www.fairchildsemi.com

Rev. 1.0.2

Features

· Current Mode Control
· Pulse by Pulse Current Limiting
· Low External Components
· Under Voltage Lockout(UVLO): 9V/15V
· Stand-by Current: Typ. 100uA
· Power Saving Mode Current: Typ. 200uA
· Operating Current: Typ. 7mA
· Soft Start
· On/Off Control
· Over Load Protection(OLP)
· Over Voltage Protection(OVP)
· Over Current Protection(OCP)
· Over Current Limit(OCL)
· Operating Frequency up to 500kHz
· 1A Totem-Pole Output Current

Applications

· Off-Line & DC-DC Converter

Description

The FAN7554 is a fixed frequency current mode PWM
controller. It is specially designed for off-line and DC to DC
converter applications with minimal external components.
These integrated circuits feature a trimmed oscillator for
precise duty cycle control, a temperature compensated
reference, an ON/OFF control, a high gain error amplifier, a
current sensing comparator, and a high current totem-pole
output. The FAN7554 has various protection functions such
as an over load protection, an over current protection, and
the over voltage protection, which include built-in auto
restart circuit. The FAN7554 is available in the 8-DIP
package as well as the 8-SOP package.

FAN7554

Versatile PWM Controller

8-DIP

8-SOP

FAN7554

Internal Block Diagram

Absolute Maximum Ratings

( Ta = 25

C, unless otherwise specified )

Note:
1. Junction -to -air thermal resistance test environments.
-. Pneumatic heat sink fixture.
-. Clamping pressure 60psi through 12mm diameter cylinder.
-. Thermal grease applied between PKG and heat sink fixture

Parameter

Symbol

Value

Unit

Supply Voltage

Vcc

Output Current

±1

Input Voltage to FB Pin

-0.3 to V

Input Voltage to IS Pin

-0.3 to V

Power Dissipation at T

8-DIP
8-SOP

0.85
0.42

Operating Temperature

OPR

-25 to +85

Storage Temperature

STG

-55 to +150

Thermal Resistance, Junction-to-Air (Note1)
8-DIP
8-SOP

147.8
291.4

C/W

OSC

Rt/Ct

Vcc

OUT

GND

I S

S/S

1.5V

3.5V

0.3V

14V

15V/9V

UVLO

OLP

5uA

Vcc

Offset(0.1V)

PWM

MAX. 1V

UVLO-out

CLK

PWR

SAVE

off

Vref

100uA

Vref

1mA

Vref

OVP

34V

OVP-out

OCL-out

OCL

OSC

6
6

7
7

1
1

5
5

4
4

3
3

8
8

Rt/Ct

Vcc

OUT

GND

I S

2
2

S/S

1.5V

3.5V

0.3V

14V

15V/9V

UVLO

OLP

5uA

Vcc

5uA

Vcc

Offset(0.1V)

PWM

MAX. 1V

UVLO-out

CLK

PWR

SAVE

off

Vref

100uA

Vref

1mA

Vref

OVP

34V

OVP-out

OCL-out

OCL

FAN7554

Temperature Characteristics

( -25

C )

PIN Array

PIN Definitions

Parameter

Symbol

Value

Unit

Vref Temperature Stability

REF

±0.5

Fosc Temperature Stability

OSC

±5

Pin Number

Pin Name

Pin Function Description

Inverting(-) Input of PWM Comparator, ON/OFF Control & OLP Sensing
Terminal.

S/S

Soft Start

Non-Inverting(+) Input of PWM Comparator, OCL Sensing Terminal

Rt/Ct

Oscillator Time Constant(Rt/Ct)

GND

Ground

OUT

Output of Gate Driver

Vcc

Power Supply

Vref

Output of 5V Reference

Vref

Vcc

OUT

GND

Y
Y

Y W

W
W

W W

W
W

A
A

A N

N
N

N 7

7
7

7 5

5
5

5 5

5
5

5 4

4
4

F
F

Rt/Ct

S/S

FAN7554

Electrical Characteristics

(Ta = 25

C, Vcc=16V, Rt=10k

, Ct=3.3nF unless otherwise specified)

Parameter

Symbol

Conditions

Min.

