BD7F005EFJ-C (开发中) [ROHM]
BD7F005EFJ-C is an opto-coupler-less isolated flyback converter. Feedback circuit by optocouplers or the auxiliary winding of transformers becomes unnecessary, contributing to reduction of set parts. Furthermore, the adoption of original adapted ON-time control technology enables fast load response. In addition, the various protection function realizes the designs of isolated power supply application for high reliability.;型号: | BD7F005EFJ-C (开发中) |
厂家: | ROHM |
描述: | BD7F005EFJ-C is an opto-coupler-less isolated flyback converter. Feedback circuit by optocouplers or the auxiliary winding of transformers becomes unnecessary, contributing to reduction of set parts. Furthermore, the adoption of original adapted ON-time control technology enables fast load response. In addition, the various protection function realizes the designs of isolated power supply application for high reliability. |
文件: | 总35页 (文件大小:1270K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
Datasheet
Isolated DC/DC Converter IC
Isolated Type Fly-back Converter IC
with Integrated Switching MOSFET
for Automotive
BD7F005EFJ-C
General Description
Key Specifications
◼ Input Voltage Range:
VIN Pin
BD7F005EFJ-C is an opto-coupler-less isolated flyback
converter. Feedback circuit by optocouplers or the
auxiliary winding of transformers becomes unnecessary,
contributing to reduction of set parts. Furthermore, the
adoption of original adapted ON-time control technology
enables fast load response. In addition, the various
protection function realizes the designs of isolated power
supply application for high reliability.
3.4 V to 42.0 V
60 V (Max)
363 kHz (Typ)
± 2.8 % (Typ)
0 μA (Typ)
SW Pin
◼ Switching Frequency:
◼ Reference Voltage Precision:
◼ Shutdown Current:
◼ Operating Ambient Temperature Range
-40 °C to +125 °C
Features
Package
HTSOP-J8
W (Typ) x D (Typ) x H (Max)
◼ AEC-Q100 Qualified(Note 1)
4.9 mm x 6.0 mm x 1.0 mm
◼ No Need for Optocoupler and Third Winding of
Transformer
◼ Set Output Voltage with Two External Resistors and
Ratio of Transformer Turns
◼ Adopt of Original Adapted ON-time Control Technology
Fast Load Response
◼ High Efficiency at Light Load Mode (PFM Operation)
◼ Shutdown Function / Enable Control
◼ Built-in 60 V Switching MOSFET
◼ Frequency Spectrum Spread
◼ Soft Start Function
◼ Load Compensation Function
◼ Various Protection Function
Input Low Voltage Lockout (UVLO)
Over Current Protection (OCP)
Thermal Shutdown (TSD)
Applications
◼
Automotive Isolated Power Supplies
(E-Comp, Inverter etc)
◼
Industrial Isolated Power Supplies
REF Pin Open Protection (REFOPEN)
Short Circuit Protection (SCP)
Battery Short Protection (BSP)
◼ HTSOP-J8 Package
(Note 1) Grade 1
Typical Application Circuit
VF
VOUT+
VIN
VIN
NS
NP
SDX/EN
VOUT-
SW
FB
REF GND
L_COMP
RFB
RREF
〇Product structure : Silicon integrated circuit 〇This product has no designed protection against radioactive rays.
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BD7F005EFJ-C
Contents
General Description........................................................................................................................................................................1
Features..........................................................................................................................................................................................1
Key Specifications ..........................................................................................................................................................................1
Package..........................................................................................................................................................................................1
Applications ....................................................................................................................................................................................1
Typical Application Circuit...............................................................................................................................................................1
Contents .........................................................................................................................................................................................2
Pin Configuration ............................................................................................................................................................................3
Pin Descriptions..............................................................................................................................................................................3
Block Diagram ................................................................................................................................................................................3
Description of Blocks ......................................................................................................................................................................4
1
2
3
4
5
6
7
8
9
INTERNAL REGULATOR ....................................................................................................................................................4
Input Low Voltage Lock Out (UVLO) ....................................................................................................................................4
Thermal Shutdown (TSD) ....................................................................................................................................................5
SW VOLTAGE DETECTION ................................................................................................................................................5
SOFT START.......................................................................................................................................................................5
PWM COMPARATOR ..........................................................................................................................................................5
ADAPTIVE ON TIME CONTROLLER..................................................................................................................................5
Maximum Frequency Limit Function (MAX FREQ) ..............................................................................................................5
DRIVER ...............................................................................................................................................................................5
10 Nch MOSFET.......................................................................................................................................................................5
11 LOAD COMPENSATION .....................................................................................................................................................6
12 Frequency Spectrum Spread (SPECTRUM SPREAD) ........................................................................................................6
13 Over Current Protection (OCP), Battery Short Protection (BSP)..........................................................................................6
14 Short Circuit Protection (SCP), REF Pin Open Protection (REFOPEN)...............................................................................7
Absolute Maximum Ratings ............................................................................................................................................................8
Thermal Resistance........................................................................................................................................................................8
Recommended Operating Conditions.............................................................................................................................................8
Electrical Characteristics.................................................................................................................................................................9
Typical Performance Curves.........................................................................................................................................................10
Application Examples ...................................................................................................................................................................18
1
2
3
4
5
6
7
8
9
Output Voltage ...................................................................................................................................................................18
Transformer........................................................................................................................................................................20
Output Capacitor................................................................................................................................................................22
Input Capacitor...................................................................................................................................................................22
Secondary Output Diode....................................................................................................................................................23
Output Resistor and Output Zener Diode (Minimum Load Current) ...................................................................................23
Snubber Circuit ..................................................................................................................................................................24
Setting of SDX/EN Pin Resistor .........................................................................................................................................24
The Output Voltage Compensation Function by L_COMP Pin Resistor.............................................................................25
10 The Influence to Frequency and Output Voltage for Each Load.........................................................................................26
I/O Equivalence Circuits................................................................................................................................................................27
Operational Notes.........................................................................................................................................................................28
Ordering Information.....................................................................................................................................................................30
Marking Diagram ..........................................................................................................................................................................30
Physical Dimension and Packing Information...............................................................................................................................31
Revision History............................................................................................................................................................................32
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Pin Configuration
Pin Descriptions
Pin No.
Pin Name
GND
Function
1
2
3
4
5
6
7
8
-
GND pin
SDX/EN
L_COMP
REF
Shutdown/Enable control pin
Setting pin of load current compensation value pin
Output voltage setting pin
FB
Output voltage setting pin
No Connect(Note 1)
N.C.
SW
Switching output pin
VIN
Power supply input pin
EXP-PAD
Connect EXP-PAD to GND on PCB(Note 2)
(Note 1) The N.C pin does not have internal connection. Open the pin when mounting board.
(Note 2) The EXP-Pad pin is connected to GND on the mounting board.
Block Diagram
VIN
FB
SW
SPECTRUM
SPREAD
SW
VOLTAGE
DETECTION
SCP
INTERNAL
REGULATOR
REFOPEN
PWM
COMPARATOR
Nch
MOSFET
ADAPTIVE
ON-TIME
VINTREF
DRIVER
CONTROLLER
SOFT
START
UVLO
TSD
SDX/EN
OCP
BSP
MAXFREQ
LOAD
COMPENSATION
REF
L_COMP
GND
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Description of Blocks
1
INTERNAL REGULATOR
This is regulator block for internal circuits.
This block shuts itself down at the shutdown status of SDX/EN pin voltage VSDX or less.
When SDX/EN pin voltage rises above VSDX, IC consumption current increases.
When SDX/EN pin voltage is above VEN1, IC enters the enable status and starts switching operation.
The soft start function operates for tSS period from switching start, and the output voltage rises slowly.
When SDX/EN pin voltage falls below VEN2, IC enters the disable status and the switching operation is stopped.
VIN
pin voltage
VEN1
VEN2
VSDX
SDX/EN
pin voltage
tss
Output
voltage
Switching
ON
Figure 1. Startup and Stop Timing Chart
2
Input Low Voltage Lock Out (UVLO)
This is the protection function for the low input voltage of the VIN pin.
When VIN pin voltage falls below VUVLO1, IC detects UVLO and stops switching operation.
When VIN pin voltage rises above VUVLO2, IC starts switching operation and a soft start function operates during the
period of tSS
.
