NCP1362ABDR2G_技术文档

Primary Side PWM

Controller for Low Power

Offline SMPS

NCP1362

The NCP1362 offers a new solution targeting output power levels

from a few watts up to 50 W in a universal−mains flyback application.

Thanks to a Novel Method this new controller saves the secondary

feedback circuitry for Constant Voltage and Constant Current

regulation, achieving excellent line and load regulation without

traditional opto coupler and TL431 voltage reference.

The NCP1362 operates in valley lockout quasi−resonant peak

current mode control mode at high load to provide high efficiency.

When the power on the secondary side starts to diminish, the

controller automatically adjusts the duty−cycle then at lower load the

controller enters in pulse frequency modulation at fixed peak current

with a valley switching detection. This technique allows keeping the

output regulation with tiny dummy load. Valley lockout at the first 4

valleys prevent valley jumping operation and then a valley switching

at lower load provides high efficiency.

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8

1

SOIC−8

CASE 751AZ

MARKING DIAGRAM

8

P1362yy

ALYW

G

1

Features

• Constant Voltage Primary−Side Regulation < 5%

• Constant Current Primary−Side Regulation < 5%

IC (Pb−Free)

P1362yy = Specific Device Code

(See page 28)

• LFF and BO Feature on a Dedicated Pin:

A

L

Y

W

G

= Assembly Location

= Wafer Lot

= Year

= Work Week

= Pb−Free Package

♦ BO Detection

♦ LFF for CC Regulation Improvement

• Quasi−Resonant with Valley Switching Operation

• Optimized Light Load Efficiency and Stand−by Performance

• Maximum Frequency Clamp (No Clamp, 80, 110 and 140 kHz)

• Cycle by Cycle Peak Current Limit

PINOUT DIAGRAM

• Output Voltage Under Voltage and Over Voltage Protection

1

(UVP or OVP)

Vs/ZCD

BO/LFF

VCC

GND

COMP

Fault

CS

• Secondary Diode or Winding Short−Circuit Protection

• Wide Operation V Range (up to 28 V)

CC

DRV

• Low Start−up Current

(Top View)

• CS & V /ZCD Pin Short and Open Protection

S

• Internal Temperature Shutdown

ORDERING INFORMATION

See detailed ordering and shipping information on page 28 of

this data sheet.

• Internal and Fixed Frequency Jittering for Better EMI Signature

• Dual Frozen Peak Current to Both Optimize Light Load Efficiency

(10% Load) and Stand−by Performance (No−load)

• Fault Input for Severe Fault Conditions, NTC Compatible for OTP

• These are Pb−Free Devices

Applications

• Low Power ac−dc Adapters for Routers and Set−Top Box

• Low Power ac−dc Adapters for Chargers

1

Publication Order Number:

July, 2020 − Rev. 2

NCP1362/D

NCP1362

2

0

Ac

Out

3

5

0

4

1

RTN_Out

NCP1362

VS/ZCD

1

2

3

4

8

7

6

5

BO/LFF

VCC

COMP

Fault

CS

GND

2

DRV

0

Figure 1. NCP1362 Typical Application Schematic for AC Input Voltage

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2

NCP1362

Line

FeedForward

POReset

UVLO

I_%VBO

V_dd

V_cc

VCC and Logic

Management of

double hiccup

V_{CC (Reset)}

V_{CC (OVP)}

DbleHiccup

POReset

EN_UVP

Double_Hiccup_ends

BO/LFF

SS

Reset

Soft Start

BO_EN

BO_DIS

Blanking

V_{BO (EN)}

V_{BO (ON)}

V_HL(on)

QR multi−mode

Valley lockout &

Valley Switching

BO_OK

&

VCO management

Sampled V^out

Vs /

ZCD

Zero Crossing &

Signal Sampling

SS

FB_CC

Control Law

FB

CC

&

High_Line

Control

Primary Peak

Current Control

V_{ref_CC}

FB_CV

UVLO

S

Q

R

V

V_CC(OVP)

cc

OVP_Cmp

4 clk

Counter

UVP

SCP

Clamp

OVP

126% V_{ref_CV 1}

DRV

GND

UVP_Cmp

EN_UVP

OTA

Comp

S

R

UVP

DbleHiccup

Q

POReset

V_UVP

V_{ref_CV1}

Peak current

Control

V_DD

I_CS

1/Kcomp

FB Reset

V_fault(OVP)

V_DD

V_Jitter

I_{CS_EN}

Fault

LEB1

CS

Max_Ipk reset

OCP

Timer

Reset Timer

Count

OCP

V_{Fault (OTP)}

V_ILIM

POReset

Fault

DbleHiccup

R

Q

S

Reset

Counter

SS_end

LEB2

V_{fault (EN )}

4 clk

SCP

Counter

V_{CS(Stop )}

Note:

CS pin Fault

OVP: Over Voltage Protection

UVP: Under Voltage Protection

OCP: Over Current Protection

SCP: Short Circuit Protection

CS pin Open (V_CS> 1.2

V) & Short (V_CS< 50

mV) detection is

I_{CS_EN}

activated at each startup

t

_LEB1> t_LEB2

Figure 2. Functional Block Diagram

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NCP1362

Table 1. PIN FUNCTION DESCRIPTION

Name

Function

1

V /ZCD

s

Connected to the auxiliary winding; this pin senses the voltage output for the primary regula-

tion and detects the core reset event for the Quasi−Resonant mode of operation.

2

3

Comp

Fault

This is the error amplifier output. The network connected between this pin and the ground

adjusts the regulation loop bandwidth.

The controller enters in fault mode if the voltage of this pin is pulled above or below the fault

thresholds. A precise pullup current allows direct interface with an NTC thermistor. Fault de-

tection triggers a latch.

4

5

6

7

8

CS

This pin monitors the primary peak current.

DRV

GND

The driver’s output to an external MOSFET gate.

Ground reference.

V

CC

This pin is connected to an external auxiliary voltage and supplies the controller.

BO/LFF

Detects too low input voltage conditions (Brown−Out). Also voltage pin level is used for build-

ing Line FeedForward compensation for improving Constant Current regulation tolerance.

Table 2. MAXIMUM RATINGS (Note 1)

Symbol

Rating

Value

Unit

V

Maximum Power Supply voltage, V pin, continuous voltage

−0.3 to 28

Internally limited

V

mA

CC(MAX)

CC

I

Maximum current for V pin

CC

DV /Dt

Maximum slew rate on V pin during start−up phase

+0.4

120

V/ms

CC

E

as

Single Pulse Avalanche Rating

mJ

V

Maximum voltage on low power pins (except pins DRV and VCC)

Current range for low power pins (except pins DRV and VCC)

−0.3, 5.5

−2, +5

V

mA

MAX

I

V

Maximum driver pin voltage, DRV pin, continuous voltage

Maximum current for DRV pin

−0.3, V

(Note 2)

V

mA

DRV(MAX)

DRV

I

−300, +500

R

Thermal Resistance Junction−to−Air, 2.0 oz Printed Circuit Copper Clad

Maximum Junction Temperature

190

150

°C/W

°C

kV

V

θ

J−A

T

J(MAX)

Operating Temperature Range

−40 to +125

−60 to +150

2

Storage Temperature Range

Human Body Model ESD Capability per JEDEC JESD22−A114F

Machine Model ESD Capability (All pins except DRV) per JEDEC JESD22−A115C

Charged−Device Model ESD Capability per JEDEC JESD22−C101E

200

500

V

Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality

should not be assumed, damage may occur and reliability may be affected.

1. This device contains latch−up protection and exceeds 100 mA per JEDEC Standard JESD78.

2. V

is the DRV clamp voltage V

when V is higher than V

. V

is V otherwise.

