MC44608P100_技术文档

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.

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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.

8

1

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

 Secondary Control with Few External Components

 These are Pb--Free Devices*

8

MC44608Pxx

AWL

YYWWG

1

Protections

 Maximum Duty Cycle Limitation

 Cycle by Cycle Current Limitation

 Demagnetization (Zero Current Detection) Protection

 “Over V_CCProtection” Against Open Loop

 Programmable Low Inertia Over Voltage Protection

Against Open Loop

MC44608Pxx = Device Code

xx = 40 or 75

A

= Assembly Location

= Wafer Lot

WL

YY

WW

G

= Year

= Work Week

= Pb--Free Package

 Internal Thermal Protection

PIN CONNECTIONS

SMPS Controller

 Pulsed Mode Techniques for a Very High Efficiency

Low Power Mode

 Lossless Startup

Demag

1

2

8

7

V

i

I

sense

 Low dV/dT for Low EMI Radiations

Control Input

GND

3

4

6

5

V

CC

Driver

(Top View)

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

download the ON Semiconductor Soldering and Mounting Techniques

Reference Manual, SOLDERRM/D.

ORDERING INFORMATION

Seedetailedorderingandshippinginformationinthepackage

dimensions section on page 2 of this data sheet.



Semiconductor Components Industries, LLC, 2010

1

Publication Order Number:

December, 2010 -- Rev. 10

MC44608/D

MC44608

Demag

Vi

1

8

DMG

+

--

UVLO2

Startup

Source

50 mV

/20 mV

9 mA

>24 mA

>120 mA

Latched off Phase

Startup Phase

Demag

Logic

V

CC

Management

6

Switching Phase

Latched off

Phase

V

CC

Output

OVP

UVLO1

UVLO2

Startup

2mS

Phase

Startup

Phase

Switching

Phase

&

200 mA

OUT Disable

DMG

1

0

OSC

S1

Buffer

5

4

Enable

Clock

&

Thermal

Shutdown

&

S

Standby

Management

OSC

&

Driver

GND

Standby

+

PWM

Latch

PWM

--

&

R

OC NOC

Output

Q

Leading Edge

Blanking

VPWM

+

2

Latched off Phase

Standby

CS

&

Isense

--

S2

S3

Regulation

Block

3

1 V

4 kHz Filter

Switching Phase

Control

Input

Figure 1. Representative Block Diagram

ORDERING INFORMATION

Device

Switching Frequency

Package

Shipping

MC44608P40G

PDIP--8

(Pb--Free)

50 Units / Rail

40 kHz

MC44608P75G

PDIP--8

(Pb--Free)

50 Units / Rail

75 kHz

MAXIMUM RATINGS

Rating

Symbol

Value

30

Unit

mA

V

Total Power Supply Current

I

CC

Output Supply Voltage with Respect to Ground

All Inputs except Vi

V

16

CC

V

inputs

--1.0 to +16

500

V

Line Voltage Absolute Rating

V

i

V

Recommended Line Voltage Operating Condition

Power Dissipation and Thermal Characteristics

V

i

400

V

Maximum Power Dissipation at T = 85C

Thermal Resistance, Junction--to--Air

P

600

100

mW

C/W

A

D

R

θ

JA

Operating Junction Temperature

T

150

C

J

Operating Ambient Temperature

T

A

-- 2 5 t o + 8 5

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.

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2

MC44608

ELECTRICAL CHARACTERISTICS

Characteristic

Symbol

Min

Typ

Max

Unit

OUTPUT SECTION

Output Resistor

Ω

Sink Resistance

R

5.0

--

8.5

15

50

15

--

OL

Source Resistance

R

OH

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

t

--

ns

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

= 2.5 mA

= 1.0 mA

d

--

2.0

48

%

V

pin3

2mA

1mA

36

43

Control Input Clamp Voltage (Switching Phase) @ I

Latched Phase Control Input Voltage (Standby) @ I

current sense section

= --1.0 mA

= +500 mA

= +1.0 mA

4.75

3.4

2.4

5.0

3.9

3.0

5.25

4.3

3.7

pin3

V

LP--stby

V

Maximum Current Sense Input Threshold

Input Bias Current

V

0.95

-- 1 . 8

180

--

1.0

--

1.05

1.8

220

--

V

CS--th

I

mA

ns

B--cs

Standby Current Sense Input Current

Startup Phase Current Sense Input Current

I

200

220

480

250

680

470

CS--stby

CS--stup

I

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

T

PLH(In/Out)

