mc44608-d.pdf

MC44608

Few External Components

Reliable and Flexible

SMPS Controller

The MC44608 is a high performance voltage mode controller

designed for off−line converters. This high voltage circuit that

integrates the startup current source and the oscillator capacitor,

requires few external components while offering a high flexibility and

reliability.

The device also features a very high efficiency standby management

consisting of an effective Pulsed Mode operation. This technique

enables the reduction of the standby power consumption to

approximately 1.0 W while delivering 300 mW in a 150 W SMPS.

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General Features

•

PDIP−8

P SUFFIX

CASE 626

Integrated Startup Current Source

•

Lossless Off−Line Startup

•

Direct Off−Line Operation

•

Fast Startup

MARKING DIAGRAM

•

Flexibility

•

Duty Cycle Control

•

Undervoltage Lockout with Hysteresis

•

On Chip Oscillator Switching Frequency 40 or 75

MC44608Pxx

AWL

YYWWG

•

Secondary Control with Few External Components

•

Pb−Free Packages are Available*

Protections

•

Maximum Duty Cycle Limitation

MC44608Pxx

= Device Code

xx = 40 or 75

•

Cycle by Cycle Current Limitation

= Assembly Location

•

Demagnetization (Zero Current Detection) Protection

= Wafer Lot

•

“Over V CC Protection” Against Open Loop

= Year

•

= Work Week

Programmable Low Inertia Over Voltage Protection

Against Open Loop

= Pb−Free Package

•

Internal Thermal Protection

PIN CONNECTIONS

SMPS Controller

•

Pulsed Mode Techniques for a Very High Efficiency

Low Power Mode

Demag

V i

•

Lossless Startup

I sense

•

Low dV/dT for Low EMI Radiations

Control Input

V CC

GND

Driver

(Top View)

ORDERING INFORMATION

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

download the ON Semiconductor Soldering and Mounting Techniques

Reference Manual, SOLDERRM/D.

See detailed ordering and shipping information in the package

dimensions section on page 2 of this data sheet.

Publication Order Number:

MC44608/D

Semiconductor Components Industries, LLC, 2006

May, 2006 − Rev. 8

MC44608

Demag

DMG

−

UVLO2

Startup

50 mV

/20 mV

9 mA

Source

>24 A

>120 A

Latched off Phase

Demag

Logic

Startup Phase

Management

Switching Phase

Latched off

Phase

Output

Startup

Phase Switching

Phase

OVP

UVLO1

2 S

Startup

Phase

UVLO2

200 A

OUT Disable

DMG

OSC

Buffer

Enable

Clock

Standby

Thermal

Standby

OSC

Shutdown

Driver

−

PWM

Management

PWM

Latc h

NOC

Leading Edge

VPWM

GND

Output

Blanking

−

Latched off Phase

Standby

Isense

Regulation

Block

1 V

4 kHz Filter

Control

Switching Phase

Input

Figure 1. Representative Block Diagram

ORDERING INFORMATION

Device

Switching Frequency

Package

Shipping

MC44608P40

PDIP−8

50 Units / Rail

40 kHz

MC44608P40G

PDIP−8

(Pb−Free)

50 Units / Rail

MC44608P75

PDIP−8

50 Units / Rail

75 kHz

MC44608P75G

PDIP−8

(Pb−Free)

50 Units / Rail

MAXIMUM RATINGS

Rating

Symbol

Value

Unit

Total Power Supply Current

I CC

Output Supply Voltage with Respect to Ground

V CC

All Inputs except Vi

V inputs

−1.0 to +16

Line Voltage Absolute Rating

V i

500

Recommended Line Voltage Operating Condition

V i

400

Power Dissipation and Thermal Characteristics

Maximum Power Dissipation at T A = 85

P D

600

Thermal Resistance, Junction−to−Air

100

C/W

Operating Junction Temperature

T J

150

Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the

Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect

device reliability.