Typ.

Max.

Unit

< REFERENCE SECTION >
Reference Output Voltage

REF

=25

C , Iref =1mA

4.90

5.00

5.10

Line Regulation

REF1

Vcc =12V ~ 25V

Load Regulation

REF2

Iref =1mA ~ 20mA

Short Circuit Output Current

= 25

0.1

0.18

< OSCILLATOR SECTION >
Oscillation Frequency

OSC

= 25

kHz

Frequency Change with Vcc

OSC1

Vcc = 12V ~ 25V

0.05

1.0

Ramp High Voltage

2.8

Ramp Low Voltage

1.2

Discharge Current

Idisch

RT/CT

= 3.3V

6.1

9.4

< PWM SECTION >
Sense Threshold Voltage

TH(IS)

= 5V

0.8

1.0

1.2

Feedback Threshold Voltage

TH(FB)

= 0V

0.2

0.3

0.4

Feedback Source Current

= 0V, V

S/S

= 5V

1.0

Max. Duty Cycle

(MAX)

Min. Duty Cycle

(MIN)

< PROTECTION SECTION >
Shutdown Delay Current

3.5

6.5

Shutdown Feedback Voltage

> 5V

5.4

6.6

Over Current Protection

> 1.5V,

> 500nS

1.6

2.4

Over Voltage Protection

OVP

< ON/OFF CONTROL SECTION >
Off Mode Sink Current

SINK

< V

TH(FB)

, V

S/S

= 5V

Off Threshold Voltage

OFF

< V

TH(FB)

1.2

1.5

1.8

< SOFT-START SECTION >
Soft Start Current

S/S

= 5V, V

S/S

= 0V

1.1

Soft Start Limit Voltage

LIM(S/S)

Vcc = 16V

5.2

<OUTPUT SECTION>
Low Output Voltage1

OL1

= 18V, I

= 50mA

0.15

0.4

High Output Voltage1

OH1

= 18V, I

= -50mA

Low Output Voltage2

OL2

= 18V, I

= 200mA

1.5

2.5

High Output Voltage2

OH2

Vcc = 18V, Io = -200mA

Rising Time (Note1)

= 25

C, C

= 1nF

Falling Time (Note1)

= 25

C, C

= 1nF

<UVLO SECTION>
Start Threshold Voltage

TH(ST)

13.2

16.2

Min. Operating Voltage

OPR(M)

8.2

10.2

FAN7554

Typical Perfomance Characteristics

[ Rt vs. Freqency ]

0.1

1.0

10.0

100.0

1000.0

10000.0

100

Rt[Kohm]

requency[kHz]

0.33n
1.1n
3.3n
11n
33n

[ Ct vs Dead time ]

0.100

1.000

10.000

100.000

0.1

100

Ct[nF]

Dead Time [usec]

1K
2K
5K
10K
20K
50K
100K

[ Ct vs Duty ]

15.0

25.0

35.0

45.0

55.0

65.0

75.0

85.0

95.0

0.1

100

Ct [nF]

Duty [%]

1K
2K
5K
10K
20K
50K
100K

[ Cload vs Tr & Tf ]

[ Cload vs Tr & Tf ] 50Khz,95% duty

100

200

300

400

500

600

700

800

100

Cload [ nF]

Time [nsec]

Tr
Tf

Figure 1. Rt vs. Frequency

Figure 2. Ct vs. Dead Time

Figure 3. Ct vs. Duty

Figure 4. Cload vs. Tr & Tf

FAN7554

Operation Description

The FAN7554 has all the basic features of the current mode SMPS control IC. Its basic configuration includes the UVLO with
6V hysteresis, a band gap reference, the oscillator that can oscillate up to 500kHz according to R

(connected externally), a

PWM logic circuit , a gate driver, and the feedback circuit that has the current source and soft start function. The FAN7554 has
various functions such as an over load protection, an over current protection, and an over voltage protection. The over load
protection forces the FAN7554 to stop its operation if the load current is higher than the preset value. The protection circuit
can also be prevented from operating during transient states by ensuring that a certain amount of the time passes before the
protection circuit operates. The shutdown circuit is configured for an auto-restart, so the FAN7554 automatically restarts when
Vcc drops to 9V (stop voltage).

