Fairchild (Now ON) FAN6749MLM, FAN6749MLM Schematic [ru]

October 2012

FAN6749 Highly Integrated Ultra Green-Mode PWM Controller

FAN6749 — Highly Integrated Ultra Green-Mode PWM Controller

Features

 High-Voltage Startup  Low Operating Current: 1.8 mA  Linearly Decreasing PWM Frequency to 24 kHz  Proprietary Frequency Hopping to Reduce EMI

 Two-Level Over-Current Protection (OCP),

1400 ms Delay for Normal Peak Load

 Two-Level OCP, 56 ms Delay for Super Peak Load  Output Short-Circuit Protection (SCP)  Peak-Current Mode Operation with Cycle-by-Cycle

Current Limiting

 HV Pin Brown-in/out Protection with Hysteresis  Constant Power Limit by HV Sampling  Internal FB Open-Loop Protection (OLP)  GATE Output Maximum Voltage Clamp: 14.5V  V

Over-Voltage Protection (OVP)

 Programmable Over-Temperature Protection (OTP)  Integrated 6ms Soft-Start Function  Internal Latch Circuit (OVP, OTP, OCP, OLP, SCP)  Internal OTP Sensor with Hysteresis

Applications

General-Purpose Switched-Mode Power Supplies and Flyback Power Converters, including:

 Power Adapters  Open-Frame SMPS; Specifically for SMPS with

Surge-Current Output, such as for Printer, Scanner, Motor Drivers

Description

The FAN6749 highly integrated PWM controller enhances the performance of flyback converters. To minimize standby power consumption, a proprietary Green-Mode function continuously decreases the switching frequency under light-load conditions. Under zero-load conditions, the power supply enters Burst Mode and completely shuts off PWM output. Green Mode helps power supplies meet international power conservation requirements.

The FAN6749 is designed for SMPS with surge-current output and incorporates a two-level Over-Current Protection (OCP) function. Besides the cycle-by-cycle current limiting, two-level OCP can handle peak loading within a specified delay time.

FAN6749 also integrates a frequency-hopping function that helps reduce EMI emission of a power supply with minimum line filters. Built-in synchronized slope compensation helps achieve stable peak-current control. To keep constant output power limit over universal AC input range, the current limit and OCP threshold voltage are adjusted according to AC line voltage detected by the HV pin. Gate output is clamped at 14.5 V to protect the external MOSFET from over-voltage damage.

Other protection functions include: AC input brownout protection with hysteresis, Short-Circuit Protection (SCP) for output-short condition, and V Protection (OVP). For over-temperature protection, an external NTC thermistor can be applied to sense the ambient temperature. When OLP, OCP, SCP, V or OTP is activated, an internal latch circuit latches off the controller. The latch resets when V

OVP OCP OLP OTP SCP

Latch Latch Latch Latch Latch

There are three differences from FAN6748 to FAN6749:

Over-Voltage

is removed.

OVP,

 Over-current protection debounce time is extended

to 1400 ms.

 Brown-out debounce time is extended to 100 ms.  No SENSE short-circuit protection function.

Ordering Information

Part Number Operating Temperature Range Package

FAN6749MLM -40 to +105°C 8-Pin Small Outline Package (SOP) Reel & Tape

Packing

Method

Application Diagram

FAN6749 — Highly Integrated Ultra Green-Mode PWM Controller

Figure 1. Typical Application

Internal Block Diagram

Figure 2. Functional Block Diagram

Marking Information

Pin Configuration

ZXYTT 6749ML TM

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) M - Manufacture Flow Code

Figure 3. Top Mark

FAN6749 — Highly Integrated Ultra Green-Mode PWM Controller

Pin Definitions

Pin # Name Description

1 GND

2 FB

3 NC No Connection

4 HV

5 RT

6 SENSE

7 VDD

8 GATE

Ground Pin. A 0.1 µF decoupling capacitor between VDD and GND is recommended. Feedback Pin. The output voltage feedback information from the external compensation circuit is

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

High-Voltage Startup. The HV pin is typically connected to the AC line input through an external

diode and a resistor (R also to sense the line voltage. The line voltage information is used for brown-out protection and power limit line compensation.

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 an NTC resistor for over-temperature protection, place a 100 k resistor to ground to prevent noise interference.

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

Power Supply of IC. A holdup capacitor typically 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

GATE-CLAMP

GND

Figure 4. Pin Configuration (Top View)

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

GATE

VDD

SENSE

FAN6749 — Highly Integrated Ultra Green-Mode 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

SENSE Pin Input Voltage -0.3 7.0 V

SENSE

VRT RT Pin Input Voltage -0.3 7.0 V

VHV

JA

Continuous Input Voltage 500

Pulse Input Voltage

Power Dissipation (T

Thermal Resistance (Junction-to-Air) 150

TJ Operating Junction Temperature -40 +125

Storage Temperature Range -55 +150

STG

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

ESD

Human Body Model

Charged Device Model

Notes:

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

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

3. Duration of pulse input voltage is less than or equal to  1 second.

4. ESD with the HV pin CDM=1000 V and HBM=500 V.

(1,2)

30 V

(3)

640

＜50°C)

400 mW

C/W

C

(4)

, JEDEC:JESD22-A114 All Pins Except HV Pin 6 kV

(4)

, JEDEC:JESD22-C101 All Pins Except HV Pin 2 kV

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 HV Startup Resistor 150 200 250 k

Electrical Characteristics

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

Symbol Parameter Conditions Min. Typ. Max. Unit

VDD Section

VOP Continuously Operating Voltage Limited by VDD OVP 25 V

Threshold Voltage to Startup VDD Rising 16 17 18 V

DD-ON

DD-OFF

DD-OLP

UVLO

RESTART

DD-LH

DD-AC

DD-SCP

D-SCP

DD-ST

DD-OP1

DD-OP2

ILH

DD-OLP

DD-OVP

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

VDD Falling

VDD Falling 6.5 7.5 8.5 V

VDD Falling 6.0 6.5 7.0 V

Threshold Voltage to Enable HV Startup to Charge VDD in Normal

VDD Falling 4.5 5.0 5.5 V

Mode

Threshold Voltage to Release Latch Mode

VDD Falling 3.5 4.0 4.5 V

Threshold Voltage on VDD Pin for Disable Brown-in to Avoid Startup Failure

Threshold Voltage on VDD Pin for Short-Circuit Protection (SCP)

Debounce Time for SCP

Startup Current V

Supply Current in PWM Operation

> V

FB>VFB-OLP

& V

DD-ON

=20 V, VFB = 3 V

FB-OLP

< V

DD-SCP

– 0.16 V 30 µA

Gate Open

Supply Current when PWM Stops VDD=15 V, VFB < 1.4 V 1.0 1.9 mA

Operating Current when V

in Protection Mode

OFF

Internal Sink Current

Threshold Voltage for V Voltage Protection

Over-Voltage Protection

Debounce Time

DD<VDD-

Over-

VDD = 5 V 100 120 140 µA

+0.1 V

DD-OLP

28.5 29.0 29.9 V

160 200 240 µs

10 11 12

UVLO

+2.5

DD-OFF

+1.0

UVLO

+3 V

DD-OFF

+1.5

+3.5 V

UVLO

+2.0 V

DD-OFF

12 17 22 ms

1.8 2.4 mA

265 325 385 µA

FAN6749 — Highly Integrated Ultra Green-Mode PWM Controller

DD-ON

GATE

UVLO

Normal Mode

RESTART

Figure 5. VDD Behavior

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