VUVLO2
VUVLO1
VIN
pin voltage
0 V
tss
Output
voltage
ON
Switching
ON
Figure 2. VIN UVLO Timing Chart
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Description of Blocks – continued
3
4
5
Thermal Shutdown (TSD)
This block is the thermal shutdown circuit that prevents heat damage to the IC. When IC junction temperature rises
more than 175 °C (Typ), IC stops switching operation. After that, when IC junction temperature falls IC restarts. The
temperature hysteresis is 25 °C (Typ). The TSD function aims to protect itself. So IC junction temperature should be
designed less than Tjmax = 150 °C. For that, it should not use as over temperature protection function of application.
SW VOLTAGE DETECTION
This block detects the flyback voltage generated in the SW pin. In turn-off of the transformer, this block converts
current to flow from the FB pin into voltage by the resistance of the REF pin and the flyback voltage is detected by this
REF pin voltage.
The IC controls REF pin voltage to be equivalent to VINTREF
.
SOFT START
When IC turns to enable status that SDX/EN pin voltage rises above VEN1, the comparison voltage of the PWM
COMPARATOR block increases gradually from 0 V to VINTREF. PWM comparator voltage is constantly VINTREF after
soft start time passed.
This operation prevents from the output voltage overshooting. The soft start time is fixed to tSS in the IC.
And, SCP protection is invalid for tMASKSCP period from start-up.
6
7
PWM COMPARATOR
This block compares REF pin voltage equivalent to feedback voltage of the output voltage with soft start voltage or
reference voltage VINTREF. This comparator output decides the ON timing.
Since it does not have error amplifier and constitutes a feedback loop by the comparator, IC enables fast control to
load response during PWM operation.
ADAPTIVE ON TIME CONTROLLER
This block is ON time control block which uses original adapted ON-time control technology.
Stable load current:
Fluctuating load current:
IC operates in PWM operation by constant ON time control.
IC operates in the constant ON time control and fluctuate the switching
frequency. It results from fast response.
Light load:
The switching frequency decreases and realizes a high efficiency by PFM
operation during discontinuous mode.
When the load current fluctuates, IC operates within fSW_MAX. IC raises the primary average current by shortening the
off time. It results from increasing the secondary current and secondary output voltage is quickly stable.
Output current
Output voltage
Primary coil current
SW pin voltage
High
Frequency
Stabilize gradually
Stable operation
Switching Frequency
Stable operation at light load
Figure 3. Load Current Response Timing Chart
8
9
Maximum Frequency Limit Function (MAX FREQ)
This function limits the maximum frequency. The switching frequency is instantly high at ON width control in start-up
or load response. It may influence to EMI. For that, IC limits max frequency less than fSW_MAX
.
DRIVER
This is the block which drives Nch MOSFET for switching.
10 Nch MOSFET
This is Nch MOSFET for switching.
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Description of Blocks – continued
11 LOAD COMPENSATION
This block compensates the decrease of output voltage caused by the change of VF characteristic in the secondary
output diode which is proportional to load current. It monitors the current flown to the switching MOSFET and a part of
the current flows to the REF pin. The quantity of compensation determines by the external resistor and capacitor at
the L_COMP pin and KL_COMP which is coefficient for SW current. For that, as the current flown from the FB pin to the
external resistor of the REF pin decreases, the output voltage decrease is compensated.
12 Frequency Spectrum Spread (SPECTRUM SPREAD)
This is the function to spread switching frequency.
The frequency spreading in the range of ±5 % contributes to low EMI.
13 Over Current Protection (OCP), Battery Short Protection (BSP)
This function is over current protection of the MOSFET.
13.1 Over Current Protection (OCP)
When the switching MOSFET is on, as the primary transformer peak current becomes ILIMIT or more, IC detects
the over current and the switching MOSFET is turned off. Because IC detects OCP per switching cycles, ON duty
is limited and the output voltage drops. In addition, to prevent miss detection by turn ON surge, the detection of
OCP is invalid for tON_MIN after the switching MOSFET is turned on.
After IC detects OCP, switching MOSFET is turn off after a delay time. When VIN voltage is increased, ILIMIT is
higher by the rise of current slope. ΔILIMIT depends on LP value of transformer.
∆퐼퐿ꢀ푀ꢀ푇 = 푉퐼푁 × 푡퐷퐸퐿퐴푌 / ꢁ푃
OCP detection delay time
푡퐷퐸퐿퐴푌
ꢁ푃
:
:
Primary inductance
푡퐷퐸퐿퐴푌 is always 0.2 µs or less.
Output voltage
ILIMIT
Primary coil current
SW pin voltage
tON_MIN
OCP
Normal
Normal
IC status
Figure 4. OCP Timing Chart
13.2 Battery Short Protection (BSP)
In the case of increasing peak current by CCM (Continuous Conduction Mode) operation such as the short of the
transformer winding or output short of secondary, large current over ILIMIT is flown to the switching MOSFET. To
prevent this phenomenon, IC is built-in BSP function. When SW pin current becomes IBSP or more at the
switching MOSFET ON, the IC detects BSP. By this function, the switching operation is stopped in the period of
tBSP. After it passes tBSP, IC recovers switching operation without soft-start function. When BSP state continues,
IC stops switching operation by SCP protection because output voltage is low. BSP is affected by the delay time
(tDELAY) the same as OCP, and IBSP increases according to VIN voltage. Also, when primary transformer is short,
the function is operated.
Battery short is happened
IBSP
Primary Coil
current
SW pin voltage
ON
tBSP
Switching
tBSP
Output voltage
Figure 5. BSP Timing Chart
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Description of Blocks – continued
14 Short Circuit Protection (SCP), REF Pin Open Protection (REFOPEN)
This is the block of the short protection and the open protection of the REF pin.
14.1 Short Circuit Protection (SCP)
As IC converts the primary flyback voltage to REF pin voltage, IC detects secondary output status. When
secondary output voltage drops, REF pin voltage also drops. When REF pin voltage is below VSCP, IC detects
SCP. When the detection continues for tMASK, the switching operation is stopped. After the time of tRESTART passes
from the stop, IC restarts with soft start function. To prevent SCP miss detection, the detection of SCP is invalid
for tMASKSCP at start-up. When REF voltage is lower than VSCP for tMASKSCP from start-up, IC stops switching for
tRESTART
.
tSS
tMASK
Output voltage
SW pin voltage
VSCP
REF pin voltage
Switching
ON
ON
tRESTART
SCP status
ON
Figure 6. SCP Timing Chart
14.2 REF Pin Open Protection (REFOPEN)
The REF pin detects the secondary output voltage status from the primary flyback voltage. When the REF pin is
open, output status is not detected, and switching MOSFET may occur malfunction. Therefore, when REF pin
voltage is above VREFOP, the IC detects REFOPEN protection. When the detection continues for tMASK, the
switching operation is stopped. After the time of tRESTART from the stop, IC restarts with soft start function.
When auto recovery, IC operates for tMASK from start-up. When REF pin voltage is above VREFOP for tMASK, IC
stops switching for tRESTART
.
tSS
Output voltage
SW pin voltage
VREFOP
REF pin voltage
tMASK
tRESTART
ON
ON
Switching
ON
REFOPEN
status
Figure 7. REFOPEN Protection Timing Chart
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Absolute Maximum Ratings (Ta = 25 °C)
Parameter
VIN Pin Voltage
Symbol
Rating
Unit
VIN
VSW
-0.3 to +45
-0.3 to +62
-0.3 to +45
-0.3 to +45
-0.3 to +7
-0.3 to +7
150
V
V
SW Pin Voltage
SDX/EN Pin Voltage
FB Pin Voltage
VSDX/EN
VFB
V
V
REF Pin Voltage
VREF
V
L_COMP Pin Voltage
Maximum Junction Temperature
Storage Temperature Range
VL_COMP
Tjmax
Tstg
V
°C
-55 to +150
°C
Caution 1: Operating the IC over the absolute maximum ratings may damage the IC. The damage can either be a short circuit between pins or an open circuit
between pins and the internal circuitry. Therefore, it is important to consider circuit protection measures, such as adding a fuse, in case the IC is
operated over the absolute maximum ratings.
