Fairchild FAN7554 Service Manual

FAN7554

Versatile PWM Controller

www.fairchildsemi.com

Features

• Current Mode Control

• Pulse by Pulse Current Limiting

• Low External Components

• Under Voltage Lockout (UV L O ): 9V /15V

• Stand-by Current: Typ. 100uA

• Power Saving Mode Cur r ent: 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 F requency 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 protec tion, 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.

8-DIP

1

8-SOP

1

©2002 Fairchild Semiconductor Corporation

Rev. 1.0.2

FAN7554

Internal Block Diagram

3.5V

3.5V

Vref

Vref

uA

uA

100

100

2

22

S/S

S/S

1k

5uA

5uA

5uA

6V

6V

1k1k

Vref

Vref

Vcc

Vcc

Vcc

OLP

OLP

+

+

_

_

FB

FB

0.3V

0.3V

+

+

_

_

1

11

_

_

+

+

1.5V

1.5V

1mA

1mA

OVP-out

OVP-out

_

_

+

+

2R

2R

OCL-out

OCL-out

S R

S R

Q

Q

MAX. 1V

MAX. 1V

R

R

Rt/Ct

Rt/Ct

4

44

off

off

on

on

OSC

OSC

PWM

PWM

_

_

+

+

Offset(0.1V)

Offset(0.1V)

UVLO-out

UVLO-out

PWR

PWR

/

/

SAVE

SAVE

CLK

CLK

Vcc

OCL

OCL

34V

34V

+

+

_

_

14V

14V

Vcc

7

77

2V

2V

6

66

OUT

OUT

I S

I S

3

33

GND

GND

5

55

Vref

Vref

8

88

Vref

Vref

S

S

Q

Q

R

R

S

S

Q

Q

R

R

OVP

OVP

UVLO

UVLO

15V/9V

15V/9V

+

+

_

_

+

+

_

_

Absolute Maximum Ratings

( Ta = 25°C, unless otherwise specified )

Parameter Symbol Value Unit

Supply Voltage Vcc 30 V
Output Current I
Input Voltage to FB Pin V
Input Voltage to IS Pin V
Power Dissipation at T

≤ 25°C

A

8-DIP
8-SOP

Operating Temperature T
Storage Temperature T
Thermal Resistance, Junction-to-Air (Note1)

8-DIP
8-SOP

Note:

1. Junction -to -air thermal resistance test environments.

-. Pneumatic heat sink fixture.

-. Clamping pressure 60psi through 12mm diameter cyl ind er.

-. Thermal gr ease applied be tween PKG and h eat sink fixtur e

O
FB

IS

P

D

OPR
STG

Rθja 147.8

±1 A

-0.3 to V

-0.3 to V

SD
OC

0.85

0.42

-25 to +85 °C

-55 to +150 °C

°C/W

291.4

V
V

W

2

Temperature Characteristics

WW

NN

( -25°C ≤ Ta ≤ 85°C )

Parameter Symbol Value Unit

Vref Temperature Stability ∆V
Fosc Temperature Stability ∆F

PIN Array

3±0.5 %

REF

2±5 %

OSC

FAN7554

Vref

8888

PIN Definitions

Pin Number Pin Name Pin Function Description

1FB
2 S/S Soft Start

3 IS Non-Inverting(+) Input of PWM Comparator, OCL Sensing Terminal
4 Rt/Ct Oscillator Time Constant(Rt/Ct)
5 GND Ground
6 OUT Output of Gate Driver
7 Vcc Power Supply
8 Vref Output of 5V Reference

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

Vcc

7777

AAAAN

N7

2222

OUT

66665

YYYYW

75

55

77

55

3333

ISS/SFB

GND

WWWWW

54

4FFFF

55

44

Rt/Ct

5

55

44441111

3

FAN7554

Electrical Characteristics

(Ta = 25°C, Vcc=16V, Rt=10kΩ, Ct=3.3nF unless otherwise specified)

Parameter Symbol Conditions Min. Typ. Max. Unit
< REFERENCE SECTION >

Reference Output Voltage V
Line Regulation ∆V
Load Regulation ∆V
Short Circuit Output Current I

REF
REF1
REF2

SC

< OSCILLATOR SECTION >

Oscillation Frequency F
Frequency Change with Vcc ∆F
Ramp High Voltage V
Ramp Low Voltage V

OSC
OSC1

RH

RL

Discharge Current Idisch V

< PWM SECTION >

Sense Threshold Voltage V
Feedback Threshold Voltage V
Feedback Source Current I
Max. Duty Cycle D
Min. Duty Cycle D

TH(IS)

TH(FB)VIS

FB

(MAX)

(MIN)