DRV

DRV(high)

CC

DRV(high) DRV CC

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NCP1362

Table 3. ELECTRICAL CHARACTERISTICS

(V = 12 V, For typical values T = 25°C, for min/max values T = −40°C to +125°C, Max T = 150°C, unless otherwise noted)

CC

j

Characteristics

SUPPLY SECTION AND V MANAGEMENT

Condition

Symbol

Min

Typ

Max

Unit

CC

V

Level at which Driving Pulses

V

increasing

V

16

6.0

−

18

6.5

20

7.0

−

V

CC

CC(on)

are Authorized

V

CC

Level at which Driving Pulses

V

CC

decreasing

CC(off)

are Stopped

Internal Latch/Logic Reset

Level

V

6.25

CC(reset)

Internal Autorecovery Reset Level

(Note 4)

V

0.6

−

V

CC(reset_auto)

Hysteresis above V

for Fast

V

−

0.2

CC(off)

CC(latch_hyst)

Hiccup in Latch Mode

Hysteresis below V

before Latch Reset

V

0.15

0.30

0.50

V

CC(off)

CC(reset_hyst)

Over Voltage Protection

Over Voltage threshold

V

24

–

26

28

V

CC(OVP)

Start−up Supply Current,

Controller Disabled or Latched

V

CC

< V

& V

CC

I

3.6

5.5

mA

CC(on)

CC(start)

increasing from 0 V

Internal IC Consumption, Steady

State

F

= 65 kHz

I

–

1.6

2.3

mA

SW

L

CC(steady)

C = 1 nF

Internal IC Consumption in

Minimum Frequency Clamp

VCO mode, F

= f

,

I

CC(VCO)

mA

SW

VCO(min)

V

= GND

Comp

f

= 1 kHz

= 200 Hz

–

325

210

430

370

VCO(min)

C = 1 nF

L

Internal IC Consumption in Fault

Autorecovery mode

Latch mode

I

–

2.0

1.0

2.2

1.2

mA

CC(auto)

Mode (after a fault when V

CC

decreasing to V

)

CC(off)

Internal IC Consumption in Fault

Mode (after a fault when V

I

CC(latch)

CC

decreasing to V

)

CC(off)

CURRENT COMPARATOR

Current Sense Voltage

Threshold

V

= V

,

V

0.76

250

–

0.8

320

50

0.84

380

110

90

V

ns

ms

V

Comp

CS

Comp(max)

ILIM

increasing

Cycle by Cycle Leading Edge

Blanking Duration

t

LEB1

Cycle by Cycle Current Sense

Propagation Delay

V

CS

> (V

+ 100 mV) to

t

ILIM

DRV turn−off

Timer Delay before Detecting an

Overload Condition

When CS pin w V

(Note 3)

T

OCP

50

1.08

−

70

ILIM

Threshold for Immediate Fault

Protection Activation

V

1.2

120

250

1.32

−

CS(stop)

Leading Edge Blanking

t

ns

mV

LEB2

Duration for V

CS(stop)

Maximum Peak Current Level at

which VCO Takes Over or Frozen

Peak Current

V

CS

increasing

V

−

CS(VCO)

0.6 V < V

< 1.9 V

Comp

(other possible options on

demand)

Minimum Peak Current Level

V

increasing

Comp

V

−

65

−

mV

CS

CS(STB)

< 0.2 V

(other possible options on

demand)

Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product

performance may not be indicated by the Electrical Characteristics if operated under different conditions.

3. The timer can be reset if there are 4 DRV cycles without overload or short circuit conditions.

4. Guaranteed by Design.

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NCP1362

Table 3. ELECTRICAL CHARACTERISTICS

(V = 12 V, For typical values T = 25°C, for min/max values T = −40°C to +125°C, Max T = 150°C, unless otherwise noted)

CC

j

Characteristics

Condition

Symbol

Min

Typ

Max

Unit

REGULATION BLOCK

Internal Voltage Reference for

Constant Current Regulation

T = 25°C

−40°C < T < 125°C

V

0.98

0.97

1.00

1.02

1.03

V

J

ref_CC

J

Internal Voltage Reference for

Constant Voltage Regulation

T = 25°C

V

2.450

2.425

2.500

2.550

2.575

J

ref_CV1

−40°C < T < 125°C

J

Error Amplifier Current

Capability

I

EA

−

40

−

mA

Error Amplifier Gain

G

150

200

250

mS

EA

Error Amplifier Output Voltage

Internal offset on Comp pin

V

−

4.9

0

1.1

−

V

Comp(max)

Comp(min)

V

Comp(offset)

Internal Current Setpoint

Division Ratio

K

Comp

−

4

−

–

Valley Thresholds

V

st

nd

rd

th

Transition from 1 to 2 Valley

V

Comp

V

Comp

V

Comp

V

Comp

V

Comp

V

Comp

V

Comp

V

Comp

decreasing

increasing

V

−

2.50

2.30

2.10

1.90

2.50

2.70

2.90

3.10

−

H2D

H3D

H4D

nd

Transition from 2 to 3 Valley

V

rd

Transition from 3 to 4 Valley

V

th

Transition from 4 Valley to VCO

V

HVCOD

V

HVCOI

th

Transition from VCO to 4 Valley

th

rd

nd

st

Transition from 4 to 3 Valley

V

H4I

H3I

H2I

rd

Transition from 3 to 2 Valley

nd

Transition from 2 to 1 Valley

Minimal Difference between any

Two Valleys

V

increasing or V

DV

H

176

−

mV

Comp

decreasing

Internal Dead Time Generation for

VCO Mode

Entering in VCO when

T

−

1.15

−

ms

DT(start)

V

is decreasing and

Comp

crosses V

HVCOD

Internal Dead Time Generation for

VCO Mode

Leaving VCO mode when

is increasing and

T

−

650

−

ns

DT(ends)

V

Comp

crosses V

HVCOI

Internal Dead Time Generation for

VCO Mode

When in VCO mode –

T

DT

ms

1−kHz option

V

Comp

V

Comp

V

Comp

V

Comp

= 1.8 V

= 1.4 V

= 0.9 V

< 0.2 V

−

1.6

11

110

1000

−

Minimum Switching Frequency in

VCO Mode

V

= GND

Option 1

Option 2

f

kHz

ms

Comp

VCO(MIN)

0.8

1.0

1.2

0.16

0.200

0.24

(other possible options on

demand)

Maximum Switching Frequency

f

MAX

Option 1

Option 2

Option 3

Option 4

−

No Clamp

80

−

88

121

153

72

99

110

140

127

Maximum On Time

T

32

36

40

on(max)

DEMAGNETIZATION INPUT – ZERO VOLTAGE DETECTION CIRCUIT and VOLTAGE SENSE

V

ZCD

V

ZCD

Threshold Voltage

Hysteresis

V

ZCD

V

ZCD

decreasing

increasing

V

ZCD(TH)

25

15

45

30

70

45

mV

V

ZCD(HYS)

Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product

performance may not be indicated by the Electrical Characteristics if operated under different conditions.

3. The timer can be reset if there are 4 DRV cycles without overload or short circuit conditions.

4. Guaranteed by Design.

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NCP1362

Table 3. ELECTRICAL CHARACTERISTICS

(V = 12 V, For typical values T = 25°C, for min/max values T = −40°C to +125°C, Max T = 150°C, unless otherwise noted)

CC

j

Characteristics

Condition

Symbol

Min

Typ

Max

Unit

DEMAGNETIZATION INPUT – ZERO VOLTAGE DETECTION CIRCUIT and VOLTAGE SENSE

Threshold Voltage for Output

Short Circuit or Aux. Winding

Short Circuit Detection

After t

ZCD

if

V

30

50

75

mV

BLANK_ZCD

ZCD(short)

V

< V

ZCD(short)

Delay after On−time that the

S

When V

> 1.7 V

t

−

0.750

0.350

−

ms

Comp

short_ZCD

V /ZCD is still Pulled to Ground

< 1.7 V

Blanking Delay after On−time

When V

> 1.7 V

< 1.7 V

t

−

1.450

0.750

−

Comp

BLANK_ZCD

(V /ZCD Pin is Disconnected from

S

the Internal Circuitry)

Timeout after Last

t

4.0

−

4.5

−

5.0

0.1

−

ms

mA

ns

out

Demagnetization Transition

Input Leakage Current

V

> V

V

= 4 V,

I

ZCD

CC

CC(on) ZCD

DRV is low

Delay from Valley Detection to

DRV Low

t

−

290

ZCD_delay

DRIVE OUTPUT − GATE DRIVE

Drive resistance

DRV Sink − V = 8 V

R

SNK

R

SRC

−

8

10

−

W

CC

DRV Source − V = 8 V

CC

Rise time

C

= 1 nF, from 10% to 90%

= 1 nF, from 90% to 10%

t

−

45

30

−

85

65

−

ns

V

DRV

r

Fall time

t

f

DRV Low voltage

V

CC

= V

+ 0.2 V, C

V

6.0

CC(off)

DRV

DRV(low)

= 220 pF, R

= 33 kW

DRV

DRV High voltage

V

= V

− 0.2 V, C

= 33 kW

V

−

12.0

13.0

V

CC

CC(OVP)

DRV

DRV(high)

= 220 pF, R

DRV

SOFT START

Internal Fixed Soft Start Duration

Current Sense peak current

t

SS

3

4

5

ms

rising from V

to V

CS(VCO)

ILIM

JITTERING

Frequency of the Jittering CS Pin

Source Current

Option 1

(other possible options on

demand)

f

1.2

40

1.5

60

1.8

80

kHz

mV

jitter

Peak Jitter Voltage Added to

PWM Comparator

Option 1

(other possible options on

demand) (Note 3)

V

jittter

BROWN−OUT & LINE FEED FORWARD

Brown−out Function is Disabled

V

BO(en)

80

100

120

mV

st

below this Level (before the 1

DRV pulse only)

Pull−down Current Source on BO

I

−

300

0.82

0.70

50

−

nA

V

BO

Pin for Open Detection

Brown−out Level at which the

Controller Starts Pulsing

V

0.74

0.63

−

0.90

0.77

−

BO(on)

Brown−out Level at which the

Controller Stops Pulsing

V

BO(off)

Brown−out Filter Time

t

ms

BO

Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product

performance may not be indicated by the Electrical Characteristics if operated under different conditions.