TH

Leading Edge Blanking Duration

MC44608P40

MC44608P75

MC44608P40

MC44608P75

T

--

LEB

DLY

Leading Edge Blanking Duration

--

Leading Edge Blanking + Propagation Delay

oscillator section

500

370

900

570

Normal Operation Frequency MC44608P40

Normal Operation Frequency MC44608P75

f

36

68

78

40

75

82

44

82

86

kHz

%

osc

max

Maximum Duty Cycle @ f = f

OVERvoltage section

d

osc

Quick OVP Input Filtering (R

= 100 kΩ)

T

--

250

2.0

120

15.3

--

ns

ms

mA

V

demag

filt

Propagation Delay (I

> I

to output low)

ovp

T

--

demag

PHL(In/Out)

Quick OVP Current Threshold

Protection Threshold Level on V

I

105

14.8

1.0

140

15.8

--

OVP

V

CC

CC--OVP

Minimum Gap Between V

and V

V

-- V

stup

V

CC--OVP

stup--th

CC--OVP

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

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3

MC44608

ELECTRICAL CHARACTERISTICS (V = 12 V, for typical values T = 25C, for min/max values T = --25C to +85C unless

CC

A

otherwise noted) (Note 2)

Characteristic

DEMAGNETIZATION DETECTION section (note 3)

Demag Comparator Threshold (V increasing)

Symbol

Min

Typ

Max

Unit

V

30

--

50

30

69

--

mV

ns

mA

V

pin1

dmg--th

Demag Comparator Hysteresis (Note 4)

H

dmg

PHL(In/Out)

Propagation Delay (Input to Output, Low to High)

t

--

300

--

Input Bias Current (V

= 50 mV)

I

-- 0 . 6

-- 0 . 9

2.05

1.4

--

demag

dem--lb

Negative Clamp Level (I

= --1.0 mA)

V

-- 0 . 7

2.3

1.7

-- 0 . 4

2.8

1.9

demag

cl--neg--dem

Positive Clamp Level @ I

= 125 mA

= 25 mA

V

demag

cl--pos--dem--H

V

cl--pos--dem--L

OVERTEMPERATURE section

Trip Level Over Temperature

Hysteresis

T

--

160

30

--

C

high

hyst

STANDBY MAXIMUM CURRENT REDUCTION section

Normal Mode Recovery Demag Pin Current Threshold

I

20

25

30

mA

dem--NM

K FACTORS SECTION FOR PULSED MODE OPERATION

I

/ I

MC44608P40

MC44608P75

10 x K1

2.4

2.8

46

1.8

90

175

3.0

--

2.9

3.3

3.8

4.2

63

--

CCS stup

/ I

CCS stup

3

/ I

10 x K2

52

--

CCL stup

2

(V

-- UVLO2) / (V

-- UVLO1)

10 x K

2.2

2.6

150

225

5.5

--

stup

sstup

2

(UVLO1 -- UVLO2) / (V

-- UVLO1)

10 x K

120

198

4.7

--

stup

sl

6

I

/ V

10 x Y

--

CS

csth

cstby

Demag ratio I

/ I

NM

Dmgr

R3

--

ovp dem

(V3

-- V 3

) / (1.0 mA -- 0.5 mA)

0.5 mA

1800

4.8

Ω

V

1.0 mA

V

Latchoff

V3

--

control

SUPPLY SECTION

Minimum Startup Voltage

Startup Voltage

V

--

12.5

9.5

--

50

13.8

10.5

--

V

ilow

V

13.1

10

CC

stup--th

Output Disabling V Voltage After Turn On

V

CC

uvlo1

stup--uvlo1

Hysteresis (V

-- V

)

H

3.1

6.6

3.4

9.5

V

stup--th

uvlo1

V

Undervoltage Lockout Voltage

V

6.2

--

7.0

--

V

CC

uvlo2

uvlo1--uvlo2

Hysteresis (V

-- V

)

H

V

uvlo1

uvlo2

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

-- ( I

)

7.0

12.8

mA

CC

i

CC

(V = 9.0 V)

CC

Switching Phase Supply Current (no load)

MC44608P40

MC44608P75

I

2.0

2.4

2.6

3.2

3.6

4.0

mA

CCS

Latched Off Phase Supply Current

Hiccup Mode Duty Cycle (no load)

I

0.3

--

0.5

10

0.68

--

mA

%

CC--latch

δ

Hiccup

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

CC

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).

