1.7A/2.5A Step-Up DC/DC Converters MSOP FEATURES Greater than Eff
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ACT6390/ACT6391
1.7A/2.5A Step-Up DC/DC Converters MSOP FEATURES
Greater than Efficiency Adjustable Output Voltage Internal Power MOSFET Peak Current Options:
GENERAL DESCRIPTION
ACT6390/ACT6391 high-performance, fixed-frequency, current-mode step-up DC/DC converters that incorporate internal power MOSFETs. ACT6390 includes integrated power MOSFET that supports peak currents 1.7A, while ACT6391's integrated 0.15 power MOSFET supports currents 2.5A. ACT6390 ACT6391 both utilize simple external loop compensation pin-selectable fixed-frequency either 700kHz 1.3MHz, allowing optimization between component size, cost, performance across wide range applications. Additional functions include externally programmable soft-start function easy inrush current control, internal over-voltage protection (OVP), cycle-by-cycle current limit protection, thermal shutdown. Both ACT6390 ACT6391 available small 8-pin MSOP-8 package.
ACT6390: 1.7A, ACT6391: 2.5A, 0.15 Selectable 700kHz/1.3MHz Frequency
Integrated Over-Voltage Protection (OVP) Programmable Soft-Start Function Thermal Shutdown Cycle-by-Cycle Over-Current Protection Small MSOP-8 Package
APPLICATIONS
Monitors Battery-Powered Equipment Set-Top Boxes Cable Modems Routers
SIMPLIFIED APPLICATION CIRCUIT
2.7V 5.5V
1.3MHz 700kHz
ACT6390 ACT6391
VOUT
FREQ COMP
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ACT6390/ACT6391
ORDERING INFORMATION
PART NUMBER
ACT6390MH-T ACT6391MH-T
CURRENT LIMIT
1.7A 2.5A
TEMPERATURE RANGE
-40°C 85°C -40°C 85°C
PACKAGE
MSOP-8 MSOP-8
PINS
PACKAGING
TAPE REEL TAPE REEL
CONFIGURATION
COMP FREQ
ACT6390 ACT6391
MSOP-8
DESCRIPTIONS
NAME
COMP FREQ
DESCRIPTION
Error Amplifier Compensation Node. Connect resistor capacitor series ground. Feedback Input. Connect this resistor divider from output output voltage. regulated 1.24V. Enable Control. Connect logic high level enable Connect logic level disable When unused, connect leave floating). Ground. Switch Output. Connect this inductor schottky diode. minimize EMI, minimize trace path between this input bypass capacitor. Supply Input. Bypass with larger capacitor. Frequency Setting Pin. logic sets switching frequency 700kHz. logic high sets switching frequency 1.3MHz. This internal 5.5µA pull-down current. Soft Start Control Input. Connect capacitor from this soft-start timing duration (tSS CSS). discharged ground shutdown. left unconnected soft start desired.
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ACT6390/ACT6391
ABSOLUTE MAXIMUM RATINGS
PARAMETER
FREQ, COMP Continuous Current Junction Ambient Thermal Resistance (JA) Maximum Power Dissipation Operating Junction Temperature Storage Temperature Lead Temperature (Soldering, sec)
VALUE
-0.3 -0.3 -0.3 Internally Limited
UNIT
°C/W
exceed these limits prevent damage device. Exposure absolute maximum rating conditions long periods affect device reliability.
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ACT6390/ACT6391
ELECTRICAL CHARACTERISTICS
(VIN VFREQ 25°C, unless otherwise specified.)
PARAMETER
Switch Voltage Rating Input Voltage Under Voltage Lockout Threshold Under Voltage Lockout Hysteresis Rising
TEST CONDITIONS
UNIT
2.35 1.3V, Switching ACT6390 ACT6391 1300 1.22 1.27V from 2.6V 5.5V 1.15V 1.35V, VCOMP 1.1V Duty Cycle ACT6390 ACT6391 12V, ACT6390 ACT6391 1.2V 1.2V, FREQ FREQ VFREQ 0.45 ACT6390 ACT6391 1.24 0.05 0.15
0.35 1700
Quiescent Supply Current
1.0V, Switching FREQ FREQ FREQ FREQ
Supply Current Shutdown Switching Frequency
Maximum Duty Cycle Feedback Voltage Input Current Voltage Line Regulation Error Amplifier Trans-conductance Error Amplifier Output Current Switch Current Limit
1.26 0.15
Switch Resistance Switch Leakage Current Current Sense Trans-resistance Soft Start Bias Current Soft Start Reset Resistance Logic High Threshold Logic Threshold Input Current FREQ Pull-down Current Thermal Shutdown Temperature Thermal Shutdown Hysteresis
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ACT6390/ACT6391
FUNCTIONAL BLOCK DIAGRAM
4.5µA COMP ERROR AMPLIFIER 1.24V ERROR COMPARATOR SOFT START
CONTROL DRIVE LOGIC
FREQ
OSCILLATOR 5.5µA
CURRENT SENSE AMPLIFIER
FUNCTIONAL DESCRIPTION
ACT6390 ACT6391 highly efficient step-up DC/DC converters that employ currentmode, fixed frequency pulse-width modulation (PWM) architecture with excellent line load regulation. ACT6390 ACT6391 operate constant switching frequency under medium high load current conditions. light loads, these devices operate pulse-skipping mode order improve light-load efficiency.