3. The timer can be reset if there are 4 DRV cycles without overload or short circuit conditions.

4. Guaranteed by Design.

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7

NCP1362

Table 3. ELECTRICAL CHARACTERISTICS

(V = 12 V, For typical values T = 25°C, for min/max values T = −40°C to +125°C, Max T = 150°C, unless otherwise noted)

CC

j

Characteristics

Condition

Symbol

Min

Typ

Max

Unit

BROWN−OUT & LINE FEED FORWARD

Line Feed Forward Compensation

Gain

K

LFF

16

20

24

mA/

V

FAULT PROTECTION

Controller Thermal Shutdown

Thermal Shutdown Hysteresis

Fault Level Detection for OVP

Device switching

(F ∼ 65 kHz) – T rising

T

−

150

120

3.15

−

°C

V

SHTDN(on)

SW

j

Device switching

(F ∼ 65 kHz) − T falling

SHTDN(off)

SW

j

Internal sampled V

increasing

V

2.95

3.35

out

OVP

V

= V

+ 26%

OVP

ref_CV1

Fault Level Detection for UVP →

Double Hiccup Autorecovery

Internal sampled V

decreasing

1.40

1.50

1.60

V

out

UVP

(UVP detection is disabled during

T

)

EN_UVP

Blanking Time for UVP Detection

Starting after the Soft start

T

−

36

60

−

ms

EN_UVP

Pull−up Current Source on CS Pin

for Open or Short Circuit Detec-

tion

When V > V

I

CS

mA

CS

CS_min

CS Pin Open Detection

CS pin open

(Note 4)

V

−

1.2

−

V

CS(open)

CS Pin Short Detection

V

−

50

3

75

−

mV

ms

CS_min

CS_short

Fault(EN)

CS pin Short Detection Timer

Fault Pin is Disabled below this

T

V

80

100

120

mV

st

Level (before the 1 DRV pulse

only)

Overvoltage Protection (OVP)

Threshold

V

increasing

V

2.79

3.00

0.40

3.21

V

Fault

Fault(OVP)

Overtemperature Protection

(OTP) Threshold

decreasing

0.390

0.415

Fault(OTP)

OTP Pull−up Current Source

= 0 V

T = 25°C

mA

I

42.5

42.9

45.0

47.5

46.5

j

Fault(OTP)

T = 110°C

I

Fault(OTP_110)

Fault Input Clamp Voltage

Fault Filter Time

I

= 0 mA (V

= open)

V

1.10

2.2

−

1.35

2.7

2

1.60

3.2

−

V

Fault

Fault(clamp)0

I

= 1 mA

Fault(clamp)1

t

ms

−

Fault(filter)

Number of Drive Cycle before

Latch Confirmation

V

= V

CS(stop)

,

t

latch(count)

−

4

−

Comp

Comp(max)

> V

CS

or Internal rebuilded

> V

V

out

OVP

Fault

ZCD(short)

or 0.40 V < V

< 3.00 V

or V

Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product

performance may not be indicated by the Electrical Characteristics if operated under different conditions.

3. The timer can be reset if there are 4 DRV cycles without overload or short circuit conditions.

4. Guaranteed by Design.

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8

NCP1362

TYPICAL CHARACTERISTICS

18.09

18.07

18.05

18.03

18.01

17.99

17.97

17.95

6.59

6.585

6.58

6.575

6.57

6.565

6.56

−50

−25

0

25

50

75

100

125

−50

−25

0

25

50

75

100

125

TEMPERATURE (5C)

Figure 3. V_CC(on)vs. Junction Temperature

TEMPERATURE (5C)

Figure 4. V_CC(off)vs. Junction Temperature

5.2

6.292

4.7

4.2

3.7

3.2

2.7

2.2

6.287

6.282

6.277

6.272

6.267

6.262

−50

−25

0

25

50

75

100

−50

−25

0

25

50

75

100

125

TEMPERATURE (5C)

Figure 5. V_CC(reset)vs. Junction Temperature

TEMPERATURE (5C)

Figure 6. I_CC(start)vs. Junction Temperature

316.5

0.808

316

315.5

315

0.806

0.804

0.802

0.8

314.5

314

313.5

313

0.798

0.796

0.794

312.5

312

−50

−25

0

25

50

75

100

−50

−25

0

25

50

75

100

125

TEMPERATURE (5C)

Figure 7. V_ILIMvs. Junction Temperature

Figure 8. t_LEB1vs. Junction Temperature

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NCP1362

TYPICAL CHARACTERISTICS (Continued)

1.209

1.207

1.205

1.203

1.201

1.199

1.197

1.195

1.193

1.191

74

69

64

59

54

−50

−25

0

25

50

75

100

125

−50

−25

0

25

50

75

100

125

TEMPERATURE (5C)

Figure 9. t_ILIMvs. Junction Temperature

Figure 10. V_CS(stop)vs. Junction Temperature

70

254

253

252

251

250

249

248

247

246

69.5

69

68.5

68

67.5

67

−50

−25

0

25

50

75

100

125

−50

−25

0

25

50

75

100

TEMPERATURE (5C)

Figure 11. V_CC(VCO)vs. Junction Temperature

Figure 12. V_CS(STB)vs. Junction Temperature

1.013

1.011

1.009

1.007

1.005

1.003

1.001

0.999

0.997

0.995

2.51

2.505

2.5

2.495

2.49

2.485

2.48

−50

−25

0

25

50

75

100

125

−50

−25

0

25

50

75

100

TEMPERATURE (5C)

Figure 13. V_{ref CC}vs. Junction Temperature

Figure 14. V_{ref CV1}vs. Junction Temperature

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10

NCP1362

TYPICAL CHARACTERISTICS (Continued)

48

47.5

47

57.7

57.2

56.7

56.2

55.7

55.2

54.7

54.2

53.7

53.2

46.5

46

45.5

45

44.5

44

43.5

43

−50

−25

0

25

50

75

100

125

−50

−25

0

25

50

75

100

125

TEMPERATURE (5C)

Figure 15. V_ZCD(TH)vs. Junction Temperature

Figure 16. V_ZCD(short)vs. Junction Temperature

1.56

1.555

1.55

3.17

3.16

3.15

3.14

3.13

3.12

1.545

1.54

−50

−25

0

25

50

75

100

125

-50

-25

0

25

50

75

100

125

TEMPERATURE (5C)

Figure 17. V_OVPvs. Junction Temperature

Figure 18. V_UVPvs. Junction Temperature

0.84

0.839

0.838

0.837

0.836

0.835

36.32

36.27

36.22

36.17

36.12

36.07

36.02

−50

−25

0

25

50

75

100

125

−50

−25

0

25

50

75

100

125

TEMPERATURE (5C)

Figure 19. T_{EN UVP}vs. Junction Temperature

Figure 20. V_BO(on)vs. Junction Temperature

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11

NCP1362

TYPICAL CHARACTERISTICS (Continued)

0.695

0.693

0.691

0.689

0.687

0.685

21.63

21.61

21.59

21.57

21.55

21.53

21.51

21.49

21.47

−50

−25

0

25

50

75

100

125

−50

−25

0

25

50

75

100

125

TEMPERATURE (5C)

Figure 21. V_BO(off)vs. Junction Temperature

Figure 22. K_LFFvs. Junction Temperature

106.5

3.011

3.006

3.001

2.996

2.991

2.986

2.981

2.976

2.971

2.966

105.5

104.5

103.5

102.5

101.5

100.5

-50

-25

0

25

50

75

100

125

−50

−25

0

25

50

75

100

125

TEMPERATURE (5C)