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4

MC44608

PIN FUNCTION DESCRIPTION

Description

Name

1

Demag

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

and 120 mA current detection. The 24 mA level is used to detect the secondary reconfiguration status and the

120 mA level to detect an Over Voltage status called Quick OVP.

2

3

I

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

sense

MOSFET. When I

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

sense

Protection function. A 200 mA 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.

4

5

6

Ground

Driver

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

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

V

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.

CC

7

8

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

i CC

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 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(Rdutycycle burst) hasno effecton

the regulation process. This resistor is used to determine the

burstdutycycledescribedinthechapter“PulsedDutyCycle

Control” on page 8.

V

LP--stby

V

CC

1

0

Stand--by

Latched off Phase

Control

Input

&

S3

3

1

S2

0

Switching Phase

PWM Latch

V

dd

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

controlled by the PWM comparator that compares the

oscillator sawtoothwiththe regulationblockoutput(referto

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.

PWM

Regulation

20 Ω

Comparator

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 Ω. 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.

Current Sense

The inductor current is converted to a positive voltage by

inserting a ground reference sense resistor R_Sensein 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:

1

Ipk

=

(A)

max

R

(Ω)

sense

A 4.0 kHz filter network is inserted between the shunt

regulator and the PWM comparator to cancel the high

frequency residual noise.

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5

MC44608

Oscillator Buffer Output

In standby mode, this current can be lowered as due to the

activation of a 200 mA current source:

R

DMG

Q

1 − (R (kΩ) × 0, 2)

cs

Ipk

=

(A)

max−stby

R

(Ω)

S

sense

Demag

1

+

--

Switching Phase

&

DMG

&

50/20 mV

200 mA

STANDBY

STARTUP

Idemag

> 24 mA

>120 mA

1

0

Current Mirror

Overcurrent

Figure 4. Demagnetization Block

Comparator

L.E.B.

Isense

OC

+

--

2

This function can be inhibited by grounding it but in this

case, the quick and programmable OVP is also disabled.

Rcs

Rsense

1 V

Oscillator

The MC44608 contains a fixed frequency oscillator. It is

built around a fixed value capacitor CT successively

charged and discharged by two distinct current sources ICH

and IDCH. The window comparator senses the CT voltage

value and activates the sources when the voltage is reaching

the 2.4 V/4.0 V levels.

Figure 3. Current Sense

Thecurrentsenseinputconsistsofafilter(6.0 kΩ, 4.0 pF)

and of a leading edge blanking. Thanks to that, this pin is not

sensitive to the power switch turn on noise and spikes and

practically in most applications, no filtering network is

required to sense the current.

Finally, this pin is used:

ICH

-- as a protection against over currents (Isense > I)

-- as a reduction of the peak current during a Pulsed Mode

switching phase.

The overcurrent propagation delay is reduced by

producing a sharp output turn off (high slew rate). This

results in an abrupt output turn off in the event of an over

current and in the majority of the pulsed mode switching

sequence.

DMG

OSC

SCH

&

from Demag

logic block

Window

comp

4 V

+

--

Clock

2.4 V

SDCH

CT

IDCH

Demagnetization Section

The MC44608 demagnetization detection consists of a

comparator designed to compare the V_CCwinding voltage

to a reference that is typically equal to 50 mV.

Figure 5. Oscillator Block

This reference is chosen low to increase effectiveness of

the demagnetization detection even during startup.

A latch is incorporated to turn the demagnetization block

output into a low level as soon as a voltage less than 50 mV

is detected, and to keep it in this state until a new pulse is

generatedontheoutput. Thisavoidsanyringingontheinput

signal which may alter the demagnetization detection.

For a higher safety, the demagnetization block output is

also directly connected to the output, which is disabled

during the demagnetization phase.

The demagnetization pin is also used for the quick,

programmable OVP. In fact, the demagnetization input

currentissensedsothatthe circuitoutputislatchedoffwhen

this current is detected as higher than 120 mA.

