Output 1.5A Less High-efficiency Step-down Switching Regulator with Bu
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Single-chip Type with Built-in Switching Regulator Series
Output 1.5A Less High-efficiency Step-down Switching Regulator with Built-in Power MOSFET
BD8312HFN
No.09027EBT04
Description ROHM's Output 1.5A Less High-efficiency Step-down Switching Regulator with Built-in Power MOSFET BD8312HFN produces step-down output including 1.2, 1.8, 3.3, from batteries, batteries such Li2cell Li3cell, etc. 5V/12V fixed power supply line. This allows easy production small power supply wide range external constants, equipped with external coil/capacitor downsized high frequency operation MHz, built-in synchronous rectification capable withstanding flexible phase compensation system board.
Features Incorporates Pch/Nch synchronous rectification capable withstanding A/15V. Incorporates phase compensation device between input output Error AMP. Small coils capacitors used high frequency operation 1.5MHz Input voltage Output current 800mA Incorporates soft-start function. Incorporates timer latch system short protecting function. small 8-pin package HSON8
Application portable equipment like DSC/DVC powered batteries Li2cell Li3cell, general consumer-equipment with V/12 lines
Operating Conditions Parameter Power supply voltage Output voltage
Symbol VOUT
Voltage circuit
Unit
Absolute Maximum Ratings Parameter Maximum applied power voltage Maximum input current Power dissipation Operating temperature range Storage temperature range Junction temperature
Symbol VCC, PVCC Iinmax Topr Tstg Tjmax
Rating +150 +150
Unit
When used more installed board, rating reduced 5.04mW/. These specifications subject change without advance notice modifications other reasons.
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1/14
2009.04- Rev.B
BD8312HFN
Electrical Characteristics Unless otherwise specified, Parameter Symbol Target Value 1.38 4.65 0.99 -0.3 ISTB1 ISTB2 1.00 1.62 5.35 1.01 Unit
Technical Note
Conditions
[Low voltage input malfunction preventing circuit] Detection threshold voltage Hysteresis range [Oscillator] Oscillation frequency [Regulator] Output voltage [Error AMP] threshold voltage Input bias current Soft-start time [PWM comparator] Duty [Output] PMOS resistance NMOS resistance Leak current [STB] control voltage [Circuit current] Standby current
PVCC
VUVhy Fosc VREG VINV IINV Dmax RONP RONN Ileak
msec
VREG monitor
VCC=12.0V
VINV=6.0V
Operation No-operation
VSTBH VSTBL
pull-down resistance
Circuit current operation
Circuit current operation PVCC
designed resistant radiation
VINV=1.2V VINV=1.2V
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2/14
2009.04- Rev.B
BD8312HFN
Description Pins VREG PGND PVCC Fig.1 Terminal layout Name VREG PGND PVCC
Technical Note
Function Ground terminal Control part power input terminal output terminal regulator internal circuit Power transistor ground terminal Coil connecting terminal DC/DC converter input terminal ON/OFF terminal Error input terminal
Block Diagram
ON/OFF
VREG
PVCC
STBY_IO
Reference
VREF
UVLO
1.5MHz
STOP
ount
DRIVER
450m
CONTROL Step down
TIMMING CONTROL
VREG
DRIVER ERROR_AMP Soft Start
ount 300m
VREF
PGND
Fig.2 Block diagram
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3/14
2009.04- Rev.B
BD8312HFN
Description Blocks Reference This block produces ERROR standard voltage. standard voltage
Technical Note
saturation regulator internal analog circuit This equipped with this regulator purpose protecting internal circuit from voltage. Therefore, this output reduced when less than there problem use. UVLOT Circuit preventing voltage malfunction Prevents malfunction internal circuit activation power supply voltage power supply voltage. Monitors voltage turn output DC/DC converter output when voltage lower than reset timer latch internal circuit soft-start circuit. This threshold contains hysteresis. Timer latch system short-circuit protection circuit When lower voltage, internal circuit starts counting. internal counter synch with OSC; latch circuit activates about 2.7msec after counter counts about 4000 oscillations turn DC/DC converter output. reset latch circuit, turn once. Then, turn again turn power supply voltage again. Circuit oscillating sawtooth waves with operation frequency fixed ERROR Error amplifier detecting output signals output control signals internal standard voltage primary phase compensation device built in-between inverting input terminal output terminal this ERROR AMP. COMP Voltage-pulse width converter controlling output voltage corresponding input voltage Comparing internal SLOPE waveform with ERROR output voltage, COMP controls pulse width output driver.