Start-Up

The start-up circuit is made up of an under voltage lock out (UVLO), the protection for low voltage conditions, and the 5V
reference (V

ref

), which supplies bias voltage to the control circuit after start-up. The start voltage of the UVLO is 15V , and

the stop voltage after turn on is 9V. It has a 6V hysteresis. The minimum operating current for start-up threshold is typically
100uA, and this can reduce the power dissipation on the start-up resistor. The Vref is composed of the band gap reference
circuit with its superior temperature characteristics and supplies power to all the FAN7554 circuits and R

, with the

exceptions of the ULVO circuit and ON/OFF control circuit.

Soft Start

The SMPS output load usually contains a capacitive load component. During initial start-up, the output voltage increases at a
fixed time constant because of this component. If the feedback loop, which controls the output voltage, was to start without
the soft start circuit, the feedback loop would appear to be open during initial start-up , so, at start-up, the feedback voltage
applied to the PWM comparator's inverting input (-) reaches its maximum value(1V).

During this time, the peak value of the drain current would stay at the maximum value, and the maximum power would be
delivered to the secondary load side from the start. When the maximum power is delivered to the secondary side for this initial
fixed time, the entire circuit is seriously stressed. The use of a soft start can avoid such stresses. At start-up, the soft start
capacitor Cs is charged by 1mA and 100uA current sources.

The voltage of the inverting terminal of the PWM comparator increases to 1/3 of the Cs voltage at a fixed time constant.
Subsequently, the drain peak current is limited by the gradual increase in the Cs voltage and this causes the output voltage to
increase smoothly. When the Cs voltage becomes greater than 3V, the diode Ds turns off consequently, the feedback capacitor
Cfb is charged by 1mA and 5uA current sources. This charge voltage determines the comparator's inverting voltage. Then, Cs
voltage charges to 5V by 100uA current source. The soft start capacitor Cs is discharged when the UVLO good logic starts, so
the soft start is repeated at re-start.

Figure 11. Low Current Start-Up & Bandgap Reference Circuit

Figure 12.

Start-Up & Circuit Characteristics

5V
Vref

Internal bias

Good logic

15V/9V

UVLO

DC Link

FAN7554

VCC

5V
Vref

Internal bias

Good logic

15V/9V

UVLO

DC Link

FAN7554

VCC

Vcc (V)

Icc(mA)

0.01

7.0

Vcc (V)

Icc(mA)

0.01

7.0

FAN7554

Oscillator

As shown in figure14, the oscillator frequency is programmed by values selected for timing components Rt and C

. Capacitor

is charged to almost 2.8V through resistor Rt from the 5V reference and discharged to 1.2V by an internal current source.

The oscillator generates the clock signal while the timing capacitor C

discharged. The gate drive output becomes low during

the clock time. Rt and C

selection determine the oscillator frequency and maximum duty cycle. Charge and discharge times

can be calculated through the equations below.

Charging time : tc = 0.55

Discharging time : td = R

ln[(0.0063

- 2.8) / (0.0063

- 3.8)]

where the oscillator frequency : fosc = (tc + td)

-1

(±10%)

When R

> 5k

, fosc = 1 / (0.55

) = 1.8 / (R

)

Figure 13. Soft Start Circuit & Circuit Flow

S/S

Vcc

5uA

100uA

1mA

Cfb

Output drive

FAN7554

S/S

Vcc

5uA

100uA

1mA

Cfb

Output drive

FAN7554

Clock

Figure 14. Oscillator Circuit

Figure 15. Sawtooth & Clock Waveform

Discharge

Gate Drive

Vref

FAN7554

2.8V

/1.2V

Discharge

Gate Drive

Vref

FAN7554

2.8V

/1.2V

Vhigh(2.8V)

