BD7J201HFN-LB_技术文档

Datasheet

Low Power Isolated Flyback Converter IC

with Integrated Switching MOSFET

BD7J201HFN-LB (Under Development) BD7J201EFJ-LB

General Description

Key Specifications

This is the product guarantees long time support in

Industrial market.

◼ Power Supply Voltage Range

VIN Pin:

8 V to 80 V

120 V (Max)

1.80 A (Typ)

400 kHz (Typ)

±1.6 %

This IC is an optocoupler-less isolated flyback converter.

It is not necessary to use any optocouplers and feedback

circuits by a third winding of transformers; these have

been ever required to obtain a stable output voltage in

conventional applications. Furthermore, adoption of the

original adapter type technology that controls on time

makes the external phase compensation parts

unnecessary, which realizes the designs of isolated

power supply application with drastic reduction of parts

number, minimization of application circuits, and high

reliability.

SW Pin:

◼ Over Current Protection Current:

◼ Switching Frequency:

◼ Reference Voltage Accuracy:

◼ Current at Shutdown:

◼ Current at Switching Operation:

0 μA (Typ)

0.45 mA (Typ)

◼ Operating Temperature Range: -40 °C to +125 °C

Packages

HSON8

W (Typ) x D (Typ) x H (Max)

2.9 mm x 3.0 mm x 0.6 mm

(BD7J201HFN-LB (Under Development))

HTSOP-J8

4.9 mm x 6.0 mm x 1.0 mm

(BD7J201EFJ-LB)

Features

◼ Long Time Support Product for Industrial Applications

◼ No Need of Any Optocouplers and Third Winding of

Transformers

◼ Set Output Voltage with Two External Resistors and

Ratio of Transformer Turns

◼ Adopt of Original Adapter Type Technology that

Controls On Time

◼ No Need of External Phase Compensation Parts by

High-speed Load Response

◼ Low Output Ripple by Fixed Switching Frequency

(At normal operation)

◼ High Efficient Light Load Mode (At PFM operation)

◼ Shutdown and Enable Control

◼ Built-in 120 V Switching MOSFET

◼ Soft Start Function

HSON8

HTSOP-J8

Application

Isolated Power Supply for Industrial Equipment

◼ Load Compensation Function

◼ Various Protection Function

◼

Input Under Voltage Lockout (VIN UVLO)

Over Current Protection (OCP)

Over Voltage Protection (OVP)

Short Circuit Protection (SCP)

Thermal Shutdown (TSD)

Battery Short Protection (BSP)

Enable Over Voltage Protection (ENOVP)

Typical Application Circuit

VIN

SDX/EN

SW

FB

L_COMP

AGND REF PGND

〇Product structure : Silicon integrated circuit 〇This product has no designed protection against radioactive rays.

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Pin Configurations

(TOP VIEW)

AGND

1

2

3

4

8

7

6

5

VIN

AGND 1

SDX/EN 2

L_COMP 3

REF 4

8 VIN

7 SW

6 PGND

5 FB

SDX/EN

L_COMP

REF

SW

PGND

FB

EXP-PAD

HSON8

HTSOP-J8

Pin Descriptions

Pin No.

Pin Name

Function

1

2

3

4

5

6

7

8

-

AGND

SDX/EN

L_COMP

REF

Analog system GND pin

Shutdown and enable control pin

Setting pin of the load current compensation value

Setting pin of the output voltage

Power system GND pin

FB

PGND

SW

Switching output pin

VIN

Power supply input pin

EXP-PAD

Connect EXP-PAD to both of the AGND and PGND pins

Block Diagram

8

5

7

VIN

FB

SW

Current Monitor

INTERNAL

REGULATOR

SCP

OVP

V_INTREF

COMPARATOR

Switching

MOSFET

ADAPTIVE

ON-TIME

CONTROLLER

Shutdown

V_INTREF

SOFT

DRIVER

Enable

2

SDX/EN

VIN UVLO

TSD

START

OCP

BSP

EN OVP

LOAD

COMPENSATION

PGND

REF

L_COMP

AGND

1

4

3

6

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Description of Blocks

1

INTERNAL REGULATOR

This is the regulator block for internal circuits.

This block also shuts itself down at the shutdown status of the SDX/EN pin voltage ≤ V_SDX

.

The SDX/EN pin voltage becomes V_EN1or more, the IC becomes enable status then it startup.

During t_SSfrom startup, the output voltage gradually rises due to the soft start function.

The SDX/EN pin voltage becomes V_EN2or less, the IC becomes disable status and stops the switching operation.

VIN pin voltage

V_EN1

V_EN2

SDX/EN pin voltage

t_SS

Setting output voltage

Setting output voltage × 0.9

Output voltage

Switching

ON

Figure 1. Startup and Stop Timing Chart

In the control method of this IC, it is necessary to operate in the status that the duty is D_MAXor less. At the startup and

stop, set the VIN pin voltage V_INto meet the next formula.

ꢀ_푃

ꢀ_푆

1

[V]

(

)

푉 >

퐼푁

× 푉_푂푈푇+ 푉_퐹ꢁ

− 1ꢂ

퐷_푀퐴푋

where:

is the VIN pin voltage.

푉

퐼푁

ꢀ_푃is the number of winding at the primary transformer.

ꢀ_푆is the number of winding at the secondary transformer.

푉_푂푈푇is the output voltage.

푉_퐹is the forward voltage of the secondary output diode.

퐷_푀퐴푋is the maximum duty.

In the case that the SDX/EN pin is shorted to the VIN pin, the duty becomes D_MAXor more at startup and stop, and

unintended output voltage may occur. Refer to Application Examples: 6 Enable Voltage and Disable Voltage for the

enable control by the VIN pin.

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Description of Blocks – continued

2

VIN UVLO

This is the input low voltage protection block.

When the VIN pin voltage becomes V_UVLO1or less, the IC detects VIN UVLO and stops the switching operation.

When the VIN pin voltage becomes V_UVLO2or more, the IC releases VIN UVLO and starts the switching operation.

During t_SSfrom the start of switching operation, the output voltage gradually rises due to the soft start function.

VIN pin voltage

V_UVLO2

V_UVLO1

0 V

t_SS

Setting output voltage

Setting output voltage × 0.9

Output voltage

Switching

ON

Figure 2. VIN UVLO Timing Chart

3

EN OVP

This is the SDX/EN pin voltage over voltage protection block.

When the SDX/EN pin voltage becomes V_ENOVP1or more, the IC detects EN OVP and stops the switching operation.

When the SDX/EN pin voltage becomes V_ENOVP2or less, the IC releases EN OVP and starts the switching operation.

During t_SSfrom the start of switching operation, the output voltage gradually rises due to the soft start function.

Figure 3. EN OVP Timing Chart

Refer Application Examples:7 Enable OVP Detect Voltage and Enable OVP Release Voltage for the enable control by

the VIN pin.