Caution 2: Should by any chance the maximum junction temperature rating be exceeded the rise in temperature of the chip may result in deterioration of the
properties of the chip. In case of exceeding this absolute maximum rating, design a PCB with thermal resistance taken into consideration by
increasing board size and copper area so as not to exceed the maximum junction temperature rating.
Thermal Resistance(Note 1)
Thermal Resistance (Typ)
Parameter
Symbol
Unit
1s(Note 3)
2s2p(Note 4)
HTSOP-J8
Junction to Ambient
Junction to Top Characterization Parameter(Note 2)
θJA
206.4
21
45.2
13
°C/W
°C/W
ΨJT
(Note 1) Based on JESD51-2 A (Still-Air).
(Note 2) The thermal characterization parameter to report the difference between junction temperature and the temperature at the top center of the outside
surface of the component package.
(Note 3) Using a PCB board based on JESD51-3.
(Note 4) Using a PCB board based on JESD51-5, 7.
Layer Number of
Measurement Board
Material
Board Size
Single
FR-4
114.3 mm x 76.2 mm x 1.57 mmt
Top
Copper Pattern
Thickness
70 μm
Footprints and Traces
Layer Number of
Measurement Board
Thermal Via(Note 5)
Material
Board Size
114.3 mm x 76.2 mm x 1.6 mmt
2 Internal Layers
Pitch
Diameter
4 Layers
FR-4
1.20 mm
Φ0.30 mm
Top
Copper Pattern
Bottom
Thickness
70 μm
Copper Pattern
Thickness
Copper Pattern
Thickness
Footprints and Traces
74.2 mm x 74.2 mm
35 μm
74.2 mm x 74.2 mm
70 μm
(Note 5) This thermal via connect with the copper pattern of layers 1,2, and 4. The placement and dimensions obey a land pattern.
Recommended Operating Conditions
Parameter
Symbol
Min
Typ
Max
Unit
Conditions
Operation Power Supply Voltage Range
Operation Voltage Range
Operation Temperature
REF Pin Resistor
VIN
VSW
3.4
-
12.0
42.0
60
V
V
VIN pin voltage
SW pin Voltage
-
Topr
-40
-
-
2.7
-
+125
-
°C
RREF
VL_COMP
CVIN
kΩ External resistor value(Note 6)
L_COMP Voltage Range
-
1.00
V
L_COMP pin voltage
VIN-GND Capacitor
10
-
-
µF
(Note 6) Set the REF resistor value of 2.7 kΩ (Typ). Choose the resistance accuracy for an output voltage accuracy.
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Electrical Characteristics (Unless otherwise Tj = -40 °C to +150 °C, VIN = 12 V, VSDX/EN = 2.5 V)
Parameter
Symbol
Min
Typ
Max
Unit
Conditions
Power Supply Block
SDX/EN = 0.3 V
Tj ≤ 125 °C
Current at Shutdown
IST
-
0
10
μA
REF = 0.6 V
Operating Current at No Switching
UVLO Detection Voltage 1
UVLO Detection Voltage 2
UVLO Voltage Hysteresis
ICC
0.43
3.00
3.20
0.12
1.00
3.20
3.40
0.20
1.70
3.40
3.60
0.28
mA
V
VUVLO1
At the VIN pin falling
At the VIN pin rising
VUVLO2
V
VUVLO_HYS
V
Shutdown and Enable Control Block
Shutdown Voltage at the SDX/EN Pin
Enable Voltage 1
VSDX
VEN1
-
-
0.3
2.10
2.00
0.26
2.00
3750
V
V
1.90
1.60
0.14
0.50
1250
2.00
1.80
0.20
1.00
2500
At the SDX/EN pin rising
At the SDX/EN pin falling
Enable Voltage 2
VEN2
V
Enable Voltage Hysteresis
SDX/EN Pin Current
VEN_HYS
ISDX/EN
RSDX/EN
V
μA
kΩ
SDX/EN = 2.5 V
SDX/EN Pin Pull-down Resistance
Reference Voltage Block
Reference Voltage
REF Pin Current
VINTREF
IREF
0.525
140
0.540
200
0.555
260
V
μA
RREF = 2.7 kΩ
Switching Block
On Resistance
RON
ILIMIT
IBSP
-
0.40
1.38
1.80
0.80
1.65
2.34
Ω
A
A
SW-GND ISW = 50 mA
Over Current Detection Current
BSP Detection Current
1.10
1.26
At PWM operation
(Duty = 40 %)
Averaging Switching Frequency
Maximum Switching Frequency
On Time
fSW
fSW_MAX
tON
300
-
363
-
430
498
kHz
kHz
μs
At PWM operation
(Duty = 40 %)
0.962
1.102
1.270
Minimum ON Time
Maximum OFF Time
tON_MIN
120
25
250
35
380
45
ns
μs
tOFF_MAX
From switching start to VINTREF
x 90 %
Soft Start Time
tSS
3.0
5.0
7.0
ms
Protection Function Block
Short Protection Detection Voltage
REFOPEN Protection Detection Voltage
SCP/REFOPEN Detection Mask Time
SCP Mask Time at Start-up
VSCP
VREFOP
tMASK
0.20
0.60
1.05
5.25
262
0.30
0.70
1.50
7.50
375
0.40
0.80
1.95
9.75
488
V
V
ms
ms
µs
ms
tMASKSCP
tBSP
BSP Stop Time at Detection
Restart Time
tRESTART
18.0
24.0
30.0
Load Compensation Block
KL_COMP (Compensation Coefficient of
REF Current for SW Current)
(Note 1)
KL_COMP
0.147
0.210
0.273 %/MΩ
(Note 1) Load compensation current coefficient is the coefficient which compensates output voltage decrease for output current.
It sets by L_COMP pin resistor. It is tested at RL_COMP = 10 kΩ.
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BD7F005EFJ-C
Typical Performance Curves
(Reference Data)
10
9
8
7
6
5
4
3
2
1
0
1.7
1.5
1.3
1.1
0.9
0.7
0.5
0.3
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 8. Current at Shutdown vs Temperature
Figure 9. Operating Current at No Switching vs Temperature
3.40
3.60
3.55
3.50
3.45
3.40
3.35
3.30
3.25
3.20
3.35
3.30
3.25
3.20
3.15
3.10
3.05
3.00
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 10. UVLO Detection Voltage1 vs Temperature
Figure 11. UVLO Detection Voltage2 vs Temperature
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Typical Performance Curves – continued
(Reference Data)
0.28
0.26
0.24
0.22
0.20
0.18
0.16
0.14
0.12
1.5
1.3
1.1
0.9
0.7
0.5
0.3
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 12. UVLO Voltage Hysteresis vs Temperature
Figure 13. Shutdown Voltage at the SDX/EN Pin
vs Temperature
2.10
2.00
1.95
1.90
1.85
1.80
1.75
1.70
1.65
1.60
2.05
2.00
1.95
1.90
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 14. Enable Voltage1 vs Temperature
Figure 15. Enable Voltage2 vs Temperature
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Typical Performance Curves – continued
(Reference Data)
0.26
0.24
0.22
0.20
0.18
0.16
0.14
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 16. Enable Voltage Hysteresis vs Temperature
Figure 17. SDX/EN Pin Current vs Temperature
3,750
0.555
0.550
0.545
0.540
0.535
0.530
0.525
3,250
2,750
2,250
1,750
1,250
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 18. SDX/EN Pin Pull-down Resistance vs Temperature
Figure 19. Reference Voltage vs Temperature
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Typical Performance Curves – continued
(Reference Data)
260
240
220
200
180
160
140
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 20. REF Pin Current vs Temperature
Figure 21. On Resistance vs Temperature
2.26
2.06
1.86
1.66
1.46
1.26
-60 -40 -20 0 20 40 60 80 100120140160180
Temperature [°C]
Figure 22. Over Current Detection Current vs Temperature
Figure 23. BSP Detection Current vs Temperature
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Typical Performance Curves – continued
(Reference Data)
440
420
400
380
360
340
320
300
500
490
480
470
460
450
440
430
420
410
400
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 24. Averaging Switching Frequency vs Temperature
Figure 25. Maximum Switching Frequency vs Temperature
1.30
1.25
1.20
1.15
1.10
1.05
1.00
0.95
400
350
300
250
200
150
100
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 26. On Time vs Temperature
(Duty = 40 %, fSW = 363 kHz)
Figure 27. Minimum ON Time vs Temperature
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Typical Performance Curves – continued
(Reference Data)
45
43
41
39
37
35
33
31
29
27
25
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 28. Maximum OFF Time vs Temperature
Figure 29. Soft Start Time vs Temperature
0.40
0.38
0.36
0.34
0.32
0.30
0.28
0.26
0.24
0.22
0.20
0.80
0.78
0.76
0.74
0.72
0.70
0.68
0.66
0.64
0.62
0.60
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 30. Short Protection Detection Voltage vs Temperature
Figure 31. REFOPEN Protection Detection Voltage
vs Temperature
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Typical Performance Curves – continued
(Reference Data)
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
9.75
9.25
8.75
8.25
7.75
7.25
6.75
6.25
5.75
5.25
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 32. SCP/REFOPEN Detection Mask Time
vs Temperature
Figure 33. SCP Mask Time at Start-up vs Temperature
500
450
400
350
300
250
30.0
28.0
26.0
24.0
22.0
20.0
18.0
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
-40 -20
0
20 40 60 80 100 120 140 160
Temperature [°C]
Figure 34. BSP Stop Time vs Temperature
Figure 35. Restart Time vs Temperature
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BD7F005EFJ-C
Typical Performance Curves – continued
(Reference Data)
Figure 36. KL_COMP vs Temperature
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BD7F005EFJ-C
Application Examples
1
Output Voltage
When the internal switching MOSFET is off, SW pin voltage ”VSW” is higher than VIN pin voltage. The secondary
output voltage is calculated by the primary flyback voltage, which is described by the difference between this SW pin
voltage and VIN pin voltage. SW pin voltage at turn off is calculated by the following formula.
