2000pcs of FAN7621BSJX or FAN7621SJX in stock for sale ,ON fairchild, new and original

FAN7621
FAN7621BSJX FAN7621SJX
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Brief Introduction of FAN7621BSJX or FAN7621

The FAN7621BSJX or FAN7621SJX is a pulse frequency modulation controller for high-efficiency half-bridge resonant converters.Offering everything necessary to build a reliable and robust resonant converter, the FAN7621B simplifies designs and improves productivity, while improving performance. The FAN7621B includes a highside gate-drive circuit, an accurate current controlled oscillator, frequency limit circuit, soft-start, and built-in protection functions. The high-side gate-drive circuit has a common-mode noise cancellation capability, which guarantees stable operation with excellent noise immunity. Using the zero-voltage-switching (ZVS) technique dramatically reduces the switching losses and efficiency is significantly improved. The ZVS also reduces the switching noise noticeably, which allows a small-sized Electromagnetic Interference (EMI) filter. The FAN7621B can be applied to various resonant converter topologies; such as series resonant, parallel resonant, and LLC resonant converters.

Features of FAN7621BSJX or FAN7621

Features
 
Variable Frequency Control with 50% Duty Cycle for Half-bridge Resonant Converter Topology
High Efficiency through Zero Voltage Switching (ZVS)
Fixed Dead Time (350ns)
Up to 300kHz Operating Frequency
Pulse Skipping for Frequency Limit (Programmable) at Light-Load Condition
Remote On/Off Control using CON Pin
Protection Functions: Over-Voltage Protection (OVP), Overload Protection (OLP), Over-Current Protection (OCP), Abnormal Over-Current Protection (AOCP), Internal Thermal Shutdown (TSD)
Applications
PDP TV LCD TV Desktop PC Server Video Game Console

FAN7621BSJX FAN7621SJX, PFM CONTROLLER FOR HALF-BRIDGE

Converter Offline Half-Bridge Topology Up to 300kHz 16-SOP

Product Attributes

Categories:      Integrated Circuits (ICs)

PMIC – AC DC Converters, Offline Switchers 

Manufacturer:          ON Semiconductor 

Packaging:        Tape & Reel (TR)    

Part Status:      Active      

Output Isolation:     Isolated  

Internal Switch(s):   No   

Voltage – Breakdown       

Topology  Half-Bridge      

Voltage – Start Up    12.5V       

Voltage – Supply (Vcc/Vdd)        10V ~ 25V        

Duty Cycle        50%

Frequency – Switching      Up to 300kHz  

Power (Watts) 192W       

Fault Protection       Current Limiting, Over Load, Over Temperature, Over Voltage     

Control Features      Frequency Control  

Operating Temperature  -40°C ~ 130°C (TJ)   

Package / Case         16-SOIC (0.209″, 5.30mm Width)   

Supplier Device Package 16-SOP    

Mounting Type:Surface MountFAN7621B — PFM Controller for Half-Bridge Resonant Converters

FAN7621B

PFM Controller for Half-Bridge Resonant Converters

FAN7621BSJX or FAN7621SJX  Features:

1,Variable Frequency Control with 50% Duty Cycle

for Half-bridge Resonant Converter Topology

2,  High Efficiency through Zero Voltage Switching (ZVS)

3,  Fixed Dead Time (350ns)

4,  Up to 300kHz Operating Frequency

5, Pulse Skipping for Frequency Limit (Programmable)

at Light-Load Condition

6,  Remote On/Off Control using CON Pin

7,  Protection Functions: Over-Voltage Protection

(OVP), Overload Protection (OLP), Over-Current

Protection (OCP), Abnormal Over-Current Protection

(AOCP), Internal Thermal Shutdown (TSD)

Applications

8, PDP and LCD TVs

9, Desktop PCs and Servers

10, Adapters

11,  Telecom Power Supplies

12, Video Game Consoles

The FAN7621BSJX FAN7621SJX is a pulse frequency modulation,

controller  for  high-efficiency  half-bridge  resonant

converters. Offering everything necessary to build a

reliable and robust resonant converter, the FAN7621B

simplifies designs and improves productivity, while

improving performance. The FAN7621B includes a high-

side gate-drive circuit, an accurate current controlled

oscillator, frequency limit circuit, soft-start, and built-in

protection functions. The high-side gate-drive circuit has

a common-mode noise cancellation capability, which

guarantees  stable  operation with excellent noise

immunity.  Using  the  zero-voltage-switching  (ZVS)

technique dramatically reduces the switching losses and

efficiency is significantly improved. The ZVS also

reduces the switching noise noticeably, which allows a

small-sized Electromagnetic Interference (EMI) filter.

