Fairchild FAN6862 service manual

FAN6862 Highly Integrated Green-Mode PWM Controller

FAN6862 — Highly Integrated Green-Mode PWM Controller

May 2012

Features

 Low Startup Current: 8µA  Low Operating Current in Green Mode: 3mA  Peak-Current Mode Operation with Cycle-by-Cycle

Current Limiting

 PWM Frequency Continuously Decreasing with

Burst Mode at Light Loads

 V

Over-Voltage Protection (OVP)

DD

 Constant Output Power Limit (Full AC Input Range)  Internal Latch Circuit for OVP, OTP  Fixed PWM Frequency (65KHz) with Frequency

Hopping

 Feedback Open-Loop Protection with 56ms Delay  Soft Start Time: 4ms  400mA Driving Capability

Applications

General-purpose switch-mode power supplies and flyback power converters, including:

 Power Adapters  Open-Frame SMPS  SMPS with Surge-Current Output, such as for

Printers, Scanners, and Motor Drivers

Description

A highly integrated PWM controller, FAN6862 provides several features to enhance the performance of flyback converters. To minimize standby power consumption, a proprietary green-mode function provides off-time modulation to continuously decrease the switching frequency under light-load conditions. Under zero-load conditions, the power supply enters burst-mode, which completely shuts off PWM output. Output restarts just before the supply voltage drops below the UVLO lower limit. This green-mode function enables power supplies to meet international power conservation requirements.

The FAN6862 is designed for SMPS and integrates a frequency-hopping function that helps reduce EMI emission of a power supply with minimum line filters. The built-in synchronized slope compensation is proprietary sawtooth compensation for constant output power limit over universal AC input range. The gate output is clamped at 18V to protect the external MOSFET from over-voltage damage.

Other protection functions include VDD over-voltage protection and over-temperature protection. For overtemperature protection, an external NTC thermistor can be applied to sense the ambient temperature. When V OVP or OTP is activated, an internal latch circuit latches off the controller.

Part Number OVP OTP OLP

FAN6862TY Latch Latch Auto Restart

FAN6862NY Latch Latch Auto Restart

DD

Ordering Information

Part Number

FAN6862TY -40 to +105°C 6-Pin SSOT-6 Tape & Reel

FAN6862NY -40 to +105°C 8-Pin Dual In-Line Package (DIP) Tube

Operating Temperature

Range

Package Packing Method

Typical Application

FAN6862 — Highly Integrated Green-Mode PWM Controller

Figure 1. Typical Application

Block Diagram

Figure 2. Block Diagram

–

Marking Information

FAN6862 — Highly Integrated Green-Mode PWM Controller

Pin Configuration

Figure 4. SSOT-6 Figure 5. DIP-8

ABx: ABD: FAN6862TY TT: Wafer Lot Code

:

_ _ _: Week Code

Year Code

Figure 3. Top Mark

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 (N:DIP) P – Y: Green Package

Manufacture Flow Code

M

Pin Definitions

Pin # DIP8

8 1 GND Ground.

7 2 FB

6 NC No Connect Pin

5 3 RT

4 4 SENSE

3 NC No Connect Pin

2 5 VDD Power Supply.

1 6 GATE

Pin #

SSOT-6

Name Description

Feedback. The FB pin provides the output voltage regulation signal. It

provides feedback to the internal PWM comparator, so that the PWM comparator can control the duty cycle. This pin also provide for OLP: if V

FB

controller stops and restarts.

Temperature Detection. An external NTC thermistor is connected from this pin to GND for over-temperature protection. The impedance of the NTC decreases at high temperatures. Once the voltage of the RT pin drops below a threshold, PWM output is disabled.

Current Sense. This pin senses the voltage across a resistor. When the voltage reaches the internal threshold, PWM output is disabled. This activates over-current protection. This pin also provides current amplitude information for current-mode control.