The complete demagnetization status DMG is used to

inhibit the recharge of the CT capacitor. Thus in case of

incomplete transformer demagnetization the next switching

cycle is postpone until the DMG signal appears. The

oscillator remains at 2.4 V corresponding to the sawtooth

valley voltage. In this way the SMPS is working in the so

called SOPS mode (Self Oscillating Power Supply). In that

case the effective switching frequency is variable and no

longer depends on the oscillator timing but on the external

working conditions (Refer to DMG signal in the Figure 6).

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6

MC44608

OSC

4 V

V

CC

13 V

Vcont

2.4 V

10 V

Clock

6.5 V

DMG

Iprim

Startup

Phase

Latched off

Phase

Switching

Phase

Figure 7. Hiccup Mode

Figure 6.

Incase of the hiccupmode, the dutycycle of the switching

phase is in the range of 10%.

The OSC and Clock signals are provided according to the

Figure 6. The Clock signals correspond to the CT capacitor

discharge. The bottom curve represents the current flowing

in the sense resistor Rcs. It starts from zero and stops when

the sawtooth value is equal to the control voltage Vcont. In

this way the SMPS is regulated with a voltage mode control.

Mode Transition

TheLWlatchFigure8isthememoryoftheworkingstatus

at the end of every switching sequence.

Two different cases must be considered for the logic at the

termination of the SWITCHING PHASE:

1. No Over Current was observed

2. An Over Current was observed

Overvoltage Protection

The MC44608 offers two OVP functions:

-- a fixed function that detects when V_CCis higher than

15.4 V

-- a programmable function that uses the demag pin. The

current flowing into the demag pin is mirrored and

compared to the reference current Iovp (120 mA). Thus this

OVP is quicker as it is not impacted by the V_CCinertia and

is called QOVP.

These 2 cases are corresponding to the signal labelled

NOCincaseof“NoOverCurrent”and“OC”incaseofOver

Current. So the effective working status at the end of the ON

time memorized in LW corresponds to Q=1 for no over

current and Q=0 for over current.

This sequence is repeated during the Switching phase.

Several events can occur:

1. SMPS switch OFF

2. SMPS output overload

3. Transition from Normal to Pulsed Mode

4. Transition from Pulsed Mode to Normal Mode

In both cases, once an OVP condition is detected, the

output is latched off until a new circuit startup.

Startup Management

The V_ipin 8 is directly connected to the HV DC rail Vin.

This high voltage current source is internally connected to

theV_CCpinandthusisusedtochargetheV_CCcapacitor.The

V_CCcapacitor charge period corresponds to the startup

phase. When the V_CCvoltage reaches 13 V, the high voltage

9.0 mA current source is disabled and the device starts

working. The device enters into the switching phase.

It is to be noticed that the maximum rating of the V_ipin 8

is 500 V. ESD protection circuitry is not currently added to

this pin due to size limitations and technology constraints.

Protection is limited by the drain--substrate junction in

avalanche breakdown. To help increase the application

safety against high voltage spike on that pin it is possible to

insert a small wattage 1.0 kΩ series resistor between the V_in

rail and pin 8.

The Figure 7 shows the V_CCvoltage evolution in case of

no external current source providing current into the V_CC

pin during the switching phase. This case can be

encountered in SMPS when the self supply through an

auxiliary winding is not present (strong overload on the

SMPS output for example). The Figure 17 also depicts this

working configuration.

Latched Off

Phase

VPWM

OUT

NOC

OC

S

R

Q

Standby

&

S

Mode

R1

R2

&

Q

LW

S1

Switch

Q

LEB out

1 V

+

CS

--

I

Startup

Switching Startup

demag

Phase > 24 mA Phase Phase

Figure 8. Transition Logic

 1. SMPS SWITCH OFF

When the mains is switched OFF, so long as the bulk

electrolithic bulk capacitor provides energy to the SMPS,

the controller remains in the switching phase. Then the peak

current reaches its maximum peak value, the switching

frequency decreases and all the secondary voltages are

reduced. The V_CCvoltage is also reduced. When V_CCis

equal to 10 V, the SMPS stops working.

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7

MC44608

 2. Overload

according to the equation of the current sense section,

page 5. The C.S. clamping level depends on the power to be

delivered to the load during the SMPS standby mode. Every

switchingsequence ON/OFF isterminatedbyanOC aslong

as the secondary Zener diode voltage has not been reached.

When the Zener voltage is reached the ON cycle is

terminatedbya true PWMaction. The proper SWITCHING

PHASE termination must correspond to a NOC condition.