4

SOFT START

When the SDX/EN pin voltage becomes V_EN1or more and enable status, the comparison voltage in the comparator

block transits slowly 0 V to V_INTREF. This operation prevents the IC from rushing current at the rising edge of the output

voltage or overshooting of the output voltage. The soft start time is fixed to t_SSin the IC.

5

COMPARATOR

In this block, the IC compares the reference voltage to the REF pin voltage that is the feedback voltage of the SW pin

voltage. This IC is superior to the response for fluctuation in load because it constitutes the feedback loop by the

comparator.

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Description of Blocks – continued

6

ADAPTIVE ON TIME CONTROLLER

This block is corresponded to the original adapter type technology that controls on time.

Stable load current:

Operates in the PWM control and fix the on time.

Fluctuating load current:

Operates in the on time control and realizes a high-speed load response by

fluctuates the switching frequency.

Light load:

Decrease the switching frequency and realizes a high efficiency.

When the load current fluctuates, the frequency becomes high. The IC raises the average of primary current by

shortening the off time and raises the secondary current.

Output voltage

Primary coil current

SW pin voltage

High

Frequency

Stabilize gradually

Stable operation

Switching Frequency

Figure 4. Transient Response Timing Chart

7

8

DRIVER

This block drives the switching MOSFET.

LOAD COMPENSATION

This block compensates the fluctuation of output voltage caused by the fluctuation of V_Fcharacteristic in the secondary

output diode corresponded to load current. This block monitors the current flowed to the switching MOSFET and pulls

the current corresponded to the quantity of compensation determined by the external resistor and capacitor at the

L_COMP pin and time constant from the REF pin. The decrease of the REF pin voltage by the drop of feedback current

flowing in the external resistor at the REF pin rises the output voltage and it is compensated.

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Description of Blocks – continued

9

OCP, BSP

This is the block of the over current protection and battery short protection.

9.1

OCP (Over Current Protection)

At the switching MOSFET on, the IC detects OCP when the peak current becomes I_LIMITor more. At this moment,

the switching MOSFET is turned off. Because of detecting OCP per switching cycles and restricting on duty, the

output voltage drops. In addition, to prevent detection error, the detection of OCP is invalidated for t_MASK1after the

switching MOSFET is turned on.

Output voltage

I_LIMIT

Primary coil current

SW pin voltage

t_MASK1

Normal

OCP

IC status

Figure 5. OCP Timing Chart

9.2

BSP (Battery Short Protection)

If the SW pin is connected to high electric potential with low impedance, large current flows when the switching

MOSFET turned on and it may destroy the IC. To prevent this, BSP is built in the IC. When the SW pin voltage becomes

V_BSPor more at the switching MOSFET on, the IC detects BSP and the switching operation is stopped. The time of

t_RESTARTafter the switching operation stopped, the switching operation is restarted. During t_SSfrom the start of switching

operation, the output voltage gradually rises due to the soft start function.

t_SS

Setting output voltage

Setting output voltage × 0.9

Output voltage

SW pin voltage

V_BSP

ON

Switching

t_RESTART

Figure 6. BSP Timing Chart

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Description of Blocks – continued

10 SCP, OVP

This is the block of the short circuit protection and over voltage protection.

10.1 SCP (Short Circuit Protection)

The REF pin obtains the secondary output voltage data from the primary flyback voltage. When the REF pin

voltage becomes V_SCPor less at the switching MOSFET off, the IC detects SCP and the switching operation is

stopped. The time of t_RESTARTafter the switching operation stopped, the switching operation is restarted. The soft

start function works and the output from restart of the switching operation to the time of t_SS, and the output voltage

rises slowly.

To prevent detection error, the detection of SCP is invalidated for t_MASK2after the switching MOSFET is turned off

and for t_MASK3from start of the switching operation.

t_SS

Setting output voltage

Setting output voltage × 0.9

Output voltage

SW pin voltage

V_SCP

REF pin voltage

Switching

ON

Figure 7. SCP Timing Chart

ON

t_RESTART

10.2 OVP (Over Voltage Protection)

The REF pin obtains the secondary output voltage data from the primary flyback voltage. When the REF pin

voltage becomes V_OVPor more at the switching MOSFET off, the IC detects OVP and the switching operation is

stopped. The time of t_RESTARTafter the switching operation stopped, the switching operation is restarted. The soft

start function works and the output from restart of the switching operation to the time of t_SS, and the output voltage

rises slowly.

To prevent detection error, the detection of OVP is invalidated for t_MASK2after the switching MOSFET is turned off.

t_SS

Setting output voltage

Setting output voltage× 0.9

Output voltage

SW pin voltage

V_OVP

REF pin voltage

ON

Switching

t_RESTART

Figure 8. OVP Timing Chart

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Absolute Maximum Ratings (Ta = 25 °C)

Parameter

VIN Pin Voltage

Symbol

Rating

Unit

100

V_{IN_MAX}

V_{SW_MAX}

V_{SDX/EN_MAX}

V_{FB_MAX}

V

120

SW Pin Voltage

100

SDX/EN Pin Voltage

FB Pin Voltage

V

V_IN- 0.3 to V_IN+ 0.3

V

7

REF Pin Voltage

V_{REF_MAX}

V_{L_COMP_MAX}

Tjmax

V

7

L_COMP Pin Voltage

Maximum Junction Temperature

Storage Temperature Range

V

150

°C

Tstg

-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)}

HSON8

Junction to Ambient

Junction to Top Characterization Parameter^{(Note 2)}

θ_JA

265.1

17

66.1

9

°C/W

Ψ_JT

HTSOP-J8

Junction to Ambient

Junction to Top Characterization Parameter^{(Note 2)}

θ_JA

206.4

21

45.2

13

°C/W

Ψ_JT

(Note 1) Based on JESD51-2A (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

FR-4

Board Size

Single

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

FR-4

Board Size

114.3 mm x 76.2 mm x 1.6 mmt

2 Internal Layers

Pitch

Diameter

4 Layers

1.20 mm

Φ0.30 mm

Top

Copper Pattern

Bottom

Thickness

70 μm

Copper Pattern

Thickness

35 μm

Copper Pattern

Thickness

70 μm

Footprints and Traces

74.2 mm x 74.2 mm

(Note 5) This thermal via connects with the copper pattern of all layers.

