Confidential MCZ5203SE APPLICATION NOTE MAR, 2012 Ver1.0 SHINDENGEN ELECTRIC MFG.CO.,LTD -1- Confidential MCZ5203SE Standard Power Supply Cautions for Use Thank you for purchasing our products. This manual contains important information on the safe use of our products. Your safety is of the utmost importance to us. Please read these instructions carefully before using our products. The following symbols mean: ! Warning Improper use of the products can result in death, serious injury, or expensive damage to equipment. ! Caution Improper use of the products can result in minor injuries or damage to equipment. ! Warning ! Warning Although we are constantly making every effort to improve the quality and reliability of our products, there nevertheless remains a certain probability that the semiconductor products may occasionally fail or malfunction. Please take careful precautions against product failures or malfunctions to avoid any injuries, fire accidents or social loss by implementing safety designs such as redundancy designs, designs for fire spread prevention, and designs for preventing malfunctions. Our semiconductor products listed in this document are not designed or manufactured to be used in devices or systems requiring extremely high levels of quality and reliability, or the failure or malfunction of which may directly threaten human lives or cause injury. In the cases where the products are to be used in devices or systems for special applications or devices or systems for specialized applications shown below, always make sure to consult us in advance. Special Applications Transportation devices (automotive, marine, etc.), communication devices for core network, traffic signal devices, fire prevention/anticrime devices, various safety devices, medical devices, etc. Specialized Applications Nuclear power control systems, aircraft and aerospace devices, submarine relay devices, and systems for preserving life, etc. Even if it is not for a special or specialized application, when IC products are to be used for devices or systems that are desired to last for a long period under continuous operation, please make sure to consult us in advance. ! Caution ! Caution ! ! ! Caution Caution Caution Do not attempt under any conditions to repair or modify IC products by yourself. Doing so could result in electric shock, device breakage, fire, and malfunction. When an abnormal condition occurs, an excessive voltage or under voltage may be generated across the output terminals of the circuit. Install preventative measures (e.g. over-voltage protection, over-current protection) for the device by considering the possibility of a malfunction and/or breakage of a load in an abnormal condition. Do not switch on the circuit before confirming the proper connection and polarity of input and output terminals as an erroneous connection may cause breakage of the protection device or smoke/fire. Do not use the circuit beyond the rated input voltage and install a protection device on the input rail to prevent smoke/fire that may be caused from an abnormal condition. If a breakdown or other abnormal condition occurs during the use of the device, immediately stop power to the device and consult us at your earliest possible convenience. ● We reserve the right to make any changes to the contents of this manual without prior notice in accordance with modifications to IC products. ● Details of specifications should be exchanged at the adoption of the IC products. ● All information included in this manual is believed to be accurate and reliable. However, our company takes no responsibility for any injury or damage incurred when using the IC products as described in this manual. Neither do we take any responsibility for issues arising from infringement of patent or other rights caused by using this manual. ● The provision of this manual does not guarantee the right to use any third party’s patent or other rights, or grant permission to use the patent or other rights of our company. ● No part of this manual may be reproduced or copied without the specific written consent of Shindengen Electric