The LW latch stores this NOC status.

The LATCHED OFF PHASE: The MODE latch is set.

The startup PHASE is similar to the Overload Mode. The

MODE latch remains in its set status (Q=1).

The SWITCHING PHASE: The standby signal is

validatedandthe 200 mAissourcedoutof the CurrentSense

pin 2.

In the hiccup mode the 3 distinct phases are described as

follows (refer to Figure 7):

The SWITCHING PHASE: The SMPS output is low and

the regulation block reacts by increasing the ON time (dmax

= 80%). The OC is reached at the end of every switching

cycle. The LW latch (Figure 8) is reset before the VPWM

signal appears. The SMPS output voltage is low. The V_CC

voltage cannot be maintained at a normal level as the

auxiliary winding provides a voltage which is also reduced

in a ratio similar to the one on the output (i.e. Vout nominal

/ Vout short--circuit). Consequently the V_CCvoltage is

reduced at an operating rate given by the combination V_CC

capacitor value together with the I_CCworking consumption

(3.2 mA) according to the equation 2. When V_CCcrosses

10V the WORKING PHASE gets terminated. The LW latch

remains in the reset status.

The LATCHED--OFF PHASE: The V_CCcapacitor

voltage continues to drop. When it reaches 6.5 V this phase

is terminated. Its duration is governed by equation 3.

ThestartupPHASEisreinitiated.Thehighvoltagestartup

current source (--I_CC1= 9.0 mA) is activated and the MODE

latch is reset. The V_CCvoltage ramps up according to the

equation 1. When it reaches 13 V, the IC enters into the

SWITCHING PHASE.

 4. Transition from Standby to Normal

The secondary reconfiguration is removed. The

regulation on the low voltage secondary rail can no longer

beachieved, thusattheendof theSWITCHINGPHASE, no

PWM condition can be encountered. The LW latch is reset.

At the next WORKING PHASE a NORMAL mode status

takes place.

In order to become independent of the recovery time

constant on the secondary side of the SMPS an additional

resetinputR2isprovidedontheMODElatch. Thecondition

Idemag<24 mA corresponds to the activation of the

secondary reconfiguration status. The R2 reset insures a

direct return into the Normal Mode.

The NEXT SWITCHING PHASE: The high voltage

current source is inhibited, the MODE latch (Q=0) activates

the NORMAL mode of operation. Figure 3 shows that no

current is injected out pin 2. The over current sense level

corresponds to 1.0 V.

Pulsed Mode Duty Cycle Control

As long as the overload is present, this sequence repeats.

TheSWITCHINGPHASEdutycycleisintherangeof10%.

During the sleep mode of the SMPS the switch S3 is

closed and the control input pin 3 is connected to a 4.6 V

voltage source thru a 500 Ω resistor. The discharge rate of

the V_CCcapacitor is given by I_CC--latch(device consumption

during the LATCHED OFF phase) in addition to the current

drawn out of the pin 3. Connecting a resistor between the

Pin 3 and GND (R_DPULSED) a programmable current is

drawn from the V_CCthrough pin 3. The duration of the

LATCHED OFF phase is impacted by the presence of the

resistor R_DPULSED. The equation 3 shows the relation to the

pin 3 current.

 3. Transition from Normal to Pulsed Mode

In this sequence the secondary side is reconfigured (refer

to the typical application schematic on page 13). The high

voltage output value becomes lower than the NORMAL

mode regulated value. The TL431 shunt regulator is fully

OFF. In the SMPS standby mode all the SMPS outputs are

lowered except for the low voltage output that supply the

wake--up circuit located at the isolated side of the power

supply. In that mode the secondary regulation is performed

by the zener diode connected in parallel to the TL431.

The secondary reconfiguration status can be detected on

the SMPS primary side by measuring the voltage level

present on the auxiliary winding Laux. (Refer to the

Demagnetization Section). In the reconfigured status, the

Laux voltage is also reduced. The V_CCself--powering is no

longer possible thus the SMPS enters in a hiccup mode

similar to the one described under the Overload condition.

