MC44603PG_技术文档

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Fixed Frequency, Variable Frequency,

Standby Mode

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MARKING

The MC44603A is an enhanced high performance controller that is

specifically designed for off−line and dc−to−dc converter applications.

This device has the unique ability of automatically changing operating

modes if the converter output is overloaded, unloaded, or shorted,

offering the designer additional protection for increased system

reliability. The MC44603A has several distinguishing features when

compared to conventional SMPS controllers. These features consist of

a foldback facility for overload protection, a standby mode when the

converter output is slightly loaded, a demagnetization detection for

reduced switching stresses on transistor and diodes, and a high current

totem pole output ideally suited for driving a power MOSFET. It can

also be used for driving a bipolar transistor in low power converters

(< 150 W). It is optimized to operate in discontinuous mode but can

also operate in continuous mode. Its advanced design allows use in

current mode or voltage mode control applications.

DIAGRAMS

MC44603AP

AWLYYWW

16

1

PDIP−16

P SUFFIX

CASE 648

MC44603ADW

AWLYYWW

16

1

SOIC−16

DW SUFFIX

CASE 751G

Features

• Pb−Free Package is Available*

Current or Voltage Mode Controller

A

= Assembly Location

= Wafer Lot

= Year

• Operation up to 250 kHz Output Switching Frequency

• Inherent Feed Forward Compensation

WL

YY

WW

= Work Week

• Latching PWM for Cycle−by−Cycle Current Limiting

• Oscillator with Precise Frequency Control

High Flexibility

PIN CONNECTIONS

• Externally Programmable Reference Current

• Secondary or Primary Sensing7

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• Synchronization Facility

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• High Current Totem Pole Output

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• Undervoltage Lockout with Hysteresis

Safety/Protection Features

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• Overvoltage Protection Against Open Current and Open Voltage Loop

• Protection Against Short Circuit on Oscillator Pin

• Fully Programmable Foldback

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• Soft−Start Feature

• Accurate Maximum Duty Cycle Setting

• Demagnetization (Zero Current Detection) Protection

• Internally Trimmed Reference

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ORDERING INFORMATION

See detailed ordering and shipping information in the package

dimensions section on page 378 of this data sheet.

• Enhanced Output Drive

GreenLine Controller: Low Power Consumption in Standby Mode

• Low Startup and Operating Current

• Fully Programmable Standby Mode

• Controlled Frequency Reduction in Standby Mode

• Low dV/dT for Low EMI Radiations

*For additional information on our Pb−Free strategy

and soldering details, please download the

ON Semiconductor Soldering and Mounting

Techniques Reference Manual, SOLDERRM/D.

©

Semiconductor Components Industries, LLC, 2004

358

Publication Order Number:

February, 2004 − Rev. 3

MC44603A/D

MC44603A

MAXIMUM RATINGS

Rating

Symbol

(I + I )

Value

30

Unit

mA

V

Total Power Supply and Zener Current

CC

Z

Supply Voltage with Respect to Ground (Pin 4)

V

18

C

V

CC

Output Current (Note 1)

Source

mA

I

−750

750

O(Source)

Sink

I

O(Sink)

Output Energy (Capacitive Load per Cycle)

W

5.0

ꢀJ

V

R

F Stby

, C , Soft−Start, R , R

Inputs

V

in

V

in

−0.3 to 5.5

T

ref

P Stby

Foldback Input, Current Sense Input,

E/A Output, Voltage Feedback Input,

Overvoltage Protection, Synchronization Input

V

−0.3 to

V

+ 0.3

CC

Synchronization Input

High State Voltage

V

+ 0.3

V

IH

CC

Low State Reverse Current

Demagnetization Detection Input Current

Source

V

−20

mA

IL

I

−4.0

10

demag−ib (Source)

Sink

I

demag−ib (Sink)

Error Amplifier Output Sink Current

Power Dissipation and Thermal Characteristics

P Suffix, Dual−In−Line, Case 648

I

20

mA

E/A (Sink)

Maximum Power Dissipation at T = 85°C

P

0.6

W

A

D

Thermal Resistance, Junction−to−Air

R

ꢁ

JA

100

°C/W

DW Suffix, Surface Mount, Case 751G

Maximum Power Dissipation at T = 85°C

P

0.45

145

150

W

°C/W

°C

A

D

Thermal Resistance, Junction−to−Air

Operating Junction Temperature

R

ꢁ

JA

T

J

Operating Ambient Temperature

T

A

−25 to +85

°C

1. Maximum package power dissipation limits must be observed.

2. ESD data available upon request.

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359

MC44603A

ELECTRICAL CHARACTERISTICS (V and V = 12 V, (Note 3), R = 10 kꢂ, C = 820 pF, for typical values T =

CC

C

ref

T

A

25°C, for min/max values T = −25° to +85°C (Note 4), unless otherwise noted.)

A

Characteristic

OUTPUT SECTION

Symbol

Min

Typ

Max

Unit

Output Voltage (Note 5)

V

Low State (I

= 100 mA)

= 500 mA)

V

−

1.0

1.4

1.2

2.0

Sink

OL

High State (I

= 200 mA)

= 500 mA)

V

−

1.5

2.0

2.7

Source

OH

Output Voltage During Initialization Phase

V

OL

V

= 0 to 1.0 V, I

= 1.0 to 5.0 V, I

= 5.0 to 13 V, I

= 10 ꢀA

−

0.1

1.0

CC

Sink

= 100 ꢀA

Sink

= 1.0 mA

Output Voltage Rising Edge Slew−Rate (C = 1.0 nF, T = 25°C)

dVo/dT

−

300

−

V/ꢀs

L

J

Output Voltage Falling Edge Slew−Rate (C = 1.0 nF, T = 25°C)

−300

L

J

ERROR AMPLIFIER SECTION

Voltage Feedback Input (V

= 2.5 V)

V

2.42

−2.0

65

2.5

−0.6

70

2.58

−

V

E/A out

FB

Input Bias Current (V = 2.5 V)

I

ꢀA

dB

FB

FB−ib

Open Loop Voltage Gain (V

= 2.0 to 4.0 V)

A

VOL

−

E/A out

ERROR AMPLIFIER SECTION (continued)

Unity Gain Bandwidth

BW

MHz

T = 25°C

−

4.0

−

J

T = −25° to +85°C

J

5.5

10

Voltage Feedback Input Line Regulation (V = 10 to 15 V)

V

−10

−

mV

mA

CC

FBline−reg

Output Current

Sink (V

= 1.5 V, V = 2.7 V)

I

Sink

2.0

12

−

E/A out

FB

T = −25° to +85°C

A

Source (V

= 5.0 V, V = 2.3 V)

I

Source

−2.0

−

−0.2

E/A out

FB

T = −25° to +85°C

A

Output Voltage Swing

V

High State (I

Low State (I

= 0.5 mA, V = 2.3 V)

V

OH

5.5

6.5

1.0

7.5

1.1

E/A out (source)

FB

= 0.33 mA, V = 2.7 V)

V

OL

−

E/A out (sink)

FB

REFERENCE SECTION

Reference Output Voltage (V = 10 to 15 V)

V

2.4

−500

−40

2.5

−

2.6

V

CC

ref

Reference Current Range (I = V /R , R = 5.0 k to 25 kꢂ)

I

−100

ꢀA

mV

ref

ref ref

ref

Reference Voltage Over I Range

ꢃ

V

−

40

ref

OSCILLATOR AND SYNCHRONIZATION SECTION

Frequency

f

kHz

%/V

OSC

T = 0° to +70°C

A

44.5

44

−

48

−

51.5

52

−

T = −25° to +85°C

A

Frequency Change with Voltage (V = 10 to 15 V)

ꢃ

f

/

ꢃ

V

0.05

CC

OSC

3. Adjust V above the startup threshold before setting to 12 V.

CC

4. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.

5. V must be greater than 5.0 V.

C

6. Standby is disabled for V

< 25 mV typical.

R P Stby

7. If not used, Synchronization input must be connected to Ground.

8. Synchronization Pulse Width must be shorter than t = 1/f

.

OSC

9. This function can be inhibited by connecting Pin 8 to GND. This allows a continuous current mode operation.

10.This function can be inhibited by connecting Pin 5 to V

.

CC

11. The MC44603A can be shut down by connecting the Soft−Start pin (Pin 11) to Ground.

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360

MC44603A

ELECTRICAL CHARACTERISTICS (continued) (V and V = 12 V, (Note 3), R = 10 kꢂ, C = 820 pF, for typical values T =

CC

C

ref

T

A

25°C, for min/max values T = −25° to +85°C (Note 4), unless otherwise noted.)

A

Characteristic

Symbol

Min

Typ

Max

Unit

OSCILLATOR AND SYNCHRONIZATION SECTION

Frequency Change with Temperature (T = −25° to +85°C)

ꢃ f

/ꢃ T

OSC

−

0.05

1.8

−

%/°C

A

Oscillator Voltage Swing (Peak−to−Peak)

V

1.65

1.95

V

OSC(pp)

Ratio Charge Current/Reference Current

I

/I

−

charge ref

T = 0° to +70°C (V = 2.0 V)

0.375

0.37

78

0.4

−

0.425

0.43

82

A

CT

T = −25° to +85°C

A

Fixed Maximum Duty Cycle = I

/(I

+ I

charge

)

D

80

%

discharge discharge

Ratio Standby Discharge Current versus I

(Note 6)

I

/

disch−Stby

−

R F Stby

T = 0° to +70°C

I

0.46

0.43

2.4

0.53

−

0.6

0.63

2.6

A

R F Stby

T = −25° to +85°C (Note 8)

A

V

(I

= 100 ꢀA)

V

2.5

21

−

V

kHz

ꢀA

V

R F Stby R F Stby

R F Stby

Frequency in Standby Mode (R

Current Range

(Pin 15) = 25 kꢂ)

F

18

24

F Stby

Stby

R F Stby

I

−200

−50

Synchronization Input Threshold Voltage (Note 7)

V

3.2

0.45

3.7

0.7

4.3

0.9

inthH

inthL

Synchronization Input Current

I

−5.0

−

0

ꢀA

ꢀs

Sync−in

Minimum Synchronization Pulse Width (Note 8)

UNDERVOLTAGE LOCKOUT SECTION

Startup Threshold

t

−

0.5

Sync

V

13.6

14.5

15.4

V

stup−th

Output Disable Voltage After Threshold Turn−On (UVLO 1)

V

disable1

disable2

T = 0° to +70°C

A

8.6

8.3

7.0

9.0

−

9.4

9.6

8.0

T = −25° to +85°C

A

Reference Disable Voltage After Threshold Turn−On (UVLO 2)

DEMAGNETIZATION DETECTION SECTION (Note 9)

Demagnetization Detect Input

V

7.5

V

Demagnetization Comparator Threshold (V

Decreasing)

V

50

−

65

0.25

−

80

−

mV

ꢀs

ꢀA

V

Pin 9

demag−th

Propagation Delay (Input to Output, Low to High)

−

Input Bias Current (V

= 65 mV)

I

−0.5

−

demag

demag−lb

Negative Clamp Level (I

= −2.0 mA)

C

−0.38

0.72

−

demag

L(neg)

Positive Clamp Level (I

= 2.0 mA)

−

V

demag

L(pos)

SOFT−START SECTION (Note 11)

Ratio Charge Current/I

I

/I

ss(ch) ref

−

ref

T = 0° to +70°C

0.37

0.36

1.5

0.4

−

0.43

0.44

−

A

T = −25° to +85°C

A

Discharge Current (V

Clamp Level

= 1.0 V)

I

5.0

2.4

mA

V

soft−start

discharge

V

2.2

2.6

ss(CL)

3. Adjust V above the startup threshold before setting to 12 V.

CC

4. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.