Mfg. Co., Ltd. We are happy to provide circuit design support for safe use of the IC. Please consult our sales representative . SHINDENGEN ELECTRIC MFG.CO.,LTD -2- Confidential Index 1 : General description 1.1: Features 1.2: Block diagram (SOP22) 4 1.3: Pin assignment 5 1.4: Functions 5 1.5: Application circuits 6 4 2 : Symmetric LLC converter Operating description 2.1: Features 7 2.2: Fundamental circuitry 7 2.3: Operating waveform example 2.4: Control characteristics 7 2.5: Major parameters and components 8 2.6: IC operation 9 - 10 8 3 : Selecting peripheral components 3.1: Oscillator（Rt） 3.2: Vsense brown-out protection（RvsenseL） 11 3.3: Soft start（Css） 12-13 3.4: OCP （Rocpdet/RocpL） 13-14 3.5: di/dt protection 14 3.6: Timer latch protection（CTimer） 15 3.7: High side floating Vcc (VB) 16 3.8: Gate driver 16 12 4 : Circuit diagram 4.1: Typical circuit example 17 5 : Dimensions 5.1: SOP22 (MCZ5203SE) 18 SHINDENGEN ELECTRIC MFG.CO.,LTD -3- Confidential 1 General description MCZ5203 is an advanced symmetric LLC current resonant mode controller for bridge converter. Bulit-in high voltage direct gate drivers, control circuit and optimized protections allow simplified and space/cost-saving design of power supplies for : Large screen flat panel TVs (PDP / LCD ) PSU Laser printer PSU High power adapters 1.1 Features 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Robust 600V gate driver directly drives high side Switch. Optimized gate drive capability minimizes the number of components for gate drive circuit. Optimized protective functions (OCP/burst/Timer delayed latch/Thermal) for LLC converter Advanced ZVS boundary chaser (capacitive mode protection) eliminates below resonant (capacitive di/dt) operation. OCP operates by detecting peak primary current with 0.345V / threshold. Vcc supplies up to 35V with 13.5V/8.4V UVLO Built-in voltage regulator of 10V for gate driver Independent high side / low side Gate driver UVLO with hysterisis Adjustable soft starting function Anti-di/dt startup function eliminates improper startup of Non ZVS operation Optimized brown out protection 1.2 Block diagram （SOP22） SHINDENGEN ELECTRIC MFG.CO.,LTD -4- Confidential 1.3 Pin assignment 1.4 Functions Pin number SOP22 name 1 Vsen 2 FB 3 Ct 4 Rt 5 GND 7 TIMER 8 SS 10 Vc1 12 OCP 13 Vc2 14 PGND 15 VGL 6,9,11,16, 17,18,19 (NC) 20 VB 21 VS 22 VGH function DC input voltage monitoring Feedback signal input with Feedback loop open detection Timing capacitor Ct determines Dead time and fmin (minimum operating frequency) and also fss(startup frequency) Timing resistor Rt determines fmin Signal ground. This pin should be connected to PGND directly. CTimer determines the time period of burst mode in OCP or another abnormal operation. Startup timing capacitor Css determines the soft-starting time Voltage supply input for control circuit with 13.5V/8.4V UVLO Maximum rated voltage is 35V Main resonant current sensing with +0.345V threshold for peak current limiting ,+/- 60mV for didt protection Voltage regulator output for Gate driver Vc2=10V. Power ground This pin should be connected to low side MOSFET source directly Low side gate driver output No connection Voltage source of High side gate driver supplied from Vc2 through bootstrap circuit Floating driver reference voltage ( = Source pin of high side MOSFET) High side gate driver output SHINDENGEN ELECTRIC MFG.CO.,LTD -5- Confidential 1.5 Applicable circuits Most simple SEPP(Single Ended Push-Pull) Input ripple current reduction (Half Bridge) High power (Full Bridge) SHINDENGEN ELECTRIC MFG.CO.,LTD -6- Confidential 2 Symmetric LLC converter Operating Description 2.1 Features Symmetric LLC resonant converter application is expanding widely due to its extremely high power conversion efficiency and low noise characteristics. It’s resonant tank consists of L/L/C connected in series. ZVS/ZCS operation minimizes switching loss and voltage spike. a) The voltage applied to main switch is clamped to input voltage (Vbulk), consequently no spike voltage is generated. b) Main switch turn-off current can be kept to constant and low level independent of load