SOFT START Circuit preventing in-rush current startup bringing output voltage DC/DC converter into soft-start Soft-start time synch with internal OSC, output voltage DC/DC converter reaches voltage after about 8000 oscillations. DRIVER/TIMING CONTROL CMOS inverter circuit driving built-in synchronous rectification synchronous rectification time preventing feedthrough about nsec.
STBY_IO Voltage applied pin) control ON/OFF Turned when voltage higher applied turned when terminal open applied. Incorporates approximately pull-down resistance. Pch/Nch Built-in synchronous rectification switching coil current DC/DC converter Incorporates PchFET capable withstanding V.and capable withstanding Since current rating this 1.0A, should used within 1.0A including current ripple current coil.
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4/14
2009.04- Rev.B
BD8312HFN
Reference data Unless otherwise specified,
1.02 1.02
Technical Note
1.01 1.01
VREG VOLTAGE
THRESHOLD
THRESHOLD
1.00
1.00
0.99
0.99
0.98 TEMPERATURE
0.98
TEMPERATURE
Fig.3. threshold temperature property
Fig.4. threshold power supply property
Fig.5. VREG output temperature property
FREQUENCY
FREQUENCY [MHz]
VREG[V]
TEMPERATURE
Fig.6. VREG output power supply property
Fig.7. fosc temperature property
Fig.8. fosc voltage property
3.50
Hysteresis width UVLO release voltage
0.25
ID=500mA
ID=500mA
Hysteresis VoltageVhys Vhys[V]
3.30
0.20
RESISTANCE
3.10
0.15
2.90
0.10
UVLO detection voltage
2.70 0.05
RESISTANCE
2.50
0.00
TEMPARATURE
Environmental temperature [°C]
Fig.9. UVLO threshold temperature property
Fig.10. resistance temperature property
Fig.11. resistance power supply property
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5/14
2009.04- Rev.B
BD8312HFN
Technical Note
1000
ID=500mA
ID=500mA
SWOUT Resistance
SWOUT Resistance
Voltage
TEMPARATURE
Fig.12. resistance temperature property
Fig.13. resistance power supply property
Fig.14. threshold temperature property
1000
1000
[uA]
[uA]
TEMPARATURE
Fig.15. Circuit current temperature property
Fig.16. Circuit current voltage property
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6/14
2009.04- Rev.B
BD8312HFN
Example Application Input: output: 500mA
Technical Note
VBAT=4.510V
GRM188B11A105KA61 Murata
PVCC
ON/OFF 10pF
VREG
GRM188B11A105KA61 Murata
3.3V/500mA
200k
PGND
4.7H 1098AS-4R7MTOKO
GRM31CB11A106KA01 Murata
Fig.17 Reference application diagram
Reference application data
3.35
3.33
VCC=7.5V VCC=5.5V
OUTPUT VOLTAGE
VCC=4.5V
EFFICIENCY
VCC=7.5V VCC=5.5V
3.31
VCC=4.5V
3.29
3.27
1000
3.25 1000
OUTPUT CURRENT [mA]
OUTPUT CURRENT [mA]
Fig.18 Power conversion efficiency (VOUT
Fig.19 Load regulation (VOUT
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7/14
2009.04- Rev.B
BD8312HFN
Reference application data (Input output
Technical Note
Gain [dB]
Gain
Phase
Gain [dB] Phase [deg]
Phase
Phase [deg] Gain [dB] -120 -180
1000 10000 [Hz] Frequency [Hz]
Gain Phase
-120 -180 100000 1000000 Phase [deg]
Phase [deg]
Gain
1000 10000 [Hz] Frequency [Hz] -120 -180 100000 1000000
1000 10000
100000 1000000
Frequency [Hz] [Hz]
Fig.20 Frequency response (VCC=4.5V, Io=250mA)
Phase
Fig.21 Frequency response (VCC=6.0V, Io=250mA)
Phase [deg] Gain [dB] 1000 10000 100000
Gain Phase
Fig.22 Frequency response (VCC=8.4V, Io=250mA)
Phase
Phase [deg]
Gain
Gain [dB]
Gain
Gain [dB] 1000 10000 100000 [Hz] Frequency [Hz]
-120 -180 1000000
1000 10000 100000
-120 -180 1000000
-120 -180 1000000
Frequency[Hz] [Hz]
Frequency [Hz] [Hz]
Fig.23 Frequency response (VCC=10V, Io=250mA)
Phase
Fig.24 Frequency response (VCC=4.5V, Io=500mA)
Fig.25 Frequency response (VCC=6.0V, Io=500mA)
Phase [deg]
Gain [dB]
Gain [dB]
Gain
Phase
-120 -180 Phase [deg]
-120 -180 1000 10000 100000 1000000
1000
Gain
10000
100000
1000000
Frequency[Hz] [Hz]
Frequency [Hz] [Hz]
Fig.26 Frequency response (VCC=8.4V, Io=500mA)
Fig.27 Frequency response (VCC=10V, Io=500mA)