Vlow(1.2V)

Sawtooth waveform

Internal clock

Vhigh(2.8V)

Vlow(1.2V)

Sawtooth waveform

Internal clock

[ Rt > 5k

]

[ Rt < 5k

]

Vhigh(2.8V)

Vlow(1.2V)

Sawtooth waveform

Internal clock

Vhigh(2.8V)

Vlow(1.2V)

Sawtooth waveform

Internal clock

[ Rt > 5k

]

[ Rt < 5k

]

FAN7554

Feedback

As shown in figure16, the internal oscillator clock turns on the MOSFET. The feedback comparator operates to turn it off
again, when the MOSFET current reaches a set value proportional to Vfb. The feedback capacitor Cfb is charged by the inter-
nal current sources , 1mA and 5uA, and is discharged by the secondary side photo-coupler to control the output voltage.

Delayed Shutdown

During the normal operation, the feedback voltage is between 0~3V. If the output terminal overloads or an error happens to
the feedback loop, the delayed shutdown circuit operates. When the feedback voltage is less than 3V, the feedback capacitor is
charged by current sources, 1mA and 5uA; when the feedback voltage becomes greater than 3V, the capacitor is charged by the
5uA current source because diode D1 turns off. When the feedback voltage is less than 3V, the charge slope becomes an expo-
nential function and, when it is greater than 3V, the charge slope becomes linear. When the feedback voltage reaches almost
6V, the FAN7554 shuts down. The shut down circuit is configured for
auto-restart, so it automatically restarts when Vcc reaches the under voltage 9V.

Figure 16. Feedback & PWM Circuit

OUT

Vcc

5uA

1mA

Cfb

FAN7554

OSC

DRIN

Vfb/3

Vsense

Vfb

OUT

Vcc

5uA

1mA

Cfb

FAN7554

OSC

DRIN

Vfb/3

Vsense

Vfb

Figure 17-A . Delayed Shutdown & Feedback Circuit

OUT

Vcc

5uA

1mA

Cfb

FAN7554

OSC

DRIN

UVLO - out

Shutdown

Over Current
Comparator

OUT

Vcc

5uA

1mA

Cfb

FAN7554

OSC

DRIN

UVLO - out

Shutdown

Over Current
Comparator

FAN7554

Gate Driver

The gate drive circuit has the totem-pole output configuration. The output has 1A peak current and 200mA average current
drive ability.

ON/OFF Control

The FAN7554 is able to use the feedback pin for ON/OFF control by placing NPN transistor between the cathode of the
KA431 and ground as shown in figure 19. When the transistor turns on, the current flows through the photo diode and
saturates the photo transistor. As a result, the feedback voltage is dropped to zero. When the feedback voltage is below 0.3V,
the soft start voltage starts to discharge by connecting the internal resistor 1k

in parallel with the external capacitor Cs. When

the soft start voltage becomes less than 1.5V, all the blocks in the FAN7554 are turned off , with the exceptions of the UVLO
block and ON/OFF control block. The operation current is about 200uA. So the stand-by power is reduced and SMPS
efficiency is improved. When the feedback voltage exceeds 0.3V, the FAN7554 normally operates by turning on Vref block.