Driver Output. The totem-pole output driver for driving the power MOSFET.

is larger than the trigger level and delays for a long time, the

FAN6862 — Highly Integrated 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. All voltage values, except differential voltages, are given with respect to GND pin.

Symbol Parameter Min. Max. Unit

VDD Supply Voltage 30 V

VL Input Voltage to FB, SENSE, RT Pin -0.3 7.0 V

PD Power Dissipation at TA<50°C

ΘJC Thermal Resistance (Junction-to-Case)

TJ Operating Junction Temperature -40 +150 °C

T

Storage Temperature Range -55 +150 °C

STG

TL Lead Temperature, Wave Soldering, 10 Seconds +260 °C

ESD

Human Body Model, JESD22-A114 3.00

Charge Device Model, JESD22-C101 1.25

SSOT-6

DIP-8 800

SSOT-6

DIP-8 67

300

115

mW

°C/W

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. Max. Unit

TA Operating Ambient Temperature -40 +105 °C

Electrical Characteristics

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

Symbol Parameter Test Condition Min. Typ. Max. Unit

VDD Section

V

Continuously Operating Voltage 24 V

DD-OP

V

Turn-on Threshold Voltage 15 16 17 V

DD-ON

V

Turn-off Voltage 7.5 8.5 9.5 V

DD-OFF

V

Threshold voltage for Latch-Off release 3 4 5 V

DD-LH

I

Startup Current V

DD-ST

I

Normal Operating Supply Current CL=1nF 3 4 mA

DD-OP

I

Green-Mode Operating Supply Current GATE open, VFB=V

DD-BM

V

VDD Over-Voltage Protection 24 25 26 V

DD-OVP

t

D-VDDOVP

VDD OVP Debounce Time 30 50 μs

I

Latch-Off Holding Current VDD=5V 40 65 μA

DD-LH

Feedback Input Section

AV Input-Voltage to Current-Sense Attenuation 1/4.0 1/3.5 1/3.0 V/V

ZFB Input Impedance 5.5 kΩ

V

FB Pin Open Voltage 5.0 5.2 5.4 V

FB-OPEN

V

FB-OLP

t

D-OLP

Threshold Voltage for Open-Loop Protection

Open-Loop Protection Delay Time 53 56 60 ms

Current Sense Section

tPD Delay to Output 100 250 ns

t

Leading-Edge Blanking Time 270 360 ns

LEB

V

Flat Threshold Voltage for Current Limit Duty>51% 0.47 0.50 0.53 V

STHFL

V

Valley Threshold Voltage for Current Limit Duty=0% 0.41 0.44 0.47 V

STHVA

V

Slope Compensation Duty=DCY

SLOPE

t

SOFT-START

Period During Startup time 2.50 4.00 5.25 ms

Oscillator Section

Center Frequency

f

Normal PWM Frequency

OSC

Hopping Range VFB≥V

Hopping Range*1VFB=V

t

Hopping Period 1*1 V

hop-1

t

Hopping Period 3*1 V

hop-3

f

Green Mode Minimum Frequency 18.0 22.5 25.0 kHz

OSC-G

V

FB-ZDC

FB-N

FB-G

FB Threshold Voltage For Frequency Reduction

FB Voltage at f

1.9 2.1 2.3 V

OSC-G

FB Threshold Voltage for Zero Duty 1.7 V

fDV Frequency Variation vs. VDD Deviation VDD=11.5V to 20V 0 0.02 2.00 %

fDT

Frequency Variation vs. Temperature Deviation

–0.16V 8 30 μA

DD-ON

FB-G

2.5 mA

4.3 4.6 4.9 V

0.273 V

MAX

V

FB>VFB-N

FB≥VFB-N

FB=VFB-G

62 65 68

FB-N

FB-G

±3.7 ±4.2 ±4.7

±2.9

4.4 ms

11.5 ms

2.0 2.2 2.4 V

T

= -40 to +105°C 2 %

A

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FAN6862 — Highly Integrated Green-Mode PWM Controller

kHz