푁푃
( )
× 푉푂푈푇 + 푉퐹
푉
푆푊
= 푉 +
[V]
ꢀꢂ
푁푆
where:
푉
푉
ꢀꢂ
is SW pin voltage.
is VIN pin voltage.
푆푊
푁푃 is the number of winding at the primary transformer.
푁푆 is the number of winding at the secondary transformer.
푉푂푈푇 is the Output voltage.
푉퐹 is the forward voltage of the secondary output diode.
VF
VOUT+
VOUT-
VIN
VIN
NS
NP
SDX/EN
SW
FB
REF GND
L_COMP
RFB
RREF
Figure 37. Application Block Diagram
The external resistor RFB between the FB pin and the SW pin converts the primary flyback voltage into FB pin inflow
current IFB. IFB is calculated by the formula below because FB pin voltage is nearly equal to VIN pin voltage by IC’s
internal circuit.
푁푃
푁푆
푁푃
푁푆
(
)
(
)
푉 +
ꢀꢂ
× 푉푂푈푇 + 푉퐹 − 푉퐹퐵
× 푉푂푈푇 + 푉퐹
푉
푆푊
− 푉퐹퐵
퐼퐹퐵
=
=
=
[A]
푅퐹퐵
푅퐹퐵
푅퐹퐵
where:
퐼퐹퐵 is FB pin inflow current.
푉퐹퐵 is FB pin voltage.
푅퐹퐵 is the external resistor between the FB pin and the SW pin.
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1
Output Voltage – continued
FB current IRFB flows to the REF pin and the external resistor RREF between the REF pin and the GND pin.
REF pin voltage is calculated by below equation.
푅ꢃ퐸퐹 푁푃
( )
× 푉푂푈푇 + 푉퐹
푉ꢃ퐸퐹
=
×
[V]
푅퐹퐵 푁푆
where:
푉ꢃ퐸퐹 is REF pin voltage.
푅ꢃ퐸퐹 is the external resistor between the REF pin and the GND pin.
RREF resistor is necessary to set 2.7 kΩ because REF pin current is equivalent to IREF and REF pin voltage is
equivalent to VINTREF
.
0.54 ꢄ
푅ꢃ퐸퐹
=
= ꢅ .7 푘훺
200 µ퐴
Therefore, REF pin resistor is always needed to set RREF = 2.7 kΩ .
REF pin voltage is input to the comparator with the reference voltage VINTREF in the IC. By the internal circuit, REF pin
voltage is equal to the reference voltage. Therefore, the output voltage and REF pin voltage is calculated by the
formula below.
푅퐹퐵 푁푆
[V]
푉푂푈푇
=
×
× 푉
− 푉퐹
ꢀꢂ푇ꢃ퐸퐹
푅ꢃ퐸퐹 푁푃
To be shown to the equation, the output voltage is set by the number of winding ratio of the primary and secondary
transformer (NP/NS) and the resistance ratio of RFB and RREF. According to the relational expression in above, the
external resistor RFB between the FB pin and the SW pin is calculated by the formula below.
푅ꢃ퐸퐹
푁푃
푁푆
( )
× 푉푂푈푇 + 푉퐹
푅퐹퐵
=
×
[Ω]
푉
ꢀꢂ푇ꢃ퐸퐹
The ESR of the transformer on the secondary side as well as VF causes the output voltage drop.
And, when transformer coupling is low, the NP/NS turns ratio changes and output voltage is lower than the setting
voltage. Therefore, adjust the output voltage by actual evaluation of power supply.
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Application Examples – continued
2
Transformer
2.1 The Determine of Winding Ratio NP / NS
The winding ratio is the parameter for setting output voltage, Max output power, Duty, SW pin voltage.
The duty of flyback converter is calculated by the following equation:
푁푃
푁푆
(
)
× 푉푂푈푇 + 푉퐹
[%]
ꢆ푢푡푦 =
푁푃
푁푆
( )
× 푉푂푈푇 + 푉퐹
푉 +
ꢀꢂ
푁푃 is the Primary transformer winding
푁푆 is the Secondary transformer winding
푉푂푈푇 is the Output voltage
푉퐹 is the forward voltage of secondary output diode
푉
ꢀꢂ
is VIN pin voltage
The winding ratio is calculated by below equation.
푁푃
ꢆ푇푌푃
푉
ꢀꢂ
=
×
푁푆 1 − ꢆ푇푌푃 푉푂푈푇 + 푉퐹
ꢆ푇푌푃 is the Duty of VIN voltage (Typ)
In the middle VIN voltage of usual operating range, it recommends that DTYP is set from 30 % to 50 %.
First, it recommends to set DTYP = 40 %. The winding ratio is limited by the maximum duty(DMAX) in minimum
input voltage condition. DMAX given by the formula below must be not over 70 %. When duty is over 70 %,
change DTYP to be lower. If Duty is over 70 %, OFF time is short and the output voltage may change due to the
shift in flyback voltage detection.
푉
푁푃
ꢆ푀퐴푋
ꢀꢂ(푀푖푛)
=
×
푁푆 1 − ꢆ푀퐴푋 푉푂푈푇(푀푎푥) + 푉퐹(푀푎푥)
where:
ꢆ푀퐴푋 is the Maximum duty of minimum VIN voltage condition
푉푂푈푇(푀푎푥) is the Maximum output voltage
푉퐹(푀푎푥) is the Maximum forward voltage (VF) of Secondary diode
Flyback voltage is calculated by below calculation.
푁푃
[V]
(
)
푉푂ꢃ = 푉푂푈푇 + 푉퐹 ×
푁푆
SW pin voltage calculated below must be set so that the withstand voltage is not exceeded.
푉
푆푊
= 푉
+ 푉푂ꢃ + 푉
푆푈ꢃ퐺퐸
[V]
ꢀꢂ(푀푎푥)
For example, when it has the delating of 90 % for SW pin voltage, SW pin voltage is needed to be less than the
value which calculated below.
( )
= 6ꢇ 푉 × 1ꢇꢇ % − 1ꢇ % = ꢈꢉ 푉
푉
푆푊
In the case of VIN(Max)=30 V and VOR=10 V, VSURGE voltage is needed to be less than 14 V. This value is calculated
below.
(
)
ꢈꢉ 푉 − 3ꢇ 푉 + 1ꢇ 푉 = 1ꢉ 푉
VSURGE is occurred by the leakage of transformer. If VSURGE is higher, it needs to decrease the voltage by
re-designing transformation structure or snubber circuit adjustment.