Figure 23. V_Fault(EN)vs. Junction Temperature

Figure 24. V_Fault(OVP)vs. Junction Temperature

0.407

45.3

0.406

0.405

0.404

0.403

0.402

0.401

0.4

45.2

45.1

45

44.9

44.8

44.7

44.6

44.5

44.4

0.399

0.398

−50

−25

0

25

50

75

100

125

−50

−25

0

25

50

75

100

125

TEMPERATURE (5C)

Figure 25. V_Fault(OTP)vs. Junction Temperature

Figure 26. I_Fault(OTP)vs. Junction Temperature

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12

NCP1362

Table 4. FAULT MODES

Event

Timer Protection

Next Device Status

Release to Normal Operation Mode

Overcurrent

OCP Timer

Double Hiccup

− Resume to normal operation: if 4 pulses from

FB Reset & then Reset timer

V

> V

CS

ILIM

− Resume operation after Double Hiccup

Winding Short

> V

4 Consecutive Pulses

Double Hiccup

Resume operation after Double Hiccup

V

with V > V

CS

CS(stop)

CS CS(stop)

CS Pin Fault:

Short & Open

Before Start−up

Immediate

Resume operation after Double Hiccup

ZCD Short

4 Consecutive Pulses

V

< V

BLANK_ZCD

after

ZCD

ZCD(short)

t

time

Low Supply

< V

10−ms Timer

Simple Hiccup

Double Hiccup

Resume operation after Simple Hiccup

Resume operation after Double Hiccup

V

CC

CC(off)

High Supply

> V

V

CC

CC(ovp)

Internal V

out

4 Consecutive Pulses

out

OVP: V > 126% V

ref_CV1

Internal V

out

4 Consecutive Pulses

Double Hiccup

Resume operation after Double Hiccup

out

ref_CV1

UVP: V < 60% V

,

when V is Decreasing Only

out

Internal TSD

10−ms Timer

Resume operation after Double Hiccup &

T < (T

)

SHTDN(off)

NOTE: Latching off protection available upon request.

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13

NCP1362

APPLICATION INFORMATION

The NCP1362 is a flyback power supply controller

providing a means to implement primary side constant−

current regulation and secondary side constant−voltage

regulation. NCP1362 implements a current−mode

architecture operating in quasi−resonant mode. The

controller prevents valley−jumping instability and steadily

locks out in a selected valley as the power demand goes

down. As long as the controller is able to detect a valley, the

new cycle or the following drive remains in a valley. Thanks

to a dedicated valley detection circuitry operating at any line

and load conditions, the power supply efficiency will always

be optimized. In order to prevent any high switching

frequency two frequency clamp options are available.

• Soft−Start: 4−ms internal fixed soft start guarantees

a peak current starting from zero to its nominal value

with smooth transition in order to prevent any

overstress on the power components at each startup.

• Cycle−by−Cycle Peak Current Limit: If the max peak

current reaches the V

level, the over current

ILIM

protection timer is enabled and starts counting. If the

overload lasts T delay, then the fault is detected and

OCP

the controller stops immediately driving the power

MOSFET. The controller enters in a double hiccup

mode before autorecovering with a new startup cycle.

• V Over Voltage Protection: If the V voltage

CC

reaches the V

threshold the controller enters in

CC(OVP)

• Quasi−Resonance Current−mode Operation:

implementing quasi−resonance operation in peak

current−mode control optimizes the efficiency by

switching in the valley of the MOSFET drain−source

voltage. Thanks to a proprietary circuitry, the controller

locks−out in a selected valley and remains locked until

the input voltage significantly changes. Only the four

first valleys could be locked out. When the load current

diminishes, valley switching mode of operation is kept

but without valley lock−out. Valley−switching

operation across the entire input/output conditions

brings efficiency improvement and lets the designer

build higher−density converters.

fault mode. Thus it stops driving pulse on DRV pin.

The part enters in double hiccup mode before resuming

operation.

• Winding Short−Circuit Protection: An additional

comparator senses the CS signal and stops the

controller if V reaches V

+ 50% (after a reduced

CS

ILIM

LEB: t

). Short circuit protection is enabled only if

LEB2

4 consecutive pulses reach SCP level. This small

counter prevents any false triggering of short circuit

protection during surge test for instance. This fault is

detected and operations will be resumed like in a case

of V Over Voltage Protection.

CC

• V Over Voltage Protection: if the internally−built

out

• Frequency Clamp: As the frequency is not fixed and

output voltage becomes higher than V

level

OVP

dependent on the line, load and transformer

(V

ref_CV1

+ 26%) a fault is detected. This fault is

specifications, it is important to prevent switching

frequency runaway for applications requiring maximum

switching frequencies up to 90 kHz or 130 kHz. Three

frequency clamp options at 80 kHz, 110 kHz or

140 kHz are available for this purpose. In case

frequency clamp is not needed, a specific version of the

NCP1362 exists in which the clamp is deactivated.

detected and operations are resumed like in the

Over Voltage Protection case.

V

CC

• V Under Voltage Protection: After each circuit power

out

on sequence, V UVP detection is enabled only after

out

the startup timer T . This timer ensures that the

EN_UVP

power supply is able to fuel the output capacitor before

checking the output voltage in on target. After this

startup blanking time, UVP detection is enabled and

monitors the Output voltage level. When the power

supply is running in constant−current mode and when

• Primary Side Constant Current Regulation: NCP1362

controls and regulates the output current at a constant

level regardless of the input and output voltage

conditions. This function offers tight over power

protection by estimating and limiting the maximum

output current from the primary side, without any

particular sensor.

the output voltage falls below V

level, the controller

UVP

stops sending drive pulses and enters a double hiccup

mode before resuming operations.

• V /ZCD Pin Short Protection: at the beginning of each

S

V

OUT

off−time period, the V /ZCD pin is tested to check

S

CV Mode

whether it is shorted or left open. In case a fault is

detected, the controller enters in a double hiccup mode

before resuming operations.

V

NOM

CC Mode

• EMI Jittering: a low−frequency triangular voltage

waveform is added to the CS pin. This helps spreading

out energy in conducted noise analysis. Jittering is

disabled in frequency foldback mode.

I

OUT

0

I

• Frequency Foldback: In frequency foldback mode,

NOM

the system reduces the switching frequency by adding

Figure 27. Constant−Voltage & Constant−Current

th

some dead−time after the 4 valley is detected.

Mode

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14

NCP1362

The controller will still run in valley switching mode

even when the FF is enabled.

• Line FeedForward: By monitoring the voltage

available on BO pin it is possible to create a line

feedforward compensation in order to improve the

constant current accuracy.

• Temperature Shutdown: if the junction temperature

reaches the T

level, the controller stop driving the

SHTDN

power MOSFET until the junction temperature

decreases to T , then the operation is resumed

after a double hiccup mode.

• Fault Input: the NCP1362 includes a dedicated fault

input. It can be used to sense an overvoltage condition

and latch off the controller by pulling up the pin above

SHTDN(off)

• Brown−Out Detection: BO pin monitors bulk voltage

level via resistive divider and thus assures that the

application is working only for designed bulk voltages.

When BO pin is grounded before start−up

the upper fault threshold, V

, typically 3.0 V.

Fault(OVP)

The controller is also disabled if the Fault pin voltage,

, is pulled below the lower fault threshold,

V

Fault

V

, typically 0.4 V. The lower threshold is

Fault(OTP)

(V < V

dynamic frequency clamp are disabled.

), Brown−Out, Line FeedForward and

normally used for detecting an overtemperature fault

(by the means of an NTC). If this pin is grounded

before start−up, then its associated feature are disabled.

BO

BO(en)

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15

NCP1362

DETAILED APPLICATION INFORMATION

Start−up Sequence

The NCP1362 start−up voltage is made purposely high to

permit large energy storage in a small V capacitor value.

This helps operate with a small start−up current which,

start−up time. To further reduce the standby power, the

start−up current of the controller is extremely low (see

I

). The start−up resistor can therefore be connected

CC

CC(start)

to the bulk capacitor or directly to the mains input voltage to

further reduce the power dissipation.

together with a small V capacitor, will not hamper the

CC

R

Start−up

Input

Mains

V

CC

C

bulk

Aux.

