CURRENT MODE PWM+PFM CONTROLLER WITH BUILT-IN HIGH VOLTAGE MOSFET

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CURRENT MODE PWM+PFM CONTROLLER WITH BUILT-IN HIGH VOLTAGE MOSFET DESCRIPTION SD6835 is curren mode PWM+PFM conroller used for SMPS wih buil-in high-volage MOSFET and exernal sense resisor.

1 CURRENT MODE PWM+PFM CONTROLLER WITH BUILT-IN HIGH VOLTAGE MOSFET DESCRIPTION SD6835 is curren mode PWM+PFM conroller used for SMPS wih buil-in high-volage MOSFET and exernal sense resisor. I feaures low sandby power and low sar curren. In sandby mode, he circui eners burs mode o reduce he sandby power dissipaion. The swich frequency is 25~67KHz decided by he load wih jier frequency for low EMI. Buil-in peak curren compensaion circui makes he limi peak curren sable even wih differen inpu AC volage. Buil-in limi oupu power compensaion circui o balance he limi oupu power under differen AC volage inpus. Buil-in slope compensaion circui o adap o more ransformer applicaions. Maximum peak curren compensaion during power-on reduces pressure on ransformer o avoid sauraion, he peak curren compensaion will decrease for balance afer power-on. Limi oupu curren can be adjused hrough he resisor conneced o CS. I inegraes various proecions such as undervolage lockou, overvolage proecion, overload proecion, leading edge blanking and hermal shudown. The circui will resar unil normal if proecion occurs. APPLICATIONS SMPS FEATURES Energy Sar 2.0 sandard Lower sar-up curren (4µA) Various swiching frequency following load for he high efficiency EMI Frequency jier for low EMI Overvolage, overload and over emperaure proecions Exernal peak curren sense resisor * Limi oupu power compensaion Slope compensaion Undervolage lockou Buil-in high volage MOSFET Auo resar mode Peak curren compensaion Maximum peak curren compensaion for iniializaion o realize he sof sar funcion. Burs mode Cycle by cycle curren limi Hp:// Page 1 of 9

2 ORDERING INFORMATION Par No. Package Marking Maerial Packaging SD6835 DIP SD6835 Pb free Tube TYPICAL OUPUT POWER CAPABILITY 190~265V 85~265V Par No. Adaper Open Adaper Open SD W 26W 20W 24W BLOCK DIAGRAM VCC 3 GND V 8.5V FB Reduced frequency conrol Inernal bias OSC Frequency jier S R Slope volage Q Limi oupu power compensaion circui Conrol driver CS 6 Drain 7 8 Level shif + - COMP Leading edge blanking Over volage, over curren, over load and over emperaure proecion Burs mode conrol Peak curren compensaion Slope compensaion circui FB 4 Slope volage 2 CS ABSOLUTE MAXIMUM RATING Characerisics Symbol Raing Uni Drain-Gae Volage (R GS=1MΩ) V DGR 650 V Gae-Source (GND) Volage V GS ±30 V Drain Curren Pulse noe1 I DM 20 A Coninuous Drain Curren (T amb=25 C) I D 7.0 A Signal Pulse Avalanche Energy noe2 E AS 350 mj Power Supply Volage V CC,MAX 28 V Feedback inpu volage V FB -0.3~7 V Peak curren sense volage V CS -0.3~2 V Allowable Power Dissipaion P D 6.3 W Ambien hermal resisance θja 77 C/W Surface hermal resisance θjc 20 C/W Operaing Juncion Temperaure T J +150 C Operaing Temperaure Range T ORG -25~+85 C Hp:// Page 2 of 9

3 Characerisics Symbol Raing Uni Sorage Temperaure Range T STG -55~+150 C Noe: 1. Pulse widh is limied by maximum juncion emperaure; 2. L=51mH, T J=25 C(sar). ELECTRICAL CHARACTERISTICS (for MOSFET, unless oherwise specified, T amb =25 C) Characerisics Symbol Tes condiions Min. Typ. Max. Uni Drain-Source Breakdown Volage BV DSS V GS=0V, I D=50µA V Zero Gae Volage Drain Curren Saic Drain-Source On Resisance I DSS V DS=650V, V GS=0V µa V DS=480V, V GS=0V T amb=125 C µa R DS(ON) V GS=10V, I D=3A Ω Inpu Capaciance C ISS V GS=0V, V DS=25V, f=1mhz pf Oupu Capaciance C OSS V GS=0V, V DS=25V, f=1mhz pf Reverse Transfer Capaciance C RSS V GS=0V, V DS=25V, f=1mhz pf Turn On Delay Time T D(ON) V DD=0.5BV DSS, I D=25mA ns Rise Time T R V DD=0.5BV DSS, I D=25mA ns Turn Off Delay Time T D(OFF) V DD=0.5BV DSS, I D=25mA ns Fall Time T F V DD=0.5BV DSS, I D=25mA ns ELECTRICAL CHARACTERISTICS (unless oherwise specified, V CC =12V, T amb =25 C) Characerisics Symbol Tes condiions Min. Typ. Max. Uni Undervolage Secion Sar Threshold Volage V START V Sop Threshold Volage V STOP V Oscillaor Secion Max. Oscillae Frequency f OSCMAX V FB=3V KHz Min. Oscillae Frequency f OSCMIN V BURL<V FB<V BURH KHz Frequency jier Frequency Change Wih Temperaure f MOD Oscillae frequency is he ±1.5 ±2.5 ±3.5 KHz maximum C T amb +85 C -- ±5 ±10 % Maximum Duy cycle D MAX % Feedback Secion MAX. Feedback Source Curren I FBMAX V FB=0V ma Shudown Feedback Volage (over load proecion) V SD V Hp:// Page 3 of 9

