Fairchild FAN6756 service manual

FAN6756 — mWSaver™ PWM Controller

May 2012

Features

 Single-Ended Topologies, such as Flyback and

Forward Converters

 mWSaver™ Technology

- Achieves Low No-Load Power Consumption:

Less than 30mW at 230V Included)

(EMI Filter Loss

AC

- Eliminates X Capacitor Discharge Resistor Loss

with AX-CAP™ Technology

- Linearly Decreases Switching Frequency to

23KHz

- Burst Mode Operation at Light-Load Condition

- Impedance Modulation in Standby Mode for

“Deep” Burst Mode Operation

- Low Operating Current (450µA) in Standby Mode

- 500V High-Voltage JFET Startup Circuit to

Eliminate Startup Resistor Loss

 Highly Integrated with Rich Features

- Proprietary Frequency Hopping to Reduce EMI

- High-Voltage Sampling to Detect Input Voltage

- Peak-Current-Mode Control with Slope

Compensation

- Cycle-by-Cycle Current Limiting with Line

Compensation

- Leading Edge Blanking (LEB)

- Built-In 8ms Soft-Start

 Advanced Protections

- Brown-In/Brownout Recovery

- Internal Overload/Open-Loop Protection (OLP)

- V

Under-Voltage Lockout (UVLO)

DD

- V

Over-Voltage Protection (V

DD

OVP)

- Over-Temperature Protection (OTP)

- Current-Sense Short-Circuit Protection (SSCP)

Description

The FAN6756 is a next-generation Green Mode PWM controller with innovative mWSaver™ technology, which dramatically reduces standby and no-load power consumption, enabling conformance to worldwide Standby Mode efficiency guidelines.

An innovative AX-CAP™ method minimizes losses in the EMI filter stage by eliminating the X-cap discharge resistors while meeting IEC61010-1 safety requirements. Standby Mode clamps feedback voltage and modulates feedback impedance with an impedance modulator during Burst Mode operation, which forces the system to operate in a “deep” Burst Mode with minimum switching losses.

Protections ensure safe operation of power system in various abnormal conditions. Proprietary frequencyhopping function decreases EMI emission and built-in synchronized slope compensation allows more stable Peak-Current-Mode control over wide range of input voltage and load conditions. The proprietary internal line compensation ensures constant output power limit over entire universal line voltage range.

Requiring a minimum number of external components, FAN6756 provides a basic platform that is well suited for cost-effective flyback converter designs that require extremely low standby power consumption.

Applications

Flyback power supplies that demand extremely low standby power consumption, such as:

 Adapters for Notebooks, Printers, Game Consoles,

etc.

 Open-Frame SMPS for LCD TV, LCD Monitors,

Printer Power, etc.

Related Resources



Evaluation Board: FEBFAN6756MR_T03U065A

Ordering Information

Part Number

Protections

OLP OVP OTP SSCP

FAN6756MRMY A/R L L A/R

FAN6756MLMY L L L A/R

Note:

1. A/R = Auto Recovery Mode protection, L = Latch Mode protection.

(1)

Operating

Temperature Range

-40 to +105°C

Package

8-Pin, Small Outline

Package (SOP)

Packing

Method

Tape & Reel

Application Diagram

FAN6756 — mWSaver™ PWM Controller

Internal Block Diagram

Figure 1. Typical Application Diagram

Figure 2. Functional Block Diagram

Marking Information

ZXYTT 6756ML TPM

Pin Configuration

ZXYTT 6756MR TPM

FAN6756 — mWSaver™ PWM Controller

F - Fairchild Logo

Z - Plant Code X - 1-Digit Year Code Y - 1-Digit Week Code TT - 2-Digit Die Run Code T - Package Type (M=SOP) P - Y: Green Package M - Manufacture Flow Code

Figure 3. Top Mark

SOP-8

GND

FB

NC

HV

18

2

3

GATE

7

6

54

VDD

SENSE

RT

Figure 4. Pin Configuration (Top View)

Pin Definitions

Pin # Name Description

1 GND Ground Pin. Placing a 0.1µF decoupling capacitor between VDD and GND is recommended.

Feedback Pin. The output voltage feedback information from the external compensation circuit is

2 FB

3 NC No Connection

4 HV

5 RT

6 SENSE

7 VDD

8 GATE

fed into this pin. The PWM duty cycle is determined by comparing the FB signal with the currentsense signal from the SENSE pin.