In the SMPS standby mode the 3 distinct phases are:

The SWITCHING PHASE: Similar to the Overload

mode. The current sense clamping level is reduced

Pulsed Mode Phases

Equations 1 through 8 define and predict the effective

behavior during the PULSED MODE operation. The

equations 6, 7, and 8 contain K, Y, and D factors. These

factors are combinations of measured parameters. They

appear in the parameter section “Kfactors for pulsed mode

operation” page 4. In equations 3 through 8 the pin 3 current

is the current defined in the above section “Pulsed Mode

Duty Cycle Control”.

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8

MC44608

EQUATION 1

Startup Phase Duration:

C

× (V

− UVLO2)

stup

Vcc

t

=

start–up

I

stup

where: I_stupis the startup current flowing through V_CCpin

_Vccis the V_CCcapacitor value

C

EQUATION 2

Switching Phase Duration:

C

× (V

− UVLO1)

+ I

stup

Vcc

t

=

switch

I

ccS

G

where: I_ccSis the no load circuit consumption in switching phase

_Gis the current consumed by the Power Switch

I

EQUATION 3

Latched--off Phase Duration:

C

× (UVLO1 − UVLO2)

Vcc

t

=

latched−off

I

+ I

ccL

pin3

where: I_ccLis the latched off phase consumption

I_pin3is the current drawn from pin3 adding a resistor

EQUATION 4

Burst Mode Duty Cycle:

t

switch

d

=

BM

t

+ t

start−up

switch

latched−off

EQUATION 5

C

× (V

−UVLO1)

+ I

stup

Vcc

I

ccS

G

d

=

BM

C

×(V

− UVLO2)

C

× (V

−UVLO1)

C

× (UVLO1−UVLO2)

stup

I

stup

+ I

Vcc

+

I

+ I

ccL pin3

stup

ccS

G

EQUATION 6

1

d

=

BM

I

+ I

I

+ I

ccS

I

G

ccS

+ I

G

1 +

k

×

+

k

×



 



S∕Stup

S∕L

I

stup

ccL pin3

where: k_S/Stup= (V_stup-- UVLO2)/(V_stup-- UVLO1)

_S/L= (UVLO1 -- UVLO2)/(V_stup-- UVLO1)

k

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9

MC44608

EQUATION 7

1

d

=

BM

I

+ I

⎧

⎫

⎧

stup

ccS

I

G

1 +

×

⎩

k

+

k

×

 _⎪⎪

⎪

S∕Stup

S∕L

I

+ I

stup

ccL

pin3

⎭

⎩

EQUATION 8

1

d

=

BM

⎧

⎫

⎧

⎪

I

⎪

G

1

I

1 +

k1 +

× k

+ (k

×

)

_⎨ 

⎬

⎪

S∕Stup

S∕L

I

stup

pin3

⎪

k2+

 

I

stup

⎩

⎭

⎩

⎭

where: k1 = I_ccs/I_stup

k2 = I_{ccL/ stup}

I

k_S/Stup= (V_stup--UVLO2)/(V_stup--UVLO1)

k_S/L= (UVLO1--UVLO2)/(V_stup--UVLO1)

PULSED MODE CURRENT SENSE CLAMPING LEVEL

Equations 9, 10, 11 and 12 allow the calculation of the Rcs value for the desired maximum current peak value during the

SMPS standby mode.

EQUATION 9

V

− (R × I

)

cs

cs–th

Ipk

=

stby

R

S

where: V_cs--this the CS comparator threshold

_csis the CS internal current source

I

R_Sis the sensing resistor

R_csis the resistor connected between pin 2 and R_S

EQUATION 10

I

cs

1 −  _cs

R

×



V

cs–th

Ipk

= V

×

stby

EQUATION 11

Ipk = V

cs–th

R

S

1 − (R × Y

cs

)

cs–stby

stby

cs–th

R

S

where: Y_cs--stby= I_cs/V_cs--th

Taking into account the circuit propagation delay (δt_cs) and the Power Switch reaction time (δt_ps):

EQUATION 12

1 − (R × Y

cs

)

V

× (δt + δt

)

ps

cs–stby

cs

in

Ipk

=

V

×

+





stby

cs–th

R

L

p

S

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10

MC44608

60

50

79.0

77.0

85 C

t_rise

-- 2 5  C

75.0

25 C

40

30

73.0

71.0

t_fall

69.0

67.0

65.0

20

10

11

12

V

13

14

15

2.5

15

10

11

12

13

14

15

2.5

0.0

Voltage (V)

Pin6 V Voltage (V)