Frequency Selection
ACT6390 ACT6391 include pinselectable operating frequency drive FREQ logic high 1.3MHz operation, drive FREQ logic 700kHz operation. Selectable operating frequency, combination with external compensation network, allows wide range flexibility optimizing total solution size cost. FREQ internally pulled down 5.5µA, this left unconnected achieve 700kHz operating frequency.
Soft-Start
ACT6390 ACT6391 both offer programmable soft-start function which minimizes inrush current during startup. soft-start period programmed connecting capacitor (CSS) between Operation soft-start function follows: when disabled, actively discharged Upon enabling charged with 4.5µA current that voltage increases controlled manner. peak inductor current limited voltage that input current limited until soft-start period expires, regulator achieve full output current rating. soft-start period calculated simple function soft-start capacitor using equation:
Setting Output Voltage
ACT6390 ACT6391 both feature external adjustable output voltages 12V. program output voltage, simply connect resistive voltage divider between output, with resistors according following equation:
Where 1.24V.
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SLOPE COMPENSATION
CLOCK
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ACT6390/ACT6391
Inductor Selection
step-up converter, switch duty cycle determined input voltage (VIN) output voltage (VOUT), given following formula:
LMIN
(VOUT
1.75
(10)
VOUT VOUT
Where current sense trans-resistance, 0.45 ACT6390, ACT6391. example: 3.3V, VOUT 12V, 700kHz IOUT 250mA, 85%, FREQ
Define
VOUT
(11)
Where: inductor ripple current steady state, typically chosen about 0.3,
0.85 3.3V 3.3V 7.99µH 250mA
Select 10µH Assuming minimum input voltage cost external components used, yielding efficiency just 80%.
IL(DC) inductor current, given
VOUT IOUT
,MAX
(MAX
1.25
(12) (13) (14)
Where typical efficiency. Solving equations (3),(4),(5) inductor value,
(12V 0.32
(VOUT
IPEAK (MAX 1.25
0.32 1.41A
stability,
This equation used determine correct trade-off between efficiency, current ripple, size cost. When selecting inductor make sure that inductors maximum current saturation current exceed maximum operation point, calculated ,MAX (MAX (MIN
IL(PEAK ,MAX IL(DC,MAX IL(MAX IOUT (MAX (MIN [VOUT -VIN (MIN (MIN VOUT
LMIN
(12V 3.3V 0.45
1.75 700kHz
(15)
Which meets slope compensation requirement.
Loop Compensation
COMP
RCOMP CCOMP2 CCOMP
output voltage greater than times input voltage, that means duty cycle greater than 50%, slope compensation required stability. When operating this condition ensure that inductor value greater than LMIN:
ACT6390 ACT6391 feature simple loop compensation scheme. Simple follow procedure detailed below determine suitable compensation components. best results sure prototype confirm values, adjust compensation network inspecting transient response, example) needed optimize results your particular application. When converter operates with continuous inductor current, right-half-plane zero exits loop's gain-frequency response. ensure stability,
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ACT6390/ACT6391
Rev0, 13-May-08 cross-over frequency (unity gain-frequency) should less than one-fifth right-half-plane zero fZ(RHP), lower than one-fifteenth switching frequency fsw. CCOMP2,
CCOMP2 COUT RESR RCOMP
(23)
(RHP
LOAD 2VOUT
(16)
value CCOMP2 calculated (23) smaller than 10pF, CCOMP2 omitted. example:
Choose
(RHP then calculate CCOMP:
CCOMP
LOAD VOUT RLOAD VOUT
(17)
(RHP)
250mA 57.8kHz (12V
(RHP 11.56
(3.3V
(24)
Choose
CCOMP
Select RCOMP meet transient-droop requirements.
3.3V 150µS 6.26nF (25) 0.45 (12V
RCOMP
RCOMP VOUT IOUT
Choose CCOMP 6.8nF Assume that 200mV transient droop accepted:
(18)
(19)
(26)
Where: transient droop percentage which accepted, calculated
VOUT VOUT
0.45 250mA1 RCOMP 186.3k (27) 3.3V 0.85 Choose RCOMP 180k
(20)
COUT
defined equation typical efficiency. VFB: feedback voltage, 1.24V trans-conductance error amplifier. output capacitor chosen output pole canceling RCOMP, CCOMP zero.
RCOMP CCOMP 180k 6.8nF 25.5 (28) RLOAD 0.25
COUT chosen either 22µF 33µF, choose 33µF reduce droop.