Recommended Operating Conditions

Parameter

Symbol

Min

Typ

Max

Unit

Conditions

Power Supply Voltage Range 1

Power Supply Voltage Range 2

Power Supply Voltage Range 3

Operating Temperature

V_IN

V_SW

8

-

48

-

80

110

0.5

V

The VIN pin voltage

The SW pin Voltage

The L_COMP pin voltage

V_{L_COMP_MAX2}

Topr

-

V

-40

-

+125

°C

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Electrical Characteristics (Unless otherwise specified V_IN= 48 V, V_SDX/EN= 2.5 V, Ta = 25 °C)

Parameter

Symbol

Min

Typ

Max

Unit

Conditions

Power Supply Block

Current at Shutdown

I_ST

I_CC

-

0

10

1.10

6.0

6.2

-

μA V_SDX/EN= 0 V

Current at Switching Operation

VIN UVLO Voltage 1

0.45

5.0

5.2

0.2

mA V_REF= 0.85 V (At PFM operation)

V_UVLO1

V_UVLO2

V_{UVLO_HYS}

4.0

4.2

-

V

At V_INfalling

At V_INrising

VIN UVLO Voltage 2

VIN UVLO Voltage Hysteresis

Shutdown and Enable Control Block

Shutdown Voltage

V_SDX

V_EN1

-

0.3

V

Enable Voltage 1

1.75

2.00

1.80

0.2

2.25

At V_SDX/ENrising

At V_SDX/ENfalling

Enable Voltage 2

V_EN2

1.55

2.05

V

Enable Voltage Hysteresis

Enable Over Protection Voltage 1

Enable Over Protection Voltage 2

V_{EN_HYS}

V_ENOVP1

V_ENOVP2

-

V

3.06

3.50

3.30

0.2

3.94

V

At V_SDX/ENrising

At V_SDX/ENfalling

2.86

3.74

V

Enable Over Protection Voltage Hysteresis V_{ENOVP_HYS}

-

V

SDX/EN Pin Inflow Current

I_SDX/EN

V_CLPEN

0.89

1.78

5.3

2.85

μA

V

SDX/EN Pin Clamp Voltage

-

SDX/EN Pin Pull-down Resistance 1

SDX/EN Pin Pull-down Resistance 2

SDX/EN Pin Pull-down Resistance 3

SDX/EN Pin Pull-down Resistance 4

R_SDX/EN1

R_SDX/EN2

R_SDX/EN3

R_SDX/EN4

1315

106

1421

33

kΩ

Reference Voltage Block

Reference Voltage

REF Pin Current

V_INTREF

I_REF

0.738 0.750 0.762

V

-

100

-

μA

Switching Block

On Resistance

R_ON

I_LIMIT

0.25

1.44

-

0.50

1.80

400

0.75

380

550

20

1.00

2.16

-

Ω

A

Between SW and PGND pins

Over Current Protection Current

Switching Frequency

On Time

f_SW

kHz At PWM operation (Duty=30 %)

t_ON

0.60

280

410

14

0.90

480

690

26

μs At PWM operation (Duty=30 %)

Minimum On Time

Minimum Off Time

Maximum Off Time

Soft Start Time

t_{ON_MIN}

t_{OFF_MIN}

t_{OFF_MAX}

t_SS

ns

μs

0.8

50

2.0

-

4.5

-

ms From rise-up to V_REFx 90 %

Maximum Duty

D_MAX

D_MIN

%

Minimum Duty

-

20

Protection Function Block

Short Circuit Protection Detection Voltage

Over Voltage Protection Detection Voltage

Battery Short Protection Detection Voltage

Restart Time

V_SCP

V_OVP

-

0.50

0.95

2.0

-

V

V_BSP

V

t_RESTART

t_MASK1

t_MASK2

t_MASK3

2.0

ms

ns

Over Current Protection Mask Time

280

Short and Over Voltage Protection

Mask Time

-

430

550

-

ns

μs

Short Protection Mask Time at Startup

Load Compensation Block

Internal Resistor at L_COMP Pin

R_INTCOMP

K

-

100

-

kΩ

%

Compressor Magnification

in Current Monitor

0.005

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Typical Performance Curves

(Reference Data)

1.00

0.90

0.80

0.70

0.60

0.50

0.40

0.30

0.20

0.10

0.00

6.0

5.5

5.0

4.5

4.0

-40 -20

0 20 40 60 80 100120140

-40 -20

0 20 40 60 80 100120140

Temperature [°C]

Figure 9. Current at Switching Operation vs Temperature

Figure 10. VIN UVLO Voltage 1 vs Temperature

2.50

2.30

2.10

1.90

1.70

1.50

4.00

3.80

3.60

3.40

3.20

3.00

-40 -20

0 20 40 60 80 100120140

-40 -20

0 20 40 60 80 100120140

Temperature [°C]

Figure 11. Enable Voltage 1 vs Temperature

Figure 12. Enable Over Protection Voltage 1 vs Temperature

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Typical Performance Curves – continued

(Reference Data)

4.00

3.00

2.00

1.00

0.00

0.850

0.800

0.750

0.700

0.650

-40 -20

0 20 40 60 80 100120140

-40 -20

0 20 40 60 80 100120140

Temperature [°C]

Figure 13. SDX/EN Pin Inflow Current vs Temperature

Figure 14. Reference Voltage vs Temperature

1.00

0.90

0.80

0.70

0.60

0.50

0.40

0.30

0.20

0.10

0.00

3.00

2.50

2.00

1.50

1.00

-40 -20

0 20 40 60 80 100120140

-40 -20

0 20 40 60 80 100120140

Temperature [°C]

Figure 15. On Resistance vs Temperature

Figure 16. Over Current Protection Current vs Temperature

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Typical Performance Curves – continued

(Reference Data)

2.00

1.80

1.60

1.40

1.20

1.00

0.80

0.60

0.40

0.20

0.00

500

460

420

380

340

300

-40 -20

0

20 40 60 80 100120140

-40 -20

0 20 40 60 80 100120140

Temperature [°C]

Figure 17. On Time vs Temperature

Figure 18. Switching Frequency vs Temperature

600

700

650

600

550

500

450

400

550

500

450

400

350

300

250

200

-40 -20

0 20 40 60 80 100120140

-40 -20

0 20 40 60 80 100120140

Temperature [°C]

Figure 19. Minimum On Time vs Temperature

Figure 20. Minimum Off Time vs Temperature

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Typical Performance Curves – continued

(Reference Data)

30

25

20

15

10

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

-40 -20

0 20 40 60 80 100120140

-40 -20

0 20 40 60 80 100120140

Temperature [°C]

Figure 21. Maximum Off Time vs Temperature

Figure 22. Soft Start Time vs Temperature

0.60

0.55

0.50

0.45

0.40

1.10

1.05

1.00

0.95

0.90

0.85

0.80

-40 -20

0 20 40 60 80 100120140

-40 -20 0 20 40 60 80 100120140

Temperature [°C]

Figure 23. Short Circuit Protection Detection Voltage

vs Temperature

Figure 24. Over Voltage Protection Detection Voltage

vs Temperature

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Typical Performance Curves – continued

(Reference Data)

3.0

2.5

2.0

1.5

1.0

500

400

300

200

100

-40 -20 0 20 40 60 80 100120140

Temperature [°C]

Figure 25. Battery Short Protection Detection Voltage

vs Temperature

Figure 26. Over Current Protection Mask Time

vs Temperature

600

500

400

300

200

1000

900

800

700

600

500

400

300

200

100

0

-40 -20

0 20 40 60 80 100120140

-40 -20

0 20 40 60 80 100120140

Temperature [°C]

Figure 27. Short and Over Voltage Protection Mask Time

vs Temperature

Figure 28. Short Protection Mask Time at Startup

vs Temperature

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Typical Performance Curves – continued

(Reference Data)

15.0

12.0

9.0

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

6.0

3.0

0.0

0

20

40

60

80

100

-40 -20

0 20 40 60 80 100120140

VIN Pin Voltage [V]

Temperature [°C]

Figure 29. Restart Time vs Temperature

Figure 30. Maximum Output Power vs VIN Pin Voltage

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Application Examples

1

Output Voltage

When the internal switching MOSFET is off, the SW pin voltage becomes higher than the 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. The SW pin voltage at turn off is calculated by the formula below.

