH one-cell Li-Ion/Li-polymer battery. RT9278 boost converter with control loop, provide efficiency using synchronous rectifier. maximum peak current internal switch limited keeps output voltage regulated when input voltage exceeds setting output voltage. output voltage external resister divider, fixed reduce external components. integrates linear controller linear regulator. RT9278 available VDFN-10L package.
Features
Efficiency Synchronous Boost Converter High Supply Capability Current Limit Input Voltage Range 1.5V 5.5V 600kHz Fixed Switching Rate Adjustable Output Voltage Options 5.5V Output Voltage Keep Regulated when Input Voltage Exceed Setting Output Voltage Supply Current Shutdown Mode External Compensation Network Build Linear Controller Linear Regulator Over Temperature Protection Small 10-Lead VDFN Package RoHS Compliant 100% Lead (Pb)-Free
Applications Ordering Information
RT9278 Package Type VDFN-10L (V-Type) Operating Temperature Range Free with Commercial Standard Green (Halogen Free with Commercial Standard)
Note Richtek Pb-free Green products }RoHS compliant compatible with current requirements IPC/JEDEC J-STD-020. }Suitable SnPb Pb-free soldering processes. }100% matte (Sn) plating.
COMP
Digital Still Camera Camera White Flash Light PDAs Portable Device
Configurations
(TOP VIEW)
LDRI PGND VOUT
VDFN-10L
Marking Information
marking information, contact sales representative directly through Richtek distributor located your area, otherwise visit website detail.
DS9278-04 August 2007
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RT9278
Typical Application Circuit
Chip Enable 10uH 4.7uF 2.2k 12nF Chip Shutdown 100ms
RT9278 VOUT
AO7401 2.2uF
700mA 100ms Power
PGND LDRI
COMP
300k
0.28
Figure Novel Up-Down Driver Power with Strobe Mode
Note Patent Pending.
Chip Enable 10uH Chip Shutdown 4.7uF 2.2k 12nF
RT9278 VOUT
Istrobe AO3403 2.2uF IMovie GPIO 300k
700mA 200mA 2.8V
100ms
PGND LDRI
COMP
Power
18.2k GPIO
0.28
IStrobe (GPIO_HI 0.2) (IMovie
Figure Novel Up-Down Driver Power with Strobe Mode Movie Mode
Note
Patent Pending. GPIO Signal pull high before enable
Chip Enable 4.7uH 10uF 2.5k Chip Shutdown RT9278 COMP VOUT PGND LDRI 10uF
AO3403 510k 100pF 470k
VOUT 3.3V
2.2nF
150k
Figure Synchronous Boost Converter with Load Disconnect Shutdown
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RT9278
1.6V
4.7uH 10uF
GPIO
RT9278 VOUT
10pF
AO3403 732k 226k 20uF 620k 22pF
PGND
VOUT 3.3V
3.3nF
COMP
510k
LDRI
40.2k
Figure Boost-LDO Application Constant Output Voltage
1.6V 3.0V
4.7uH 20uF
GPIO
RT9278 VOUT
10pF
VOUT1 3.3V/300mA AO3403 470k 150k 40uF 887k 22pF 30uF
VOUT2 1.8V/150mA
PGND
3.9k 1.5nF
COMP
510k
LDRI
110k
Figure Synchronous Boost Converter Driver Dual Output Voltage
Chip Enable Chip Shutdown RT9278 40uF VOUT
10uF
LDRI RCOMP
CCOMP
COMP PGND
Figure Synchronous Boost Converter
DS9278-04 August 2007
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RT9278
Input Voltage Output Voltage 1.5~3.0 1.5~3.3 3.0~4.5 (µH)
Table Component Selection Figure (L=2.2µH)
COUT (µF) RCOMP CCOMP (nF) (pF)
Table Component Selection Figure (L=4.7µH)
Input Voltage Output Voltage 1.5~3.0 1.5~3.3 3.0~4.5 (µH) COUT (µF) RCOMP CCOMP (nF) (pF)
Table Component Selection Figure (L=6.8µH)
Input Voltage Output Voltage 1.5~3.0 1.5~3.3 3.0~4.5 (µH) COUT (µF) RCOMP CCOMP (nF) (pF)
Table Component Selection Figure (L=10µH)
Input Voltage Output Voltage 1.5~3.0 1.5~3.3 3.0~4.5 (µH) COUT (µF) RCOMP CCOMP (nF) (pF)
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DS9278-04 August 2007
Preliminary Functional Description
Name COMP VOUT PGND LDRI Feedback Input Pin. Feedback Compensation Pin. Ground. Enable Input Switch Node. Output Device Input Power Pin. Power Ground. Linear Controller Driver Output. Linear Controller Feedback Input. Function
RT9278
Exposed (11)
exposed must soldered large connected maximum power dissipation.
