Fairchild FAN6862R service manual

FAN6862R / FAN6862L Highly Integrated Green-Mode PWM Controller

FAN6862R/L — 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)  Over-Temperature Protection (OTP)  Fixed PWM Frequency (65KHz) with Frequency

Hopping

 Feedback Open-Loop Protection with 56ms Delay  Soft-Start Time: 5ms  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, FAN6862R/L 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 FAN6862R/L 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 V protection, over-temperature protection, and overload protection. For over-temperature protection, an external NTC thermistor can be applied to sense the ambient temperature. When OVP, OTP, or OLP is activated, an internal protection circuit switches off the controller.

Part Number OVP OTP OLP

FAN6862RTY Auto Restart Auto Restart Auto Restart

FAN6862LTY Latch Latch Latch

over-voltage

DD

Ordering Information

Part Number Operating Temperature Range Package Packing Method

FAN6862RTY -40 to +105°C 6-Pin SSOT-6 Tape & Reel

FAN6862LTY -40 to +105°C 6-Pin SSOT-6 Tape & Reel

Typical Application

FAN6862R/L — Highly Integrated Green-Mode PWM Controller

Figure 1. Typical Application

Block Diagram

Figure 2. Block Diagram

Marking Information

FAN6862R/L — Highly Integrated Green-Mode PWM Controller

ABxTT

Pin Configuration

••••

---

Figure 3. Top Mark

Figure 4. Pin Assignments

ABx: ABA: FAN6862LTY

ABC: FAN6862RTY

TT: Wafer Lot Code

:

_ _ _: Week Code

Year Code

Pin Definitions

Pin # Name Function Description

1 GND Ground Ground

The FB pin provides the output voltage regulation signal. It provides feedback to the

2 FB Feedback

3 RT

4 SENSE

5 VDD Power Supply Power supply

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

Temperature

Detection

Current

Sense

internal PWM comparator for control of the duty cycle. This pin also provide for OLP: if V stops and restarts.

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.

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.

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

FB

FAN6862R/L — 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 300 mW

ΘJC Thermal Resistance (Junction-to-Case) 115 °C/W

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

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

VDD Over-Voltage Protection (Latch-Off) 24 25 26 V

DD-OVP

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

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

Threshold Voltage for Open-Loop Protection 4.3 4.6 4.9 V

FB-OLP

t

Open-Loop Protection Delay Time 53 56 60 ms

D-OLP

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 VFB>V

f

Normal PWM Frequency

OSC

Hopping Range VFB≥V

Hopping Range*1 VFB=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-N

FB-G

FB-ZDC

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

GATE Open, VFB=V

FB≥VFB-N

FB=VFB-G

FB-G

MAX

62 65 68

FB-N

FB-G

4.4 ms

11.5 ms

0.273 V

2.5 mA

±3.7 ±4.2 ±4.7

±2.9

2.3 2.5 2.7 V

TA= -40 to +105°C 2 %

Continued on the following page…

FAN6862R/L — Highly Integrated Green-Mode PWM Controller

kHz