Operating Ambient Temperature

T A

−25 to +85

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MC44608

ELECTRICAL CHARACTERISTICS

Characteristic

Symbol

Min

Typ

Max

Unit

OUTPUT SECTION

Output Resistor

Sink Resistance

R OL

5.0

8.5

Source Resistance

R OH

−

Output Voltage Rise Time (from 3.0 V up to 9.0 V) (Note 1)

t r

−

Output Voltage Falling Edge Slew−Rate (from 9.0 V down to 3.0 V) (Note 1)

t f

−

CONTROL INPUT SECTION

Duty Cycle @ I pin3 = 2.5 mA

d 2mA

−

2.0

Duty Cycle @ I pin3 = 1.0 mA

d 1mA

Control Input Clamp Voltage (Switching Phase) @ I pin3 = −1.0 mA

4.75

5.0

5.25

Latched Phase Control Input Voltage (Standby) @ I pin3 = +500

V LP−stby

3.4

3.9

4.3

Latched Phase Control Input Voltage (Standby) @ I pin3 = +1.0 mA

V LP−stby

2.4

3.0

3.7

current sense section

Maximum Current Sense Input Threshold

V CS−th

0.95

1.0

1.05

Input Bias Current

I B−cs

−1.8

−

1.8

Standby Current Sense Input Current

I CS−stby

180

200

220

Startup Phase Current Sense Input Current

I CS−stup

180

200

220

Propagation Delay (Current Sense Input to Output @ V TH T MOS = 3.0 V)

T PLH(In/Out)

−

220

−

Leading Edge Blanking Duration

MC44608P40

T LEB

−

480

−

Leading Edge Blanking Duration

MC44608P75

T LEB

−

250

−

Leading Edge Blanking + Propagation Delay

MC44608P40

T DLY

500

680

900

Leading Edge Blanking + Propagation Delay

MC44608P75

T DLY

370

470

570

oscillator section

Normal Operation Frequency MC44608P40

f osc

kHz

Normal Operation Frequency MC44608P75

f osc

kHz

Maximum Duty Cycle @ f = f osc

d max

OVERvoltage section

Quick OVP Input Filtering (R demag = 100 k

)

T filt

−

250

−

Propagation Delay (I demag > I ovp to output low)

T PHL(In/Out)

−

2.0

−

Quick OVP Current Threshold

I OVP

105

120

140

Protection Threshold Level on V CC

V CC−OVP

14.8

15.3

15.8

Minimum Gap Between V CC−OVP and V stup−th

V CC−OVP − V stup

1.0

−

1. This parameter is measured using 1.0 nF connected between the output and the ground.

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MC44608

ELECTRICAL CHARACTERISTICS (V CC = 12 V, for typical values T A = 25

C, for min/max values T A = −25

C to +85

C unless

otherwise noted) (Note 2)

Characteristic

Symbol

Min

Typ

Max

Unit

DEMAGNETIZATION DETECTION section (note 3)

Demag Comparator Threshold (V pin1 increasing)

V dmg−th

Demag Comparator Hysteresis (Note 4)

H dmg

−

Propagation Delay (Input to Output, Low to High)

t PHL(In/Out)

−

300

−

Input Bias Current (V demag = 50 mV)

I dem−lb

−0.6

−

Negative Clamp Level (I demag = −1.0 mA)

V cl−neg−dem

−0.9

−0.7

−0.4

Positive Clamp Level @ I demag = 125

V cl−pos−dem−H

2.05

2.3

2.8

Positive Clamp Level @ I demag = 25

V cl−pos−dem−L

1.4

1.7

1.9

OVERTEMPERATURE section

Trip Level Over Temperature

T high

−

160

−

Hysteresis

T hyst

−

STANDBY MAXIMUM CURRENT REDUCTION section

Normal Mode Recovery Demag Pin Current Threshold

I dem−NM

K FACTORS SECTION FOR PULSED MODE OPERATION

I CCS / I stup

MC44608P40

10 x K1

2.4

2.9

3.8

−

I CCS / I stup

MC44608P75

10 x K1

2.8

3.3

4.2

−

10 3 x K2

I CCL / I stup

−

10 2 x K sstup

(V stup − UVLO2) / (V stup − UVLO1)

1.8

2.2

2.6

−

10 2 x K sl

(UVLO1 − UVLO2) / (V stup − UVLO1)

120

150

−

10 6 x Y cstby

I CS / V csth

175

198

225

−

Demag ratio I ovp / I dem NM

Dmgr

3.0

4.7

5.5

−

(V3 1.0 mA − V3 0.5 mA ) / (1.0 mA − 0.5 mA)

−

1800

−

V control Latchoff

−

4.8

−

SUPPLY SECTION

Minimum Startup Voltage

V ilow

−

V CC Startup Voltage

V stup−th

12.5

13.1

13.8

Output Disabling V CC Voltage After Turn On

V uvlo1

9.5

10.5

Hysteresis (V stup−th − V uvlo1 )