The FAN7621B can be applied to various resonant

converter topologies; such as series resonant, parallel

resonant, and LLC resonant converters.

Related Resources

AN4151 — Half-bridge LLC Resonant Converter Design

using FSFR-series Fairchild Power Switch (FPS TM )

FAN7621BSJ

-40°C ~ 130°C  16-Lead Small Outline Package (SOP)

-50 -25 0 25 50 75 100

Temp ( O C)

Normalized at 25 O C

Figure 14. CON Pin Enable Voltage vs. Temperature  Figure 15. OCP Voltage vs. Temperature

© 2009 Fairchild Semiconductor Corporation  www.fairchildsemi.com

FAN7621B • Rev. 1.0.1  9

FAN7621B — PFM Controller for Half-Bridge Resonant Converters

Functional Description

1. Basic Operation: FAN7621B is designed to drive

high-side and low-side MOSFETs complementarily with

50% duty cycle. A fixed dead time of 350ns is introduced

between consecutive transitions, as shown in Figure 16.

High-side

MOSFET

gate drive

Low-side

MOSFET

gate drve

Dead time

time

Figure 16. MOSFETs Gate Drive Signal

2. Internal Oscillator: FAN7621B employs a current-

controlled oscillator, as shown in Figure 17. Internally,

the voltage of R T pin is regulated at 2V and the charging

/ discharging current for the oscillator capacitor, C T , is

obtained by copying the current flowing out of R T  pin

(I CTC ) using a current mirror. Therefore, the switching

frequency increases as I CTC increases.

Figure 17. Current Controlled Oscillator

3. Frequency Setting: Figure 18 shows the typical

voltage gain curve of a resonant converter, where the

gain is inversely proportional to the switching frequency

in the ZVS region. The output voltage can be regulated

by modulating the switching frequency. Figure 19 shows

the typical circuit configuration for R T pin, where the

opto-coupler transistor is connected to the R T pin to

modulate the switching frequency.

Figure 21. Internal Block of Control Pin

Protection: When the control pin voltage exceeds 5V,

protection  is  triggered.  Detailed  applications  are

described in the protection section.

Pulse Skipping: FAN7621B stops switching when the

control pin voltage drops below 0.4V and resumes

switching when the control pin voltage rises above 0.6V.

To use pulse-skipping, the control pin should be

connected to the opto-coupler collector pin.

© 2009 Fairchild Semiconductor Corporation  www.fairchildsemi.com

FAN7621B • Rev. 1.0.1  13

FAN7621B — PFM Controller for Half-Bridge Resonant Converters

6. PCB Layout Guideline: Duty imbalance problems

may occur due to the radiated noise from main

transformer, the inequality of the secondary-side leakage

inductances of main transformer, and so on. Among

them, it is one of the dominant reasons that the control

components in the vicinity of R T pin are enclosed by the

primary current flow pattern on PCB layout. The direction

of the magnetic field on the components caused by the

primary current flow is changed when the high-and-low

side MOSFET turns on by turns. The magnetic fields with

opposite direction from each other induce a current

through, into, or out of the R T pin, which makes the turn-

on duration of each MOSFET different. It is strongly

recommended to separate the control components in the

vicinity of R T pin from the primary current flow pattern on

PCB layout. Figure 28 shows an example for the duty-

balanced case. The yellow and blue lines show the

primary current flows when the lower-side and higher-

side MOSFETs turns on, respectively. The primary

current does not enclose any component of controller.

In addition, it is helpful to reduce the duty imbalance to

make the loop configured between CON pin and opto-

coupler as small as possible, as shown in the red line in

Figure 28.

Figure 28. Example for Duty Balancing

© 2009 Fairchild Semiconductor Corporation  www.fairchildsemi.com

FAN7621B • Rev. 1.0.1  14

FAN7621B — PFM Controller for Half-Bridge Resonant Converters

Typical Application Circuit (Half-Bridge LLC Resonant Converter)

Application  Device  Input Voltage Range  Rated Output Power

Output Voltage

(Rated Current)

LCD TV  FAN7621B

390V DC

(340~400V DC )

192W  24V-8A

Features

High efficiency ( >94% at 400V DC input)

Reduced EMI noise through zero-voltage-switching (ZVS)

Enhanced system reliability with various protection functions

FAN7621

FAN7621B — PFM Controller for Half-Bridge Resonant Converters

Typical Application Circuit  (Continued)

Usually, LLC resonant converters require large leakage inductance value. To obtain a large leakage inductance,

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