Voltage
VSW
VSURGE
VOR
VIN
Time
Figure 38. SW Waveform
When designed transformer, temporarily set winding ratio to satisfy above. When the winding ratio is decided,
RFB can be set and VOUT also can be set.
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2
Transformer – continued
2.2 The Calculation of LP, LS
The transformer should be set LP and LS value that power supply works CCM operation.
For that, LP and Ls is determined to use “k” which is the indicator of CCM operation.
k is expressed from Figure 39 ISPK, ISB by the following equation.
푘 = (퐼푆푃퐾 − 퐼푆퐵)/퐼푆푃퐾
where:
퐼푆푃퐾 is the Secondary transformer peak current
퐼푆퐵 is the Secondary transformer bottom current
푘 is the Indicator of CCM ratio (It guides that it sets k = 0.25 when designing at first.)
IPEAK
Primary
current
IPPK
Secondary
current
IPB
ISPK
ISB
time
Figure 39. The Waveform Example of Primary and Secondary Current of Transformer
where:
퐼푃푃퐾 is the Primary transformer peak current
퐼푃퐵 is the Primary transformer bottom current
ILIMIT shown in electric characteristics determines maximum primary peak current.
It enables to decide capable secondary minimum peak current from minimum ILIMIT
.
푁푃
[A]
퐼푆푃퐾ꢊ(푀푖푛) = 퐼퐿ꢀ푀ꢀ푇(푀푖푛)
×
푁푆
Next, ISPK2(Max) is calculated from secondary maximum output current (IOUT(Max)).
ꢅ × 퐼푂푈푇 푀푎푥
1
휂
(
)
[A]
퐼푆푃퐾2 푀푎푥
=
)
×
(
(
)
(
)
1 − ꢆ푀퐴푋 × ꢅ − 푘
휂 is the Efficiency of power supply, it recommends to set to about 70 %
In order to output IOUT(Max), the condition of ISPK2(Max) < ISPK1(Min) must be satisfied.
If not satisfied, re-design to change k value. The higher the k value, the wider the load area of DCM
(Discontinuous Conduction Mode) operation. k = 1 means that the operation is DCM at all loads. IC has
advantage of fast response and low EMI characteristics in CCM operation. For that, k is recommended lower
value. Even if k value is high, there is no problem to output voltage regulation operation.
The secondary inductance LS(Max) is calculated by the following equation.
2
(
)
(
)
ꢅ − 푘 × 푉푂푈푇 + 푉퐹 × (1 − ꢆ푀퐴푋
)
ꢁ푆(푀푎푥)
=
[µH]
ꢅ × 퐼푂푈푇(푀푎푥) × 푓푠푤(푀푎푥) × 푘
where:
푓
is the Switching frequency (fSW(Max) is set to 430 kHz in IC)
)
(
푆푊 푀푎푥
퐼푂푈푇 푀푎푥 is the Maximum secondary output current
(
)
Primary inductance LP is calculated by below.
푁푃
푁푆
2
ꢁ푃 = ꢁ푆 × (
)
[µH]
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2
Transformer – continued
2.3 The Calculation of IPRMS and ISRMS
Maximum primary RMS current (IPRMS) and Maximum secondary RMS current (ISRMS) are calculated below.
ꢋ퐼푃푃퐾2 + 퐼푃푃퐾 × 퐼푃퐵 + 퐼푃퐵2ꢌ × ꢆ푀퐴푋
[A]
√
=
퐼푃ꢃ푀푆
3
2
ꢋ퐼푆푃퐾 + 퐼푆푃퐾 × 퐼푆퐵 + 퐼푆퐵2ꢌ × (1 − ꢆ푀퐴푋
)
[A]
√
=
퐼푆ꢃ푀푆
3
When selecting the wire diameter of transformer, refer to this RMS current.
3
Output Capacitor
The output capacitor place as close to the secondary diode as possible. Output capacitor value COUT is needed to set
from the output ripple voltage (ΔVO) and start-up time. The output ripple voltage which occurs by switching is
calculated by below equation.
퐼푂푈푇(푀푎푥) × ꢆ푀퐴푋
훥푉푂 =
[V]
푓푆푊(푀푎푥) × 퐶푂푈푇
On the other hand, when output capacitor is large, start-up time is long.
When SCP detection mask time (tMASKSCP) in start-up is passed, if REF voltage is lower than VSCP, power supply
cannot output. Therefore, COUT must be satisfied below condition.
푁푃
( )
ꢏ × 1 − ꢆ푢푡푦 − 퐼푂푈푇 푀푎푥 }
( )
푡푀퐴푆퐾푆ꢍ푃(푀푖푛) × {ꢎ퐼퐿ꢀ푀ꢀ푇 푀푖푛
×
푉
(
)
1
퐶푂푈푇 ≤ ×
ꢅ
푁푆
푉
[µF]
푆ꢍ푃(푀푎푥)
푉푂푈푇 × (
)
ꢀꢂ푇ꢃ퐸퐹(푀푖푛)
푽
푺푪푷(푴풂풙)
Here,
= 0.762
푽
푰푵푻푹푬푭(푴풊풏)
A large output capacitance is required to hold the output voltage for load response or input voltage response. As a
guide for output capacitor, it recommends the capacitance of 20 µF or more. And, ceramic capacitor may be lower
capacitance because of temperature characteristics and variance, DC bias characteristics. It needs to select the parts
to care them.
4
Input Capacitor
It uses ceramic capacitor to input capacitor and it is placed as close to the IC as possible.
The capacitor value is set 10 µF or more.
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Application Examples – continued
5
Secondary Output Diode
Because the forward voltage (VF) of secondary output diode causes an error in the output voltage, it needs to use SBD
or FRD which is low forward voltage (VF). And, the peak of diode reverse voltage must not exceed the rating of the
diode. The secondary RMS current must be set that it does not exceed the rating current. Generally, it is
recommended that the reverse voltage of secondary output diode sets to have margin of 30 % or more.
푁푆
[V]
푉ꢃ = (푉
×
+ 푉푂푈푇) × 1.3 + 푉
푆푈ꢃ퐺퐸
ꢀꢂ(푀푎푥)
푁푃
where:
푉ꢃ is the reverse voltage of secondary output diode
is VIN maximum pin voltage
푉
ꢀꢂ(푀푎푥)
푁푃 is the primary winding turns of transformer
푁푆 is the secondary winding turns of transformer
푉푂푈푇 is the Output voltage
푉
푆푈ꢃ퐺퐸
is the Surge voltage of transformer generated to the diode
And it is recommended that rating current of output diode margin twice or more for ISRMS
.
6
Output Resistor and Output Zener Diode (Minimum Load Current)
The output voltage raises in no load or light load. This is the reason IC is always worked by the minimum switching
frequency which is determined by maximum OFF time tOFF_MAX and minimum ON time tON_MIN at light loads.
Because power supply supplies minimum power POMIN by this minimum switching frequency, output voltage raises
when secondary power is lighter than PO_MIN. PO_MIN is calculated by below.
ꢖ
ꢄ
ꢊ
ꢑꢒ(ꢓꢔꢕ)
2
ꢐ푂_푀ꢀꢂ
=
× 푡푂ꢂ_푀ꢀꢂ(푀푎푥) ×
ꢘ
ꢙꢒ_ꢓꢑꢒ(ꢓꢔꢕ)
[W]
2×퐿
ꢚꢘ
ꢗ
ꢙꢛꢛ_ꢓꢜꢝ(ꢓꢞꢟ)
푃
ꢙ_ꢓꢑꢒ
퐼푂푈푇_푀ꢀꢂ
=
By the equation, IOUT_MIN can be also calculated.
ꢄ
ꢙꢠꢡ
When the raise of secondary output voltage is unacceptable, it needs to connect zener diode to secondary output. It
operates output voltage suppression less than zener diode voltage.
And it can prevent to rise output voltage by losses which is occurred to connect resistors to secondary output. The
secondary load resistor ROUT is less than below equation is needed. Secondary resistor loss is calculated by the
equation.