5. V must be greater than 5.0 V.

C

6. Standby is disabled for V

< 25 mV typical.

R P Stby

7. If not used, Synchronization input must be connected to Ground.

8. Synchronization Pulse Width must be shorter than t = 1/f

.

OSC

9. This function can be inhibited by connecting Pin 8 to GND. This allows a continuous current mode operation.

10.This function can be inhibited by connecting Pin 5 to V

.

CC

11. The MC44603A can be shut down by connecting the Soft−Start pin (Pin 11) to Ground.

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361

MC44603A

ELECTRICAL CHARACTERISTICS (continued) (V and V = 12 V, (Note 3), R = 10 kꢂ, C = 820 pF, for typical values T =

CC

C

ref

T

A

25°C, for min/max values T = −25° to +85°C (Note 4), unless otherwise noted.)

A

Characteristic

Symbol

Min

Typ

Max

Unit

SOFT−START SECTION (Note 11)

Duty Cycle (R

Duty Cycle (V

= 12 kꢂ)

D

36

−

42

−

49

0

%

soft−start

soft−start (Pin 11)

soft−start 12k

= 0.1 V)

D

soft−start

OVERVOLTAGE SECTION

Protection Threshold Level on V

V

2.42

1.0

2.5

2.58

3.0

V

ꢀs

V

OVP

OVP−th

Propagation Delay (V

> 2.58 V to V Low)

−

OVP

CC

out

Protection Level on V

V

CC prot

T = 0° to +70°C

16.1

15.9

17

17.9

18.1

A

T = −25° to +85°C

A

−

Input Resistance

−

kꢂ

T = 0° to +70°C

1.5

1.4

2.0

3.0

3.4

A

T = −25° to +85°C

A

−

FOLDBACK SECTION (Note 10)

Current Sense Voltage Threshold (V

= 0.9 V)

V

0.86

0.89

0.9

V

foldback (Pin 5)

CS−th

Foldback Input Bias Current (V

= 0 V)

I

−6.0

−2.0

−

ꢀ

A

foldback (Pin 5)

foldback−lb

STANDBY SECTION

Ratio I

/I

I

/I

R P Stby ref

−

R P Stby ref

T = 0° to +70°C

0.37

0.36

0.4

0.43

0.44

A

T = −25° to +85°C

A

−

Ratio Hysteresis (V Required to Return to Normal Operation from Standby

V /V

h

−

h

R P Stby

Operation)

T = 0° to +70°C

1.42

1.4

1.5

−

1.58

1.6

A

T = −25° to +85°C

A

Current Sense Voltage Threshold (V

= 1.0 V)

V

0.28

0.31

0.34

V

R P Stby (Pin 12)

CS−Stby

CURRENT SENSE SECTION

Maximum Current Sense Input Threshold

(V = 2.3 V and V

V

0.96

1.0

1.04

CS−th

= 1.2 V)

foldback (Pin 6)

feedback (Pin 14)

Input Bias Current

I

−10

−2.0

−

ꢀ

A

CS−ib

Propagation Delay (Current Sense Input to Output at V of

−

120

200

ns

TH

MOS transistor = 3.0 V)

TOTAL DEVICE

Power Supply Current

I

mA

CC

Startup (V = 13 V with V Increasing)

−

13

0.3

17

−

0.45

20

−

CC

Operating T = −25° to +85°C (Note 3)

A

Power Supply Zener Voltage (I = 25 mA)

V

18.5

−

V

CC

Z

Thermal Shutdown

−

155

−

°C

3. Adjust V above the startup threshold before setting to 12 V.

CC

4. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.

5. V must be greater than 5.0 V.

C

6. Standby is disabled for V

< 25 mV typical.

R P Stby

7. If not used, Synchronization input must be connected to Ground.

8. Synchronization Pulse Width must be shorter than t = 1/f

.

OSC

9. This function can be inhibited by connecting Pin 8 to GND. This allows a continuous current mode operation.

10.This function can be inhibited by connecting Pin 5 to V

.

CC

11. The MC44603A can be shut down by connecting the Soft−Start pin (Pin 11) to Ground.

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362

MC44603A

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ꢤ

ꢌꢑ

ꢡꢏ ꢫꢝꢷ ꢦ ꢘ ꢩ ꢐ

ꢎ

ꢘ ꢐ ꢙ

ꢎ

ꢓ ꢓ

ꢎ

ꢘ ꢐ ꢙ

ꢎ

ꢘ ꢐ ꢙ

ꢎ

ꢘ ꢐ ꢙ

ꢎ

ꢘ ꢐ ꢙ

ꢎ

ꢘ ꢐ ꢙ

ꢎ

ꢘ ꢐ ꢙ

ꢆ

ꢶ

ꢅ

ꢂ

ꢎ

ꢘ ꢐ ꢙ

ꢆꢶ ꢉ ꢞ

ꢘ ꢐ ꢙ

ꢆ

ꢶ

ꢁ

ꢞ

ꢘ ꢐ ꢙ

ꢞ

ꢢ

ꢚ

ꢖ

ꢥ

ꢛ

ꢆ ꢶꢃ ꢞ

ꢘ ꢐ ꢙ

ꢆ

ꢶ

ꢅ

ꢞ

ꢆ

ꢶ

ꢃ

ꢞ

ꢘ

ꢐ

ꢙ

ꢘ

ꢐ

ꢙ

ꢀ

ꢶ

ꢁ

ꢧ

ꢂ

ꢶ

ꢆ

ꢀ

ꢫ

ꢗ

ꢪ

ꢑ

ꢘ

ꢚ

ꢖ

ꢥ

ꢛ

ꢔ

ꢎ

ꢪ

ꢡ

ꢐ

ꢣ

ꢦ

ꢛ

ꢀ

ꢅ

ꢁ

ꢅ

ꢶ

ꢆ

ꢧ

ꢎ

ꢓ

ꢗ

ꢔ

ꢎ

ꢪ

ꢞ

ꢵ

ꢡ

ꢏ

ꢫ

ꢝ

ꢷ

ꢦ

ꢘ

ꢩ

ꢐ

ꢱ

ꢅ

ꢢ

ꢐ

ꢤ

ꢰ

ꢀ

ꢶ

ꢆ

ꢬ

ꢯ

ꢓ

ꢕ

ꢘ

ꢐ

ꢜ

ꢖ

ꢳ

ꢏ

ꢘ

ꢌ

ꢘ

ꢸ

ꢅ

ꢵ

ꢥ

ꢦ

ꢝ

ꢧ

ꢅ

ꢶ

ꢂ

ꢎ

ꢅ

ꢗ

ꢀ

ꢶ

ꢁ

ꢎ

ꢀ

ꢃ

ꢵ

ꢮ

ꢘ

ꢌ

ꢘ

ꢯ

ꢬ

ꢍ

ꢣ

ꢏ

ꢙ

ꢏ

ꢐ

ꢘ

ꢓꢕ ꢘꢘ ꢐ ꢜꢖ

ꢚ ꢐꢜ ꢫꢐ ꢞꢜ ꢍ ꢕ ꢖ

ꢅ

ꢶ

ꢂ

ꢎ

ꢓ

ꢌ

ꢬ

ꢍ

ꢦ

ꢐ

ꢜ

ꢫ

ꢖ

ꢏ

ꢌ

ꢈ

ꢀ

ꢄ

ꢗ

ꢀ

ꢶ

ꢆ

ꢎ

ꢼ

ꢎ

ꢻ

ꢔ

ꢀ

ꢂ

ꢎ

ꢢ

ꢌ

ꢣ

ꢤ

ꢥ

ꢦ

ꢝ

ꢧ

ꢓ

ꢅ

ꢶ

ꢃ

ꢎ

ꢂ

ꢶ

ꢆ

ꢬ

ꢯ

ꢞ

ꢜ

ꢍ

ꢕ

ꢖ

ꢵ

ꢇ

ꢶ

ꢆ

ꢎ

ꢀ

ꢚ

ꢱ

ꢡ

ꢱ ꢎ ꢳ

ꢬ ꢦ ꢲ

ꢺ

ꢚ

ꢪ

ꢏ

ꢜ

ꢧ

ꢌ

ꢜ

ꢣ

ꢛ

ꢗ

ꢓ

ꢚ ꢚ

ꢌ

ꢫ

ꢏ

ꢖ

ꢏ

ꢨ

ꢐ

ꢋ

ꢘ

ꢕ

ꢐ

ꢻ

ꢌ

ꢩ

ꢏ

ꢝ

ꢚ

This device contains 243 active transistors.