RCOMP
RLOAD COUT 33µF 233k CCOMP 6.8nF
(29)
COUT
RCOMP CCOMP RLOAD
ceramic capacitor used with assumed 20m,
(21)
(ESR
CCOMP2 optional used when output capacitor significant ESR. will form zero follows:
241kHz
(30)
fZ(ESR) Since zero frequency greater than pole frequency ,CCOMP2 omitted. tantalum capacitor used, whose about 0.5,
(ESR
RESR COUT
(22)
this zero occurs higher frequency than cross-over frequency, ignored. Otherwise, should canceled with pole capacitor
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ACT6390/ACT6391
(ESR)
9.64kHz 33µF
(31)
fZ(ESR)
RESR COUT 33µF 70.8 RCOMP 233k Choose CCOMP2 82pF CCOMP2
(32)
Rectifier Selection
optimal performance, rectifier should Schottky rectifier that rated handle both output voltage well peak switch current.
Over Voltage Protection
ACT6390 ACT6391 both feature internal automatic over-voltage protection (OVP). Once outputs achieve regulation, voltage falls below 0.125V controller will automatically disable latch off, preventing controller from running open-loop potentially damaging load. re-enable converters, simply cycle remove reapply power input.
Shutdown
Drive disable reduce supply current just 0.1µA. with nonsynchronous step-up DC/DC converters, external Schottky diode provides path from input output shutdown. result, output drops diode voltage drop below input shutdown.
Thermal Shutdown
ACT6390 ACT6391 both feature integrated thermal overload protection. Both devices automatically disabled when their junction temperatures exceed 160°C, automatically re-enable when temperature decreases 20°C.
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ACT6390/ACT6391
TYPICAL PERFORMANCE CHARACTERISTICS
(VIN 3.3V, FREQ 25°C, unless otherwise specified.)
ACT6390 Efficiency Output Current
3.3V VOUT FREQ 2.7µH FREQ 5.4µH ACT6390-001
ACT6390 Efficiency Output Current
ACT6390-002 VOUT FREQ 10µH FREQ 5.4µH
Efficiency
Efficiency
1000
1000
Output Current (mA)
Output Current (mA)
ACT6390 Efficiency Output Current
3.3V VOUT 0.40 ACT6390-003
ACT6390 Load Supply Current
ACT6390-004
Supply Current (mA)
0.36
Efficiency
FREQ 10µH FREQ 5.4µH
FREQ 5.4µH
0.32
0.28
FREQ 10µH
0.24
0.20 1000
Output Current (mA)
ACT6390 Maximum Output Current Input Voltage Maximum Output Current (mA)
2200 1800 1400 1000 VOUT ACT6390-005 FREQ
VOUT VOUT
Input Voltage
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ACT6390/ACT6391
TYPICAL PERFORMANCE CHARACTERISTICS
(VIN 3.3V, FREQ 25°C, unless otherwise specified.)
ACT6391 Efficiency Output Current
3.3V VOUT ACT6391-006 FREQ 5.4µH
ACT6391 Efficiency Output Current
ACT6391-007 VOUT
Efficiency
Efficiency
FREQ 4.7µH
FREQ 10µH
FREQ 4.7µH
1000
1000
Output Current (mA)
Output Current (mA)
ACT6391 Efficiency Output Current
ACT6391-008 3.3V VOUT FREQ 10µH 0.40
ACT6391 Load Supply Current
ACT6391-009 VOUT
Supply Current (mA)
0.36 0.32 FREQ 10µH FREQ 4.7µH
Efficiency
FREQ 4.7µH
0.28
0.24
0.20 1000
Output Current (mA)
ACT6391 Maximum Output Current Input Voltage Maximum Output Current (mA)
2400 FREQ 2000 1600 1200 VOUT VOUT VOUT ACT6391-010
Input Voltage
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ACT6390/ACT6391
PACKAGE OUTLINE
MSOP-8 PACKAGE OUTLINE DIMENSIONS
DIMENSION SYMBOL MILLIMETERS
0.820 0.020 0.750 0.250 0.090 2.900 2.900 4.750 1.100 0.150 0.950 0.380 0.230 3.100 3.100 5.050
DIMENSION INCHES
0.032 0.001 0.030 0.010 0.004 0.114 0.114 0.187
0.043 0.006 0.037 0.015 0.009 0.122 0.122 0.199
0.650 0.400 0.800
0.026 0.016 0.031
Active-Semi, Inc. reserves right modify circuitry specifications without notice. Users should evaluate each product make sure that suitable their applications. Active-Semi products intended authorized critical components lifesupport devices systems. Active-Semi, Inc. does assume liability arising product circuit described this datasheet, does convey patent license. Active-Semi logo trademarks Active-Semi, Inc. more information this other products, contact sales@activesemi.com visit http://www.active-semi.com. other inquiries, please send 1270 Oakmead Parkway, Suite 310, Sunnyvale, California 94085-4044,
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