High-Voltage Startup. The HV pin is typically connected to the AC line input through two external diodes and one resistor (R

). This pin is used, not only to charge the VDD capacitor during

HV

startup, but also to sense the line voltage. The line voltage information is used for brownout protection and power limit line compensation. This pin also is used to intelligently discharge the EMI filter capacitor when the removal of the AC line voltage is detected.

Over-Temperature Protection. An external NTC thermistor is connected from this pin to the GND pin. Once the voltage of the RT pin drops below the threshold voltage, the controller latches off the PWM. The RT pin also provides external latch protection. If the RT pin is not connected to the NTC resistor for over-temperature protection, it is recommended to place a 100k resistor to ground to prevent noise interference.

Current Sense. The sensed voltage is used for Peak-Current-Mode control, short-circuit protection, and cycle-by-cycle current limiting.

Power Supply of IC. Typically a hold-up capacitor connects from this pin to ground. A rectifier diode, in series with the transformer auxiliary winding, connects to this pin to supply bias during normal operation.

Gate Drive Output. The totem-pole output driver for the power MOSFET; internally limited to V

GATE-CLAMP

.

FAN6756 — mWSaver™ PWM Controller

Absolute Maximum Ratings

Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only.

Symbol Parameter Min. Max. Unit

VDD DC Supply Voltage

VFB FB Pin Input Voltage -0.3 7.0 V

V

SENSE Pin Input Voltage -0.3 7.0 V

SENSE

VRT RT Pin Input Voltage -0.3 7.0 V

VHV HV Pin Input Voltage 500 V

PD

ΘJA

Power Dissipation (TA=50°C)

Thermal Resistance (Junction-to-Air) 150

TJ Operating Junction Temperature -40 +125

T

Storage Temperature Range -55 +150

STG

TL Lead Temperature (Wave Soldering or IR, 10 Seconds) +260

Human Body Model,

ESD

JEDEC:JESD22-A114

Charged Device Model, JEDEC:JESD22-C101

Notes:

2. All voltage values, except differential voltages, are given with respect to the network ground terminal.

3. Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device.

4. ESD level with the HV pin is CDM=1250V and HBM=500V.

(2,3)

30 V

400 mW

°C/W

°C

All Pins Except HV Pin

(4)

6000

V

All Pins Except HV Pin

(4)

2000

Recommended Operating Conditions

The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to Absolute Maximum Ratings.

Symbol Parameter Min. Typ. Max. Unit

RHV Resistance on HV Pin 150 200 250 k

FAN6756 — mWSaver™ PWM Controller

Electrical Characteristics

VDD=15V and TA=25°C unless otherwise noted.