Figure 1. Representative Block Diagram

http://onsemi.com

363

MC44603A

ꢀ

ꢆꢆ

ꢀ

ꢆ

ꢓ

ꢺ

ꢀ

ꢆ

ꢍ

ꢢ

ꢋ

ꢎ

ꢋ

ꢺ

ꢅ

ꢀ

ꢂ°

ꢁ

ꢓ

ꢎ

ꢋ

ꢗ

ꢺ

ꢅ

ꢺ ꢀ ꢆ ꢧ

ꢀ ꢁ ꢎ

ꢂ °ꢓ

ꢓꢓ

ꢓ ꢓ

ꢺ

ꢯ

ꢓ

ꢺ ꢂꢆ ꢆ ꢍꢢ

ꢋ

ꢘ

ꢐ

ꢙ

ꢗ

ꢺ ꢅ ꢶꢆ ꢧ

ꢢ ꢚ ꢖꢥ ꢛ

ꢓ

ꢺ

ꢀ

ꢆ

ꢍ

ꢢ

ꢋ

ꢗ

ꢺ

ꢂ

ꢶ

ꢆ

ꢧ

ꢢ

ꢚ

ꢖ

ꢥ

ꢛ

ꢀ

ꢆ

ꢀ

ꢆ

ꢗ

ꢺ

ꢅ ꢈ ꢧ

ꢢ

ꢚ

ꢖ

ꢥ

ꢛ

ꢗ

ꢺ

ꢀ

ꢆ

ꢧ

ꢢ ꢚ ꢖꢥ ꢛ

ꢓ

ꢺ ꢅ ꢅꢆ ꢆ ꢍ ꢢ

ꢋ

ꢄ

ꢶ

ꢄ

ꢆ

ꢀ

ꢆꢽ

ꢧ

ꢀꢆ

ꢆꢽ

ꢧ

ꢀ

ꢶꢆ

ꢽ

ꢳ

ꢀ

ꢆꢽ

ꢧ

ꢀ

ꢆꢆ

ꢽ

ꢧ

ꢀ ꢶꢆ ꢽ ꢳ

ꢙ

ꢾ

ꢔ

ꢫꢝ

ꢏ

ꢣ

ꢦꢖ

ꢌꢘ

ꢢꢘ

ꢐ

ꢭꢕ

ꢐ

ꢜꢝ

ꢛ

ꢊꢿ

ꣀꢒ

ꢙ ꢾ ꢔ

ꢔꢚ ꢓ

ꢫ

ꢝ

ꢏ

ꢣ

ꢦ

ꢖ

ꢌ

ꢘ

ꢢ

ꢘ

ꢐ

ꢭ

ꢕ

ꢐ

ꢜ

ꢝ

ꢛ

ꢊ

ꢿ

ꣀ

ꢒ

ꢔ

ꢚ

ꢓ

Figure 2. Timing Resistor versus

Oscillator Frequency

Figure 3. Standby Mode Timing Capacitor

versus Oscillator Frequency

ꢂ

ꢃ

ꢅ

ꢆ

ꢶ

ꢃ

ꢄ

ꢅ

ꢀ

ꢆ

ꢇ

ꢀ

ꢆ

ꢇ

ꢉ

ꢈ

ꢁ

ꢂ

ꢃ

ꢎ

ꢗ

ꢓ

ꢺ

ꢉ

ꢀ

ꢅ

ꢎ

ꢧ

ꢎ

ꢺ

ꢓ ꢓ

ꢀ

ꢅ

ꢎ

ꢓ

ꢆ

ꢶ

ꢄ

ꢉ

ꢈ

ꢀ

ꢆ

ꢗ

ꢓ

ꢺ

ꢀ

ꢅ

ꢆ

ꢧ

ꢍ

ꢘ

ꢐ

ꢙ

ꢘ

ꢐ

ꢙ

ꢺ

ꢅ

ꢆ

ꢍ

ꢢ

ꢺ

ꢋ

ꢉ

ꢢ

ꢋ

ꢃ

ꢄ

ꢰ

ꢂ

ꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆ

ꢰ

ꢂ

ꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳ

ꢴ

ꢞ

ꢮ

ꢠ

ꢋ

ꢮ

ꢳ

ꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ

°

ꢓ

ꢒ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳ

ꢴ

ꢞ

ꢮ

ꢠ

ꢋ

ꢮ

ꢳ

ꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ

°

ꢓ

ꢒ

Figure 4. Oscillator Frequency

versus Temperature

Figure 5. Ratio Charge Current/Reference

Current versus Temperature

ꢁ

ꢃ

ꢅ

ꢆ

ꢈ

ꢁ

ꢂ

ꢃ

ꢄ

ꢆ

ꢈ

ꢁ

ꢂ

ꢃ

ꢄ

ꢆ

ꢄ

ꢆ

ꢎ

ꢺ

ꢅ

ꢀ

ꢅ

ꢆ

ꢓ

ꢎ

ꢍ

ꢎ

ꢺ ꢀ ꢅ ꢎ

ꢓ ꢓ

ꢓ

ꢆ

ꢅ

ꢀ

ꢆ

ꢰ

ꢓ

ꢋ

ꢺ

ꢅ

ꢆ

ꢢ

ꢓ

ꢋ

ꢺ

ꢅ ꢅꢆ ꢆ ꢍ ꢢ

ꢅ ꢂ°ꢓ

ꢻ

ꢂ

°

ꢯ

ꢆ

ꢓ

ꢕ

ꢘ

ꢐ

ꢜ

ꢖ

ꢓ

ꢕ

ꢘ

ꢐ

ꢜ

ꢖ

ꢰ

ꢅ

ꢆ

ꢀ

ꢅ

ꢄ

ꢃ

ꢰ

ꢀ

ꢃꢆ

ꢁꢆ

ꢉꢆ

ꢆ ꢆ

ꢆ

ꢅ

ꢀ

ꢆ

ꢅ

ꢀ

ꢆ

ꢎ

ꢌ

ꢣ

ꢖ

ꢦ

ꢩ

ꢐ

ꢎ

ꢔ

ꢎ

ꢌ

ꢣ

ꢖ

ꢦ

ꢩ

ꢐ

ꢆ

ꢰ

ꢆ

ꢞ

ꢓ

ꢀ

ꢆ

ꢰ

ꢀ

ꢰ

ꢂ

ꢀ

ꢶ

ꢆ

ꢀ

ꢫ

ꢱ

ꢡ

ꢏ

ꢨ

ꢀ

ꢶ

ꢆ

ꢀ

ꢫ

ꢱ

ꢡ

ꢏ

ꢨ

Figure 6. Output Waveform

Figure 7. Output Cross Conduction

http://onsemi.com

364

MC44603A

ꢂ

ꢃ

ꢆꢆ

ꢈꢂ

ꢂꢆ

ꢅꢂ

ꢆꢆ

ꢅ

ꢶ

ꢂ

ꢆ

ꢶ

ꢀ

ꢶ

ꢂ

ꢆ

ꢄ

ꢈꢂ

ꢂꢆ

ꢅꢂ

ꢎ

ꢗ

ꢓ

ꢺ

ꢉ

ꢀ

ꢅ

ꢎ

ꢧ

ꢎ

ꢺ

ꢓ ꢓ

ꢀ

ꢅ

ꢎ

ꢧ

ꢓ

ꢀ

ꢆ

ꢗ

ꢓ

ꢋ

ꢺ

ꢀ

ꢆ

ꢘ

ꢐ

ꢙ

ꢘ

ꢐ

ꢙ

ꢺ

ꢅꢆ

ꢍ

ꢢ

ꢺ

ꢋ

ꢉ

ꢅ

ꢆ

ꢍ

ꢢ

ꢋ

ꢶ

ꢺ

ꢅ

ꢂ

°

ꢓ

ꢯ

ꢄ ꢆꢆ

ꢰ

ꢂꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆꢆ

ꢆ

ꢀ

ꢞ

ꢆ

ꢅ

ꢆ

ꢄ

ꢆ

ꢃ

ꢆ

ꢂ ꢆ ꢆ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳ

ꢴ

ꢞ

ꢮ

ꢠꢋ

ꢋ

ꢮ

ꢳ

ꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ°

ꢓ

ꢒ

ꢾ ꢔ

ꢫꢌ ꢕ ꢘ ꢝꢐ

ꢼꢋ

ꢪ

ꢼ

ꢋ

ꢚ

ꢔ

ꢼꢗ

ꢓꢮ

ꢓ

ꢼ

ꢗ

ꢗꢮ

ꢠꢋ

ꢊ

ꢬꢯ

ꢒ

Figure 8. Oscillator Discharge Current

versus Temperature

Figure 9. Source Output Saturation Voltage

versus Load Current

ꢅ

ꢀ

ꢶ

ꢆ

ꢉ

ꢁ

ꢆ

ꢎ

ꢺ

ꢀ

ꢅ

ꢎ

ꢓ ꢓ

ꢚ

ꢏ

ꢌ

ꢜ

ꢦ

ꢧ

ꢚꢦ ꢖꢕ ꢘꢦꢖ ꢏ ꢌꢜ

ꢟ ꢺ ꢀ ꢆ

ꢊꢻ

ꢤ

ꢖꢌ

ꢎ

ꢒ

ꢓꢓ

ꢶ

ꢁ

ꢅ

ꢉ

ꢀ ꢃ ꢆ

ꢎ

ꢺ

ꢄ

ꢅ

ꢀ

ꢆ

ꢬ

ꢎ

ꢏ ꢜ

ꢶ

ꢆ

ꢖ

ꢌ

ꢃ

ꢶꢆ

ꢎ

ꢔ

ꢗ

ꢋ

ꢆꢆ

ꢧ

ꢻ

ꢀ

ꢆ

ꢃ

ꢅ

ꢆ

ꢺ

ꢅ ꢂ°ꢓ

ꢯ

ꢂ

ꢆ

ꢋ

ꢎ

ꢺ

ꢅ

ꢺ

ꢫ

ꢂ°

ꢓ

ꢅ ꢎ

ꢯ

ꢀ

ꢓꢓ

ꢀ

ꢃ

ꢆ

ꢉ

ꢀ

ꢆ

ꢅ

ꢪ

ꢕꢣ ꢫꢐꢤ ꢻ ꢌꢦ ꢤ

ꢆ

ꢿ

ꣀ

ꢗ

ꢦ

ꢖ

ꢐ

ꢰ

ꢅ

ꢰ ꢃ ꢆ

ꢃ

ꢀ ꢆ

ꢆ

ꢀ

ꢅ

ꢄ

ꢆ

ꢀ

ꢆ

ꢅ

ꢆ

ꢄ

ꢆ

ꢃ

ꢆ

ꢂ

ꢆ

ꢀ

ꢆ

ꢀ

ꢆ

ꢀ

ꢆ

ꢀ

ꢆ

ꢞ

ꢾ

ꢚ

ꢞ

ꢠ

ꣂ

ꢔ

ꢼ

ꢋ

ꢪ

ꢼ

ꢋ

ꢓ

ꢼ

ꢗ

ꢮ

ꢠ

ꢋ

ꢊ

ꢬ

ꢯ

ꢒ

ꢙ

ꢾ

ꢢ

ꢗ

ꢮ

ꢹ

ꢼ

ꢮ

ꢠ

ꢓ

ꣁ

ꢊ

ꢧ

ꢿ

ꣀ

ꢒ

ꢫ

ꢏ

ꢜ

ꢧ

Figure 10. Sink Output Saturation Voltage

versus Sink Current

Figure 11. Error Amplifier Gain and Phase

versus Frequency

ꢅ

ꢶ

ꢁ

ꢆ

ꢉ

ꢆ

ꢂ

ꢆ

ꢂ

ꢆ

ꢂ

ꢎ

ꢺ

ꢀ

ꢅ

ꢎ

ꢌ

ꢎ

ꢺ ꢀ ꢅ ꢎ

ꢓ ꢓ

ꢓ

ꢈ

ꢁ

ꢂ

ꢟ ꢺ ꢀꢆ

ꢎ

ꢗ

ꢂ

ꢆ

ꢂ

ꢺ

ꢅ

ꢶ

ꢆ

ꢖ

ꢃ

ꢶ

ꢆ

ꢎ

ꢔ

ꢺ

ꢀ

ꢆ

ꢧ

ꢻ

ꢅ

ꢶ

ꢂ

ꢃ

ꢆ

ꢰ

ꢆ

ꢰ

ꢂ

ꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆ

ꢂ

ꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳ

ꢴ

ꢞ

ꢮ

ꢠ

ꢋ

ꢮ

ꢳ

ꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ

°

ꢓ

ꢒ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳ

ꢴ

ꢞ

ꢮ

ꢠ

ꢋ

ꢮ

ꢳ

ꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ

°

ꢓ

ꢒ

Figure 12. Voltage Feedback Input

versus Temperature

Figure 13. Demag Comparator Threshold

versus Temperature

http://onsemi.com

365

MC44603A

ꢀ

ꢆ

ꢂ ꢶꢆ

ꢄ

ꢶ

ꢅ

ꢀ

ꢆ

ꢪ

ꢘ

ꢏ

ꢜ

ꢖ

ꢐ

ꢤ

ꢝ

ꢏ

ꢘ

ꢝ

ꢕ

ꢏ

ꢖ

ꢥ

ꢌ

ꢦ

ꢘ

ꢤ

ꢷ

ꢐ

ꢦ

ꢖ

ꢫ

ꢏ

ꢜ

ꢧ

ꢐ

ꢲ

ꢦ

ꢬ

ꢍ

ꢣ

ꢐ

ꢉ

ꢁ

ꢆ

ꢃ

ꢄ

ꢅ

ꢶꢆ

ꢅꢶ ꢆ ꢌꣀ

ꢻ

ꢓ

ꢌꢍꢍ ꢐꢘ

ꢻ

ꢄ

ꢶ

ꢆ

ꢬ

ꢖ

ꢗ

ꢪ

ꢆ

ꢶ

ꢆ

ꢁ

ꣃ

ꢯ

ꢟ

ꢘ

ꢦꢍ

ꢷ

ꢫ

ꢘ

ꢐꢍ

ꢘ

ꢐꢫ

ꢐ

ꢜ

ꢖ

ꢫꢛ

ꢬꢬ

ꢐ

ꢖ

ꢘ

ꢏꢝ

ꢦ

ꢣ

ꢣꢦ

ꢛ

ꢌꢕ

ꢃ

ꢆ

ꢶꢆ

ꢎ

ꢗ

ꢓ

ꢺ

ꢉ

ꢀ

ꢅ

ꢎ

ꢧ

ꢓꢓ

ꢅ

ꢶ

ꢇ

ꢙ

ꢌꢘ ꢋ ꢺ ꢈ ꢆ°ꢓ

ꢯ

ꢡꢊ ꢬ ꢦ ꢲ ꢒ

ꢀ

ꢆ

ꢅ

ꢀ

ꢆ

ꢶꢆ

ꢘ ꢐ ꢙ

ꢺ

ꢅꢆ

ꢍ

ꢢ

ꢋ

ꢉ

ꢰ

ꢂ

ꢆ

ꢰ

ꢅꢂ

ꢆ

ꢅꢂ

ꢂꢆ

ꢈ

ꢂ

ꢀ ꢆꢆ

ꢆ

ꢀ

ꢆ

ꢅ

ꢆ

ꢄ

ꢆ

ꢃ

ꢆ

ꢂ ꢆ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳꢴ

ꢞꢮ

ꢠꢋ

ꢋ

ꢮ

ꢳ

ꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ

°

ꢓ

ꢒ

ꢻ

ꢾ

ꢻ

ꢮ

ꢠ

ꢟ

ꢋ

ꢿ

ꢔ

ꢢ

ꢓ

ꢔ

ꢪ

ꢮ

ꢗ

ꢊ

ꢬ

ꢒ

Figure 14. Current Sense Gain

versus Temperature

Figure 15. Thermal Resistance and Maximum

Power Dissipation versus P.C.B. Copper Length

ꢀ

ꢃ

ꢆ

ꢶ

ꢄ

ꢂ

ꢆ

ꢶ

ꢄ

ꢅ

ꢆ

ꢂ

ꢶ

ꢅ

ꢆ

ꢉ

ꢆ

ꢶꢅ

ꢶꢀ

ꢶꢆ

ꢆ

ꢂ

ꢆ

ꢂ

ꢆ

ꢎ

ꢗ

ꢓ

ꢺ

ꢀ

ꢅ

ꢎ

ꢧ

ꢗ

ꢓ

ꢺ ꢀ ꢆ ꢧ

ꢘ ꢐ ꢙ

ꢓ

ꢀ

ꢆ

ꢺ

ꢉ

ꢅ

ꢆ

ꢍ

ꢢ

ꢘ

ꢐ

ꢙ

ꢋ

ꢺ

ꢉ

ꢅ

ꢆ

ꢍ

ꢢ

ꢋ

ꢆ

ꢰ

ꢂ

ꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆ

ꢅ

ꢶ

ꢆ

ꢃ

ꢶ

ꢆ

ꢁ

ꢶ

ꢆ

ꢉ

ꢶ

ꢆ

ꢀ

ꢆ

ꢀ

ꢅ

ꢀ

ꢃ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳ

ꢴ

ꢞ

ꢮ

ꢠ

ꢋ

ꢮ

ꢳ

ꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ

°

ꢓ

ꢒ

ꢎ

ꢾ ꢚ

ꢓ ꢓ

ꢼ

ꢪ

ꢻ

ꣁ

ꢎ

ꢔ

ꢻ

ꢋ

ꢯ

ꢟ

ꢮ

ꢊ

ꢎ

ꢒ

Figure 16. Propagation Delay Current Sense

Input to Output versus Temperature

Figure 17. Startup Current versus V_CC

ꢅ

ꢀ

ꢶ

ꢂ

ꢀ

ꢁ

ꢃ

ꢅ

ꢆ

ꢅ

ꢀ

ꢶ

ꢆ

ꢂ

ꢆ

ꢂ

ꢆ

ꢉ

ꢶ

ꢆ

ꢅ

ꢀ

ꢆꢶ

ꢇꢶ

ꢋ

ꢗ

ꢓ

ꢎ

ꢺ ꢅ ꢂ °ꢓ

ꢘ ꢐ ꢙ

ꢺ ꢉ ꢅꢆ ꢍꢢ

ꢁ

ꢃ

ꢅ

ꢯ

ꢺ

ꢀ

ꢆ

ꢧ

ꢋ

ꢞ

ꢓ ꢓ

ꢺ

ꢅ

ꢂ

ꢬ

ꢯ

ꢺ

ꢆ

ꢎ

ꢢꢴ

ꢓ ꢚ

ꢆ

ꢰ

ꢅ

ꢶ

ꢆ

ꢃ

ꢶ

ꢆ

ꢁ

ꢶ

ꢆ

ꢉ

ꢶ

ꢆ

ꢀ

ꢆ

ꢀ

ꢅ

ꢀ

ꢃ

ꢀ

ꢁ

ꢂ

ꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆ

ꢎ

ꢾ

ꢚ

ꢼ

ꢪ

ꢻ

ꣁ

ꢎ

ꢔ

ꢻ

ꢋ

ꢯ

ꢟ

ꢮ

ꢊ

ꢎ

ꢒ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳ

ꢴ

ꢞ

ꢮ

ꢠ

ꢋ

ꢮ

ꢳ

ꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ

°

ꢓ

ꢒ

ꢓ

Figure 18. Supply Current versus

Supply Voltage

Figure 19. Power Supply Zener Voltage

versus Temperature

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366

MC44603A

ꢀ

ꢂ

ꢶ

ꢂ

ꢆ

ꢂ

ꢆ

ꢇ

ꢶ

ꢂ

ꢆ

ꢂ

ꢆ

ꢂ

ꢇ

ꢶꢅ

ꢀ

ꢃꢶ

ꢄꢶ

ꢇ

ꢉ

ꢶꢆ

ꢶꢂ

ꢎ

ꢞ

ꢜꢝ

ꢘ

ꢐ

ꢦꢫ

ꢏꢜ

ꢩ

ꢎ

ꢡꢐ ꢝꢘ ꢐ ꢦꢫ ꢏꢜ ꢩ

ꢓ ꢓ

ꢓ

ꢂ

ꢰ

ꢆ

ꢰ

ꢂ

ꢆ

ꢰ

ꢅꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆꢆ

ꢂ

ꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ ꢆ ꢆ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳꢴ

ꢞ

ꢮ

ꢠ

ꢋ

ꢋꢮ

ꢳꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗꢮ

ꢊ°

ꢓꢒ

ꢋ

ꢯ

ꢾ ꢯ

ꢳꢴ

ꢞ

ꢮꢠ

ꢋ

ꢋꢮ

ꢳꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼꢗ

ꢮ

ꢊ °

ꢓꢒ

Figure 20. Startup Threshold Voltage

versus Temperature

Figure 21. Disable Voltage After Threshold

Turn−On (UVLO1) versus Temperature

ꢉ

ꢶ

ꢆ

ꢉ

ꢁ

ꢃ

ꢅ

ꢆ

ꢅ ꢶꢁ ꢆ

ꢈ

ꢶ

ꢅ ꢶꢂ ꢂ

ꢈ

ꢁ

ꢶ

ꢅ

ꢶꢂ

ꢶꢃ

ꢶꢄ

ꢆ

ꢂ

ꢆ

ꢂ

ꢎ

ꢺ ꢀ ꢅ ꢎ

ꢓ ꢓ

ꢎ

ꢡꢐ ꢝꢘꢐꢦ ꢫꢏꢜ ꢩ

ꢓꢓ

ꢆ

ꢰ

ꢉ

ꢰ

ꢂꢆ

ꢰ

ꢅꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆ

ꢂ

ꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳ

ꢴ

ꢞ

ꢮ

ꢠ

ꢋ

ꢮ

ꢳ

ꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ

°

ꢓ

ꢒ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳ

ꢴ

ꢞ

ꢮ

ꢠ

ꢋ

ꢮ

ꢳ

ꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ

°

ꢓ

ꢒ

Figure 22. Disable Voltage After Threshold

Figure 23. Protection Threshold Level on

Turn−On (UVLO2) versus Temperature

V_OVPversus Temperature

ꢀ

ꢉ

ꢂ

ꢈ

ꢄ

ꢶ

ꢆ

ꢗ

ꢓ

ꢺ ꢀꢆ ꢧ

ꢺ ꢉ ꢅ ꢆ ꢍꢢ

ꢘ

ꢐ

ꢙ

ꢋ

ꢀ

ꢈ

ꢶ

ꢅ

ꢶ

ꢂ

ꢆ

ꢂ

ꢪ

ꢏ

ꢜ

ꢁ

ꢔ

ꢍ

ꢐ

ꢜ

ꢀ

ꢎ

ꢗ

ꢓ

ꢺ

ꢉ

ꢀ

ꢅ

ꢎ

ꢧ

ꢓ

ꢁ

ꢶ

ꢂ

ꢁ

ꢀ

ꢶ

ꢀ

ꢆ

ꢘ

ꢐ

ꢙ

ꢺ

ꢅ

ꢆ

ꢍ

ꢢ

ꢋ

ꢀ

ꢆ

ꢰ

ꢂ

ꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆ

ꢂ

ꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳ

ꢴ

ꢞ

ꢮ

ꢠ

ꢋ

ꢮ

ꢳ

ꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ

°

ꢓ

ꢒ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳ

ꢴ

ꢞ

ꢮ

ꢠ

ꢋ

ꢮ

ꢳ

ꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ

°

ꢓ

ꢒ

Figure 24. Protection Level on V_CC

versus Temperature

Figure 25. Propagation Delay (V_OVP> 2.58 V

to V_outLow) versus Temperature

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367

MC44603A

ꢅ

ꢈ

ꢁ

ꢆ

ꢂ

ꢆ

ꢶꢄ

ꢄ

ꢅ

ꢀ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢎ

ꢗ

ꢪ

ꢚ

ꢖ

ꢤ

ꢥ

ꢛ

ꢊ

ꢪ

ꢏ

ꢜ

ꢀ

ꢅ

ꢒ

ꢅ ꢃ

ꢅ ꢄ

ꢂ

ꢆ

ꢂ

ꢎ

ꢺ

ꢀ

ꢅ

ꢎ

ꢓ

ꢎꢌꢣ ꢖ ꢦꢩꢐ ꢞ ꢜꢝꢘꢐ ꢦꢫꢏ ꢜ ꢩ

ꢗ

ꢓ

ꢺ

ꢀ

ꢅ

ꢆ

ꢧ

ꢍ

ꢘ ꢐ ꢙ

ꢺ

ꢉ

ꢢ

ꢋ

ꢪ

ꢏꢜ

ꢀ

ꢅ

ꢓ

ꢣ

ꢦ

ꢬ

ꢍꢐ

ꢤ

ꢦ

ꢖ

ꢀ

ꢶ

ꢆ

ꢎ

ꢆ

ꢰ

ꢆ

ꢰ

ꢂ

ꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅꢂ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ

ꢆꢆ

ꢂ

ꢆ

ꢰ

ꢅ

ꢂ

ꢆ

ꢅ

ꢂ

ꢆ

ꢈ

ꢂ

ꢀ ꢆ ꢆ

ꢋ

ꢯ

ꢾ

ꢯ

ꢳꢴ

ꢞꢮ

ꢠꢋ

ꢋꢮ

ꢳꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼ

ꢗ

ꢮ

ꢊ°

ꢓꢒ

ꢋ

ꢯ

ꢾ ꢯ

ꢳꢴ

ꢞ

ꢮꢠ

ꢋ

ꢋꢮ

ꢳꢪ

ꢮ

ꢗ

ꢯ

ꢋ

ꢼꢗ

ꢮ

ꢊ °

ꢓꢒ

Figure 26. Standby Reference Current

versus Temperature

Figure 27. Current Sense Voltage Threshold

Standby Mode versus Temperature

PIN FUNCTION DESCRIPTION

1

Name

Description

This pin is the positive supply of the IC. The operating voltage range after startup is 9.0 to 14.5 V.