condition. c) Transformer is excited symmetrically, thus magnetics size can be minimized. d) Sinusoidal resonant current waveform results in extremely low EMI characteristics. e) Output rectified current is also partially sinusoidal, and Trr loss and switching noise can be minimized. f) The voltage applied to output diode is clamped to the output voltage (or x2) independent of load condition or input voltage. g) Excellent cross regulation characteristics for multiple output converters due to symmetric bridge operation. rd h) No requirement of auxiliary 3 winding helps to optimize resonant condition and transformer design 2.2 Fundamental circuitry（SEPP） Lr Lm Cp1 Q1 Lr Vbulk RL D2 Q2 Cp2 st :1 resonant inductance nd :2 resonant inductance (magnetizing inductance) Cr :resonant capacitance Cp1/2 :ZVS resonant capacitance Q1/Q2 :Main switch D1/D2 :Commutating diode RL :Equivalent Load resistance D1 Lm Cr Fig.1 LLC configuration Fig.2 simplified dc/dc converter 2.3 Operating waveform example Output ripple voltage(Vo) Q2 Idrain (Id(2) Q2 Vds (Vds2) Fig.3 Vds / Idrain / Vo ripple Fig.4 Zoom of turn off period SHINDENGEN ELECTRIC MFG.CO.,LTD -7- Confidential 2.4 Control characteristics ZVS boundary Voltage vs.frequency characteristics are shown in Fig.5. LLC converter operates in above-resonance region. (above ZVS boundary) Output voltage can be stabilized by varying operating frequency, decreasing the operating frequency when input voltage becomes lower or load becomes larger, and increasing when higher or smaller respectively. Vout frequency Fig.5 Output voltage vs operating frequency characteristics 2.5 Major parameters and components Table 1. Major parameters Vc1 IC Vcc supply 15-22Vdc is recommended.(min.14.0V for startup in worst case) Vbulkreset Brown–out detection voltage threshold Brown-out protection operating voltage. The threshold value is determined considering resonant condition and hold-up time. Minimum frequency Fmin is determined considering resonant frequency at Vin min / Po max condition. Maximum frequency Fmax is determined considering controllable area at Vbulk max with min load and ZVS condition. Startup frequency Fss is determined considering MOSFET Vds,output diode inrush current and Vout rise timing during startup tss Soft starting time Required soft starting time tTIMER Burst mode operation interval Especially important for short circuit condition and feedback loop open condition. See section 3.6 fmin fmax fss Table 2 .Recommended components RvsenseH Vbulk divider high side Isense=1uA required Ct Timing capacitor Ct determines fmin / fmax / fss / DT.Stable temperature characteristics type is recommended. In case of MLCC, type CH or COG. RocpH Current sensing filtering resistor Primary current sensing filtering resistor. Around 10 ohm is recommended. CocpL Current sensing filtering capacitor Primary current sensing filtering capacitor.1000pF-10000pF. Rfb I(F/B) limitation resistor Limiting I(F/B) and setting fmax. Normally a few k ohms. Refer to characteristic diagrams. High voltage assured type is recommended. Table 3. Circuit constants obtained from the formulas Vbulk divider low side Obtained from Vbulkreset and RvsenseH. Timing resistor Obtained from fmin and Ct Sensing resistor Primary resonant current sensing RocpL OCP sensing divider Primary current sensing voltage divider Css Soft start timing capacitor Obtained from tss. Burst operation timing capacitor Obtained from ttimer RvsenseL Rt Rocpdet Ctimer SHINDENGEN ELECTRIC MFG.CO.,LTD -8- Confidential 2.6 IC operation Power ON（mode A）: Under the condition of input bulk voltage Vbulk is applied (Vsense >1.4V), operation starts when Vc1 terminal voltage reaches 13.5V. After soft starting period (tss), the frequency is stabilized at nominal operating frequency depending on resonant tank and input/output condition. Power ON（mode B）: When Vbulk is applied after Vc1 is supplied, gate drive pulse is generated at Vsense>1.1V with fixed fss operation. Then normal soft starting operation begins when Vsense reaches 1.4V and operation is stabilized in normal operating frequency after the soft starting period as mode