Winding

C

VCC

Figure 28. The Startup Resistor can be Connected to the Input Mains for Further Power Dissipation Reduction

Ǹ

The first step starts with the calculation of the needed V

V_ac,rms

2

CC

* V_CC(on)

capacitor which will supply the controller when it operates

until the auxiliary winding takes over. Experience shows

p

I_CVcc,min

+

(eq. 3)

R_start−up

that this time t can be between 5 ms and 20 ms. If we

1

To make sure this current is always greater than 16 mA,

consider we need at least an energy reservoir for a t time of

1

then the minimum value for R

can be extracted:

start−up

10 ms, the V capacitor must be larger than:

CC

Ǹ

85 2

p

I_CC t₁

* 18

1.6 m 10 m

C_VCC

w

w 1.4 mF (eq. 1)

R_start−up

v

v 1.17 MW

(eq. 4)

18 * 6.5

V

_CC(on)* V_CC(off)

17.3 m

This calculation is purely theoretical, considering

a constant charging current. In reality, the take over time can

be shorter (or longer!) and it can lead to a reduction of the

Let us select a 1.5 mF capacitor at first and experiments in

the laboratory will let us know if we were too optimistic for

the time t . The V capacitor being known, we can now

1

CC

V

capacitor. Thus, a decrease in charging current and an

evaluate the charging current we need to bring the V

CC

increase of the start−up resistor can be experimentally

tested, for the benefit of standby power. Laboratory

experiments on the prototype are thus mandatory to fine tune

the converter. If we chose the 1.2−MW resistor as suggested

by Eq. 4, the dissipated power at high line amounts to:

voltage from 0 V to the V

to be selected to ensure a start−up at the lowest mains (85 V

rms) to be less than 3 s (2.5 s for design margin):

of the IC. This current has

CC(on)

V_CC(on) C_Vcc

18 1.5 m

I_charge

w

w 11 mA (eq. 2)

t_start−up

2.5

ǒ_{230 2}Ǔ²

2

Ǹ

V_ac,peak

If we account for the I

= 6.3 mA (maximum) that

CC(start)

P_{Rstart−up,max}

[

[ 24 mW (eq. 5)

will flow inside the controller, then the total charging current

delivered by the start−up resistor must be 17.3 mA. If we

connect the start−up network to the mains (half−wave

connection then), we know that the average current flowing

4 R_start−up

4 1.1 M

Primary Side Regulation: Constant Current Operation

Figure 29 portrays idealized primary and secondary

transformer currents of a flyback converter operating in

Discontinuous Conduction Mode (DCM).

into this start−up resistor will be the smallest when V

CC

reaches the V

of the controller:

CC(on)

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16

NCP1362

I_p(t)

I_{p, pk}

time

I_{p, pk}

N_ps

I_s(t), I_OUT

I_{s, pk}

=

I

_OUT= <I_s(t)>

time

t_on

t_demag

t_sw

Figure 29. Primary and Secondary Transformer Current Waveforms

When the primary power MOSFET is turned on, the

primary current is illustrated by the green curve of

Figure 29. When the power MOSFET is turned off the

primary side current drops to zero and the current into the

secondary winding immediately rises to its peak value equal

to the primary peak current divided by the primary to

secondary turns ratio. This is an ideal situation in which the

leakage inductance action is neglected.

As the controller monitors the primary peak current via

the sense resistor and due to the internal current setpoint

divider (K

) between the CS pin and the internal

comp

feedback information, the output current could be written as

follow:

V_{ref_CC}

I_out

+

(eq. 10)

8N_ps R_sense

The output current value is set by choosing the sense

resistor value:

The output current delivered to the load is equal to the

average value of the secondary winding current, thus we can

write:

V_{ref_CC}

R_sense

+

(eq. 11)

8N_ps I_out

I_p,pk

t_demag

I_out+ 〈i_sec(t)〉 +

(eq. 6)

t_sw

2N_ps

Primary Side Regulation: Constant Voltage Operation

In primary side constant voltage regulation, the output

voltage is sensed via the auxiliary winding. During the

on−time period, the energy is stored in the transformer gap.

During the off−time this energy stored in the transformer is

delivered to the secondary and auxiliary windings.

As illustrated by Figure 30, when the transformer energy

is delivered to the secondary, the auxiliary voltage sums the

output voltage scaled by the auxiliary and secondary turns

ratios and the secondary forward diode voltage. This

secondary forward diode voltage could be split in two

elements: the first part is the forward voltage of the diode

Where:

• t is the switching period

SW

• t

is the demagnetizing time of the transformer

demag

• N is the secondary to primary turns ratio, where

PS

N & N are respectively the transformer primary and

P

S

secondary turns:

N_s

N_p

N_ps

+

(eq. 7)

• I is the magnetizing peak current sensed across the

p,pk

sense resistor on CS pin:

(V ), and the second is related to the dynamic resistance of

f

V_CS

the diode multiplied by secondary current (R y I (t)).

D

S

I_p,pk

+

(eq. 8)

R_sense

Where this second term will be dependant of the load and

line conditions.

Internal constant current regulation block is building the

constant current feedback information as follow:

t_SW

V_{FB_CC}+ V_{ref_CC}

(eq. 9)

t_demag

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17

NCP1362

N_pa

N_ps

N_pa

N_ps

V_AUX(t)

V_out

+V I

( )

V_out

f

sec

0V

time

N

p

a

*V_IN

N_ps

I_{p, pk}

I_p(t)

time

I_s(t), I_OUT

I_{p, pk}

N_ps

I_{s, pk}

=

I

_OUT= <I_s(t)>

time

t_on

t_demag

t_sw

Figure 30. Typical Idealized Waveforms of a Flyback Transformer in DCM

To reach an accurate primary−side constant−voltage

regulation, the controller detects the end of the

demagnetization time and precisely samples output voltage

level seen on the auxiliary winding. As this moment

coincides with the secondary−side current equal to zero, the

diode forward voltage drop becomes independent from the

loading conditions.

Figure 31 illustrates how the constant voltage feedback

has been built. The auxiliary winding voltage must be scaled

down via the resistor divider to V

level before

ref_CV1

building the constant voltage feedback error.

R_s2

V_{ref_CV1}

+

V_aux

(eq. 14)

R

_s1) R_s2

By inserting Eg. 12 into Eq. 14 we obtain the following

equation:

Thus when the secondary current I (t) reaches zero

s

ampere, the auxiliary is sensed:

R_s2

N_pa

V_{ref_CV1}

+

V_out

(eq. 15)

V_aux+ V_out

(eq. 12)

R

_s1) R_s2

N_ps

Once the sampled V is applied to the negative input

out

Where: N is the auxiliary to primary turns ratio, where N

pa

p

terminal of the operational transconductance amplifier

(OTA) and compared to the internal voltage reference an

adequate voltage feedback is built. The OTA output being

pinned out, it is possible to compensate the converter and

adjust step load response to what the project requires.

& N are respectively the primary and auxiliary turns:

a

N_a

N_pa

+

(eq. 13)

N_p

Vs /ZCD

Sampled V_out

Comp

Zero Crossing &

Signal Sampling

R _s1

OTA

t _{Blank_ZCD}

t_{Short_ZCD}

R _s2

R1

C1

V _{ref_CV1}

C2

FB_CV

Figure 31. Constant Voltage Feedback Arrangement

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18

NCP1362

When the power MOSFET is released at the end of the on

1. An internal switch grounds the V /ZCD pin during

S

time, because of the transformer leakage inductance and the

drain lumped capacitance some voltage ringing appears on

the drain node. These voltage ringings are also visible on the

auxiliary winding and could cheat the controller detection

circuits. To avoid false detection operations, two protecting

t

+ t

in order to protect the pin from

on

short_ZCD

negative voltage.

2. In order to prevent any misdetection from the zero

crossing block an internal switch disconnects

V /ZCD pin until t

time ends.

S

blank_ZCD

circuits have been implemented on the V /ZCD pin (see

S

Figure 32):

Figure 32. V_S/ZCD Pin Waveforms

Constant−Current and Constant−Voltage Overall

Regulation

is detected by monitoring the transformer auxiliary winding

voltage. Turning on the power switch once the transformer

is demagnetized (or reset) reduces turn−on switching losses.

Once the transformer is demagnetized, the drain voltage

starts ringing at a frequency determined by the transformer

magnetizing inductance and the drain lumped capacitance,

eventually settling at the input voltage value. A QR

controller takes advantage of the drain voltage ringing and

turns on the power switch at the drain voltage minimum or

“valley” to reduce turn−on switching losses and

electromagnetic interference (EMI).