V

CC

2

V

The output high state (V ) is set by the voltage applied to this pin. With a separate connection to the

C

OH

power source, it can reduce the effects of switching noise on the control circuitry.

3

4

5

Output

GND

Peak currents up to 750 mA can be sourced or sunk, suitable for driving either MOSFET or Bipolar tran-

sistors. This output pin must be shunted by a Schottky diode, 1N5819 or equivalent.

The ground pin is a single return, typically connected back to the power source; it is used as control and

power ground.

Foldback Input

The foldback function provides overload protection. Feeding the foldback input with a portion of the V

CC

voltage (1.0 V max) establishes on the system control loop a foldback characteristic allowing a smoother

startup and sharper overload protection. Above 1.0 V the foldback input is inactive.

6

7

Overvoltage

Protection

When the overvoltage protection pin receives a voltage greater than 17 V, the device is disabled and

requires a complete restart sequence. The overvoltage level is programmable.

Current Sense

Input

A voltage proportional to the current flowing into the power switch is connected to this input. The PWM

latch uses this information to terminate the conduction of the output buffer when working in a current

mode of operation. A maximum level of 1.0 V allows either current or voltage mode operation.

8

9

Demagnetization

Detection

A voltage delivered by an auxiliary transformer winding provides to the demagnetization pin an indication

of the magnetization state of the flyback transformer. A zero voltage detection corresponds to complete

core saturation. The demagnetization detection ensures a discontinuous mode of operation. This function

can be inhibited by connecting Pin 8 to GND.

Synchronization

Input

The synchronization input pin can be activated with either a negative pulse going from a level between

0.7 V and 3.7 V to GND or a positive pulse going from a level between 0.7 V and 3.7 V up to a level high-

er than 3.7 V. The oscillator runs free when Pin 9 is connected to GND.

10

11

C

The normal mode oscillator frequency is programmed by the capacitor C choice together with the R

T ref

T

resistance value. C , connected between Pin 10 and GND, generates the oscillator sawtooth.

T

Soft−Start/D

Voltage−Mode

/

A capacitor, resistor or a voltage source connected to this pin limits the switching duty−cycle. This pin

can be used as a voltage mode control input. By connecting Pin 11 to Ground, the MC44603A can be

shut down.

max

12

R

A voltage level applied to the R

turn into the reduced frequency mode of operation (i.e. standby mode). An internal hysteresis comparator

allows to return in the normal mode at a higher output power level.

pin determines the output power level at which the oscillator will

P Standby

13

14

E/A Out

The error amplifier output is made available for loop compensation.

Voltage Feedback This is the inverting input of the Error Amplifier. It can be connected to the switching power supply output

through an optical (or other) feedback loop.

15

16

R

The reduced frequency or standby frequency programming is made by the R

resistance choice.

F Standby

R

ref

R

sets the internal reference current. The internal reference current ranges from 100 ꢀA to 500 ꢀA.

ref

This requires that 5.0 kꢂ ≤ R ≤ 25 kꢂ.

ref

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368

MC44603A

ꢠ

ꢌꢰ

ꢋꢦ

ꢧꢐ

ꢔ

ꢨꢐ

ꢘ

ꢻ ꢌꢌ ꢍ ꢢꢦ ꢏꢣ ꢕꢘ ꢐ

꣆

ꢅ

ꢶ

ꢆ

ꢀ

ꢫ

ꢚ

ꢖ

ꢦ

ꢘ

ꢖ

ꢕ

ꢍ

ꢗꢐ ꢫꢖ ꢦꢘ ꢖ

ꢎ

ꢓꢓ

ꢎ

ꢓꢓ ꢍ ꢘ ꢌ ꢖ

ꢎ

ꢫ

ꢖ

ꢕ

ꢍ

ꢰ

ꢖ

ꢷ

ꢠꢌ ꢘꢬ ꢦ ꢣ ꢳꢌ ꢤ ꢐ

ꢎ

ꢤ ꢏ ꢫꢦ ꢥ ꢣ ꢐ ꢀ

ꢤ ꢏ ꢫꢦ ꢥ ꢣ ꢐ ꢅ

ꢎ

ꢘ ꢐ ꢙ

ꢼ ꢎꢻꢔ ꢀ

ꢎ

ꢪ ꢏ ꢜ ꢀ ꢀ

ꢊ ꢚ ꢌ ꢙꢖ ꢰ ꢚ ꢖꢦ ꢘ ꢖꢒ

ꢎ

ꢔ

ꢎ

ꢪ

ꢔ

ꢕ

ꢖ

ꢔ ꢕꢖ ꢍꢕꢖ

ꢞ

ꢓꢓ

ꢀꢈ

ꢬ

ꢯ

ꢆꢶ

ꢄ

ꢬ

ꢯ

Figure 28. Starting Behavior and Overvoltage Management

ꢎ

ꢡ ꢐ ꢬꢦ ꢩ ꢞꢜ

ꢔ

ꢕꢖ

ꢍꢕ

ꢖ

ꢊꢪ

ꢏ

ꢜ

ꢄꢒ

ꢎ

ꢡ ꢐ ꢬꢦ ꢩ ꢔꢕ ꢖ

ꢎ

ꢡꢐ ꢬ ꢦ ꢩ ꢔꢕ ꢖ

ꢡ

ꢐ

ꢬ

ꢦ

ꢩ

ꢜ

ꢐ

ꢖ

ꢏ

ꣀ

ꢦ

ꢖ

ꢏ

ꢖ

ꢌ

ꢜ

ꢎ

ꢔ ꢫꢝꢏꢣ ꢣꢦ ꢖ ꢌꢘ

ꢡ ꢐ ꢬꢦ ꢩ ꢞꢜ

ꢳꢦ ꢜ ꢦꢩ ꢐ ꢬꢐ ꢜ

ꢴ ꢕꢙ ꢙꢐ ꢘ

ꢔ

ꢕ

ꢖ

ꢍ

ꢕ

ꢖ

Figure 29. Demagnetization

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369

MC44603A

ꢎ

ꢓꢓ

ꢎ

ꢫꢖꢕ ꢍ ꢰ ꢖꢷ

ꢎ

ꢤ ꢏ ꢫꢦ ꢥ ꢣ ꢐ ꢀ

ꢤ ꢏ ꢫꢦ ꢥ ꢣ ꢐ ꢅ

ꢎ

ꢘ ꢐ ꢙ

ꢼ

ꢎ

ꢻ

ꢔ

ꢀ

ꢎ

ꢪ

ꢏ

ꢜ

ꢀ

ꢊꢚ ꢌꢙ ꢖꢰ ꢚ ꢖꢦ ꢘꢖ ꢒ

ꢔ

ꢕ

ꢖ

ꢍꢕ

ꢖ

ꢊ

ꢪ

ꢏꢜ

ꢄꢒ

ꢞ

ꢓ

ꢀꢈ

ꢬ

ꢯ

ꢆꢶ ꢄ ꢬ

ꢯ

Figure 30. Switching Off Behavior

ꢄ

ꢀ

ꢶ

ꢁ

ꢎ

ꢓ

ꢋ

ꢶ

ꢀ

ꢶ

ꢆ

ꢎ

ꢚ

ꢖ

ꢥ

ꢛ

ꢎ

ꢡ ꢐ ꢬꢦ ꢩ ꢔꢕ ꢖ

ꢎ

ꢔꢚ ꢓ

ꢎ

ꢔꢚ ꢓ ꢍ ꢘ ꢌ ꢖ

ꢎ

ꢡ

ꢐ

ꢬ

ꢦ

ꢩ

ꢔ

ꢕ

ꢖ

ꢎ

ꢔꢚ ꢓ ꢍ ꢘ ꢌ ꢖ

ꢚ

ꢛꢜ

ꢝꢷ

ꢘꢌ

ꢜꢏ

ꣀꢦ

ꢖ

ꢏ

ꢌꢜ

ꢞ ꢜꢍꢕ

ꢖ

ꢔ ꢫꢝꢏꢣ ꢣꢦ ꢖ ꢌꢘ

ꢎ

ꢔꢚ ꢓ

ꢓ

ꢋ

ꢎ

ꢚ ꢖꢥ ꢛ

Figure 31. Oscillator

http://onsemi.com

370

MC44603A

ꢎ

ꢘ ꢐ ꢙ

ꢎ

ꢵ ꢀꢶ ꢁ ꢎ

ꢓꢚ ꢚ

ꢞ ꢜꢖ ꢐ ꢘ ꢜꢦ ꢣ ꢓꢣ ꢦꢬ ꢍ

ꢚ

ꢌꢙ

ꢖ

ꢰ

ꢚ

ꢖ

ꢦꢘ

ꢖ

ꢮ

ꢲ

ꢖ

ꢐ

ꢘ

ꢜ

ꢦꢣ

ꢓꢣ

ꢦ

ꢬ

ꢍ

ꢎ

ꢄ

ꢀ

ꢶ

ꢁ

ꢎ

ꢓ ꢋ

ꢎ

ꢣ

ꢌ

ꢑ

ꢶ

ꢓ ꢋ

ꢎ

ꢔꢚ ꢓ

ꢔ

ꢕꢖ

ꢍ

ꢕ

ꢖ

ꢊꢪ

ꢏ

ꢜ

ꢄ

ꢒ

Figure 32. Soft−Start & D_max

OPERATING DESCRIPTION

ꢵ

Error Amplifier

A fully compensated Error Amplifier with access to the

inverting input and output is provided. It features a typical

dc voltage gain of 70 dB. The noninverting input is

internally biased at 2.5 V and is not pinned out. The

converter output voltage is typically divided down and

monitored by the inverting input. The maximum input bias

current with the inverting input at 2.5 V is −2.0 ꢀA. This can

cause an output voltage error that is equal to the product of

the input bias current and the equivalent input divider source

resistance.