ꢖ
ꢄ
ꢙꢠꢡ
[W]
ꢐ퐿푂푆푆
=
ꢃ
ꢙꢠꢡ
2
2
푉푂푈푇
푉푂푈푇
×
푅푂푈푇
≤
=
[Ω]
2
ꢐ푂_푀ꢀꢂ
푉
1
ꢀꢂ(푀푎푥)
2
× 푡푂ꢂ_푀ꢀꢂ(푀푎푥)
ꢅ × ꢁ푃
푡푂ꢂ_푀ꢀꢂ(푀푎푥) + 푡푂퐹퐹_푀퐴푋(푀푖푛)
In fact, even if ROUT resistance which is calculated above equation is used, output voltage rises transiently in switching
OFF time. For that, ROUT should be set low enough. ROUT needs to adjust through evaluation. ROUT resistor is needed to
notice power dissipation.
The reason of output voltage raise refers to Application Examples: “10.The Influence to Frequency and Output Voltage
for Each Load”.
VF
VOUT
NP
NS
ROUT
Figure 40. Zener Diode and Resistor to Secondary Output
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Application Examples – continued
7
Snubber Circuit
When the combination degree of transformer is low or large current line of board is long, the large surge voltage
may be occurred in the SW pin at turn OFF timing of MOSFET. Preventing it, the snubber circuit shown in figure 41 is
used. This snubber circuit clamps fly-back voltage + surge voltage when the voltage exceeds snubber voltage.
VF
Vz
VOUT
NP
NS
VF2
Figure 41. Snubber Circuit
The clamp voltage is determined the following equation.
푉ꢍ퐿퐴푀푃 = 푉퐹2 + 푉
[V]
푧
where:
푉ꢍ퐿퐴푀푃 is the Clamp setting voltage of snubber circuit
푉퐹2 is the Forward voltage of SBD
푉 is the Zener diode voltage
푧
ꢂ
ꢗ
( )
× 푉푂푈푇 + 푉퐹 ), large current flows to
When the clamp setting voltage is lower than flyback voltage ( equal to
ꢂ
ꢢ
Zener diode in the turn off. Therefore, the snubber voltage (VCLAMP) must be higher than flyback voltage.
When snubber circuit is slow response, it may not clamp setting voltage.
So, SW voltage must be evaluated.
8
Setting of SDX/EN Pin Resistor
8.1 Setting of Enable Voltage
It can set enable voltage VIN_ENABLE by following equation after releasing VIN UVLO.
푅ꢊ + (푅2//푅푆퐷푋/퐸ꢂ
푅2//푅푆퐷푋/퐸ꢂ
)
[V]
푉
= 푉퐸ꢂꢊ ×
ꢀꢂ_퐸ꢂ퐴퐵퐿퐸
where:
푉
is the Target VIN operating start voltage
ꢀꢂ_퐸ꢂ퐴퐵퐿퐸
푉퐸ꢂꢊ is the Enable voltage 1
푅2//푅푆퐷푋/퐸ꢂ is the Divided resistor between R2 and RSDX/EN which is IC internal resistor
VIN
R1
VIN
SDX/EN
R2
RSDX/EN
Figure 42. Resistors Connected to the SDX/EN Pin
8.2 Setting of Disable Voltage
It can set disable voltage VIN_DISABLE at VIN pin voltage falling by following equation.
푅ꢊ + (푅2//푅푆퐷푋/퐸ꢂ
푅2//푅푆퐷푋/퐸ꢂ
)
[V]
푉
= 푉퐸ꢂ2 ×
ꢀꢂ_퐷ꢀ푆퐴퐵퐿퐸
where:
푉
is the Target VIN operating stop voltage
ꢀꢂ_퐷ꢀ푆퐴퐵퐿퐸
푉퐸ꢂ2 is the Enable voltage2
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Application Examples – continued
9
The Output Voltage Compensation Function by L_COMP Pin Resistor
This IC is built in output voltage compensation function which is prevented that output voltage decrease when
primary transformer peak current (IP) increase. The cause of the drop of output voltage VOUT are the forward voltage
change of secondary diode and transformer leakage etc.
The example of output voltage compensation is shown in Figure 43.
VOUT
With Load compensation
No load compensation
IOUT
Figure 43. L_COMP Voltage Compensation Example
This function compensates the output voltage by increasing IREFCOMP current to the REF current that determines the
output voltage.
ꢂ
ꢄ
ꢢ
푉푂푈푇 = 푅퐹퐵
×
× ꢎ ꢑꢒꢡꢣꢤꢛ + 퐼ꢃ퐸퐹ꢍ푂푀푃ꢏ − 푉퐹
[V]
ꢂ
ꢃ
ꢣꢤꢛ
ꢗ
V
INTREF
REF current
is fiexed to 200 µA (Typ). IREFCOMP is increased for primary current increasing. As the result,
ꢥ
REF
output voltage is compensated by output current on the secondary side.
IREFCOMP is calculated to below.
퐼ꢃ퐸퐹ꢍ푂푀푃 = 푅퐿_ꢍ푂푀푃 × ꢦ퐿_ꢍ푂푀푃 × 퐼푆푊(퐴푣푒)
[µA]
where:
푅퐿_ꢍ푂푀푃 is the Resistor connected to the L_COMP pin
퐼푆푊(퐴푣푒) is the Averaging current flown to the SW pin
ꢦ퐿_ꢍ푂푀푃 is the Fixed value determined by IC
Averaging current ISW(Ave) of the SW pin can be converted below.
푁푆
푁푃
1
= 퐼푂푈푇 × ×
휂
푁푆
푁푃
퐼푆푊(퐴푣푒) = 퐼푆(퐴푣푒)
×
[A]
where:
휂 is the efficiency (It recommends 70 % in design. And adjust RL_COMP in application evaluation.)
Because ISW(Ave) is proportional to IOUT as shown in the above equation, it enables to compensate output voltage. The
compensation degree can adjust by resistor value of the L_COMP pin.
Because ISW is triangle wave current, connect the capacitor 0.1 µF or more at the L_COMP pin to flatten it.
The resistor value of the L_COMP pin is calculated by the following equation.
퐼ꢃ퐸퐹ꢍ푂푀푃
1
푅퐿_ꢍ푂푀푃
=
×
[kΩ]
퐼푆푊(퐴푣푒) ꢦ퐿_ꢍ푂푀푃
Be sure to evaluate the output voltage characteristics in the application and adjust L_COMP resistance as necessary.
And, if the function is no use, the L_COMP pin is needed to connect to GND.
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Application Examples – continued
10 The Influence to Frequency and Output Voltage for Each Load
This IC enables high efficiency to be lower switching frequency in light load. In CCM operation, the switching
frequency is fSW for a constant load. When the load is light, the operation is changed from CCM operation to DCM
operation. Then, switching frequency is reduced from fSW
.
The output load IOUT_ SW1 is calculated below.
f
2
(
)
푉 × ꢆ푢푡푦
ꢀꢂ
1
퐼푂푈푇_ 푆푊ꢊ
푓
= ×
× 휂
[A]
ꢅ
ꢁ푃 × 푓 × 푉푂푈푇
푆푊
where:
퐼푂푈푇_ 푆푊ꢊ
푓
is the Switched output current from DCM to CCM
푓
푆푊
is the Switching frequency
푉
ꢀꢂ
is VIN pin voltage
ꢁ푃 is the Primary inductance
푉푂푈푇 is the Output voltage
휂 is the Efficiency
As the load is further lightened, the ON time and OFF time decreases. ON time is operated by tON_MIN
The load current operated by tON_MIN is below.
.
1
= ×
ꢅ
푓
푆푊
× ꢋ푉 × 푡푂ꢂ_푀ꢀꢂꢌ2
ꢀꢂ
퐼푂푈푇_ 푆푊2
푓
× 휂
[A]
ꢁ푃 × 푉푂푈푇
where:
퐼푂푈푇_ 푆푊2
푓
is the Load current operated by minimum ON time
푡푂ꢂ_푀ꢀꢂ is the Minimum ON time
As the load is further lightened, the ON time is not shorter than the tON_MIN and the OFF time is longer.
Because IC is determined maximum OFF time.
fSW_MIN is calculated to below.
1
푓
=
[kHz]
푆푊_푀ꢀꢂ
푡푂ꢂ_푀ꢀꢂ + 푡푂퐹퐹_푀퐴푋
where:
푓
is the Minimum switching frequency
푆푊_푀ꢀꢂ
푡푂퐹퐹_푀퐴푋 is the Maximum OFF time
Therefore, constant output power is generated by fSW_MIN operation in no load or light load.
For that, output voltage raises in no load or light load.