4 Characerisics Symbol Tes condiions Min. Typ. Max. Uni Shudown Feedback Delay Time T SD FB is increased o 5V from 0V ms insanly Shudown Delay Curren I DELAY V FB=5V µa CS secion Max. value of CS V CSMAX V Curren Limi Secion Peak curren I OVER Maximum inducor curren A Burs mode Burs Mode High Volage V BURH FB volage V Burs Mode Low Volage V BURL FB volage V Proecion Secion Overvolage Proecion V OVP V CC volage V Over Temperaure Proecion T OTP C Leading-edge Blanking Time T LEB ns Toal Sandby Curren Sar Curren I START V CC increases from 0V o 12V µa Quiescen Curren I STATIC V CC=12V, V FB=0V ma Operaing Curren I OP V CC=12V, V FB=3V ma PIN CONFIGURATION GND 1 8 Drain CS VCC 2 3 SD Drain Drain FB 4 5 NC Noe: i is recommended o connec pin 5 o pin Drain for beer hea dissipaion. PIN DESCRIPTION Pin No. Pin Name I/O Funcion descripion 1 GND I Ground 2 CS I Peak curren sense pin 3 V CC I Power supply pin 4 FB I/O Feedback inpu pin 5 NC -- NC 6, 7, 8 Drain O Drain of MOSFET Hp:// Page 4 of 9

5 FUNCTION DESCRIPTION SD6835 is designed for off-line SMPS, consising of high volage MOSFET, opimized gae driver and curren mode PWM+PFM conroller which includes frequency oscillaor and various proecions such as undervolage lockou, overvolage proecion, overload proecion, and over emperaure proecion. Frequency jier generaed from oscillaor is used o lower EMI. Peak curren compensaion reduces he pressure on ransformer during circui sars and peak curren limi can be adjused by resisor hrough CS pin. Burs mode is adoped during ligh load o lower sandby power dissipaion, and funcion of lead edge blanking eliminaes he MOSFET error shudown caused by inerference hrough minimizing MOSFET urning on ime. Few peripheral componens are needed for higher efficiency and higher reliabiliy and i is suiable for flyback converer and forward converer. 1. Under Volage Lockou and Self-Sar A he beginning, he capacior conneced o pin V CC is charged via sar resisor by high volage AC and he circui sars o work if volage a V CC is 16V. The oupu and FB source curren are shudown if here is any proecion during normal operaion and V CC is decreased because of powering of auxiliary winding. The whole conrol circui is shudown if volage a V CC is 8.5V below o lower curren dissipaion and he capacior is recharged for resaring. VCC VSTART VSTOP 0 ICC 0 Powered by sar resisor Powered by assisan winding Powered by sar resisor 2. Frequency Jier and reduced frequency mode The oscillaion frequency is kep changed for low EMI and decreasing radiaion on one frequency. The oscillaion frequency changes wihin a very small range o simplify EMI design. The rule of frequency changing (frequency cener is 67KHz): ±2.5KHz change in 4ms, 63 frequency poins in all. For high efficiency, reduced frequency mode is adoped wih wo mehods: 1. Frequency f is reduced according o curren oupu from FB pin. If I FB is higher han I 1, he frequency f decreases from 67KHz and f is 25KHz when he I FB increases o I 2 or higher. This is shown in lef diagram below. 2. I PK is changed according o I FB, shown in righ diagram below. Hp:// Page 5 of 9