ꢀ_푃

( )

× 푉_푂푈푇+ 푉_퐹+ ꢃ_푆× 퐸ꢄ푅

푉

푆푊

= 푉 +

[V]

퐼푁

ꢀ_푆

where:

푉

퐼푁

is the SW pin voltage.

is the VIN pin voltage.

푆푊

ꢀ_푃is the number of winding at the primary transformer.

ꢀ_푆is the number of winding at the secondary transformer.

푉_푂푈푇is the output voltage.

푉_퐹is the forward voltage of the secondary output diode.

ꢃ_푆is the secondary transformer current.

퐸ꢄ푅 is the secondary total impedance (secondary transformer winding resistance and board).

The external resistor R_FBbetween the FB and SW pins converts the primary flyback voltage into the FB pin inflow

current I_RFB. The FB pin inflow current I_RFBis calculated by the formula below because the FB pin voltage is nearly

equal to the VIN pin voltage by the IC’s internal circuit.

푉

− 푉_퐹퐵

푆푊

ꢃ_ꢅ퐹퐵

=

푅_퐹퐵

ꢀ_푃

ꢀ_푆

(

)

푉 +

퐼푁

× 푉_푂푈푇+ 푉_퐹+ ꢃ_푆× 퐸ꢄ푅 − 푉_퐹퐵

푅_퐹퐵

ꢀ_푃

ꢀ_푆

(

)

× 푉_푂푈푇+ 푉_퐹+ ꢃ_푆× 퐸ꢄ푅

[A]

푅_퐹퐵

where:

ꢃ_ꢅ퐹퐵is the FB pin inflow current.

푉_퐹퐵is the FB pin voltage.

푅_퐹퐵is the external resistor between the FB and SW pins.

Furthermore, the REF pin voltage is calculated by the formula below because the FB pin inflow current flows into the

external resistor R_REFbetween the REF and AGND pins.

푅_ꢅꢆ퐹ꢀ_푃

( )

× 푉_푂푈푇+ 푉_퐹+ ꢃ_푆× 퐸ꢄ푅

푉_ꢅꢆ퐹

=

×

[V]

푅_퐹퐵

ꢀ_푆

where:

푉_ꢅꢆ퐹is the REF pin voltage.

푅_ꢅꢆ퐹is the external resistor between the REF and AGND pins.

It is necessary to be set the resistor R_REFas the current flowing in the REF pin becomes I_REFwhen the REF pin voltage

is equal to V_INTREF

.

This IC’s internal circuit is designed as R_REF= 7.5 kΩ according to the formula below.

푉

퐼푁푇ꢅꢆ퐹

푅_ꢅꢆ퐹

=

[Ω]

ꢃ_ꢅꢆ퐹

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1

Output Voltage – continued

The REF pin voltage is input to the comparator with the reference voltage in the IC. By the internal circuit in the IC, the

REF pin voltage becomes equal to the reference voltage. Therefore, the output voltage and the REF pin voltage is

calculated by the formula below.

푅_퐹퐵

ꢀ_푆

[V]

푉_푂푈푇

=

×

× 푉_ꢅꢆ퐹− 푉_퐹− ꢃ_푆× 퐸ꢄ푅

푅_ꢅꢆ퐹ꢀ_푃

The output voltage is set by the number of winding ratio of the primary and secondary transformer and the resistance

ratio of R_FBand R_REF. In addition, V_Fand ESR is factor of the error in the output voltage. According to the above formula,

the external resistor between the FB and SW pins R_FBis calculated by the formula below.

푅_ꢅꢆ퐹ꢀ_푃

(

)

푅_퐹퐵

=

×

× 푉_푂푈푇+ 푉_퐹+ ꢃ_푆× 퐸ꢄ푅

[Ω]

푉_ꢅꢆ퐹ꢀ_푆

V_F

I_S

V_IN

N_P/N_S

V_OUT

I_RFB

R_FB

FB

SW

COMPARATOR

ADAPTIVE

DRIVER

ON-TIME

CONTROLLER

V_INTREF

I_P

V_{L_COMP}

Current

Monitor

I_{L_COMP}

REF

PGND

L_COMP

C_{L_COMP}

R_REF

R_{L_COMP}

Figure 31. Control Block Diagram

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Application Examples – continued

2

Transformer

2.1 Number of Winding Ratio

The number of winding ratio is the parameter with which the output voltage, maximum output electric power, duty

and the SW pin voltage is set.

The duty of flyback converter is calculated by the formula below.

ꢀ_푃

ꢀ_푆

(

)

× 푉_푂푈푇+ 푉_퐹

퐷푢푡푦 =

[%]

ꢀ_푃

ꢀ_푆

( )

× 푉_푂푈푇+ 푉_퐹

푉 +

퐼푁

where:

ꢀ_푃is the number of winding at the primary transformer.

ꢀ_푆is the number of winding at the secondary transformer.

푉_푂푈푇is the output voltage.

푉_퐹is the forward voltage of the secondary output diode.

푉

퐼푁

is the VIN pin voltage.

It is necessary to set the duty to D_MAXor less for the stable control. By the restriction of the minimum on time, the

minimum duty is determined to D_MINand the number of winding ratio must meet the conditional expression below.

퐷_푀퐼푁

푉

ꢀ_푃

퐷_푀퐴푋

푉

퐼푁

×

<

×

1 − 퐷_푀퐼푁푉_푂푈푇+ 푉_퐹ꢀ_푆1 − 퐷_푀퐴푋푉_푂푈푇+ 푉_퐹

where:

퐷_푀퐼푁is the minimum duty.

퐷_푀퐴푋is the maximum duty.

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2

Transformer – continued

2.2

Primary Inductance

The right half plane zero point occurs in the feedback loop of flyback converter.

The right half plane zero frequency f_{RHP_ZERO}is calculated by the formula below.

2

ꢀ

ꢀ_푆

푉

퐼푁

ꢇ

^푃ꢈ × {

} × 푅_푂푈푇

ꢀ_푃

ꢀ_푆

( )

× 푉_푂푈푇+ 푉_퐹

푉 +

퐼푁

푓

=

[Hz]

ꢅ퐻푃_푍ꢆꢅ푂

ꢀ_푃

ꢀ_푆

(

)

× 푉_푂푈푇+ 푉_퐹

ꢉ휋 ×

× 퐿_푃

ꢀ_푃

( )

× 푉_푂푈푇+ 푉_퐹

푉 +

퐼푁

ꢀ_푆

where:

푓

is the right half plane zero frequency.