And the IC builds in frequency spectrum spread function for EMI improvement. For that, the switching frequency is
changed within a constant rate. An output voltage ripple which is dependent on spectrum spread occurs by the
function.
SwitchingFrequency
fSW
Frequency
Spectrum Spread
fSW _MIN
IOUT_MIN
IOUT_fSW 2
IOUT_fSW 1
IOUT
Figure 44. Switching Frequency
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BD7F005EFJ-C
I/O Equivalence Circuits
1
GND
2
SDX/EN
3
L_COMP
4
REF
Internal
Supply
GND
SDX/EN
REF
L_COMP
GND
RSDX/EN
GND
GND
SW
VIN
5
FB
6
7
8
N.C.
VIN
SW
VIN
FB
GND
GND
GND
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BD7F005EFJ-C
Operational Notes
1. Reverse Connection of Power Supply
Connecting the power supply in reverse polarity can damage the IC. Take precautions against reverse polarity when
connecting the power supply, such as mounting an external diode between the power supply and the IC’s power
supply pins.
2. Power Supply Lines
Design the PCB layout pattern to provide low impedance supply lines. Furthermore, connect a capacitor to ground at
all power supply pins. Consider the effect of temperature and aging on the capacitance value when using electrolytic
capacitors.
3. Ground Voltage
Ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition.
4. Ground Wiring Pattern
When using both small-signal and large-current ground traces, the two ground traces should be routed separately but
connected to a single ground at the reference point of the application board to avoid fluctuations in the small-signal
ground caused by large currents. Also ensure that the ground traces of external components do not cause variations
on the ground voltage. The ground lines must be as short and thick as possible to reduce line impedance.
5. Recommended Operating Conditions
The function and operation of the IC are guaranteed within the range specified by the recommended operating
conditions. The characteristic values are guaranteed only under the conditions of each item specified by the electrical
characteristics.
6. Inrush Current
When power is first supplied to the IC, it is possible that the internal logic may be unstable and inrush current may flow
instantaneously due to the internal powering sequence and delays, especially if the IC has more than one power
supply. Therefore, give special consideration to power coupling capacitance, power wiring, width of ground wiring, and
routing of connections.
7. Testing on Application Boards
When testing the IC on an application board, connecting a capacitor directly to a low-impedance output pin may
subject the IC to stress. Always discharge capacitors completely after each process or step. The IC’s power supply
should always be turned off completely before connecting or removing it from the test setup during the inspection
process. To prevent damage from static discharge, ground the IC during assembly and use similar precautions during
transport and storage.
8. Inter-pin Short and Mounting Errors
Ensure that the direction and position are correct when mounting the IC on the PCB. Incorrect mounting may result in
damaging the IC. Avoid nearby pins being shorted to each other especially to ground, power supply and output pin.
Inter-pin shorts could be due to many reasons such as metal particles, water droplets (in very humid environment) and
unintentional solder bridge deposited in between pins during assembly to name a few.
9. Unused Input Pins
Input pins of an IC are often connected to the gate of a MOS transistor. The gate has extremely high impedance and
extremely low capacitance. If left unconnected, the electric field from the outside can easily charge it. The small
charge acquired in this way is enough to produce a significant effect on the conduction through the transistor and
cause unexpected operation of the IC. So unless otherwise specified, unused input pins should be connected to the
power supply or ground line.
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Operational Notes – continued
10. Regarding the Input Pin of the IC
This monolithic IC contains P+ isolation and P substrate layers between adjacent elements in order to keep them
isolated. P-N junctions are formed at the intersection of the P layers with the N layers of other elements, creating a
parasitic diode or transistor. For example (refer to figure below):
When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode.
When GND > Pin B, the P-N junction operates as a parasitic transistor.
Parasitic diodes inevitably occur in the structure of the IC. The operation of parasitic diodes can result in mutual
interference among circuits, operational faults, or physical damage. Therefore, conditions that cause these diodes to
operate, such as applying a voltage lower than the GND voltage to an input pin (and thus to the P substrate) should be
avoided.
Resistor
Transistor (NPN)
Pin A
Pin B
Pin B
B
E
C
Pin A
B
C
E
P
P+
P+
N
P+
P
P+
N
N
N
N
N
N
N
Parasitic
Elements
Parasitic
Elements
P Substrate
GND GND
P Substrate
GND
GND
Parasitic
Elements
Parasitic
Elements
N Region
close-by
Figure 45. Example of Monolithic IC Structure
11. Ceramic Capacitor
When using a ceramic capacitor, determine a capacitance value considering the change of capacitance with
temperature and the decrease in nominal capacitance due to DC bias and others.
12. Thermal Shutdown Circuit (TSD)
This IC has a built-in thermal shutdown circuit that prevents heat damage to the IC. Normal operation should always
be within the IC’s maximum junction temperature rating. If however the rating is exceeded for a continued period, the
junction temperature (Tj) will rise which will activate the TSD circuit that will turn OFF power output pins. When the Tj
falls below the TSD threshold, the circuits are automatically restored to normal operation.
Note that the TSD circuit operates in a situation that exceeds the absolute maximum ratings and therefore, under no
circumstances, should the TSD circuit be used in a set design or for any purpose other than protecting the IC from
heat damage.
13. Over Current Protection Circuit (OCP)
This IC incorporates an integrated overcurrent protection circuit that is activated when the load is shorted. This
protection circuit is effective in preventing damage due to sudden and unexpected incidents. However, the IC should
not be used in applications characterized by continuous operation or transitioning of the protection circuit.
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BD7F005EFJ-C
Ordering Information
B D 7
F
0
0
5 E F
J
-
CE2
Package
Product Class
EFJ: HTSOP-J8
C: for Automotive
Packaging and Forming Specification
E2: Embossed Tape and Reel (HTSOP-J8)
Marking Diagram
HTSOP-J8 (TOP VIEW)
Part Number Marking
LOT Number
D 7 F 0 0 5
Pin 1 Mark
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Physical Dimension and Packing Information
Package Name
HTSOP-J8
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BD7F005EFJ-C
Revision History
Date
Revision
001
Changes
New Release
13.Dec.2022
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Notice
Precaution on using ROHM Products
(Note 1)
1. If you intend to use our Products in devices requiring extremely high reliability (such as medical equipment
,
aircraft/spacecraft, nuclear power controllers, etc.) and whose malfunction or failure may cause loss of human life,
bodily injury or serious damage to property (“Specific Applications”), please consult with the ROHM sales
representative in advance. Unless otherwise agreed in writing by ROHM in advance, ROHM shall not be in any way
responsible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of any
ROHM’s Products for Specific Applications.
(Note1) Medical Equipment Classification of the Specific Applications
JAPAN
USA
EU
CHINA
CLASSⅢ
CLASSⅣ
CLASSⅡb
CLASSⅢ
CLASSⅢ
CLASSⅢ
2. ROHM designs and manufactures its Products subject to strict quality control system. However, semiconductor
products can fail or malfunction at a certain rate. Please be sure to implement, at your own responsibilities, adequate
safety measures including but not limited to fail-safe design against the physical injury, damage to any property, which
a failure or malfunction of our Products may cause. The following are examples of safety measures:
[a] Installation of protection circuits or other protective devices to improve system safety
[b] Installation of redundant circuits to reduce the impact of single or multiple circuit failure
3. Our Products are not designed under any special or extraordinary environments or conditions, as exemplified below.
Accordingly, ROHM shall not be in any way responsible or liable for any damages, expenses or losses arising from the
use of any ROHM’s Products under any special or extraordinary environments or conditions. If you intend to use our
Products under any special or extraordinary environments or conditions (as exemplified below), your independent
verification and confirmation of product performance, reliability, etc, prior to use, must be necessary:
[a] Use of our Products in any types of liquid, including water, oils, chemicals, and organic solvents
[b] Use of our Products outdoors or in places where the Products are exposed to direct sunlight or dust
[c] Use of our Products in places where the Products are exposed to sea wind or corrosive gases, including Cl2,
H2S, NH3, SO2, and NO2
[d] Use of our Products in places where the Products are exposed to static electricity or electromagnetic waves
[e] Use of our Products in proximity to heat-producing components, plastic cords, or other flammable items
[f] Sealing or coating our Products with resin or other coating materials
[g] Use of our Products without cleaning residue of flux (Exclude cases where no-clean type fluxes is used.