As already presented in the two previous paragraphs, the

controller integrates two different feedback loops: the first

one deals with the constant−current regulation scheme while

the second one builds the constant−voltage regulation. One

of the two feedback paths sets the primary peak current into

the transformer. During startup phase, however, the peak

current is controlled by the softstart.

Zero Current Detection

The NCP1362 integrates a quasi−resonant (QR) flyback

controller. The power switch turn−off of a QR converter is

determined by the peak current whose value depends on the

feedback loop. The switch restart event is determined by the

transformer demagnetization end. The demagnetization end

As sketched by Figure 33, a valley is detected once the

ZCD pin voltage falls below the QR flyback

demagnetization threshold, V

, typically 45 mV.

ZCD(TH)

The controller will switch once the valley is detected or

increment the valley counter depending on FB voltage.

ZCD

R

s1

QR multi−mode

Valley lockout &

Valley Switching &

VCO management

R

s2

V_ZCD(TH)

S

R

DRV

(Internal)

Q

Blanking

T_{blank_ZCD}

Timeout − t_out

Figure 33. Valley Lockout Detection Circuitry Internal Schematic

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19

NCP1362

Timeout

Valley LockOut (VLO) and Frequency Foldback (FF)

The ZCD block actually detects falling edges of the

The operating frequency of a traditional Quasi−Resonant

(QR) flyback controller is inversely proportional to the

system load. In other words, a load reduction increases the

operating frequency. A maximum frequency clamp can be

useful to limit the operating frequency range. However,

auxiliary winding voltage applied to the ZCD pin. At

start−up or during other transient phases, the ZCD

comparator may be unable to detect such an event. Also, in

the case of extremely damped oscillations, the system may

not succeed in detecting all the valleys required by valley

lockout operation (VLO, see next section). In this condition,

the NCP1362 ensures continued operation by incorporating

a maximum timeout period that resets itself when a

demagnetization phase is properly detected. In case the

ringing signal is too weak or heavily damped, the timeout

signal supersedes the ZCD signal for the valley counter.

Figure 33 shows the timeout period generator circuit

when associated with

a

valley−switching circuit,

instabilities can arise because of the discrete frequency

jumps. The controller tends to hesitate between two valleys

and audible noise can be generated

To avoid this issue, the NCP1362 incorporates

a proprietary valley lockout circuitry which prevents

so−called valley jumping. Once a valley is selected, the

controller stays locked in this valley until the input level or

output power changes significantly. This technique extends

QR operation over a wider output power range while

maintaining good efficiency and naturally limiting the

maximum operating frequency.

schematic. The timeout duration, t , is set to 4.5 ms (typ.).

out

In VLO operation, the timeout occurrences are counted

instead of valleys when the drain−source voltage

oscillations are too damped to be detected. For instance,

assume the circuit must turn on at the third valley and the

ZCD ringing only enables the detection of:

st

th

The operating valley (from 1 to 4 valley) is determined

by the internal feedback level (Internal FB node on

Figure 2). As FB voltage level decreases or increases, the

valley comparators toggle one after another to select the

proper valley.

• Valleys #1 to #2: the circuit generates a DRV pulse t

out

(steady−state timeout delay) after valley #2 detection.

• Valley #1: the timeout delay must run twice so that the

The decimal counter increases each time a valley is detected.

The activation of an “n” valley comparator blanks the “n−1”

circuit generates a DRV pulse 9 ms (2 × t typ.) after

out

valley #1 detection.

or “n+1” valley comparator output depending if V

FB

decreases or increases, respectively. Figure 34 shows

a typical frequency characteristic obtained at low line in

a 10−W charger.

F_swvs. P_out, when P_outis æ

Fsw versus Pout at VINlow

_outis

F_swvs. P_out, when P

5

1.0 × 10

7.5 × 10

5.0 × 10

2.5 × 10

3^rd

2^nd

1^st

5^th

4^th

VLO mode

Frequency

Foldback

Mode

4

3^rd

2^nd

1^st

5^th

4^th

Frequency Foldback

Mode

VLO mode

0

1

2

3

4

5

Pout (W)

6

7

8

9

10

Figure 34. Typical Switching Frequency vs. Output Power Relationship in a 10−W Adapter

When an “n” valley is asserted by the valley selection

circuitry, the controller locks in this valley until the FB

voltage decreases to the lower threshold (“n+1” valley

activates) or increases to the “n valley threshold” + 600 mV

(“n−1” valley activates). The regulation loop adjusts the

peak current to deliver the necessary output power at the

valley operating point. Each valley selection comparator

features a 600−mV hysteresis that helps stabilize operation

despite the FB voltage swing produced by the regulation

loop.

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20

NCP1362

Table 5. VALLEY FB THRESHOLD ON CONSTANT VOLTAGE REGULATION

FB Falling

FB Rising

st

nd

th

1

to 2 Valley

2.5 V

2.3 V

2.1 V

1.9 V

FF Mode to 4

2.5 V

2.7 V

2.9 V

3.1 V

nd

rd

th

rd

2

to 3 Valley

4

to 3 Valley

th

rd

nd

3

4

to 4 Valley

3

to 2 Valley

th

nd

st

to FF Mode

2

to 1 Valley

Frequency Foldback (FF)

efficiency benefit inherent to the QR operation, the

controller turns on again with the next valley after the dead

time has ended. As a result, the controller will still run in

valley switching mode even when the FF is enabled. This

dead−time increases when the FB voltage decays. There is

no discontinuity when the system transitions from VLO to

FF and the frequency smoothly reduces as FB goes below

1.9 V.

As the output current decreases (FB voltage decreases),

the valleys are incremented from 1 to 4. In case the fourth

valley is reached, the FB voltage further decreases below

1.9 V and the controller enters the frequency foldback mode

(FF). The current setpoint being internally forced to remain

above V

(setpoint corresponding to V

), the

CS(VCO)

Comp

controller regulates the power delivery by modulating the

switching frequency. When an output current increase

causes FB to exceed the 2.5−V FF upper threshold (600−mV

hysteresis), the circuit recovers VLO operation.

In frequency foldback mode, the system reduces the

switching frequency by adding some dead−time after the 4

The dead−time is selected to generate a 1.15−ms

dead−time when V

is decreasing and crossing V

Comp

HVCOD

(1.9 V typ.). At this moment, it can linearly go down to the

minimal frequency limit. The generated dead−time is 650 ns

th

when V

is increasing and crossing V

(2.5 V typ.).

Comp

HVCOI

valley is detected. However, in order to keep the high

Operating

Mode

VCO

th

4

Valley

Max Peak

Current

Pout Increasing

rd

3

Clamped to

V

CS

= V

ILIM

nd

2

Valley

Pout decreasing

st

1

V

Comp

1.9

2.1

2.3

2.5

2.7

2.9

3.1

4.3 V

Figure 35. Valley Lockout Threshold

Stand−by Mode

The NCP1362 implements a peak control mode when the

load is closed to 0. From frozen peak current in FF mode

(250 mV here), the maximum voltage threshold on CS pin

is reduced to 65 mV when the Comp voltage crossed

0.260 V. If the 65−mV threshold is reached in 200 ns for

instance due to small primary inductance, the minimum ON

time will be defined by the 320−ns leading edge blanking

duration and the propagation delay (50 ns) so 370 ns

typically.

An high frozen peak current is necessary to have good

efficiency at 10% of the load. On the other hand, the standby

performance will not be optimized. Indeed, in no load

condition, the switching frequency has to be high enough to

have a good transient response and then keep the output

voltage within the limits. If we set a minimum switching

frequency, the only parameter that can be adjusted to deliver

less power is the primary peak current as shown in Eq. 16.

2

1

2

P_out

+

I_p,pk f_SW h

(eq. 16)

www.onsemi.com

21

NCP1362

Figure 36. Frequency Foldback and Standby Mode Behavior with 1−kHz Minimum Frequency Clamp,

V

_CS(VCO)= 250 mV and V_CS(STB)= 65 mV

Current Setpoint

• A minimum setpoint is forced that equals V

CS(VCO)

< 1.9 V

As explained in this operating description, the current

setpoint is affected by several functions. Figure 37

summarizes these interactions. As shown by this figure, the

current setpoint is the output of the control law divided by

(250 mV, typ.) when 0.760 V < V

comp

• A second minimum setpoint is forced that equals

(65 mV, typ.) when V < 0.260 V

V

CS(STB)

comp

• The peak current is linearly reduced between this two

previous frozen peak current (V & V

K

comp

(4 typ.). This current setpoint is clamped by the

)

CS(STB)

CS(VCO)

soft−start slope as long as the peak current requested by the

FB_CV or FB_CC level are higher. The softstart clamp is

starting from the frozen peak current (V

(0.8 V typ.) within 4 ms (t ).