The Error Amp output (Pin 13) is provided for external

loop compensation. The output voltage is offset by two

diode drops (≈ 1.4 V) and divided by three before it connects

to the inverting input of the Current Sense Comparator. This

guarantees that no drive pulses appear at the Output (Pin 3)

ꢀ

ꢶ

ꢆ

ꢬ

ꢯ

ꢓꢌ ꢬꢍ ꢐ ꢜꢫꢦ ꢖ ꢏꢌ ꢜ

ꢮ

ꢘ

ꢣ

ꢌ

ꢘ

ꢏ

ꢀ

ꢄ

ꢗ

ꢢ ꢴ

ꢯ

ꢬꢍ

ꢏꢙ

ꢐꢘ

ꢗ

ꢙ

ꢅ

ꢗ

ꢓ

ꢅ ꢶꢂ ꢎ

ꢙ

ꢀ

ꢃ

ꢗ

ꢎꢌ ꢣꢖ ꢦ ꢩꢐ

ꢢꢐ ꢐꢤ ꢥ ꢦ ꢝꢧ

ꢓ ꢕꢘ ꢘ ꢐ ꢜ ꢖ ꢚꢐ ꢜ ꢫ ꢐ

ꢓ ꢌꢬ ꢍꢦ ꢘ ꢦ ꢖꢌ ꢘ

ꢞ

ꢜꢍ

ꢕ

ꢖ

ꢀ

ꢶꢆ

ꢎ

ꢂ

ꢢꢌ ꢣꢤ ꢥ ꢦꢝꢧ

ꢟ

ꢠꢡ

ꢃ

ꢞ ꢜꢍ ꢕ ꢖ

ꢢꢘ

ꢌ

ꢬ

ꢪ

ꢌ

ꢑ

ꢐ

ꢘ

ꢚ

ꢕ

ꢍ

ꢣ

ꢛ

ꢔ

ꢕ

ꢖ

ꢍ

ꢕ

ꢖ

ꢗ

ꢅ

ꢗ

ꢀ

Figure 33. Error Amplifier Compensation

when Pin 13 is at its lowest state (V ). The Error Amp

minimum feedback resistance is limited by the amplifier’s

minimum source current (0.2 mA) and the required output

OL

Current Sense Comparator and PWM Latch

The MC44603A can operate as a current mode controller

or as a voltage mode controller. In current mode operation,

the MC44603A uses the current sense comparator. The

output switch conduction is initiated by the oscillator and

terminated when the peak inductor current reaches the

voltage (V ) to reach the current sense comparator’s 1.0 V

OH

clamp level:

3.0 (1.0 V) ) 1.4 V

R

f(min)

[

+ 22 kꢂ

0.2 mA

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371

MC44603A

threshold level established by the Error Amplifier output

(Pin 13). Thus, the error signal controls the peak inductor

current on a cycle−by−cycle basis. The Current Sense

Comparator PWM Latch ensures that only a single pulse

appears at the Source Output during the appropriate

oscillator cycle.

connected to the charging current source (0.4 I ) and so,

ref

the discharge current source has to be higher than the

charge current to be able to decrease the C voltage (refer

T

to Figure 36).

This condition is performed, its value being (2.0 I ) in

ref

normal working and (0.4 I + 0.5 I

in standby mode).

ref

F Stby

The inductor current is converted to a voltage by inserting

ꢎ

the ground referenced sense resistor R in series with the

ꢘ ꢐ ꢙ

S

power switch Q1.

ꢆ ꢶꢃ ꢞ

ꢘ ꢐ ꢙ

This voltage is monitored by the Current Sense Input

(Pin 7) and compared to a level derived from the Error Amp

output. The peak inductor current under normal operating

conditions is controlled by the voltage at Pin 13 where:

ꢓ

ꢎ ꢔꢚ ꢍ ꢘ ꢌ ꢖ

ꢎ

ꢔꢚ ꢓ ꢍ ꢘ ꢌ ꢖ

ꢀ

ꢶ

ꢆ

ꢎ

ꢔ

ꢚ

ꢓ

ꢔ

ꢚ

ꢓ

ꢻ

ꢌ

ꢑ

ꢗ

ꢹ

ꢓ

꣇ ꢀ ꢶ ꢁ ꢎ

ꢋ

ꢀ

ꢶ

ꢁ

V

ꢻ

(Pin 13) – 1.4 V

ꢔ

ꢚ

ꢓ

ꢡꢏ ꢫꢝꢷꢦ ꢘ ꢩꢐ

I

[

pk

ꢚ

3 R

ꢗ

ꢹ

S

ꢓ

ꢔꢚ ꢓ ꢿ ꢏ ꢩ ꢷ

ꢚ

ꢎ

ꢛ ꢜ ꢝꢷ ꢘ ꢌ

ꢀ

ꢆ

ꢡꢏ ꢫꢝꢷ

ꢚ

The Current Sense Comparator threshold is internally

clamped to 1.0 V. Therefore, the maximum peak switch

current is:

ꢓ

ꢋ

ꢄ

ꢶ

ꢁ

ꢎ

ꢡ ꢐ ꢬ ꢦ ꢩ

ꢓ

ꢔ ꢕ ꢖ

ꢔꢚ ꢓ ꢗꢐ ꢩ ꢕ ꢣ

1.0 V

ꢆ

ꢀ

I

[

pk(max)

R

S

ꢀ

ꢆ

ꢞ

ꢗꢐ ꢩ ꢕ ꢣ

ꢎ

ꢏ ꢜ

ꢞ

ꢡꢏ ꢫꢝꢷ ꢦ ꢘ ꢩ ꢐ

ꢎ

ꢓ

ꢀꢃ

ꢼ

ꢎ

ꢻ

ꢔ

Figure 35. Oscillator

ꢎ

ꢔ

ꢚ

ꢓ

ꢍ

ꢘ

ꢌ

ꢖ

ꢗ

ꢅ

ꢹ

ꢀ

ꢎ

ꢡ

ꢐ

ꢬ

ꢦ

ꢩ

ꢔ

ꢕ

ꢖ

ꢄ

ꢎ

ꢘ ꢐ ꢙ

ꢚ

ꢗ

ꢡ

ꢗ

ꢄ

ꢋ

ꢷ

ꢐ

ꢘ

ꢬ

ꢦ

ꢣ

ꢹ

ꢀ

ꢠ

ꢂ

ꢉ

ꢀ

ꢇ

ꢪ

ꢘ

ꢌ

ꢖ

ꢐ

ꢝ

ꢖ

ꢏ

ꢌ

ꢜ

ꢞ

ꢓ

ꢷ

ꢦ

ꢘ

ꢩ

ꢐ

ꢔ

ꢚ

ꢓ

ꢗ

ꢐ

ꢩ

ꢕ

ꢣ

ꢪ

ꢻ ꢦꢖ ꢝꢷ

꣄

ꢳ

ꢆ

ꢶ

ꢃ

ꢞ

ꢘ

ꢐ

ꢙ

ꢓ

ꢕ

ꢘ

ꢐ

ꢜ

ꢖ

ꢀ

ꢶ

ꢁ

ꢎ

ꢐ

ꢚ

ꢕ

ꢥ

ꢫ

ꢖ

ꢘ

ꢦ

ꢖ

ꢐ

ꢀ

ꢆ

ꢚ

ꢐ

ꢜ

ꢫ

ꢐ

ꢗ

ꢓ

ꢕ

ꢘ

ꢌ

ꢘ

ꢬ

ꢐ

ꢜ

ꢍ

ꢖ

ꢦ

ꢚ

ꢐ

ꢖ

ꢜ

ꢫ

ꢐ

ꢈ

ꢆ

ꢀ

ꢞ

ꢗ

ꢆ

ꢀ

꣈

ꢡ

ꢓ

ꢏ

ꢫ

ꢝ

ꢷ

ꢦ

ꢘ

ꢩ

ꢐ

ꢪ

ꢷ

ꢦ

ꢫ

ꢓ

ꢚ

ꢓ

ꢘ

ꢦ

ꢌ

ꢘ

ꢷ

ꢦ

ꢘ

ꢩ

ꢐ

ꢪ

ꢷ

ꢦ

ꢫ

ꢐ

ꢓ

ꢋ

Figure 34. Output Totem Pole

ꢡ

ꢏ

ꢫ

ꢝ

ꢷ

ꢦ

ꢘ

ꢩ

ꢐ

ꢞ

ꢗ

ꢐ

ꢩ

ꢕ

ꢣ

Series gate resistor, R2, will dampen any high frequency

oscillations caused by the MOSFET input capacitance and

any series wiring inductance in the gate−source circuit.

Diode D is required if the negative current into the output

drive pin exceeds 15 mA.

Figure 36. Simplified Block Oscillator

Two comparators are used to generate the sawtooth. They

compare the C voltage to the oscillator valley (1.6 V) and

T

peak reference (3.6 V) values. A latch (L

the oscillator state.

In addition to the charge and discharge cycles, a third state

can exist. This phase can be produced when, at the end of the

discharge phase, the oscillator has to wait for a

synchronization or demagnetization pulse before restarting.

) memorizes

disch

Oscillator

The oscillator is a very accurate sawtooth generator that

can work either in free mode or in synchronization mode. In

this second mode, the oscillator stops in the low state and

waits for a demagnetization or a synchronization pulse to

start a new charging cycle.

During this delay, the C voltage must remain equal to the

T

• The Sawtooth Generation:

oscillator valley value (]1.6 V). So, a third regulated

In the steady state, the oscillator voltage varies between

about 1.6 V and 3.6 V.

current source I

controlled by C

, is connected

Regul

OSC Regul

to C in order to perfectly compensate the (0.4 I ) current

T

ref

The sawtooth is obtained by charging and discharging an

external capacitor C (Pin 10), using two distinct current

sources = I

source that permanently supplies C .

T

The maximum duty cycle is 80%. Indeed, the on−time is

allowed only during the oscillator capacitor charge.

and I

. In fact, C is permanently

discharge T

charge

http://onsemi.com

372

MC44603A

Consequently:

= C x ꢃ V/I

charge

That is why, the MC44603A demagnetization detection

T

charge

consists of a comparator that can compare the auxiliary

winding voltage to a reference that is typically equal to

65 mV.

T

= C x ꢃ V/I

discharge

T discharge

where:

T

charge

is the oscillator charge time

ꢃ V is the oscillator peak−to−peak value

I

is the oscillator charge current

charge

ꢆ

ꢶꢈ

ꢂ

ꢎ

and

T

ꣅꢐ ꢘꢌ ꢓꢕ ꢘ ꢘꢐ ꢜꢖ

ꢡꢐ ꢖ ꢐꢝꢖ ꢏ ꢌꢜ

ꢎ

is the oscillator discharge time

ꢪ

ꢏ

ꢜ

ꢉ

discharge

I

is the oscillator discharge current

discharge

So, as f = 1 /(T

arrangement is not activated, the operating frequency can be

obtained from the graph in Figure 2.

+ T

) when the Regul

S

charge

discharge

ꢁ

ꢰ

ꢂ

ꢬ

ꢎ

ꢆ ꢶꢄ ꢄ ꢎ

NOTE: The output is disabled by the signal V

when

OSC prot

V

CT

is lower than 1.0 V (refer to Figure 31).