ꢅ퐻푃_푍ꢆꢅ푂

ꢀ_푃is the number of winding at the primary transformer.

ꢀ_푆is the number of winding at the secondary transformer.

is the VIN pin voltage.

푉

퐼푁

푉_푂푈푇is the output voltage.

푉_퐹is the forward voltage of the secondary output diode.

푅_푂푈푇is the load resistance.

퐿_푝is the primary inductance.

For the insurance of stability, the right half plane zero frequency f_{RHP_ZERO}must be set to more than one quarter

of the switching frequency f_SW. By this, the conditional expression below is required.

1

푓

> × 푓

ꢅ퐻푃_푍ꢆꢅ푂

푆푊

4

2

ꢉ × 퐷푢푡푦 × 푉

퐼푁

퐿_푝<

[H]

(

)

푉_푂푈푇+ 푉_퐹× ꢃ_{푂푈푇_푀퐴푋}× 휋 × 푓

푆푊

where:

푓

is the switching frequency.

푆푊

ꢃ_{푂푈푇_푀퐴푋}is the maximum value of the output current.

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2.2

Primary Inductance – continued

The minimum value of primary inductance can be found by the relation of input and output electric power. If the

L_Pbecomes lower, the peak current of primary transformer becomes higher. Because the desired output electric

power cannot be obtained if the peak current value becomes the over current protection current or more, the

lower limit of the necessary primary inductance value corresponding to maximum load is calculated by the

conditional expression below.

1

퐿_푝> ×

ꢉ

푉

²× 푡_푆× 퐷푢푡푦²× 휂

퐼푁

[H]

ꢃ_{ꢊ퐼푀퐼푇_푀퐼푁}× 퐷푢푡푦 × 푉 × 휂 − 푉_{푂푈푇_푀퐴푋}× ꢃ_{푂푈푇_푀퐴푋}

퐼푁

where:

푡_푆is the cycle of switching.

휂 is the efficiency.

ꢃ_{ꢊ퐼푀퐼푇_푀퐼푁}is the minimum value of over current protection current.

푉_{푂푈푇_푀퐴푋}is the maximum value of output voltage.

According to the above, the primary inductance must meet the conditional expression below.

1

ꢉ

푉

²× 푡_푆× 퐷푢푡푦²× 휂

퐼푁

×

ꢃ_{ꢊ퐼푀퐼푇_푀퐼푁}× 퐷푢푡푦 × 푉 × 휂 − 푉_{푂푈푇_푀퐴푋}× ꢃ_{푂푈푇_푀퐴푋}

퐼푁

2

ꢉ × 퐷푢푡푦 × 푉

퐼푁

< 퐿_푝<

[H]

(

)

푉_푂푈푇+ 푉_퐹× ꢃ_{푂푈푇_푀퐴푋}× 휋 × 푓

푆푊

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2

Transformer – continued

2.3

Leak Inductance

The moment the internal switching MOSFET is turned off, the leak inductance of transformer causes the ringing

at the SW pin. Insert the snubber circuit not to exceed the absolute maximum rating of the SW pin voltage. It is

necessary to settle down within t_MASK2for the prevention of the error in the secondary output voltage.

Voltage

V_{SW_MAX}

<t_MASK2

(Note 1)

Primary Flyback Voltage

V_IN

Time

ꢀ_ꢋ

( )

× 푉_ꢌꢍꢎ+ 푉_ꢏ+ ꢃ_ꢄ× 퐸ꢄ푅

Primary Flyback Voltage =

(Note 1)

ꢀ

ꢄ

Figure 32. Leak Inductance

2.4

2.5

Winding Resistance

The primary winding resistance lowers the efficiency of electricity. The secondary winding resistance also lowers

the output voltage as well as the efficiency of electricity. According to them, it is recommended to use the

transformer which has small winding resistance.

Saturated Current

Because the core of transformer saturates if the primary transformer current exceeds its rating saturated current,

the energy does not transmit to the secondary side. The primary transformer current increases rapidly because

the inductance value drops if the core saturates. Set the primary transformer current to less than its rating

saturated current.

3

Output Capacitor

It is necessary to select the proper secondary output capacitor for the stable operation. Refer to the formula below and

select the appropriate capacitor.

2

1

ꢀ_푃

퐶_푂푈푇= 1.6 × 10^ꢐ9

×

× ꢁ × 퐷푢푡푦ꢂ

ꢀ_푆

[F]

퐿_푃

where:

퐶_푂푈푇is the value of output capacitor.

퐿_푃is the primary inductance.

ꢀ_푃is the number of winding at the primary transformer.

ꢀ_푆is the number of winding at the secondary transformer.

In addition, it is necessary for the output voltage to rise within t_SS. Therefore, consider the conditional expression below

to select the output capacitor too. The startup error may occur because the short circuit protection operates if the

capacitor value is extremely large.

ꢀ_푃

ꢀ_푆

(

)

푡_푆푆× ꢑꢇꢃ_{ꢊ퐼푀퐼푇_푀퐼푁}

×

ꢈ × 1 − 퐷푢푡푦 − ꢃ_{푂푈푇_푀퐴푋}

ꢒ

1

퐶_푂푈푇≤ ×

ꢉ

[F]

푉_푂푈푇

where:

푡_푆푆is the soft start time.

ꢃ_{ꢊ퐼푀퐼푇_푀퐼푁}is the minimum value of over current protection current.

ꢃ_{푂푈푇_푀퐴푋}is the maximum value of output current.

푉_푂푈푇is the output voltage.

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Application Examples – continued

4

Input Capacitor

Use the ceramic capacitor for the input capacitor and locate the input capacitor as near as possible to the VIN pin.

The pattern of board and location of capacitor may cause malfunction.

It is necessary to set the value of input capacitor so that the ripple voltage of the VIN pin becomes 4 % or less of the

VIN pin voltage. Confirm that at the load fluctuation and startup too.

5

Secondary Output Diode

It is recommended to use the schottky barrier diode whose forward voltage V_Fis small because the V_Fbecomes the

factor of error in the output voltage. Select the secondary output diode so that the forward current does not exceed its

rating.

The reverse voltage V_Roccurring at the secondary output diode is calculated by the formula below when the internal

switching MOSFET is on.

ꢀ_푆

[V]

푉_ꢅ= 푉 ×

+ 푉_푂푈푇

퐼푁

ꢀ_푃

where:

푉_ꢅis the reverse voltage at the secondary output diode.

is the VIN pin voltage.

푉

퐼푁

ꢀ_푃is the number of winding at the primary transformer.

ꢀ_푆is the number of winding at the secondary transformer.

푉_푂푈푇is the output voltage.

Furthermore, the ringing piles up the reverse voltage V_Rat the secondary output diode the moment the internal

switching MOSFET is turned on. Set the peak voltage of V_Rnot to exceed the rating of secondary output diode.