Function Block Diagram
COMP Error AMPLIFIER VREF 0.8V Oscillator Shutdown Control Slope Compensation Current Sense Error Comparator
VOUT
Control Driver Logic
PGND LDRI
VREF 0.2V
DS9278-04 August 2007
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RT9278
Operation
RT9278 integrates high-efficiency step-up DC-DC converter linear regulator controller. boost converter based fixed frequency, pulse-width-modulation (PWM) controller using synchronous rectifier obtain maximum efficiency. Current mode control with external compensation network makes easy stabilize system keep maximum flexibility. linear regulator controller drive external P-Channel MOSFET switch load disconnection. keeps output voltage regulated even when input voltage exceeds nominal output voltage, keeps output voltage completely disconnected from input voltage (battery) when chip shutdown mode Soft-start When chip enabled. Soft-start achieved ramping duty from very small normal operation. ramping duty achieved sourcing from error amplifier compensation capacitor. When output voltage regulated, duty enters normal operation, error amplifier sink source 22uA. soft-start time following formula RCOMP CCOMP
RCOMP CCOMP compensation components. Current limit current NMOS sensed cycle cycle prevent over current. When over current limit, then NMOS off. This state latched then reset automatically next clock cycle. Over voltage When chip voltage higher than 6.5V, Switch off. When Over Voltage Protection relieved, chip operates well again. Thermal protection Thermal protection function integrated chip. When chip temperature higher than 180°C, controllers shutdown. 20°C hysteresis range temperature prevent unstable operation when thermal protection happens. When thermal protection relieved, chip operates well again.
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DS9278-04 August 2007
Preliminary Absolute Maximum Ratings
RT9278
(Note
Supply Voltage, Voltage 0.3V Other pins 0.3V Power Dissipation, 25°C VDFN-10L 1.43W Package Thermal Resistance (Note VDFN-10L 3x3, 70°C/W Lead Temperature (Soldering, sec.)- 260°C Operation Temperature Range -40°C 85°C Storage Temperature Range 65°C 150°C Susceptibility (Note (Human Body Mode)
Recommended Operating Conditions
(Note
Ambient Temperature Range 70°C Junction Temperature Range 125°C
Electrical Characteristics
(VBAT 1.8V, VOUT 3.3V, 25°C, unless otherwise specified)
Parameter Start-Up Voltage Operating Voltage Range, After start-up VOUT Output Voltage Range VOUT Over Voltage Protection Switch-off Current (VBAT) Shutdown Current Feedback Reference Voltage Switching Frequency Maximum Duty Switch Resistance Switch Resistance Current Limit Setting Error Amplifier Compensation Source Current Compensation Sink Current
Symbol VBAT VOUT_ADJ IOFF D(MAX)
Test Conditions
-1.1 -0.784
-6.5 0.01
-5.5 -350 0.816
Units
VOUT 3.3V, 0.9V Open Loop Close Loop, 3.3V
VOUT 3.3V VOUT 3.3V VOUT 3.3V
continued
DS9278-04 August 2007
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RT9278
Parameter Linear Controller Feedback Voltage Linear Controller Input High Level Threshold Input Level Threshold Thermal Shutdown Thermal Shutdown Hysterises
Symbol Test Conditions Units
VLFB
-0.4
-180
-1.3
Note 1.Stresses listed above "Absolute Maximum Ratings" cause permanent damage device. These stress ratings. Functional operation device these other conditions beyond those indicated operational sections specifications implied. Exposure absolute maximum rating conditions extended periods remain possibility affect device reliability. Note Devices sensitive. Handling precaution recommended. Note device guaranteed function outside operating conditions. Note measured natural convection 25°C high effective thermal conductivity test board JEDEC 51-7 (2S2P, 4-Layers) thermal measurement standard.
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DS9278-04 August 2007
Preliminary Typical Operating Characteristics
Frequency Temperature
0.804 0.803
RT9278
Reference Voltage Temperature
Reference Voltage
3.3V
Frequency (kHz)
0.802 0.801 0.799 0.798 0.797
3.3V
0.796
Temperature (°C)
Temperature (°C)
Efficiency Output Current
Refer Application Circuit Figure
Efficiency Output Current
VOUT 5.0V
VOUT 3.3V
Efficiency
Efficiency
3.0V 2.5V 2.0V 1.5V
4.5V 4.0V 3.5V 3.0V 2.5V 2.0V 1.5V
1000
1000
Output Current (mA)
Output Current (mA)
Input Voltage Output Voltage
3.350 3.325 5.150 5.100
Input Voltage Output Voltage
Output Voltage
3.300 3.275 3.250 3.225
Output Voltage
5.050 5.000 4.950 4.900
VOUT 3.3V
3.200 4.850
VOUT 5.0V
1.925 2.25 2.575 1.93 2.58 3.225 3.55 3.875 3.23 3.88
Input Voltage
Input Voltage
DS9278-04 August 2007
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Refer Application Circuit Figure
RT9278
Output Voltage Output Current
3.310 3.305 3.300 3.295 3.290 3.285 3.280 3.275 3.270 3.265 3.260 3.255 3.250 1000 4.98 4.97 4.96