ꢔ

ꢜ

ꢰꢋ

ꢏꢬ

ꢐ

ꢔ

ꢙꢙ

ꢰ

ꢋ

ꢏꢬ

ꢐ

ꢡꢐ ꢦ ꢤꢰ ꢋ ꢏꢬ ꢐ

Synchronization and Demagnetization Blocks

To enable the output, the L

output must be low. Reset is activated by the L

latch complementary

OSC

Figure 38. Demagnetization Detection

output

disch

during the discharge phase. To restart, the L

(refer to Figure 35). To perform this, the demagnetization

signal and the synchronization must be low.

has to be set

OSC

A diode D has been incorporated to clamp the positive

applied voltages while an active clamping system limits the

negative voltages to typically −0.33 V. This negative clamp

level is sufficient to avoid the substrate diode switching on.

In addition to the comparator, a latch system has been

incorporated in order to keep the demagnetization block

output level low as soon as a voltage lower than 65 mV is

detected and as long as a new restart is produced (high level

on the output) (refer to Figure 39). This process prevents

ringing on the signal at Pin 8 from disrupting the

demagnetization detection. This results in a very accurate

demagnetization detection.

• Synchronization:

The synchronization block consists of two comparators

that compare the synchronization signal (external) to 0.7 and

3.7 V (typical values). The comparators’ outputs are

connected to the input of an AND gate so that the final output

of the block should be:

− high when 0.7 < SYNC < 3.7 V

− low in the other cases.

As a low level is necessary to enable the output,

synchronized low level pulses have to be generated on the

output of the synchronization block. If synchronization is

not required, the Pin 9 must be connected to the ground.

The demagnetization block output is also directly

connected to the output, disabling it during the

demagnetization phase (refer to Figure 34).

NOTE: The demagnetization detection can be inhibited by

connecting Pin 8 to the ground.

ꢄ

ꢶ

ꢈ

ꢎ

ꢔ

ꢫ

ꢝ

ꢏ

ꢣ

ꢦ

ꢖ

ꢌ

ꢘ

ꢚ

ꢇ

ꢛ

ꢜ

ꢝ

ꢔ

ꢫ

ꢝ

ꢏ

ꢣ

ꢦ

ꢖ

ꢌ

ꢘ

ꢔ

ꢕ

ꢖ

ꢍ

ꢕ

ꢖ

ꢗ

ꢹ

ꢴ

ꢕ

ꢙ

ꢐ

ꢘ

ꢡ

ꢚ

ꢐ

ꢬ

ꢦ

ꢩ

ꢕ

ꢖ

ꢍ

ꢕ

ꢖ

ꢴ

ꢕ

ꢙ

ꢐ

ꢘ

ꢆ

ꢶ

ꢈ

ꢎ

ꢓ

Figure 37. Synchronization

ꢠ

ꢐ

ꢬ

ꢩ

ꢦ

ꢍ

ꢖ

ꢏ

ꢨ

ꢩ

ꢐ

ꢯ

ꢝ

ꢫ

ꢖ

ꢏ

ꢖ

ꢨ

ꢐ

ꢬ

ꢎ

ꢡ

ꢐ

ꢬ

ꢦ

ꢩ

ꢔ

ꢕ

ꢖ

ꢓ

ꢣ

ꢦ

ꢏ

ꢜ

ꢚ

ꢛ

ꢉ

• Demagnetization:

ꢓ

ꢡ

ꢐ

ꢬ

In flyback applications, a good means to detect magnetic

saturation of the transformer core, or demagnetization,

consists in using the auxiliary winding voltage. This voltage

is:

ꢁ

ꢂ

ꢬ

ꢎ

ꢡ

Figure 39. Demagnetization Block

− negative during the on−time,

− positive during the off−time,

− equal to zero for the dead−time with generally some

− ringing (refer to Figure 38).

Standby

• Power Losses in a Classical Flyback Structure

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373

MC44603A

ꢓ

ꢠ

ꢣ ꢦꢬ ꢍ ꢏꢜ ꢩ

Also,

ꢐ

ꢖ

ꢑ

ꢌ

ꢘꢧ

ꢎ

ꢏ ꢜ

V

R

CS

S

ꢗ

ꢞ ꢓ ꢻ

I

+

pk

ꢵ

ꢯꢓ ꢻ ꢏꢜ ꢐ

where R is the resistor used to measure the power switch

S

ꢗ

ꢫ ꢖꢦ ꢘ ꢖ ꢕ ꢍ

current.

2

Thus, the input power is proportional to V

(V being

CS

ꢎ

ꢓꢓ

the internal current sense comparator input).

That is why the standby detection is performed by creating

a V threshold. An internal current source (0.4 x I ) sets

ꢀꢁꢂꢂꢃꢄꢅꢆ

CS

ref

ꢗ

ꢚ

the threshold level by connecting a resistor to Pin 12.

As depicted in Figure 41, the standby comparator

ꢚ

ꢜ

ꢕ

ꢥ

ꢐ

ꢘ

noninverting input voltage is typically equal to (3.0 x V

+

CS

Figure 40. Power Losses in a Classical

Flyback Structure

V ) while the inverter input value is (V

+ V ).

F

R P Stby

F

ꢔ

ꢫ

ꢝ

ꢏ

ꢷ

ꢣ

ꢦ

ꢘ

ꢖ

ꢩ

ꢌ

ꢐ

ꢘ

ꢎ

ꢘ ꢐ ꢙ ꢘ ꢐ ꢙ

ꢎ

ꢘ ꢐ ꢙ ꢘ ꢐ ꢙ

ꢡ

ꢏꢫ

In a classical flyback (as depicted in Figure 40), the

standby losses mainly consist of the energy waste due to:

ꢓ

ꢕꢘ

ꢘ

ꢐ

ꢜ

ꢖ

ꢆ ꢶ ꢁ ꢞ

ꢘ ꢐ ꢙ

ꢆ

ꢶꢃ

ꢞ

ꢆ ꢶ ꢉ ꢞ

ꢘ ꢐ ꢙ

ꢎ

ꢘ ꢐ ꢙ

ꢆ ꢶ ꢅꢂ

ꢞ

ꢢ ꢚ ꢖꢥ ꢛ

− the startup resistor R

→ P

ꢗ

startup

ꢆ ꢶꢅ ꢞ

ꢘ ꢐ ꢙ

ꢪ

ꢚ

ꢖ

ꢥ

ꢛ

ꢆ

ꢀ

− the consumption of the IC and the power

− switch control

ꢀ

ꢅ

ꢀ

ꢆ

ꢓ

ꢚ

ꢖ

ꢥ

ꢛ

→ P

control

− the inrush current limitation resistor R

ICL

ꢀ

ꢄ

ꢞ

ꢡꢏ ꢫꢝꢷ ꢦ ꢘ ꢩ ꢐ

ꢡ

ꢏ

ꢫ

ꢝ

ꢷ

ꢦ

ꢘ

ꢩ

ꢐ

ꢱ

ꢅ

− the switching losses in the power switch → P

− the snubber and clamping network

SW

ꢮ

ꢗ

ꢯ ꢬ ꢍ ꢔꢕ ꢖ

ꢅ

ꢀ

ꢗ

ꢓ

ꢶ

ꢚ

ꢶ

ꢓ

ꢌ

ꢬ

ꢍ

ꢦ

ꢘ

ꢦ

ꢖ

ꢌ

ꢘ

→ P

SN−CLN

ꢓ

ꢕ

ꢘ

ꢐ

ꢜ

ꢖ

ꢳ

ꢏ

ꢘ

ꢌ

ꢘ

ꢸ

ꢅ

P

startup

is nearly constant and is equal to:

ꢗ

2

ǒ

Ǔ

(V –V ) ńR

in CC startup

Figure 41. Standby

P

ICL

only depends on the current drawn from the mains.

Losses can be considered constant. This waste of energy

decreases when the standby losses are reduced.

The V

threshold level is typically equal to

)/3] and if the corresponding power threshold is

CS

[(V

R P Stby

P

increases when the oscillator frequency is

control

labelled P

:

thL

increased (each switching requires some energy to turn on

the power switch).

V

2

R P Stby

_{+ 0.5 x L x}ǒ Ǔ

P

thL

x f

S

3.0 R

P

SW

and P

are proportional to the switching

S

SN−CLN

frequency.

And as:

Consequently, standby losses can be minimized by

decreasing the switching frequency as much as possible.

The MC44603A was designed to operate at a standby

frequency lower than the normal working one.

• Standby Power Calculations with MC44603A

During a switching period, the energy drawn by the

transformer during the on−time to be transferred to the

output during the off−time, is equal to:

V

+ R

x 0.4 x I

ref

R P Stby

P Stby

V

ref

R

ref

x 0.4 x

R P Stby

10.6 x R x R

P

thL

S

ref

_xǸ

R

+

P Stby

V

ref

L x f

S

Thus, when the power drawn by the converter decreases,

decreases and when V becomes lower than [V

V

CS

CS−th

1

2

E + x L x I

pk

x (V

)/3], the standby mode is activated. This results in

2

R P Stby

an oscillator discharge current reduction in order to increase

the oscillator period and to diminish the switching

where:

− L is the transformer primary inductor,

− l is the inductor peak current.

frequency. As it is represented in Figure 41, the (0.8 x I

)

ref

pk

current source is disconnected and is replaced by a lower

value one (0.25 x I ).

Input power is labelled P :

in

F Stby

2

x f

pk

S

P

in

+ 0.5 x L x I

Where: I

= V /R

ref F Stby

F Stby

where f is the normal working switching frequency.

S

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374

MC44603A

In order to prevent undesired mode switching when power

is close to the threshold value, a hysteresis that is

ꢪ

ꢎ

ꢏ ꢜ ꢀ ꢀ

ꢎꢌ ꢣꢖ ꢦ ꢩꢐ

ꢓ

ꢋ

ꢊ ꢪꢏꢜ ꢀ ꢆ ꢒ

proportional to V

is incorporated creating a second

R P Stby

V

CS

threshold level that is equal to [2.5 x (V

)/3].

ꢡ

R P Stby

ꢬ ꢦ ꢲ

When the standby comparator output is high, a second

current source (0.6 x I ) is connected to Pin 12.

Finally, the standby mode function can be shown

graphically in Figure 42.

ref

Figure 44. Maximum Duty Cycle Control

Using the internal current source (0.4 I ), the Pin 11

ref

voltage can easily be set by connecting a resistor to this pin.

If a capacitor is connected to Pin 11, the voltage increases

from 0 to its maximum value progressively (refer to Figure

45), thereby, implementing a soft−start. The soft−start

ꢪ

ꢏ ꢜ

ꢙ

ꢚ

capacitor is discharged internally when the V (Pin 1)

CC

voltage drops below 9.0 V.