However, this internal FB value is also limited by the

following functions:

• In addition, a second OCP comparator ensures that in

any case the current setpoint is limited to V . This

ILIM

) to V

CS(VCO)

ILIM

ensures the MOSFET current setpoint remains limited

ss

to V

in a fault condition.

ILIM

Peak Current

Control

Comp

SoftStart

FB_CV

FB_CC

Control Law

For

Primary Peak

Current Control

PWM Comp

1/K_comp

FB Reset

PWM

Latch

Reset

CS

OCP

Comp

LEB1

Max_Ipk reset

R_CS

R_sense

C_CS

OCP

Timer

Count

OCP

V_ILIM

Reset Timer

POReset

DbleHiccup

Reset

Counter

Short Circuit

Comp

LEB2

4 clk

SCP

Counter

V_CS(Stop)

Figure 37. Current Setpoint

www.onsemi.com

22

NCP1362

A 2^ndOver−Current Comparator for Abnormal

Overcurrent Fault Detection

A severe fault like a winding short−circuit can cause the

switch current to increase very rapidly during the on−time.

consecutive abnormal overcurrent faults cause the

controller to enter in auto−recovery mode. The count to 4

provides noise immunity during surge testing. The counter

is reset each time a DRV pulse occurs without activating the

fault overcurrent comparator or after double hiccup

sequence or if the power supply is unplugged with a new

startup sequence after the initial power on reset.

The current sense signal significantly exceeds V

. But,

ILIM

because the current sense signal is blanked by the LEB

circuit during the switch turn on, the power switch current

can abnormally increase, possibly causing system damages.

The NCP1362 protects against this dangerous mode by

adding an additional comparator for abnormal overcurrent

fault detection or short−circuit condition. The current sense

signal is blanked with a shorter LEB duration, t

typically 120 ns, before applying it to the short−circuit

comparator. The voltage threshold of this extra comparator,

Jittering Capability

In order to help meet the EMI requirements, the NCP1362

features the jittering capability to average the spectrum rays

over the frequency range. The function consists of adding a

voltage ripple to the peak current information in order to

change the operation frequency. The peak−to−peak

amplitude of the ripple waveform is 60 mV at 1.5 kHz.

,

LEB2

V

, is typically 1.2 V, set 50% higher than V

. This

CS(stop)

ILIM

is to avoid interference with normal operation. Four

V_DD

V_CS

V_Jitter

Time

V_jitter

To CS

Comparator

F

jitter

CS

R_LFF

R_Sense

Figure 38. Frequency Jittering

Brown−out Function

Fault Mode and Protection

The Brown−out circuitry offers a way to protect the

application from operation under too low input voltage. The

controller allows the output pulses, only if the input voltage

• CS Pin: at each startup, a 60−mA (I ) current source

CS

pulls up the CS pin to disable the controller if the pin is

left open or grounded. Then the controller enters in

a double hiccup mode.

is above V

level. An extra comparator detects if the BO

BO(on)

pin is grounded for disabling the BO feature. The internal

circuitry, depicted by Figure 39, offers a way to observe the

bulk voltage.

• V /ZCD Pin: after sending the first drive pulse the

S

controller checks the correct wiring of V /ZCD pin:

S

after the ZCD blanking time, if there is an open or short

conditions, the controller enters in double hiccup mode.

V_bulk

BO/LFF

R_upper

Sample

& Hold

1 ms

Filter

BO_EN

C_BO

R_lower

BO_DIS

V_BO(EN)

Start−up

I_BO

50 ms

Filter

I_{BO_en}

BO_OK

1 ms Filter

STB mode

V_BO(ON)

Figure 39. Internal Brown−out Configuration

www.onsemi.com

23

NCP1362

The following figures illustrate the behavior of the

Brown−out pin:

V_CC

V_CC(on)

V_CC(off)

Time

V_BO

V_BO(on)

V_BO(off)

Time

DRV

Figure 40. Brown−out Input Functionality − V_CC< V_CC(on)

V_CC

V_CC(on)

V_CC(off)

Time

V_BO

V_BO(on)

V_BO(off)

Time

DRV

Figure 41. Brown−out Input Functionality − V_CC> V_CC(on)

www.onsemi.com

24

NCP1362

0.8

Calculation of the resistors divider:

R_lower+ 10 M

+ 71.2 kW

(eq. 18)

113 * 0.8

V_BO(on)

R_lower+ R_upper

(eq. 17)

With a selected 71.5−kW normalized 1% resistor for

, it is now possible to calculate all the bulk levels

versus the internal voltage references of the BO pin.

V

_bulk* V_BO(on)

R

lower

If the power supply must start pulsing at V = 80 V rms

in

(V

= 113 V) with a selected R

= 10 MW:

bulk

upper

Table 6. EXAMPLE OF BROWN−OUT LEVELS WITH R_lower= 71.5 kW & R_upper= 10 MW

Parameters

BO Pin Level (V)

Bulk Level (V)

14.0

V

in

Level (V rms)

V

BO(en)

V

BO(on)

V

BO(off)

0.1

0.8

0.7

10

112.7

79.7

69.7

98.6

Line Feed Forward

These resistances have to be adjusted after measurements

according to the bulk capacitor ripple and also the capacitor

connected on the BO pin.

There is the possibility for the customer to disable the BO

protection if this function is not needed. To implement this

Sensing input line voltage via BO pin allows to generate

a current to CS pin directly proportional to the input line

level in order to compensate the over current on CS pin due

to the propagation delay. The resistor in series with the CS

pin adjusts the compensation level.

feature, the BO pin voltage is checked when V crosses

CC

V

CC(on)

threshold. If the BO voltage is still below V

BO(EN)

after the V , the BO function is disabled.

CC(on)

V_DD

Rupper

BO/LFF

+

V

−

V _bulk

CS

k

_LFF*V

I_LFF

R_LFF

R_Sense

V _BO(on)

Rlower

C_BO

Figure 42. Internal Line Feed Forward Configuration

I

LFF

52 mA

K

LFF

= 20 mA/V

0 mA

V

BO(on)

3.4 V

Figure 43. Transfer Function of the Line Feed Forward

www.onsemi.com

25

NCP1362

Calculation of the resistor (R ) for compensating the

Numerical application yields:

LFF

overpower.

Let’s assume the power supply needs to have

a compensation of 45 mV (V ) at 265 V rms (V ).

First, it is needed to calculate what is the BO level

corresponding to the line voltage (here 265 V rms) of the

desired compensation level:

71.5 k

71.5 k ) 10 M

45 mV

Ǹ

(eq. 21)

(eq. 22)

V_{BO_LFF}+ 265 2

+ 2.66 V

+ 1.2 kW

LFF

in

R_LFF

+

mA

( )

2.66 V * 0.8 V

20

V

The offset voltage can affect the standby power

performance by reducing the peak current setpoint in

light−load conditions. For this reason, it is desirable to

cancel its action as soon as the VCO mode occurs. A typical

curve variation is shown in Figure 44. At low power, below

the VCO mode starting point, the LFF current is linearly

absorbed and no offset is created through the CS pin when

the Comp pin voltage is below 1.6 V. When feedback

increases again and reaches the 1.6−V threshold, OPP starts

to build up and reaches its full value at 1.9 V.

R_lower

V_{BO_LFF}+ V_bulk

(eq. 19)

R_lower) R_upper

Then, the resistor value to be inserted between the CS

resistor and CS pin could be calculated, as illustrated here

after:

V_LFF

R_LFF

+

(eq. 20)

ǒ_V

Ǔ

K_LFF

_{BO_LFF}* V_BO(on)

max

V

Comp

V

Comp

Decreases

Increases

1.9 V

1.6 V

t

100

0

t

Figure 44. The LFF Current is Applied when the Comp Voltage Exceeds 1.6 V. It is 0 below it

Fault Input

This function is typically used to detect a V or auxiliary

CC

The NCP1362 includes a dedicated fault input accessible

via the Fault pin. Figure 45 shows the architecture of the

Fault input. The controller can be latched by pulling up the

winding overvoltage by means of a Zener diode generally in

series with a small resistor (see Figure 45).