6 f (KHz) IPK(A) PFM mode Burs mode PWM mode PWM mode Burs mode 0 IFB (ma) IFB (ma) I1 I I1 I Peak curren sense resisor The exernal resisor (R CS ) conneced o pin CS is used for peak curren limi, he peak curren is given by: I = V PKMAX CSMAX/RCS 4. Peak curren compensaion and iniializaion Generally, limi peak curren changes wih differen inpus. Limi peak curren is hold in his circui because of peak curren compensaion. Larger peak curren compensaion for higher inpu AC volage, i decreases o zero wih ligh load and no peak curren compensaion in burse mode. Maximum peak curren compensaion during power-on reduces pressure on ransformer o avoid sauraion, he peak curren compensaion will decrease for balance afer power-on. The duraion is decided by he load. 5. Slope compensaion When he circui is working wih heavy load or even full load, he swich duy cycle increasing over 50% will occur, which leads o sysem insabiliy due o he sub-harmonic oscillaion. In order o eliminae he subharmonic oscillaion, he slope compensaion circui is used o conrol he sysem. The bigger he duy cycle is, he greaer he slope compensaion is. 6. Limi oupu power compensaion The limi oupu power difference under differen AC volage inpus is caused by he coninuous mode, he limi oupu power compensaion circui is used o reduce his difference. The bigger he duy cycle is, he greaer he compensaion is. 7. Burs mode Working in his mode can reduce power dissipaion. I works normally when FB is 0.5V above, and during 0.35V<FB <0.5V, here are wo differen condiions: when FB changes from low o high, here is no acion for swich and i is he same wih condiion of FB lower han 0.35V; he oher is ha FB changes form high o low, comparison value is increased for increasing urning on ime o decrease swich loss. In his mode, swiching frequency is down o 25KHz. For his mode, during FB changes from high o low, he oupu volage increases (increasing speed is decided by load) because of he high comparison value o decrease FB unil i is 0.35V below; when FB <0.35V, here is no acion for swich and oupu volage decrease (decreasing speed is also decided by load) o increase FB volage. FB volage is 0.5V below wih ligh load. This is repeaed o decrease acion of swich for lower power dissipaion. Hp:// Page 6 of 9

7 0.5V 0.35V Oupu curren Oupu No oupu Oupu No oupu 8. Leading Edge Blanking For his curren-conrolled circui, here is pulse peak curren during he ransien of swich urning on and here is an error operaion if he curren is sampled during his ime. And leading edge blanking is adoped o eliminae his error operaion. The oupu of PWM comparaor is used for conrolling shudown afer he leading edge blanking if here is any oupu drive. MOSFET Drive signal Inducance burr MOSFET Drive signal Inducance burr Curren on MOSFET Curren on MOSFET Large duy facor LEB LEB Small duy facor LEB 9. Over Volage Proecion The oupu is shudown if volage a V CC exceeds he hreshold value and his sae is kep unil he circui is powered on rese. 10. Overload Proecion FB volage increases if here is overload and he oupu is shudown afer he shudown delay ime when FB volage is up o he feedback shudown volage. This sae is kep unil he circui is powered on rese. 11. Cycle By Cycle Peak Curren Limi During each cycle, he peak curren value is decided by he comparison value of he comparaor, which will no exceed he peak curren limied value o guaranee he curren on MOSFET will no be larger han he raing curren. The oupu power will no increase if he curren reaches he peak value o limi he max. oupu power. The oupu volage decreases and FB volage increases if here is overload and corresponding proecion occurs. 12. Thermal Shudown If he circui is over emperaure, he over emperaure proecion will shu down he oupu o preven he circui from damage. This sae keeps unil he circui resars afer cooling down. Hp:// Page 7 of 9

8 TYPICAL APPLICATION CIRCUIT (HV) Vin n1:1 Vo + n2: Drain Drain Drain NC SD6835 GND CS VCC FB RCS VFB IFB Vo Vcc Ccc CFB Noe: The circui and parameers are for reference only, please se he parameers of he real applicaion circui based on he real es. Hp:// Page 8 of 9

9 PACKAGE OUTLINE DIP UNIT: mm ± ± degree MIN 4.36MAX 0.46 ± MIN CAUTION ELECTROSTATIC SENSITIVE DEVICE DO NOT OPEN OR HANDLE EXPECT AT A STATIC-FREE WORKSTATION MOS DEVICES OPERATE NOTES: Elecrosaic charges may exis in many hings. Please ake following prevenive measures o preven effecively he MOS elecric circui as a resul of he damage which is caused by discharge: The operaor mus pu on wris srap which should be earhed o agains elecrosaic. Equipmen cases should be earhed. All ools used during assembly, including soldering ools and solder bahs, mus be earhed. MOS devices should be packed in anisaic/conducive conainers for ransporaion. Disclaimer : reserves he righ o make changes o he informaion herein for he improvemen of he design and performance wihou furher noice! Cusomers should obain he laes relevan informaion before placing orders and should verify ha such informaion is complee and curren. All semiconducor producs malfuncion or fail wih some probabiliy under special condiions. When using producs in sysem design or complee machine manufacuring, i is he responsibiliy of he buyer o comply wih he safey sandards sricly and ake essenial measures o avoid siuaions in which a malfuncion or failure of such producs could cause loss of body injury or damage o propery. will supply he bes possible produc for cusomers! Hp:// Page 9 of 9

CURRENT MODE PWM+PFM CONTROLLER WITH BUILT-IN HIGH VOLTAGE MOSFET

CURRENT MODE PWM+PFM CONTROLLER WITH BUILT-IN HIGH VOLTAGE MOSFET DESCRIPTION SD6832 is current mode PWM+PFM controller with built-in highvoltage MOSFET used for SMPS It features low standby power and