Figure 17-B . Delayed Shutdown & Feedback Waveform

Vfb

Slope (dv/dt) = 5uA / Cfb

Shutdown start point

Vfb

Slope (dv/dt) = 5uA / Cfb

Shutdown start point

Figure 18. Gate Drive Circuit

DRAIN

FAN7554

OUT

Clock

Shutdown

DRAIN

FAN7554

OUT

Clock

Shutdown

FAN7554

OUT

Clock

Shutdown

FAN7554

Figure 19. ON/OFF Control Circuit

0.3V

Cfb

Vref

Internal bias

Good logic

15V/9V

UVLO

VCC

3.5V

1.5V

S/S

Vcc

5uA

100uA

Vref

OFF

FAN7554

Remote control

PWR

SAVE

0.3V

Cfb

Vref

Internal bias

Good logic

15V/9V

UVLO

VCC

3.5V

1.5V

S/S

Vcc

5uA

100uA

Vref

OFF

FAN7554

Remote control

PWR

SAVE

Figure 20. ON-OFF Control Circuit Waveforms

Vref

t
t

ttt

Icc

4.5mA

0.2mA

S/S

Slope (dv/dt) = 1k

* Cs

Slope (dv/dt) = 100uA / Cs

1.5V

Slope (dv/dt) = (1mA +100uA) / Cs

0.3~3V

0.3V

Slope (dv/dt) = (5uA) / Cfb

Vfb

Slope (dv/dt) = (1mA +5A) / Cfb

ON Signal

OFF Signal

OFF State

Normal State

Vref

t
t

ttt

Icc

4.5mA

0.2mA

S/S

Slope (dv/dt) = 1k

* Cs

Slope (dv/dt) = 100uA / Cs

1.5V

Slope (dv/dt) = (1mA +100uA) / Cs

0.3~3V

0.3V

Slope (dv/dt) = (5uA) / Cfb

Vfb

Slope (dv/dt) = (1mA +5A) / Cfb

ON Signal

OFF Signal

OFF State

Normal State

FAN7554

Protection Circuits

The FAN7554 has many built-in protection circuits that do not need additional components, providing reliability without cost
increase. These protection circuits have the auto-restart configuration. In this configuration, the protection circuits reset when
Vcc is below UVLO stop threshold (9V) and restarts when Vcc is above UVLO start threshold voltage (15V)

Over Voltage Protection

Abnormalities may occur in the SMPS secondary side feedback circuit. First, when the feedback pin is short to the ground, the
feedback voltage is zero and the FAN7554 is unable to start switching. Second, when the feedback circuit is open, the
secondary voltage generally becomes much greater than the rated voltage as the primary side continues to switch at the
maximum current level. This may cause the blowing off the fuse or, in serious cases, fires. It is possible that the devices
directly connected to the secondary output without a regulator could be destroyed. Even in these cases, the over voltage
protection circuit operates. Since Vcc is proportional to the output , in an over voltage situation, it also will increase. In the
FAN7554, the protection circuit operates when Vcc exceeds 34V. Therefore ,in normal operation, Vcc must be set below 34V.

Over Load Protection

An overload is the state in which the load is operating normally but in excess of the preset load. The overload protection circuit
can force the FAN7554 to stop its operation . The protection can also operate in transient states such as initial SMPS operation.
Because the transient state returns to the normal state after a fixed time, the protection circuit need not to operate during this
time. That is, the FAN7554 needs the time to detect and decide whether it is an overload condition or not. The protection
circuit can be prevented from operating during transient states by ensuring that a certain amount of time passes before the
protection circuit operates. The above operations are executed as follows: Since the FAN7554 adopts a current mode, it is
impossible for current to flow above a maximum level. For a fixed input voltage, this limits power. Therefore, if the power at
the output exceeds this maximum, Vo, shown in figure21, becomes less than the set voltage, and the KA431pulls in only the
given minimum current. As a result, the photo-coupler's secondary side current becomes zero. The same goes for the
photo-coupler's primary side current. Consequently, when the full current 1mA flows through the internal resistor
(2R + R = 3R), Vfb becomes approximately 3V and from that time, the 5uA current source begins to charge Cfb, the
photo-coupler's secondary current is almost zero. The FAN7554 shuts down when Vfb reaches 6V.