Neglecting the resistor voltage drop, the OVP threshold is

then:

pin above the upper fault threshold, V

, typically

Fault(OVP)

3.0 V. An active clamp prevents the Fault pin voltage from

reaching the V if the pin is open. To reach the upper

threshold, the external pull−up current has to be higher than

the pull−down capability of the clamp.

V_AUX(OVP)+ V_Z) V_Fault(OVP)

(eq. 24)

Fault(OVP)

where V is the Zener diode voltage.

Z

The controller can also be latched off if the Fault pin

voltage, V , is pulled below the lower fault threshold,

, typically 0.4 V. This capability is normally used

for detecting an overtemperature fault by means of an NTC

V

_Fault(OVP)* V_Fault(clamp)

3 V * 1.35 V

1.35 kW

Fault

+

,

R_Fault(clamp)

V

Fault(OTP)

(eq. 23)

i.e. approximately 1.2 mA.

www.onsemi.com

26

NCP1362

thermistor. A pull up current source I

, (typically

that is 8.9 kW typically.

Fault(OTP)

45 mA) generates a voltage drop across the thermistor. The

resistance of the NTC thermistor decreases at higher

temperatures resulting in a lower voltage across the

thermistor. The controller detects a fault once the thermistor

The controller bias current is reduced during power up by

disabling most of the circuit blocks including I

.

Fault(OTP)

This current source is enabled once V reaches V

CC

CC(on)

A bypass capacitor is usually connected between the Fault

and GND pins. It will take some time for V to reach its

voltage drops below V

.

Fault(OTP)

Fault

The circuit detects an overtemperature situation when:

steady state value once I

is enabled. Therefore, the

Fault(OTP)

lower fault comparator (i.e. overtemperature detection) is

R_NTC I_Fault(OVP)+ V_Fault(OVP)

(eq. 25)

ignored during soft−start.

Hence, the OTP protection trips when

V_Fault(OVP)

R_NTC

+

(eq. 26)

I_Fault(OTP)

Vaux

2 ms

Blanking

V_DD

V_Fault(OVP)

V_Z

Fault

NTC

2 ms

Blanking

R_fault(clamp)

Up Counter

Fault

4

Reset

Clock

SS_end

V_Fault(OTP)

S

Latch

OVP/OTP gone

Q

R

BO_DIS

Sample

& Hold

V_CC(Reset)

BO_EN

1 ms

Filter

Fault pin

disabled

BO_NOK

V_Fault(EN)

Start−up

Figure 45. Fault Detection Schematic

As a matter of fact, the controller operates normally while

the Fault pin voltage is maintained within the upper and

lower fault thresholds. Upper and lower fault detector have

blanking delays to prevent noise from triggering them. Both

OVP and OTP comparator output are validated only if its

high−state duration lasts a minimum of 2 ms. Below this

value, the event is ignored. Then, a counter ensures that

OVP/OTP events occurred for 4 successive drive clock

pulses before actually latching the part.

feature, the fault pin voltage is checked when V crosses

CC

V

CC(on)

threshold. If the voltage is still below V

Fault(EN)

after the V , the fault pin is disabled.

CC(on)

Thermal Shutdown

An internal thermal shutdown circuit monitors the

junction temperature of controller die of the IC. The

controller is disabled if its junction temperature exceeds the

thermal shutdown threshold (T

). A continuous V

SHDN

CC

hiccup is initiated after a thermal shutdown fault is detected.

The controller restarts at the next V once the IC

When the part is latched−off, the drive is immediately

CC(on)

turned off and V goes in endless hiccup mode. The power

CC

temperature drops below T

reduced by the thermal

SHDN

supply needs to be un−plugged to reset the part as a result of

a BO_NOK (BO fault condition) if Brown−Out feature is

shutdown hysteresis (T ). The thermal shutdown is

SHDN(off)

also cleared if V drops below V

sequences commences at the next V

. A new power up

once all the faults

CC

CC(reset)

enabled otherwise V

.

CC(Reset)

CC(on)

There is the possibility for the customer to disable the fault

pin protection if this function is not needed or to reduce the

IC consumption in stand−by mode. To implement this

are removed.

www.onsemi.com

27

NCP1362

Table 7. ORDERING TABLE OPTION

OPN #

NCP1362_ _

Minimum Switching

Frequency in VCO Mode (kHz)

Maximum Switching Frequency (kHz)

Jittering Frequency

0.2

1

x

No

x

80

110

140

Enable

Disable

NCP1362AADR2G

NCP1362ABDR2G

x

Table 8. ORDERING INFORMATION

Device

†

Device Marking

P1362AA

Package

Shipping

NCP1362AADR2G

SOIC−8

(Pb−Free)

2500 / Tape & Reel

NCP1362ABDR2G

P1362AB

†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging

Specifications Brochure, BRD8011/D.

www.onsemi.com

28

MECHANICAL CASE OUTLINE

PACKAGE DIMENSIONS

SOIC−8

CASE 751AZ

ISSUE B

8

1

DATE 18 MAY 2015

SCALE 1:1

NOTES 4&5

0.10 C D

NOTES:

1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994.

2. CONTROLLING DIMENSION: MILLIMETERS.

3. DIMENSION b DOES NOT INCLUDE DAMBAR PROTRUSION.

ALLOWABLE PROTRUSION SHALL BE 0.004 mm IN EXCESS OF

MAXIMUM MATERIAL CONDITION.

455CHAMFER

D

h

NOTE 6

D

A

2X

H

8

5

4. DIMENSION D DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS

OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS

SHALL NOT EXCEED 0.006 mm PER SIDE. DIMENSION E1 DOES

NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. INTERLEAD

FLASH OR PROTRUSION SHALL NOT EXCEED 0.010 mm PER SIDE.

5. THE PACKAGE TOP MAY BE SMALLER THAN THE PACKAGE BOT

TOM. DIMENSIONS D AND E1 ARE DETERMINED AT THE OUTER

MOST EXTREMES OF THE PLASTIC BODY AT DATUM H.

6. DIMENSIONS A AND B ARE TO BE DETERMINED AT DATUM H.

7. DIMENSIONS b AND c APPLY TO THE FLAT SECTION OF THE LEAD

BETWEEN 0.10 TO 0.25 FROM THE LEAD TIP.

0.10 C D

NOTES 4&5

E

E1

L2

SEATING

PLANE

L

C

DETAIL A

1

4

0.20 C D

8X b

8. A1 IS DEFINED AS THE VERTICAL DISTANCE FROM THE SEATING

PLANE TO THE LOWEST POINT ON THE PACKAGE BODY.

B

M

0.25

C A-B D

NOTE 6

MILLIMETERS

TOP VIEW

NOTES 3&7

DIM MIN

MAX

1.75

0.25

---

DETAIL A

A

A1

A2

b

---

0.10

1.25

0.31

0.10

A2

^NOc^{TE 7}

0.10 C

0.51

0.25

c

D

4.90 BSC

A

E

6.00 BSC

3.90 BSC

1.27 BSC

e

END VIEW

SEATING

PLANE

E1

e

C

A1

SIDE VIEW

NOTE 8

h

0.25

0.40

0.41

1.27

L

0.25 BSC

L2

RECOMMENDED

SOLDERING FOOTPRINT*

GENERIC

MARKING DIAGRAM*

8X

0.76

8

XXXXX

ALYWX

8X

1.52

G

1

7.00

XXXXX = Specific Device Code

A

L

= Assembly Location

= Wafer Lot

Y

W

G

= Year

= Work Week

= Pb−Free Package

1

1.27

PITCH

DIMENSIONS: MILLIMETERS

*This information is generic. Please refer

to device data sheet for actual part

marking. Pb−Free indicator, “G”, may

or not be present.

*For additional information on our Pb−Free strategy and soldering

details, please download the ON Semiconductor Soldering and

Mounting Techniques Reference Manual, SOLDERRM/D.

Electronic versions are uncontrolled except when accessed directly from the Document Repository.

Printed versions are uncontrolled except when stamped “CONTROLLED COPY” in red.

DOCUMENT NUMBER:

DESCRIPTION:

98AON34918E

SOIC−8

PAGE 1 OF 1

ON Semiconductor and

are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries.

ON Semiconductor reserves the right to make changes without further notice to any products herein. ON Semiconductor makes no warranty, representation or guarantee regarding

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1


型号：	NCP1362ABDR2G
厂家：	ONSEMI
描述：	Primary Side PWM Controller for Low Power Offline SMPS
文件：	总30页 (文件大小：639K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

NCP1362ABDR2G [ONSEMI]

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