Output Voltage Output Current
Output Voltage
Output Voltage
4.95 4.94 4.93 4.92 4.91 4.90 4.89 4.88 4.87 4.86 4.85
VOUT 3.3V
3.0V 2.5V 2.0V 1.5V
VOUT 5.0V
4.2V 4.0V 3.5V 3.0V 2.5V 2.0V 1.5V
1000
Output Current (mA)
Output Current (mA)
Power Efficiency Input Voltage
Normal Operation
Refer Application Circuit Figure VOUT
(10mV/Div) (5V/Div)
Power Efficiency
(1V/Div)
(500mA/Div) 1.5V, VOUT ILOAD 100mA
3.5V, ILED 200mA, 4.7µH
Time (1µs/Div)
Input Voltage
Normal Operation
VOUT
(10mV/Div) (5V/Div)
Normal Operation
VOUT
(10mV/Div)
(1V/Div)
(1V/Div)
1.5V, VOUT ILOAD 300mA
(5V/Div) (500mA/Div) 4.2V, VOUT ILOAD 100mA
(1A/Div)
Time (1µs/Div)
Time (1µs/Div)
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DS9278-04 August 2007
RT9278
Load Transient Regulation
1.5V, VOUT ILOAD 100mA 300mA
Normal Operation
VOUT
(1V/Div)
Load Current (mA) Output Voltage Deviation (mV)
4.2V, VOUT ILOAD 300mA
(10mV/Div)
(5V/Div)
(500mA/Div)
Time (1µs/Div)
Time (1ms/Div)
Load Transient Regulation
4.2V, VOUT ILOAD 100mA 400mA
Flash
3.0V, Power 200mA 700mA
Load Current (mA)
(100mV/Div) (2V/Div)
GPIO Output Voltage Deviation (mV)
-100 (500mA /Div)
ILED Time (1ms/Div)
(500mA/Div)
Time (10ms/Div)
Flash
3.77V, Power 200mA 700mA
Flash
4.3V, Power 200mA 700mA
(100mV/Div) (2V/Div)
(100mV/Div) (2V/Div)
GPIO
(500mA /Div)
GPIO
(500mA/Div)
ILED
(500mA/Div) Mode Transition
ILED
(500mA/Div)
Time (10ms/Div)
Time (10ms/Div)
DS9278-04 August 2007
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RT9278
Application Information
RT9278 integrates high-efficiency synchronous rectifier step-up DC-DC converter linear regulator controller. fully utilize advantages, peripheral components should appropriately selected. following information provides basic considerations component selection. Inductor Selection better efficiency high switching frequency converter, inductor selection proper core material such ferrite core reduce core loss choose wire reduce copper loss. most important point prevent core saturated when handling maximum peak current. Using shielded inductor minimize radiated noise sensitive applications. maximum peak inductor current maximum input current plus half inductor ripple current. calculated peak current smaller than current limitation electrical characteristics. typical setting inductor ripple current maximum input current. selection IIN(MAX) IRIPPLE IIN(MAX) (IOUT(MAX) VOUT VIN(MIN) minimum inductance value derived from following equation: IIN(MIN)2 [VOUT VIN(MIN)] IOUT(MAX) VOUT fOSC
Output Capacitor Selection lower output voltage ripple, low-ESR ceramic capacitors recommended. tantalum capacitors used well, bigger than ceramic capacitor. output voltage ripple consists components: pulsating output ripple current flows through ESR, other capacitive ripple caused charging discharging. VRIPPLE VRIPPLE(ESR VRIPPLE(C) IPEAK ESRCOUT Output Voltage Setting Referring application circuits (Figure output voltage switching regulator (VOUT with below equation VOUT VFB, 0.8V (typ.)
Linear Regulator
Linear Regular MOSFETs Selection linear controller RT9278 designed drive external P-Channel MOSFET. main consideration pass MOSFETs linear regulator package selection efficient removal heat. power dissipation linear regulator Plinear (VIN-VOUT IOUT
Depending application, recommended inductor value between 2.2µH 10µH. Input Capacitor Selection better input bypassing, low-ESR ceramic capacitors recommended performance. 10µF input capacitor sufficient most applications. lower output power requirement application, this value decreased.
criterion selection package junction temperature below maximum desired temperature with maximum expected ambient temperature. Layout Guide
full plane without break. noise bypass Short wide connection MLCC capacitor between Pin7 Pin3. noise bypass capacitor close inductor, when ideal voltage source. Minimized node copper area keep away from noise sources. MOSFETs linear regulator should have wide dissipate heat.
DS9278-04 August 2007
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Preliminary Outline Dimension
RT9278
DETAIL
DETAIL Mark Options Note configuration identifier optional, must located within zone indicated.
Symbol
Dimensions Millimeters 0.800 0.000 0.175 0.180 2.950 2.300 2.950 1.500 0.500 0.350 0.450 1.000 0.050 0.250 0.300 3.050 2.650 3.050 1.750
Dimensions Inches 0.031 0.000 0.007 0.007 0.116 0.091 0.116 0.059 0.020 0.014 0.018 0.039 0.002 0.010 0.012 0.120 0.104 0.120 0.069
V-Type Package
Richtek Technology Corporation
Headquarter Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611
Richtek Technology Corporation
Taipei Office (Marketing) 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek.com
DS9278-04 August 2007
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High Efficiency Boost Converter High Power White Driver RT9278 co

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