Figure 21. Delayed Shutdown

UVLO out

Vcc

5uA

1mA

Cfb

Vfb

KA431

FAN7554

OSC

Shutdown

UVLO out

Vcc

5uA

1mA

Cfb

Vfb

KA431

FAN7554

OSC

Shutdown

5uA = (Cfb *3V)/t2

Time Constant = 3R * Cfb

Shutdown start point

5uA = (Cfb *3V)/t2

Time Constant = 3R * Cfb

Shutdown start point

FAN7554

FAN7554 Flyback Converter Demo Circuit (Fsw:100kHz)

FUSE

R104

D101

C104

T101

R108

R110

R109

R202

R203

R204

C101

C301 C302

C203

D103

IC301

IC201

Q101

LF101

TNR

D201

R201

IC101

C201

C103

C109

L201

C202

R102

FAN7554

S/S

IS Rt/Ct

Vref Vcc OUT GND

C105

R106

D102

Input:85 ~ 265V

50/60Hz

R205

NTC

R105

12V/3.5A

R101

R103

R111

C106

C107

C108

R107

C102

FUSE

R104

D101

C104

T101

R108

R110

R109

R202

R203

R204

C101

C301 C302

C203

D103

IC301

IC201

Q101

LF101

TNR

D201

R201

IC101

C201

C103

C109

L201

C202

R102

FAN7554

S/S

IS Rt/Ct

Vref Vcc OUT GND

C105

R106

D102

Input:85 ~ 265V

50/60Hz

R205

NTC

R105

12V/3.5A

R101

R103

R111

C106

C107

C108

R107

C102

FAN7554

Part List For FAN7554 Flyback Converter Demo Board

Part

Value

Note

Part

Value

Note

FUSE

CAPACITOR

FUSE

250 2A

C101

100nF/ 275V

Box Capacitor

NTC

C102

100nF/ 275V

Box Capacitor

NTC

5D-11

C103

470nF/ 400WV

Electrolytic

RESISTOR

C104

103/ 1kV

Film Capacitor

R101

330k

C105

104

Ceramic

R102

C106

1uF/ 10V

Electrolytic

R103, R104

100k

C107

101

Ceramic

R105

C108

122

Ceramic

R106

4.7k

C109

22uF/ 50V

Electrolytic

R107

12k

C201

330uF

Electrolytic

R108

C202

330uF

Electrolytic

R109

C203

104

Ceramic

R110

0.5

C301

R201

C302

R202

R203

4.7k

INDUCTOR

R204

1.2k

LF101

30mH

R205

L201

6.4uH

MOSFET

DIODE

Q101

FQP6N70

Fairchild

D201

MBRF10100CT

D101

UF4007

Fairchild

IC101

FAN7554

Fairchild

D102

1N4148

IC201

KA431

Fairchild

D103

UF4004

Fairchild

IC301

Opto-coupler

Fairchild

G3SBA60

FAN7554

Transformer Specification

Winding Specification

Electrical Characteristic

No.

Pin(S

Wire

Turns

Winding Method

0.35

12V

0.35

Closure

Pin

Spec.

Remarks

Inductance

1 - 3

400uH ±10%

100kHz, 1V

Leakagel

1 - 3

10uH MAX .

All short

12V

3mm

6mm

2mm

bottom

top

12V

3mm

6mm

2mm

bottom

top

12V

3mm

6mm

2mm

bottom

top

Schematic Diagram (Top view)

FAN7554

FAN7554 forward converter demo circuit ( fsw:100kHz)