CC

Figure 9. Output Switching Speed

Figure 10. Frequency Stability

90

80

70

60

50

40

5.08

5.07

5.06

5.05

85 C

5.04

5.03

85 C

25 C

-- 2 5  C

5.02

5.01

30

20

10

0

-- 2 5  C

5.00

4.99

25 C

4.98

0.0

0.5

1.0

1.5

2.0

0.5

1

1.5

2

Current Injected in Pin3 (mA)

Current Injected in Pin 3 (mA)

Figure 12. Vpin3 During the Working Period

Figure 11. Duty Cycle Control

5.0

4.80

4.60

4.40

4.20

4.00

4.5

4.0

3.5

3.0

2.5

2.0

1.5

-- 2 5  C

25 C

3.80

3.60

3.40

3.20

3.00

85 C

-- 1 . 6

--1.4

--1.2

--1.0 --.08

--.06

--.04

--.02

10

11

12

13

14

Current Injected in Pin 3 (mA)

Pin6 V Voltage (V)

CC

Figure 14. Device Consumption when Switching

Figure 13. Vpin3 During the Latched Off Period

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11

MC44608

11.00

10.00

9.00

12.00

-- 2 5  C

11.00

10.00

-- 2 5  C

9.00

8.00

7.00

6.00

25 C

85 C

8.00

25 C

85 C

7.00

6.00

5.00

500

0

100

200

300

400

0

100

200

300

400

500

Vi Pin8 Voltage (Vi)

Vi Pin Voltage (V)

Figure 15. High Voltage Current Source

Figure 16. Overload Burst Mode

Figure 17. Hiccup Mode Waveforms

The data in Figure 16 corresponds to the waveform in

Figure 17. The Figure 17 shows V_CC, I_CC, I_sense(pin 2) and

output switching pulses. This mode corresponds to an

overload condition.

V_out(pin 5). V_out(pin 5) in fact shows the envelope of the

http://onsemi.com

12

MC44608

The Figure 19 represents a complete power supply using the secondary reconfiguration.

The specification is as follows:

Input source:

3 Outputs

85 Vac to 265 Vac

112 V/0.45 A

16 V/1.5 A

8.0 V/1.0 A

80 W

@ Pout = 300 mW, 1.3 W

Output power

Standby mode

R F6

47288900

FI

C20

2N2FY

C11

220 pF

500 V

RFI

WIDE

MAINS

C1

FILTER

100 nF

R16

4.7 k Ω

4 kV

D18

MR856

112 V/0.45 A

1

14

C3

1 nF

D1, D2, D3, D4

1N5404

+

C12

C13

100 nF

47 mF

J3

2

250 V

12

C5

3

+

C17

120 pF

R7

47 kΩ

R1

220 mF

16 V/1.5 A

22 kΩ

400 V

5 W

C4

1 nF

D12

C6

47 nF

630 V

1

D6

MR856

R5

J4

2

D5

1N4007

1N4934

DZ1

MCR22--6

100 kΩ

D9

MR852

3

1

6

11

10

8 V/1 A

D7

C14

+

1N4148

1000 mF

1

8

35 V

7

C7

I

sense

+

22 mF

2

3

4

7

6

C16

120 pF

16 V

R19

18 kΩ

V

CC

C9

D13

470 pF

630 V

R2

1N4148

10 Ω

5

D10

MR852

D14

MR856

MTP6N60E

8

Post

Reg.

C8

100 nF

R17

2.2 kΩ

5 W

mP

+

C15

1000 mF

R4

3.9 k Ω

16 V

9

R3

0.27 Ω

R21

R9

100 kΩ

47 Ω

OPT1

C18

100 nF

R12

1 kΩ

R10

10 kΩ

C19

33 nF

DZ3

10 V

ON

OFF

R11

4.7 kΩ

DZ2

TL431CLP

R8

2.4 kΩ

ON = Normal Mode

OFF = Pulsed Mode

Figure 18. Typical Application

http://onsemi.com

13

MC44608

The secondary reconfiguration is activated by the mP

applied to the secondary windings 12--14, 10--11 and 6--7

(Vaux) are thus divided by ratio N12--14 / N9--8 (number of

turns of the winding 12--14 over number of turns of the

winding 9--8). In this reconfigured status all the secondary

voltages are lowered except the 8.0 V one. The regulation

during every pulsed or burst is performed by the zener diode

DZ3 which value has to be chosen higher than the normal

mode regulation level. This working mode creates a voltage

ripple on the 8.0 V rail which generally must be post

regulated for the microProcessor supply.