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Application Examples – continued

6

Enable Voltage and Disable Voltage

This IC becomes shutdown status when the SDX/EN pin voltage becomes V_SDXor less. At the rise of the SDX/EN pin

voltage, the IC becomes enable status and starts the operation when the voltage becomes V_EN1or more. At the fall of

the SDX/EN pin voltage, the IC becomes disable status when the voltage becomes V_EN2or less.

Shown as Figure 33, the SDX/EN pin realizes the enable control with the VIN pin by connecting the circuit divided by

the resistor R₁and R₂between the VIN and AGND pins to the SDX/EN pin.

The internal clamp element turned on and the SDX/EN pin inflow current increases if the SDX/EN pin voltage becomes

V_CLPENor more.

6.1

Enable Voltage

It is possible to set the enable voltage at the rise of the VIN pin voltage V_{IN_ENABLE}by the formula below.

푅_ꢓ× ꢔ푅₂+ 푅_{푆ꢕ푋/ꢆ푁ꢓ}ꢖ+푅₂× 푅_{푆ꢕ푋/ꢆ푁ꢓ}

푉

= V_ꢆ푁ꢓ×

[V]

퐼푁_ꢆ푁퐴퐵ꢊꢆ

푅₂× 푅_{푆ꢕ푋/ꢆ푁ꢓ}

where:

푉

is the enable voltage at the rise of the VIN pin voltage.

퐼푁_ꢆ푁퐴퐵ꢊꢆ

푉_ꢆ푁ꢓis the enable voltage 1.

It is necessary to set the duty to D_MAXor less and operate in this IC’s control method. Thus, set the enable voltage

at the rise of the VIN pin voltage V_{IN_ENABLE}to meet the conditional expression below.

ꢀ_푃

[V]

( )

× 푉_푂푈푇+ 푉_퐹

푉

>

퐼푁_ꢆ푁퐴퐵ꢊꢆ

ꢀ_푆

where:

ꢀ_푃is the number of winding at the primary transformer.

ꢀ_푆is the number of winding at the secondary transformer.

푉_푂푈푇is the output voltage.

푉_퐹is the forward voltage at the secondary output diode.

6.2

Disable Voltage

It is possible to set the disable voltage at the fall of the VIN pin voltage V_{IN_DISABLE}by the formula below.

푅_ꢓ× ꢔ푅₂+ 푅_{푆ꢕ푋/ꢆ푁ꢓ}+ 푅_{푆ꢕ푋/ꢆ푁2}ꢖ+푅₂× ꢔ푅_{푆ꢕ푋/ꢆ푁ꢓ}+ 푅_{푆ꢕ푋/ꢆ푁2}

ꢖ

[V]

푉

= V_ꢆ푁2×

퐼푁_ꢕ퐼푆퐴퐵ꢊꢆ

푅₂× ꢔ푅_{푆ꢕ푋/ꢆ푁ꢓ}+ 푅_{푆ꢕ푋/ꢆ푁2}

ꢖ

푉

is the disable voltage at the fall of the VIN pin voltage.

퐼푁_ꢕ퐼푆퐴퐵ꢊꢆ

푉_ꢆ푁2is the enable voltage 2.

V_IN

R₁

R₂

VIN

SDX/EN

AGND

R_SDX/EX1

R_SDX/EX2

Figure 33. Position of Resistors Connected to SDX/EN Pin

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Application Examples – continued

7

Enable OVP Detect Voltage and Enable OVP Release Voltage

This IC becomes disable status when the SDX/EN pin voltage becomes V_ENOVP1or more. Also, the IC becomes enable

status and starts the operation when the SDX/EN pin voltage becomes V_ENOVP2or less.

Shown as Figure 34, the SDX/EN pin realizes the enable OVP control with the VIN pin by connecting the circuit divided

by the resistor R₁and R₂between the VIN and AGND pins to the SDX/EN pin.

7.1

Enable OVP Detect Voltage

It is possible to set the enable OVP detect voltage of the VIN pin voltage V_{IN_ENOVP1}by the formula below.

푅_ꢓ× ꢔ푅₂+ 푅_{푆ꢕ푋/ꢆ푁3}ꢖ+푅₂× 푅_{푆ꢕ푋/ꢆ푁3}

푉

= V_{ꢆ푁푂ꢗ푃ꢓ}×

[V]

퐼푁_ꢆ푁푂ꢗ푃ꢓ

푅₂× 푅_{푆ꢕ푋/ꢆ푁3}

where:

푉

is the enable OVP detect voltage of the VIN pin voltage.

퐼푁_ꢆ푁푂ꢗ푃ꢓ

푉_{ꢆ푁푂ꢗ푃ꢓ}is the enable over protection voltage 1.

7.2

Enable OVP Release Voltage

It is possible to set the enable OVP release voltage of the VIN pin voltage V_{IN_ENOVP2}by the formula below.

푉

퐼푁_ꢆ푁푂ꢗ푃2

푅_ꢓ× ꢔ푅₂+ 푅_{푆ꢕ푋/ꢆ푁3}+ 푅_{푆ꢕ푋/ꢆ푁ꢘ}ꢖ+푅₂× ꢔ푅_{푆ꢕ푋/ꢆ푁3}+ 푅_{푆ꢕ푋/ꢆ푁ꢘ}

ꢖ

[V]

= V_{ꢆ푁푂ꢗ푃2}

×

푅₂× ꢔ푅_{푆ꢕ푋/ꢆ푁3}+ 푅_{푆ꢕ푋/ꢆ푁ꢘ}

ꢖ

푉

is the enable OVP release voltage of the VIN pin voltage.

퐼푁_ꢆ푁푂ꢗ푃2

푉_{ꢆ푁푂ꢗ푃2}is the enable over protection voltage 2.

V_IN

R₁

VIN

SDX/EN

AGND

R_SDX/EX3

R₂

R_SDX/EX4

Figure 34. Position of Resistors Connected to SDX/EN Pin (EN OVP)

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Application Examples – continued

8

Minimum Load Current

This IC stabilizes the secondary output voltage isolated with the transformer by the primary flyback voltage at the

internal switching MOSFET turned off. Therefore, it operates with the minimum on time t_{ON_MIN}and maximum off time

t_{OFF_MAX}even if the status is light load. The output voltage may rise in the case of the light load current because a little

energy is supplied to the secondary output by this operation. To prevent the rise of output voltage, it is necessary to

maintain the minimum load current with adding such as the dummy resistor R_DUMMY

.

The required minimum load current I_{OUT_MIN}is calculated by the formula below.

1

ꢃ_{푂푈푇_푀퐼푁}= ×

ꢉ

ꢔ푉 × 푡_{푂푁_푀퐼푁}ꢖ²

퐼푁

[A]

퐿_푃× 푉_푂푈푇× ꢔ푡_{푂푁_푀퐼푁}+ 푡_{푂퐹퐹_푀퐴푋}

ꢖ

where:

ꢃ_{푂푈푇_푀퐼푁}is the minimum output current.

is the VIN pin voltage.

푉

퐼푁

푡_{푂푁_푀퐼푁}is the minimum on time.

퐿_푃is the primary inductance.