D201

L201

FUSE

R104

D102

C104

T101

C204

R101

+12V/2A

FAN7554

F/B S/S

IS Rt/Ct

Vref Vcc OUT GND

R103

R102

R105

R106

R107

R108

R109

R113

R110

R112

R111

R203

R201

R202

C101

C301 C302

C102

C103

C105

C106

C110

C111

C107 C108

C109

C205

D103

D104

D101

IC301

IC201

Q101

L101

RT101

D202

R204

C203

+5V/3A

C201

C202

IC2

L202

Input: 85 ~ 265V

50/60Hz

D201

L201

FUSE

R104

D102

C104

T101

C204

R101

+12V/2A

FAN7554

F/B S/S

IS Rt/Ct

Vref Vcc OUT GND

R103

R102

R105

R106

R107

R108

R109

R113

R110

R112

R111

R203

R201

R202

C101

C301 C302

C102

C103

C105

C106

C110

C111

C107 C108

C109

C205

D103

D104

D101

IC301

IC201

Q101

L101

RT101

D202

R204

C203

+5V/3A

C201

C202

IC2

L202

Input: 85 ~ 265V

50/60Hz

FAN7554

Part List For FAN7554 Forward Converter Demo Board

Part

Value

Note

Part

Value

Note

FUSE

CAPACITOR

FUSE

250 2A

C101

470nF/ 275V

Box Capacitor

NTC

C102, C103

470nF/ 400WV

Electrolytic

RT101

DSC 10D-11

C104

223/ 630V

Film

RESISTOR

C105

33uF/ 35V

Film Capacitor

R101

330k

C106

104

Ceramic

R102

C107

1uF/ 35V

Electrolytic

R103, R104

56k

C108

101

Ceramic

R105, R106

220k

C109

122

Ceramic

R107

C110

272

Film

R108

C111

333

Film

R109

4.7k

C201, C202

1000uF/ 35V

Electrolytic

R110

1.2k

C203

330uF/ 16V

Electrolytic

R111

0.5

//0.5

C204

2200uF/ 16V

Electrolytic

R112

C205

104

Ceramic

R113

12k

C301, C302

332/ 1kV

Ceramic

R201, R202

10k

INDUCTOR

R203

LF101

30mH

R204

330

L201

MOSFET

DIODE

Q101

SSH8N80

Fairchild

D101

1N4004

D102

FR157

IC101

FAN7554

Fairchild

D103

UF4007

IC201

KA431

Fairchild

D201

MBRF10100CT

IC301

Opto-Coupler

Fairchild

D202

MBR3045PT

PBS406GU

FAN7554

Transformer specification

Winding Specification

Core : Powder 27 pi 16grade
5V : 12T (

2 )

12V : 27T (

1.2

1 )

No.

Pin(S

Wire

Turns

0.65

, 5

0.65

, 12

0.65

VCC

0.65

Nvcc ; 5turn

Np ; 32turn

Ns,12 ; 5turn

Ns,5 ; 4turn

13, 14

10,11,12

8, 9

Np ; 32turn

Ns,5 ; 4turn

Ns,12 ; 5turn

Np ; 32turn

Nvcc ; 6turn

Nvcc ; 5turn

Np ; 32turn

Ns,12 ; 5turn

Ns,5 ; 4turn

13, 14

10,11,12

8, 9

Nvcc ; 5turn

Np ; 32turn

Ns,12 ; 5turn

Ns,5 ; 4turn

13, 14

10,11,12

8, 9

Np ; 32turn

Ns,5 ; 4turn

Ns,12 ; 5turn

Np ; 32turn

Nvcc ; 6turn

Np ; 32turn

Ns,5 ; 4turn

Ns,12 ; 5turn

Np ; 32turn

Nvcc ; 6turn

Schematic Diagram (Top view)

FAN7554

8/21/02 0.0m 001

Stock#DSxxxxxxxx

2002 Fairchild Semiconductor Corporation

LIFE SUPPORT POLICY
FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES

OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR

CORPORATION. As used herein:

1. Life support devices or systems are devices or systems

which, (a) are intended for surgical implant into the body,

or (b) support or sustain life, and (c) whose failure to

perform when properly used in accordance with
instructions for use provided in the labeling, can be

reasonably expected to result in a significant injury of the

user.

2. A critical component in any component of a life support

device or system whose failure to perform can be

reasonably expected to cause the failure of the life support

device or system, or to affect its safety or effectiveness.

www.fairchildsemi.com

DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY

PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER

DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.

Ordering Information

Product Number

Package

Operating Temperature

FAN7554

8-DIP

-25

C ~ 85

FAN7554D

8-SOP

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ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: FAN7554