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8/14
2009.04- Rev.B
BD8312HFN
Reference board pattern
Technical Note
VOUT
VBAT
radiation plate rear should flat surface impedance common with PGND flat surface. recommended install another system shown drawing without connecting directly this PNGD. Produce wide pattern possible VBAT, PGND lines which large current flows. Selection Part Applications Inductor shielded inductor that satisfies current rating (current value, Ipecac shown drawing below) (direct resistance component) recommended. Inductor values affect inductor ripple current, which will cause output ripple. Ripple current reduced coil value becomes larger switching frequency becomes higher. Ipeak =Iout IL/2
Fig.28 Inductor current
VinVout
Vout
Efficiency, Output ripple current, Switching frequency) guide, inductor ripple current should about maximum input current. *Current over coil rating flowing coil brings coil into magnetic saturation, which lead lower efficiency output oscillation. Select inductor with adequate margin that peak current does exceed rated current coil. Output capacitor ceramic capacitor with recommended output order reduce output ripple. There must adequate margin between maximum rating output voltage capacitor, taking bias property into consideration. Output ripple voltage acquired following equation. Setting must performed that output ripple within allowable ripple voltage.
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9/14
2009.04- Rev.B
BD8312HFN
Output voltage setting internal standard voltage ERROR
VOUT ERROR VREF 1.0V
Technical Note
Output voltage acquired Equation (4).
(R1+R2)
Fig.29 Setting voltage feedback resistance DC/DC converter frequency response adjustment system Condition stable application condition feedback system stability under negative feedback that phase delay less when gain (0dB). Since DC/DC converter application sampled according switching frequency, bandwidth whole system (frequency which gain must controlled equal lower than 1/10 switching frequency. summary, conditions necessary DC/DC converter are: Phase delay must 135°or lower when gain dB). Bandwidth (frequency when gain must equal lower than 1/10 switching frequency. satisfy those points, Fig. should follows. BD8313HFN incorporates phase compensation devices R4=62k C2=200pF. These valuesdecide primary pole that determines bandwidth DC/DC converter. Primary pole point frequency DC/DC converter Gain
Gain
VOUT Inside
R1+R2
Fig.30 Example phase compensation setting Error Gain About 100dB Oscillator amplification VIN: Input voltage Output voltage VOUT:
Equations (2), frequency point under limitation bandwidth gain primary pole point shown below.
(R1R2) (R1+R2)
Gain
recommended that should approx.10 kHz. When load response difficult, approx. kHz. Equation (3), which determine voltage value, will order several hundred appropriate resistance value available since resistance high routing cause noise, enables easy setting.
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10/14
2009.04- Rev.B
BD8312HFN
Technical Note
setting step-up DC/DC converter, secondary pole point caused coil capacitor expressed following equation. 2(LC)
fLC=
This secondary pole causes phase rotation 180°. secure stability system, zero point places perform compensation. Zero point built-in fZ1= 2R4C2 2(R1+R3)CS 13kHz
Zero point
fZ1=
Setting half times frequency large provides appropriate phase margin. desirable about 1/20 (R1+R3) cancel phase boosting high frequencies. Those pole points summarized figure below. actual frequency property different from ideal calculation because part constants. possible, check phase margin with frequency analyzer network analyzer. Otherwise, check presence absence ringing load response waveform also check presence absence oscillation under load adequate margin.