H stup−uvlo1

−

3.1

−

V CC Undervoltage Lockout Voltage

V uvlo2

6.2

6.6

7.0

Hysteresis (V uvlo1 − V uvlo2 )

H uvlo1−uvlo2

−

3.4

−

Absolute Normal Condition V CC Start Current @ (V i = 100 V) and

(V CC = 9.0 V)

−(I CC )

7.0

9.5

12.8

Switching Phase Supply Current (no load)

MC44608P40

MC44608P75

I CCS

2.0

2.4

2.6

3.2

3.6

4.0

Latched Off Phase Supply Current

I CC−latch

0.3

0.5

0.68

Hiccup − 10 − %

2. Adjust V CC above the startup threshold before setting to 12 V. Low duty cycle pulse techniques are used during test to maintain junction

temperature as close to ambient as possible.

3. This function can be inhibited by connecting pin 1 to GND.

4. Guaranteed by design (non tested).

Hiccup Mode Duty Cycle (no load)

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MC44608

PIN FUNCTION DESCRIPTION

Name

Description

Demag

The Demag pin offers 3 different functions: Zero voltage crossing detection (50 mV), 24

A current detection

and 120

A current detection. The 24

A level is used to detect the secondary reconfiguration status and the

120

A level to detect an Over Voltage status called Quick OVP.

I sense

The Current Sense pin senses the voltage developed on the series resistor inserted in the source of the power

MOSFET. When I sense reaches 1.0 V, the Driver output (pin 5) is disabled. This is known as the Over Current

Protection function. A 200

A current source is flowing out of the pin 3 during the startup phase and during the

switching phase in case of the Pulsed Mode of operation. A resistor can be inserted between the sense resistor

and the pin 2, thus a programmable peak current detection can be performed during the SMPS standby mode.

Control Input

A feedback current from the secondary side of the SMPS via the Opto−coupler is injected into this pin. A

resistor can be connected between this pin and GND to allow the programming of the Burst duty cycle during

the standby mode.

Ground

This pin is the ground of the primary side of the SMPS.

Driver

The current and slew rate capability of this pin are suited to drive Power MOSFETs.

V CC

This pin is the positive supply of the IC. The driver output gets disabled when the voltage becomes higher than

15 V and the operating range is between 6.6 V and 13 V. An intermediate voltage level of 10 V creates a

disabling condition called Latched Off phase.

This pin is to provide isolation between the V i pin 8 and the V CC pin 6.

V i

This pin can be directly connected to a 500 V voltage source for startup function of the IC. During the startup

phase a 9.0 mA current source is internally delivered to the V CC pin 6 allowing a rapid charge of the V CC

capacitor. As soon as the IC starts−up, this current source is disabled.

OPERATING DESCRIPTION

Regulation

The switch S3 is closed in standby mode during the

Latched Off Phase while the switch S2 remains open. (See

section PULSED MODE DUTY CYCLE CONTROL).

The resistor Rdpulsed (Rduty cycle burst) has no effect on

the regulation process. This resistor is used to determine the

burst duty cycle described in the chapter “Pulsed Duty Cycle

Control” on page 8.

V LP− s tby

V CC

1 0

Stand−by

Latched off Phase

Control

Input

1 0

Switching Phase

PWM Latch

The MC44608 works in voltage mode. The on−time is

controlled by the PWM comparator that compares the

oscillator sawtooth with the regulation block output (refer to

the block diagram on page 2).

The PWM latch is initialized by the oscillator and is reset

by the PWM comparator or by the current sense comparator

in case of an over current. This configuration ensures that

only a single pulse appears at the circuit output during an

oscillator cycle.

V dd

PWM

Comparator

Regulation

Output

5 V

4 kHz

Filter

1.6 V

Figure 2. Regulator

The pin 3 senses the feedback current provided by the

Opto coupler. During the switching phase the switch S2 is

closed and the shunt regulator is accessible by the pin 3. The

shunt regulator voltage is typically 5.0 V. The dynamic

resistance of the shunt regulator represented by the zener

diode is 20

Current Sense

The inductor current is converted to a positive voltage by

inserting a ground reference sense resistor R Sense in series

with the power switch.

The maximum current sense threshold is fixed at 1.0 V.

The peak current is given by the following equation:

. The gain of the Control input is given on

Figure 11 which shows the duty cycle as a function of the

current injected into the pin 3.

A 4.0 kHz filter network is inserted between the shunt

regulator and the PWM comparator to cancel the high

frequency residual noise.

R sense (

Ipk max

) (A)

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