However, recommend sufficiently about the residue.); or Washing our Products by using water or water-soluble
cleaning agents for cleaning residue after soldering
[h] Use of the Products in places subject to dew condensation
4. The Products are not subject to radiation-proof design.
5. Please verify and confirm characteristics of the final or mounted products in using the Products.
6. In particular, if a transient load (a large amount of load applied in a short period of time, such as pulse, is applied,
confirmation of performance characteristics after on-board mounting is strongly recommended. Avoid applying power
exceeding normal rated power; exceeding the power rating under steady-state loading condition may negatively affect
product performance and reliability.
7. De-rate Power Dissipation depending on ambient temperature. When used in sealed area, confirm that it is the use in
the range that does not exceed the maximum junction temperature.
8. Confirm that operation temperature is within the specified range described in the product specification.
9. ROHM shall not be in any way responsible or liable for failure induced under deviant condition from what is defined in
this document.
Precaution for Mounting / Circuit board design
1. When a highly active halogenous (chlorine, bromine, etc.) flux is used, the residue of flux may negatively affect product
performance and reliability.
2. In principle, the reflow soldering method must be used on a surface-mount products, the flow soldering method must
be used on a through hole mount products. If the flow soldering method is preferred on a surface-mount products,
please consult with the ROHM representative in advance.
For details, please refer to ROHM Mounting specification
Notice-PAA-E
Rev.004
© 2015 ROHM Co., Ltd. All rights reserved.
Precautions Regarding Application Examples and External Circuits
1. If change is made to the constant of an external circuit, please allow a sufficient margin considering variations of the
characteristics of the Products and external components, including transient characteristics, as well as static
characteristics.
2. You agree that application notes, reference designs, and associated data and information contained in this document
are presented only as guidance for Products use. Therefore, in case you use such information, you are solely
responsible for it and you must exercise your own independent verification and judgment in the use of such information
contained in this document. ROHM shall not be in any way responsible or liable for any damages, expenses or losses
incurred by you or third parties arising from the use of such information.
Precaution for Electrostatic
This Product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. Please take proper
caution in your manufacturing process and storage so that voltage exceeding the Products maximum rating will not be
applied to Products. Please take special care under dry condition (e.g. Grounding of human body / equipment / solder iron,
isolation from charged objects, setting of Ionizer, friction prevention and temperature / humidity control).
Precaution for Storage / Transportation
1. Product performance and soldered connections may deteriorate if the Products are stored in the places where:
[a] the Products are exposed to sea winds or corrosive gases, including Cl2, H2S, NH3, SO2, and NO2
[b] the temperature or humidity exceeds those recommended by ROHM
[c] the Products are exposed to direct sunshine or condensation
[d] the Products are exposed to high Electrostatic
2. Even under ROHM recommended storage condition, solderability of products out of recommended storage time period
may be degraded. It is strongly recommended to confirm solderability before using Products of which storage time is
exceeding the recommended storage time period.
3. Store / transport cartons in the correct direction, which is indicated on a carton with a symbol. Otherwise bent leads
may occur due to excessive stress applied when dropping of a carton.
4. Use Products within the specified time after opening a humidity barrier bag. Baking is required before using Products of
which storage time is exceeding the recommended storage time period.
Precaution for Product Label
A two-dimensional barcode printed on ROHM Products label is for ROHM’s internal use only.
Precaution for Disposition
When disposing Products please dispose them properly using an authorized industry waste company.
Precaution for Foreign Exchange and Foreign Trade act
Since concerned goods might be fallen under listed items of export control prescribed by Foreign exchange and Foreign
trade act, please consult with ROHM in case of export.
Precaution Regarding Intellectual Property Rights
1. All information and data including but not limited to application example contained in this document is for reference
only. ROHM does not warrant that foregoing information or data will not infringe any intellectual property rights or any
other rights of any third party regarding such information or data.
2. ROHM shall not have any obligations where the claims, actions or demands arising from the combination of the
Products with other articles such as components, circuits, systems or external equipment (including software).
3. No license, expressly or implied, is granted hereby under any intellectual property rights or other rights of ROHM or any
third parties with respect to the Products or the information contained in this document. Provided, however, that ROHM
will not assert its intellectual property rights or other rights against you or your customers to the extent necessary to
manufacture or sell products containing the Products, subject to the terms and conditions herein.
Other Precaution
1. This document may not be reprinted or reproduced, in whole or in part, without prior written consent of ROHM.
2. The Products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written
consent of ROHM.
3. In no event shall you use in any way whatsoever the Products and the related technical information contained in the
Products or this document for any military purposes, including but not limited to, the development of mass-destruction
weapons.
4. The proper names of companies or products described in this document are trademarks or registered trademarks of
ROHM, its affiliated companies or third parties.
Notice-PAA-E
Rev.004
© 2015 ROHM Co., Ltd. All rights reserved.
Daattaasshheeeett
General Precaution
1. Before you use our Products, you are requested to carefully read this document and fully understand its contents.
ROHM shall not be in any way responsible or liable for failure, malfunction or accident arising from the use of any
ROHM’s Products against warning, caution or note contained in this document.
2. All information contained in this document is current as of the issuing date and subject to change without any prior
notice. Before purchasing or using ROHM’s Products, please confirm the latest information with a ROHM sales
representative.
3. The information contained in this document is provided on an “as is” basis and ROHM does not warrant that all
information contained in this document is accurate and/or error-free. ROHM shall not be in any way responsible or
liable for any damages, expenses or losses incurred by you or third parties resulting from inaccuracy or errors of or
concerning such information.
Notice – WE
Rev.001
© 2015 ROHM Co., Ltd. All rights reserved.
相关型号:
BD7F105EFJ-C (新产品)
BD7F105EFJ-C是不需要光耦的隔离型反激式转换器。该产品不需要由光电耦合器或变压器辅助绕组组成的反馈电路,有助于削减应用产品的部件数量。另外,该产品还通过采用ROHM自有的自适应导通时间控制技术,实现了高速负载响应。此外,还具有多种保护功能,可提高隔离型电源应用设计的可靠性。
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BD7F200EFJ-LB
本产品是面向工业设备市场的产品,保证可长期稳定供货。是适合这些用途的产品。BD7F200EFJ-LB是无需光电耦合器的绝缘型反激式转换器。为获得通过变压器绝缘的稳定的输出电压,无需以往用途中所需的光电耦合器、变压器3次绕组构成的反馈电路,大幅度减少了部件个数,可实现小型、高可靠绝缘型电源应用。采用独创的适应型导通时间控制技术,不需要以往方式中所需的外接相位补偿部件,可实现简单、高性能的绝缘型电源应用。
ROHM
BD7F200UEFJ-LB (新产品)
This product guarantees long time supply availability in the industrial instrumentation market.BD7F200 is an optocoupler-less Isolated Flyback Converter. An optocoupler or the tertiary winding feedback circuit which was needed to obtain a stable output voltage isolated by a transformer in the conventional application becomes unnecessary, thus, the number of parts is reduced drastically, producing a small-sized and high-reliability application isolated type power supply. Furthermore, a highly by the use of the Original Adapted-Type ON-Time Control Technology, it makes the external phase compensation parts become unnecessary, therefore a highly efficient isolated type power supply application can easily be produced.
ROHM
BD7F205EFJ-C (新产品)
BD7F205EFJ-C是不需要光耦的隔离型反激式转换器。该产品不需要由光电耦合器或变压器辅助绕组组成的反馈电路,有助于削减应用产品的部件数量。另外,该产品还通过采用ROHM自有的自适应导通时间控制技术,实现了高速负载响应。此外,还具有多种保护功能,可提高隔离型电源应用设计的可靠性。
ROHM
BD7J101EFJ-LB
本产品是能够保证向工业设备市场长期供应的产品,是不需要光耦的隔离型反激式转换器。使用本产品,将不再需要以往应用中为了获得稳定的输出电压而需要的由光电耦合器或变压器辅助绕组组成的反馈电路。此外,通过采用ROHM自有的自适应导通时间控制技术,也不再需要外置相位补偿器件,从而可以使隔离式电源设计所需的元器件数量显著减少,并且能够实现小型化和更高可靠性。
ROHM
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