ꢠ

꣄

ꢌ

ꢘ

ꢬ ꢦꢣ

ꢪ ꢏꢜ ꢀꢀ

ꢗ

ꢓ

ꢆ

ꢌ

ꢜ

ꢐ

ꢝ

ꢖ

ꢐꢤ

ꢖ

ꢌ

ꢪ

ꢏꢜ

ꢀ

ꢎ

ꢀ

ꢓ

ꢱ

ꢗ

ꢙ

ꢧꢏꢜ

ꢩ

ꢚ ꢖꢥ ꢛ

ꢎ

ꢗꢞ

ꢞ

ꢺ

ꢶ

ꢃ

ꢞ

ꣅ

ꢘ ꢐ ꢙ

ꣅ

ꢗ

ꢞ

ꢪ

ꢖ ꢷ ꢿ

ꢄ ꢺ ꢗ ꢓ

ꢚ

ꢖꢦ ꢜꢤꢥ ꢛ

ꢪ

ꢖ ꢷ ꢻ

ꢎ

ꢓ

ꢚ

꣉ꢊ

ꢎ

ꢒ

ꢱ

ꢄ

꣊

ꢅ

ꢶ

ꢂ

ꢲ

꣉

ꢊ

ꢎ

ꢒꢱ ꢄ꣊

ꢗ ꢪ ꢚ ꢖꢥ ꢛ

ꢀ

ꢗ

ꢪ

ꢚ

ꢖ

ꢥ

ꢛ

Figure 45. Different Possible Uses of Pin 11

Figure 42. Dynamic Mode Change

If no external component is connected to Pin 11, an

internal zener diode clamps the Pin 11 voltage to a value V

that is higher than the oscillator peak value, disabling

Z

This curve shows that there are two power threshold

levels:

− the low one:

fixed by V

soft−start and maximum duty cycle limitation.

P

thL

R P Stby

Foldback

− the high one:

As depicted in Figures 33 and 49, the foldback input (Pin

5) can be used to reduce the maximum V value, providing

foldback protection. The foldback arrangement is a

programmable peak current limitation.

f

CS

Stby

2

P

+ (2.5) x P

thL

x

f

thH

f

S

Stby

f

If the output load is increased, the required converter peak

P

+ 6.25 x P

x

thL

current becomes higher and V increases until it reaches its

S

CS

maximum value (normally, V

= 1.0 V).

CS max

Maximum Duty Cycle and Soft−Start Control

Maximum duty cycle can be limited to values less than

Then, if the output load keeps on increasing, the system is

unable to supply enough energy to maintain the output

voltages in regulation. Consequently, the decreasing output

can be applied to Pin 5, in order to limit the maximum peak

current. In this way, the well known foldback characteristic

can be obtained (refer to Figure 46).

80% by utilizing the D

and soft−start control. As

max

depicted in Figure 43, the Pin 11 voltage is compared to the

oscillator sawtooth.

ꢎ

ꢘ ꢐ ꢙ

ꢔ

ꢕ

ꢖ

ꢍ

ꢕ

ꢖ

ꢓ

ꢌ

ꢜ

ꢖ

ꢘ

ꢌ

ꢣ

ꢆꢶ ꢃ ꢞ

ꢘ ꢐ ꢙ

ꢀ

ꢔ

ꢕ

ꢖ

ꢍ

ꢕ

ꢖ

ꢡ

ꢘ

ꢏ

ꢨ

ꢐ

ꢓ

ꢡ

ꢬ

ꢦ

ꢲ

ꢬ

ꢦ

ꢲ

ꢡ

ꢅ

ꢶ

ꢃ

ꢎ

ꣅ

ꢎ

ꢔ

ꢚ

ꢓ

ꢚ

ꢌ

ꢙ

ꢖ

ꢰ

ꢚ

ꢖ

ꢦ

ꢘ

ꢖ

ꢔ

ꢫ

ꢝ

ꢏ

ꢣ

ꢦ

ꢖ

ꢌ

ꢘ

ꢓ

ꢦ

ꢍ

ꢦ

ꢝ

ꢏ

ꢖ

ꢌ

ꢘ

Figure 43. D_maxand Soft−Start

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375

MC44603A

ꢞ

Undervoltage Lockout Section

ꢎ

ꢌ ꢕ ꢖ

ꢍ ꢧ ꢬ ꢦ ꢲ

ꢎ

ꢔ

ꢗ

ꢘ ꢐ ꢙ

ꢢ ꢚ ꢖꢥ ꢛ

ꢠ

ꢌ

ꢬ

ꢏ

ꢜ

ꢦ

ꢣ

ꢪ

ꢏ

ꢜ

ꢀ

ꢂ

ꢪ

ꢏ

ꢜ

ꢀ

ꢁ

ꢎ

ꢘ

ꢐ

ꢙ

ꢐ

ꢜ

ꢦ

ꢥ

ꢣ

ꢐ

ꢠꢐ ꢑ ꢚ ꢖꢦꢘ ꢖꢕ ꢍ

ꢚ ꢐꢭꢕ ꢐꢜꢝꢐ ꢞ ꢜꢏ ꢖꢏ ꢦꢖ ꢐꢤ

ꢎ

ꢓ

ꢫꢖ ꢦ ꢘ ꢖ ꢕ ꢍ

ꢎ

ꢓ ꢓ

ꢀ

ꢗ

ꢐ

ꢙ

ꢐ

ꢩ

ꢘ

ꢐ

ꢜ

ꢦ

ꢝ

ꢜ

ꢐ

ꢤ

ꢴ

ꢓ

ꢣ

ꢕ

ꢌ

ꢘ

ꢝ

ꢘ

ꢧ

ꢐ

꣈

ꢜ

ꢎ

ꢀ

ꢆ

ꢤ ꢏ ꢫꢦ ꢥ ꢣ ꢐ ꢅ

ꢞ

ꢌ ꢕ ꢖ

ꢎ

ꢌ

ꢣ

ꢖ

ꢦ

ꢖ

ꢚ ꢌꢕ ꢘ ꢝꢐꢫ ꢟ ꢐ ꢜꢐ ꢘꢦ ꢖꢌ ꢘ

ꢀ

ꢆ

ꢔ

ꢨ

ꢐ

ꢘ

ꢣ

ꢌ

ꢦ

ꢤ

ꢊ

ꢎ ꢾ ꢞ ꢾ ꢶ ꢶ ꢶꢒ

ꢘ ꢐ ꢙ ꢘ ꢐ ꢙ

ꢎ

ꢚ ꢖ ꢦꢘ ꢖ ꢕꢍ

ꢤ ꢏ ꢫꢦ ꢥ ꢣ ꢐ ꢅ

ꢈ

ꢶ

ꢂ

ꢎ

ꢀ ꢃꢶ ꢂ ꢎ

Figure 46. Foldback Characteristic

ꢓ

ꢼ ꢎ ꢻ ꢔꢀ

ꢼ

ꢚ

ꢎ ꢻ ꢔ ꢀ

NOTE: Foldback is disabled by connecting Pin 5 to V

Overvoltage Protection

The overvoltage arrangement consists of a comparator

.

CC

ꢊ

ꢖꢌ

ꢌꢙ

ꢖ

ꢰ

ꢚ

ꢖ

ꢦꢘ

ꢖ

ꢒ

ꢎ

ꢇ ꢶ ꢆ ꢎ

ꢤ ꢏ ꢫꢦ ꢥ ꢣ ꢐ ꢀ

that compares the Pin 6 voltage to V (2.5 V) (refer to

ref

Figure 47).

Figure 48. V_CCManagement

If no external component is connected to Pin 6, the

comparator noninverting input voltage is nearly equal to:

As depicted in Figure 48, an undervoltage lockout has

been incorporated to guarantee that the IC is fully functional

before allowing system operation.

2.0 kꢂ

ǒ

Ǔ_{x V}

CC

11.6 kꢂ ) 2.0 kꢂ

This block particularly, produces V (Pin 16 voltage) and

ref

The comparator output is high when:

I

that is determined by the resistor R connected between

ref

2.0 kꢂ

Pin 16 and the ground:

ǒ

Ǔ

x V

w 2.5 V

CC

11.6 kꢂ ) 2.0 kꢂ

V

ref

R

ref

I

+

where V + 2.5 V (typically)

ref

à V

w 17 V

CC

A delay latch (2.0 ꢀs) is incorporated in order to sense

overvoltages that last at least 2.0 ꢀs.

Another resistor is connected to the Reference Block:

that is used to fix the standby frequency.

R

F Stby

If this condition is achieved, V

, the delay latch

OVP out

In addition to this, V is compared to a second threshold

CC

output, becomes high. As this level is brought back to the

input through an OR gate, V remains high (disabling

level that is nearly equal to 9.0 V (V

). UVLO1 is

disable1

OVP out

generated to reset the maximum duty cycle and soft−start

block disabling the output stage as soon as V becomes

the IC output) until V is disabled.

ref

CC

Consequently, when an overvoltage longer than 2.0 ꢀs is

lower than V

. In this way, the circuit is reset and made

disable1

detected, the output is disabled until V is removed and

CC

ready for the next startup, before the reference block is

disabled (refer to Figure 30). Finally, the upper limit for the

minimum normal operating voltage is 9.4 V (maximum

then re−applied.

The V is connected after V has reached steady state

CC

ref

in order to limit the circuit startup consumption.

The overvoltage section is enabled 5.0 ꢀs after the

value of V

) and so the minimum hysteresis is 4.2 V.

disable1

((V

)

= 13.6 V).

stup−th min

regulator has started to allow the reference V to stabilize.

ref

The large hysteresis and the low startup current of the

MC44603A make it ideally suited for off−line converter

applications where efficient bootstrap startup techniques are

required.

By connecting an external resistor to Pin 6, the threshold

V

CC

level can be changed.

ꢎ

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Figure 47. Overvoltage Protection

http://onsemi.com

376

MC44603A

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* Diode D15 is required if the negative current into the output pin exceeds 15 mA.

Figure 49. 250 W Input Power Off−Line Flyback Converter with MOSFET Switch

http://onsemi.com

377

MC44603A

250 W Input Power Fly−Back Converter

185 V − 270 V Mains Range

MC44603AP & MTP6N60E

Tests

Conditions

Results

Line Regulation

V

= 185 VAC to 270 VAC

in

F

= 50 Hz

mains

150 V

130 V

114 V

7.0 V

I

= 0.6 A

10 mV

20 mV

out

= 2.0 A

Load Regulation

150 V

V

out

= 220 VAC

= 0.3 A to 0.6 A

in

I

50 mV

Cross Regulation

V

= 220 VAC

in

out

I

(150 V) = 0.6 A

(30 V) = 0 A to 2.0 A

(14 V) = 2.0 A

(7.0 V) = 2.0 A

150 V

< 1.0 mV

81%

Efficiency

V

= 220 VAC, P = 250 W

in

Standby Mode

P input

= 220 VAC, P = 0 W

3.3 W

in

out

Switching Frequency

Output Short Circuit

Startup

20 kHz fully stable

Safe on all outputs

VAC = 160 V

P

= 270 W

out (max)

= 250 W

in

DEVICE ORDERING INFORMATION

†

Device

Operating Temperature Range

Package

PDIP−16

SOIC−16

Shipping

MC44603P

25 Units / Rail

47 Units / Rail

MC44603ADW

MCRR602ADWR2

MC44603APG

TA = −25°C to +85°C

1000 / Tape & Reel

25 Units / Rail

SOIC−16

(Pb−Free)

†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.

http://onsemi.com

378


型号：	MC44603PG
厂家：	ONSEMI
描述：	0.75A SWITCHING CONTROLLER, 250kHz SWITCHING FREQ-MAX, PDIP16, PLASTIC, DIP-16 开关光电二极管
文件：	总21页 (文件大小：390K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

MC44603PG [ONSEMI]

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