Symbol Parameter Condition Min. Typ. Max. Unit

VDD Section

VOP Continuously Operating Voltage Limited by VDD OVP 22 V

V

Threshold Voltage to Startup VDD Rising 16 17 18 V

DD-ON

V

DD-OFF

V

DD-OLP

V

UVLO

V

RESTART

V

DD-LH

V

DD-AC

I

DD-ST

I

DD-OP1

ILH

I

DD-OP2

I

DD-OLP

V

DD-OVP

t

D-VDDOVP

Threshold Voltage to Stop Switching in Protection Mode

Threshold Voltage to Turn-on HV Startup in Protection Mode

Threshold Voltage to Stop Switching in Normal Mode

V

Falling 10 11 12 V

DD

VDD Falling 6 7 8 V

VDD Falling 5.5 6.5 7.5 V

Threshold Voltage to Enable HV Startup to charge VDD in Normal

VDD Falling 5 V

Mode

Threshold Voltage to Release Latch Mode

VDD Falling 3.5 4.0 4.5 V

Threshold Voltage for Brown-in 9.0 9.5 10.0 V

Startup Current V

Supply Current in PWM Operation

Operating Current when VDD<V

DD-OFF

in Protection Mode

Supply Current when PWM Stops

Internal Sink Current from V V

in Protection Mode

DD-OLP

Threshold Voltage for VDD OverVoltage Protection

VDD Over-Voltage Protection Debounce Time

DD-OFF

to

– 0.16V 30 µA

DD-ON

VDD=15V, VFB=3V, Gate Open

1.8 mA

VDD=5V 70 µA

VDD=15V, VFB <1.4V, Gate Off

+0.1V 160 210 260 µA

V

DD-OLP

450 µA

23.5 24.5 25.5 V

110 185 260 µs

Figure 5. Timing Diagram for Brown-in Function

Continued on the following page…

FAN6756 — mWSaver™ PWM Controller

Electrical Characteristics (Continued)

VDD=15V and TA=25°C unless otherwise noted.

Symbol Parameter Condition Min. Typ. Max. Unit

HV Section

IHV Supply Current from HV Pin

V

Threshold Voltage for Brownout

AC-OFF

V

Threshold Voltage for Brown-In

AC-ON

△V

AC

t

D-AC-OFF

V

HV-DIS

t

D-HV-DIS

V

Debounce Time for Brownout 40 65 90 ms

AC-ON

- V

AC-OFF

X-Cap. Discharge Threshold

Debounce Time for Triggering X-Cap. Discharge

Oscillator Section

f

OSC

t

HOP

f

OSC-G

fDV

fDT

Switching Frequency When V

FB>VFB-N

Hopping Period VFB>V

Switching Frequency When V

FB<VFB-G

Frequency Variation vs. VDD Deviation

Frequency Variation vs. Temperature Deviation

Feedback Input Section

AV

ZFB

V

FB-OPEN

V

FB-OLP

t

D-OLP

V

FB-ZDC1

V

FB-ZDCR1

V

FB-ZDC2

V

FB-ZDCR2

Feedback Voltage to CurrentSense Attenuation

Regular FB Internal Pull-High Impedance

FB internal Biased Voltage FB Pin Open 5.2 5.4 5.6 V

Threshold Voltage for OLP 4.3 4.6 4.9 V

Debounce Time for OLP 45.0 57.5 70.0 ms

Threshold Voltage for Maximum

FB-N

Switching Frequency

Threshold Voltage for Minimum

FB-G

Switching Frequency

Threshold Voltage for Zero-Duty Cycle

Threshold Voltage for Zero-Duty Cycle Recovery

Threshold Voltage for Zero Duty Cycle in Standby Mode

Threshold Voltage for Zero-Duty Cycle Recovery in Standby Mode

VAC=90V (VDC=120V),

=0V

V

DD

DC Source Series R=200k to HV Pin

VFB<V

FB-G

R=200k to HV Pin

30 40 50 ms

Center Frequency 62 65 68

Hopping Range (V

FB>VFB-N

V

FB<VFB-G

)

4.0 6.5 ms

FB-N

20 23 26 kHz

VDD=11V to 22V 5 %

TA=-40 to 105°C

1/4.5 1/4.0 1/3.5 V/V

8.5 k

2.6 2.8 3.0 V

1.8 2.0 2.2 V

2.4 2.6 2.8 V

2.0 3.5 5.0

90 100 110

100 110 120

8 12 16

VDC

×0.45

(5)

V

DC

×0.51

VDC

×0.56

±3.7 ±4.2 ±4.7

mA

V

kHz

5 %

2.1

1.9

2.35

2.3 2.5 V

2.1 2.3 V

2.55 2.75 V

Continued on the following page…