through the switch. The dV/dt appearing on the high voltage

winding (pins 14 of the transformer) at every TMOS switch

off, produces a current spike through the series RC network

R7, C17. Accordingtothe switchpositionthisspike iseither

absorbed by the ground (switch closed) or flows into the

thyristor gate (switch open) thus firing the MCR22--6. The

closed position of the switch corresponds to the Pulsed

Mode activation. In this secondary side SMPS status the

highvoltagewinding(12--14)isconnectedthroughD12and

DZ1 to the 8.0 V low voltage secondary rail. The voltages

Figure 19. SMPS Pulsed Mode

The Figure 19 shows the SMPS behavior while working

in the reconfigured mode. The top curve represents the V_CC

voltage (pin 6 of the MC44608). The middle curve

represents the 8.0 V rail. The regulation is taking place at

11.68 V. On the bottom curve the pin 2 voltage is shown.

This voltage represents the current sense signal. The pin 2

voltage is the result of the 200 mA current source activated

during the startup phase and also during the working phase

which flows through the R4 resistor. The used high

resolution mode of the oscilloscope does not allow to show

the effective ton current flowing in the sensing resistor R11.

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14

MC44608

PACKAGE DIMENSIONS

8 LEAD PDIP

CASE 626--05

ISSUE M

NOTES:

D

1. DIMENSIONING AND TOLERANCING PER ASME

Y14.5M, 1994.

A

2. CONTROLLING DIMENSION: INCHES.

3. DIMENSION E IS MEASURED WITH THE LEADS RE-

STRAINED PARALLEL AT WIDTH E2.

4. DIMENSION E1 DOES NOT INCLUDE MOLD FLASH.

5. ROUNDED CORNERS OPTIONAL.

D1

E

8

5

4

INCHES

NOM

-- -- -- -- 0 . 2 1 0

-- -- -- -- -- -- -- --

MILLIMETERS

E1

DIM MIN

-- -- -- --

A1 0 . 0 1 5

b

C

D

MAX

MIN

NOM

-- -- -- --

0.46

0.25

MAX

A

-- -- -- --

0 . 3 8

0.35

0.20

9.02

0 . 1 3

7.62

6.10

5 . 3 3

-- -- -- --

0.56

0.36

1

0.014 0.018 0.022

0.008 0.010 0.014

0.355 0.365 0.400

NOTE 5

9.27 10.02

F

c

D1 0 . 0 0 5

0.300 0.310 0.325

E1 0.240 0.250 0.280

-- -- -- --

7.87

6.35

-- -- -- --

8.26

7.11

E

E2

TOP VIEW

END VIEW

E2

E3

e

0.300 BSC

-- -- -- -- 0 . 4 3 0

0.100 BSC

7.62 BSC

NOTE 3

-- -- -- --

2.92

-- -- -- -- 1 0 . 9 2

2.54 BSC

3.30

e/2

L

0.115 0.130 0.150

3.81

A

L

A1

SEATING

PLANE

C

E3

e

8X

b

M

0.010

C A

END VIEW

SIDE VIEW

ON Semiconductor and

are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice

to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability

arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.

“Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All

operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights

nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications

intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should

Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates,

and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death

associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal

Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.

PUBLICATION ORDERING INFORMATION

LITERATURE FULFILLMENT:

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USA/Canada

Europe, Middle East and Africa Technical Support:

Phone: 421 33 790 2910

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Phone: 81--3--5773--3850

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Order Literature: http://www.onsemi.com/orderlit

Literature Distribution Center for ON Semiconductor

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Phone: 303--675--2175 or 800--344--3860 Toll Free USA/Canada

Fax: 303--675--2176 or 800--344--3867 Toll Free USA/Canada

Email: orderlit@onsemi.com

For additional information, please contact your local

Sales Representative

MC44608/D

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15


型号：	MC44608P100
厂家：	ONSEMI
描述：	SWITCHING CONTROLLER, 110kHz SWITCHING FREQ-MAX, PDIP8, PLASTIC, DIP-8 开关光电二极管
文件：	总15页 (文件大小：266K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

MC44608P100 [ONSEMI]

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