푉_푂푈푇is the output voltage.

푡_{푂퐹퐹_푀퐴푋}is the maximum off time.

V_F

I_S

V_IN

R_DUMMY

N_P/N_S

SW

V_OUT

I_RFB

R_FB

FB

COMPARATOR

ADAPTIVE

ON-TIME

DRIVER

CONTROLLER

V_INTREF

I_P

V_{L_COMP}

Current

Monitor

I_{L_COMP}

REF

PGND

L_COMP

R_REF

C_{L_COMP}

R_{L_COMP}

Figure 35. Position of R_DUMMY

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Application Examples – continued

9

The Influence to Switching Frequency and Output Voltage for Each Load

This IC achieves high efficiency by lowering the switching frequency in the light load. In CCM (Continuous Conduction

Mode) operation, the switching frequency is f_SWfor the constant load. When the load is light, the operation is changed

from CCM to DCM (Discontinuous Conduction Mode). Then, the switching frequency is reduced from f_SW

.

The output load when the operation is changed from CCM to DCM I_{OUT_ sw1}is calculated by the formula below.

f

2

(

)

푉 × 퐷푢푡푦

퐼푁

1

= ×

ꢉ

ꢃ_{푂푈푇_ 푆푊ꢓ}

푓

× 휂

퐿_푃× 푓 × 푉_푂푈푇

푆푊

where:

ꢃ_{푂푈푇_ 푆푊ꢓ}

푓

is the switched output current from CCM to DCM.

푓

푆푊

is the switching frequency.

푉

퐼푁

is the VIN pin voltage.

퐿_푃is the primary side inductance.

푉_푂푈푇is the output voltage.

휂 is the efficiency.

As the load is lighter than I_{OUT_ sw1}

f

, the on time decreases and becomes the minimum on time t_{ON_MIN}

.

The load current when the on time becomes minimum on time I_{OUT_ SW2}

f

is calculated by the formula below.

1

= ×

ꢉ

푓

푆푊

× ꢔ푉 × 푡_{푂푁_푀퐼푁}ꢖ²

퐼푁

ꢃ_{푂푈푇_ 푆푊2}

푓

× 휂

퐿_푃× 푉_푂푈푇

where:

ꢃ_{푂푈푇_ 푆푊2}

푓

is the load current operated by minimum on time.

푡_{푂푁_푀퐼푁}is the minimum on time.

As the load is lighter than I_{OUT_ sw2}, the off time increases and becomes the maximum off time t_{OFF_MAX}.

f

Because the maximum off time t_{OFF_MAX}is determined in this IC, the switching frequency is not smaller than the

minimum switching frequency f_{SW_MIN}calculated by the formula below.

1

푓

=

푆푊_푀퐼푁

푡_{푂푁_푀퐼푁}+ 푡_{푂퐹퐹_푀퐴푋}

where:

ꢏ

is the minimum switching frequency.

푆푊_푀퐼푁

푡_{푂퐹퐹_푀퐴푋}is the maximum off time.

Therefore, a certain amount of output power is absolutely generated by the minimum switching frequency operation.

This is the reason for which the output voltage rises in the no load or the light load.

SwitchingFrequency

f_SW

f_{SW_MIN}

I_{OUT_MIN}

I_{OUT_ sw2}

I_{OUT_ sw1}

f

I_OUT

f

Figure 36. Switching Frequency vs I_OUT

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Application Examples – continued

10 Load Compensation Function

The load regulation of the output voltage is worsened by the forward voltage at the secondary output diode V_Fand the

secondary total impedance ESR. It becomes possible to improve the load regulation of the output voltage by using the

load compensation function.

Incidentally, short the L_COMP pin to the GND to invalidate this function.

V_F

V_IN

I_S

N_P/N_S

V_OUT

I_RFB

R_FB

FB

SW

COMPARATOR

V_INTREF

ADAPTIVE

ON-TIME

CONTROLLER

DRIVER

I_P

V_{L_COMP}

Current

Monitor

I_{L_COMP}

R_INTCOMP

L_COMP

REF

R_REF

PGND

C_{L_COMP}

R_{L_COMP}

Figure 37. Block Diagram of Load Compensation

t_S

SW pin voltage

t_ON

I_{P_MAX}

I_{P_MIN}

Primary transformer current I_P

Primary transformer current I_S

Figure 38. Switching Operation of Continuous Mode

Output voltage

with load compensation

without load compensation

Gradient: R_VF+ ESR

Output Current

Figure 39. Image of Load Compensation

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10 Load Compensation Function – continued

10.1 Setting of Amount of Load Compensation

This function compensates the drop of output voltage V_OUTcorresponding to the average current of primary

transformer current I_P.

The amount of load compensation is adjusted by the external capacitor C_{L_COMP}and external resistor R_{L_COMP}at

the L_COMP pin.

The relational formula between the primary transformer current I_Pand the secondary transformer current I_Sis

shown below.

ꢀ_푃

[A]

ꢃ_푃=

× ꢃ_푆

ꢀ_푆

where:

ꢃ_푃is the primary transformer current.

ꢀ_푃is the number of winding at the primary transformer.

ꢀ_푆is the number of winding at the secondary transformer.

ꢃ_푆is the secondary transformer current.

10.1.1 Setting of External Resistor at L_COMP Pin R_{L_COMP}

It is necessary to calculate the L_COMP pin current I_{L_COMP}following the formula below for the setting of

the external resistor at the L_COMP pin R_{L_COMP}

.

푉

ꢊ_ꢙ푂푀푃

[A]

ꢃ_{ꢊ_ꢙ푂푀푃}

=

푅_{퐼푁푇ꢙ푂푀푃}

where:

ꢃ_{ꢊ_ꢙ푂푀푃}is the L_COMP pin current.

is the L_COMP pin voltage.

푉

ꢊ_ꢙ푂푀푃

푅_{퐼푁푇ꢙ푂푀푃}is the internal resistor at the L_COMP pin.

L_COMP pin voltage V_{L_COMP}mentioned in the formula above is the value which is converted the current

calculated by K x I_Pflowing from Current Monitor Block to the L_COMP pin by the external resistor at the

L_COMP pin R_{L_COMP}

.

L_COMP pin voltage V_{L_COMP}is converted to L_COMP pin current I_{L_COMP}by the internal resistor at

L_COMP pin R_INTCOMP, and it compensates the REF pin current.

It is necessary to meet V_{L_COMP}≤ 0.5 V because the operational voltage’s upper limit of V_{L_COMP}is restricted

by the internal circuit.

In addition, Connect the external capacitor at the L_COMP pin C_{L_COMP}because the rapid fluctuation of

I_{L_COMP}may make the V_{L_COMP}unstable. The reference value of C_{L_COMP}is 0.1 μF.

From the above, it is necessary that V_{L_COMP}meet the conditional expression below.