< PROTECTION SECTION >

Shutdown Delay Current I
Shutdown Feedback Voltage V
Over Current Protection V
Over Voltage Protection V

SD

SD
OC

OVP

< ON/OFF CONTROL SECTION >

Off Mode Sink Current I
Off Threshold Voltage V

SINK

OFF

< SOFT-START SECTION >

Soft Start Current I
Soft Start Limit Voltage V

S/S

LIM(S/S)

<OUTPUT SECTION>

Low Output Voltage1 V
High Output Voltage1 V
Low Output Voltage2 V
High Output Voltage2 V
Rising Time (Note1) t
Falling Time (Note1) t

OL1
OH1
OL2
OH2

R

F

<UVLO SECTION>

Start Threshold Voltage V
Min. Operating Voltage V

TH(ST)

OPR(M)

Tj =25°C , Iref =1mA 4.90 5.00 5.10 V
Vcc =12V ~ 25V - 6 20 mV
Iref =1mA ~ 20mA - 6 25 mV
Tj = 25°C-0.10.18A

Tj = 25°C 455055kHz
Vcc = 12V ~ 25V - 0.05 1.0 %

--2.8-V

--1.2-V

= 3.3V 6.1 - 9.4 mA

RT/CT

VFB = 5V 0.8 1.0 1.2 V

= 0V 0.2 0.3 0.4 V

VFB = 0V, V

= 5V - 1.0 - mA

S/S

- 929598%

---0%

4V ≤ VFB ≤ V

SD

3.5 5 6.5 uA
VFB > 5V 5.4 6 6.6 V
VIS > 1.5V,

ton > 500nS

1.622.4V

- 303438V

VFB < V
VFB < V

VFB = 5V, V

TH(FB)
TH(FB)

S/S

, V

= 5V - 4 - mA

S/S

1.2 1.5 1.8 V

= 0V - 1.1 - mA

Vcc = 16V - 5.2 - V

VCC = 18V, IO = 50mA - 0.15 0.4 V
VCC = 18V, IO = -50mA 131517 V
VCC = 18V, IO = 200mA - 1.5 2.5 V
Vcc = 18V, Io = -200mA 12 14 16 V
Tj = 25°C, CL = 1nF - 80 - ns
Tj = 25°C, CL = 1nF - 40 - ns

- 13.2 15 16.2 V

- 8.2 9 10.2 V

4

FAN7554

Electrical Characteristics

(Continued)

(Ta = 25°C, Vcc=16V, Rt =10kΩ, Ct = 3.3nF unless otherwise specified)

Parameter Symbol Conditions Min. Typ. Max. Unit
<TOTAL STAND-BY CURRENT SECTION>

Start-up Current I
Operating Supply Current I
Off State Current I

Note:

1. These parameters, although guaranteed, are not 100% tested in production.

ST

OP

OFF

VFB<V

TH(FB),VS/S<VOFF

--0.10.2mA

--710mA

-0.20.4mA

5

FAN7554

Typical Perfomance Characteristics

[ Rt vs. Freqency ]

[ Rt vs. Freqency ]

[ Rt vs. Freqency ][ Rt vs. Freqency ]

[ Ct vs Dead time ]

[ Ct vs Dead time ]

[ Ct vs Dead time ][ Ct vs Dead time ]

10000.0

100.000

1000.0

10.000

100.0

0.33n

1.1n

3.3n

10.0

Frequency[kHz]

11n
33n

1.000

Dead Time [usec]

1.0

0.1
1 10 100

0.100

0.1 1 10 100

Rt[Kohm]

Figure 1. Rt vs. Frequency Figure 2. Ct vs. Dead Time

[ Cload vs Tr & Tf ]

[ Cload vs Tr & Tf ] 50Khz ,9 5% duty

[ Ct vs Duty ]

[ Ct vs Duty ]

[ Ct vs Duty ][ Ct vs Duty ]

95.0

85.0

75.0

65.0

55.0

Duty [%]

45.0

35.0

25.0

15.0

0.1 1 10 100
Ct [nF]

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

800

700

600

500

400

Time [nsec]

300

200

100

[ Cload vs Tr & Tf ] [ Cload v s Tr & Tf ]

0

110100

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

Ct[nF]

Tr
Tf

Cload [ nF]

Figure 3. Ct vs. Duty Figure 4. Cload vs. Tr & Tf

6

FAN7554

Typ ica l Performance Characteristics

Figure 5. Temperature vs. Start-up Current

(Continued)

Figure 6. Temperature vs. Operating Supply Current

Figure 7. Temperature vs. Reference Voltage

Figure 9. Temperature vs. Start Threshol d Voltage

7

Figure 8. Temperature vs. Oscillation frequency

Figure 10. Temperature vs. Min. Operating Voltage