Fig.31 Example DC/DC converter frequency property Measured with FRA5097 Corporation
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11/14
2009.04- Rev.B
BD8312HFN
Equivalence Circuit
Technical Note
VREG
PGND, PVCC
VREG
PVCC
VREG
PGND
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12/14
2009.04- Rev.B
BD8312HFN
Technical Note
Notes Absolute Maximum Rating dedicate much attention quality control these products, however possibility deterioration destruction exists impressed voltage, operating temperature range, etc., exceed absolute maximum ratings. addition, impossible predict destructive situations such short-circuit modes, open circuit modes, etc. special mode exceeding absolute maximum rating expected, please review matters provide physical safety means such fuses, etc. Potential Keep potential below minimum potential times. Thermal Design Work thermal design with sufficient margin taking power dissipation (Pd) actual operation condition into account. Short Circuit between Pins Incorrect Mounting Attention direction displacement required when installing PCB. installed wrong way, break. Also, threat destruction from short-circuits exists foreign matter invades between outputs output power supply. Operation under Strong Electromagnetic Field careful possible malfunctions under strong electromagnetic fields. Common Impedance When providing power supply wirings, show sufficient consideration lowering common impedance reducing ripple (i.e., using thick short wiring, cutting ripple down etc.) much can. Thermal Protection Circuit (TSD Circuit) This contains thermal protection circuit (TSD circuit). circuit serves shut from thermal runaway does protect assure operation itself. Therefore, circuit continuous operation after circuit tripped. Rush Current Time Power Activation careful power supply coupling capacity width power supply pattern wiring routing since rush current flows instantaneously time power activation case CMOS with multiple power supplies.
Terminal Input
This monolithic isolation substrate element isolation between each element. junctions formed various parasitic elements configured using these layers layers individual elements. example, resistor transistor connected terminal shown Fig.32: junction operates parasitic diode when (Terminal case resistor when (Pin case transistor (NPN) Also, parasitic transistor operates using layer another element adjacent previous diode case transistor (NPN) when (Pin parasitic element consequently rises under potential relationship because IC's structure. parasitic element pulls interference that could cause malfunctions destruction circuit. Therefore, caution avoid operation parasitic elements caused applying voltage input terminal lower than board), etc. Resistor (Pin (Pin Transistor (NPN)
Substrate
Parasitic Element
Parasitic Element
Substrate
Parasitic Element
Fig.32 Example simple structure Bipolar
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13/14
2009.04- Rev.B
(Pin
BD8312HFN
Ordering part number
Technical Note
Part
Part
Package HFN:HSON8
Packaging forming specification Embossed tape reel
HSON8
<Tape Reel information>
2.9±0.1 (MAX include BURR)
(0.2)
(2.2)
(0.05)
Tape Quantity
Embossed carrier tape 3000pcs
direction 1pin product upper right when hold
0.475
(0.15)
(0.3)
5678
(0.45)
(0.2) (1.8)
Direction feed
+0.1 0.13 -0.05
reel left hand pull tape right hand
1pin
1234
4321
1PIN MARK
0.6MAX
+0.03 0.02 -0.02
0.65 0.32±0.1
0.08
Direction feed
(Unit
Reel
Order quantity needs multiple minimum quantity.
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14/14
2009.04- Rev.B
Notice
Notes
copying reproduction this document, part whole, permitted without consent ROHM Co.,Ltd. content specified herein subject change improvement without notice. content specified herein purpose introducing ROHM's products (hereinafter "Products"). wish such Product, please sure refer specifications, which obtained from ROHM upon request. Examples application circuits, circuit constants other information contained herein illustrate standard usage operations Products. peripheral conditions must taken into account when designing circuits mass production. Great care taken ensuring accuracy information specified this document. However, should incur damage arising from inaccuracy misprint such information, ROHM shall bear responsibility such damage. technical information specified herein intended only show typical functions examples application circuits Products. ROHM does grant you, explicitly implicitly, license exercise intellectual property other rights held ROHM other parties. ROHM shall bear responsibility whatsoever dispute arising from such technical information. Products specified this document intended used with general-use electronic equipment devices (such audio visual equipment, office-automation equipment, communication devices, electronic appliances amusement devices). Products specified this document designed radiation tolerant. While ROHM always makes efforts enhance quality reliability Products, Product fail malfunction variety reasons. Please sure implement your equipment using Products safety measures guard against possibility physical injury, fire other damage caused event failure Product, such derating, redundancy, fire control fail-safe designs. ROHM shall bear responsibility whatsoever your Product outside prescribed scope accordance with instruction manual. Products designed manufactured used with equipment, device system which requires extremely high level reliability failure malfunction which result direct threat human life create risk human injury (such medical instrument, transportation equipment, aerospace machinery, nuclear-reactor controller, fuel-controller other safety device). ROHM shall bear responsibility Products above special purposes. Product intended used such special purpose, please contact ROHM sales representative before purchasing. intend export ship overseas Product technology specified herein that controlled under Foreign Exchange Foreign Trade Law, will required obtain license permit under Law.
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