푉

= 퐾 × 푅_{ꢊ_ꢙ푂푀푃}× ꢃ_{푃_퐴ꢗꢆ}≤ 0.5

ꢊ_ꢙ푂푀푃

ꢃ_{푃_푀퐼푁}+ ꢃ_{푃_푀퐴푋}푡_푂푁

= 퐾 × 푅_{ꢊ_ꢙ푂푀푃}

×

≤ 0.5

[V]

ꢉ

푡_푆

where:

퐾 is the compressor magnification in Current Monitor Block.

푅_{ꢊ_ꢙ푂푀푃}is the external resistor at the L_COMP pin.

ꢃ_{푃_퐴ꢗꢆ}is the average value of primary transformer current I_P.

ꢃ_{푃_푀퐼푁}is the minimum value of primary transformer current I_P.

ꢃ_{푃_푀퐴푋}is the maximum value of primary transformer current I_P.

푡_푆is the switching cycle.

푡_푂푁is the on time.

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10.1.1 Setting of External Resistor at L_COMP Pin R_{L_COMP}– continued

By the load compensation function, the feedback current flowing at the external resistor between the REF

and AGND pins R_REFis reduced by I_{L_COMP}from its original current value. As the result, the primary flyback

voltage rises and the dropped output voltage V_OUTis compensated.

The output voltage V_OUTwhen the load compensation function operates is calculated by the formula below.

ꢀ_푆

ꢀ_푃

푉_ꢅꢆ퐹

푅_ꢅꢆ퐹

푉_푂푈푇

=

× ꢁ

+ ꢃ_{ꢊ_ꢙ푂푀푃}ꢂ × 푅_퐹퐵− 푉_퐹− ꢃ_{푆_퐴ꢗꢆ}× 퐸ꢄ푅

[V]

where:

푉_푂푈푇is the output voltage.

ꢀ_푆is the number of winding at the secondary transformer.

ꢀ_푃is the number of winding at the primary transformer.

푉_ꢅꢆ퐹is the REF pin voltage.

푅_ꢅꢆ퐹is the external resistor between the REF and AGND pins.

ꢃ_{ꢊ_ꢙ푂푀푃}is the L_COMP pin current.

푅_퐹퐵is the external resistor between the FB and SW pins.

푉_퐹is the forward voltage at the secondary output diode.

ꢃ_{푆_퐴ꢗꢆ}is the average value of the secondary transformer current I_S.

퐸ꢄ푅 is the secondary total impedance (secondary transformer winding resistance and board).

Reference: The output voltage V_OUTat normal operation

ꢀ_푆푅_퐹퐵

[V]

푉_푂푈푇

=

×

× 푉_ꢅꢆ퐹− 푉_퐹− ꢃ_{푆_퐴ꢗꢆ}× 퐸ꢄ푅

ꢀ_푃푅_ꢅꢆ퐹

According to the formula above, it is necessary to establish the next formula to remove the forward voltage

at the secondary output diode V_Fand the secondary total impedance ESR by the load compensation

function.

ꢀ_푆

ꢃ_{ꢊ_ꢙ푂푀푃}

×

× 푅_퐹퐵= 푉_퐹+ ꢃ_{푆_퐴ꢗꢆ}× 퐸ꢄ푅

ꢀ_푃

Next, calculate the R_{L_COMP}by making the linear approximation R_VFof the fluctuation of the forward voltage

at the secondary output diode V_Fcorresponding to the secondary transformer current I_S.

퐾 × 푅_{ꢊ_ꢙ푂푀푃}× ꢃ_{푃_퐴ꢗꢆ}ꢀ_푆

×

× 푅_퐹퐵= ꢃ_{푆_퐴ꢗꢆ}× 푅_ꢗ퐹+ ꢃ_{푆_퐴ꢗꢆ}× 퐸ꢄ푅

푅_{퐼푁푇ꢙ푂푀푃}

ꢀ_푃

2

퐾 × 푅_{ꢊ_ꢙ푂푀푃}

푅_{퐼푁푇ꢙ푂푀푃}

ꢀ_푆

(

)

× ꢁ ꢂ × 푅_퐹퐵= 푅_ꢗ퐹+ 퐸ꢄ푅

ꢀ_푃

From the above,

2

푅_ꢗ퐹+ 퐸ꢄ푅

퐾 × 푅_퐹퐵

ꢀ_푃

ꢀ_푆

푅_{ꢊ_ꢙ푂푀푃}= 푅_{퐼푁푇ꢙ푂푀푃}

×

× ꢁ

ꢂ

[Ω]

where:

퐾 is the compressor magnification in Current Monitor Block.

푅_{ꢊ_ꢙ푂푀푃}is the external resistor at the L_COMP pin.

ꢃ_{푃_퐴ꢗꢆ}is the average value of primary transformer current I_P.

푅_{퐼푁푇ꢙ푂푀푃}is the internal resistor at the L_COMP pin.

The values of R_VFand ESR depend on the operating environment such as use parts and mounting boards.

When setting the R_{L_COMP}, adjust it monitoring the output voltage V_OUTin the range of using load current

certainly.

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I/O Equivalence Circuit

1

AGND

2

SDX/EN

3

L_COMP

4

REF

Internal

Supply

Internal

Supply

REF

SDX/EN

AGND

6

AGND

L_COMP

AGND

SW

VIN

5

FB

7

8

PGND

VIN

SW

VIN

PGND

FB

AGND

PGND

GND

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Operational Notes

1.

2.

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.

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.

4.

Ground Voltage

Ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition.

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.

6.

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.

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.

9.

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.

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

B

E

C

Pin A

B

C

E

P

P⁺

N

P⁺

P

P⁺

N

Parasitic

Elements

Parasitic

Elements

P Substrate

GND GND

P Substrate

GND

Parasitic

Elements

Parasitic

Elements

N Region

close-by

Figure 40. 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 over current 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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Ordering Information

B D 7

J

2

0

1

x

-

L B x x

Package

Product Class

HFN: HSON8

LB for Industrial Applications

EFJ: HTSOP-J8

Packaging and Forming Specification

TR: Embossed Tape and Reel (HSON8)

E2: Embossed Tape and Reel (HTSOP-J8)

Lineup

Product Name

Part Number Marking

Orderable Part Number

Package

BD7J201HFN-LB

(Under Development)

D7J201

BD7J201HFN-LBTR

BD7J201EFJ-LBE2

HSON8

BD7J201EFJ-LB

HTSOP-J8

Marking Diagrams

HTSOP-J8 (TOP VIEW)

HSON8 (TOP VIEW)

Part Number Marking

LOT Number

Part Number Marking

LOT Number

D 7 J 2 0 1

D 7 J

2 0 1

Pin 1 Mark

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Physical Dimension and Packing Information

Package Name

HSON8

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Physical Dimension and Packing Information – continued

Package Name

HTSOP-J8

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Revision History

Date

Revision

001

Changes

New Release

08.Jul.2021

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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

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

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


型号：	BD7J201HFN-LB
厂家：	ROHM
描述：	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。变压器光电转换器
文件：	总39页 (文件大小：1397K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

BD7J201HFN-LB [ROHM]

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BD8/1.5/10-4S2