A. Power OFF（mode A）: Under the condition of input bulk voltage Vbulk is applied （Vsense >1.4V）, IC operation stops when Vc1 reaches the threshold of Vc1 UVLO OFF（8.4V）. Power OFF（mode B）: When Vbulk decreases under the condition of continuous Vc1 supplied, operating frequency decreases toward fmin. The frequency starts increasing to fss level soon after Vsense decreases to 1.4V. Gate drive stops when Vsense voltage decreases to 0.7V. Fig 6. Power ON / OFF timing diagram SHINDENGEN ELECTRIC MFG.CO.,LTD -9- Confidential Under Abnormal condition: a) Feedback loop open: When operation is out of control due to input/output conditions beyond the controllable operating area,the frequency becomes to minimum (fmin). F/B loop open detector then will be activated and the gate output stops after the period of tTimer set by timing capacitor (CTimer). After the time period set by the burst mode(tb), the output restarts and is latched off in the case where this timer-latch protection operating cycle repeats twice. Restart Vc1 to release latching. b) OCP / OLP : When the voltage applied to OCP terminal exceeds Vocpth (0.345V typ), the frequency increases instantaneously and when this condition is retained, the operation follows same as above. c) Di/dt Timerection : In close to below resonant condition, di/dt Timerection activates by detecting the threshold of Vdidt (+/- 60mV), limits the frequency to decrease and restrains the output voltage. See section 3.5 for detail. d) Thermal Timerection : If IC internal temperature exceeds 140°C , output will be stopped with 40°C temperature hysteresis. Remarks: When Vbulk keeps low level, the converter is unable to stay in normal operation due to the F/B loop open Timerection and Vsense, even if Vc1 exceeds 14V. If starting the operation with Vbulk slow-up is required, adding external components as described below and in Fig.7 is recommended. 1) connect Rsen1 between Vc1 and Vsense to apply 1.5V or more to Vsense terminal, and 2) connect RTimer1 between TIMERand SGND to disable F/B loop open protection. Fig.7 additional components SHINDENGEN ELECTRIC MFG.CO.,LTD - 10 - 1% 1% RocpL 10000pF 10V Source(L) Gate(L) Css x uF 10V x uF 10V Ctimer 1% Rt 1000p COG/CH Ct Gate(H) Source(H) 0.01uF 10V RvsenseL RvsenseH Vbulk Please note this circuit is for investigation only. Do not switch on/off the Vbulk when using Rsen1 as 1) to protect MOSFETs from undesired heavy switching stress especially in mid-heavy load condition. Confidential Selecting the Components of Peripheral Circuit 3.1 Oscillator (selecting Rt) The timing of gate drive pulse VG(L) and VG(H) is determined by charging and discharging time of timing capacitor Ct. VG(L) and VG(H) drive main switches alternately and shoot through current of main switches is prohibited by dead time (DT) that is equal to discharging time of Ct +140ns as shown in Fig.8. The IC adopts non-constant dead time architecture, and the frequency and ONduty varies according to F/B terminal current and frequency increases respectively as shown in Fig.9. Larger dead time in light load condition secures ZVS over a wide frequency range. Minimum frequency (fmin) is determined by Ct and Rt. Less than 300kHz for fmax is recommended in continuous operation considering power consumption. 500 50 400 40 300 30 200 20 Ct=680pF Rt=18.9kΩ Ct=820pF Rt=16.8kΩ Ct=1000pF Rt=13.2kΩ Ct=1200pF Rt=11.6kΩ 100 0 Duty [%] frequency [kHz] fss depends on Ct, for example 185kHz with Ct=1000pF typically See characteristic diagram sheet for detail. 10 0 0 1 2 3 4 5 IFB [mA] Fig.8 Gate drive pulse timing diagram Fig.9 frequency/duty vs I(F/B) The value of tentative Rt, Rt(init), will be obtained from formula(1) using fmin and Ct value. Approximate value of fmin will be obtained from formula(2) using actual value of Rt.(Ct=680pF , Rt=18.9kohm) 5V Refer to characteristic curves to confirm Ct/Rt condition. Rt (init ) f min 1 C 1.88 2.52 t 3 2 f min 4.2 10 Ct 1.88 2.5V [ohm] ---(1) Rt 1 Ct 1.88 Ct Rt [Hz] ---(2) Ct 1.88 2 2.52 4.2 10 3 2.52 / Rt GND Fig.10 Ct / Rt internal block SHINDENGEN ELECTRIC MFG.CO.,LTD - 11 - Confidential 3.2 Brown-out protection (selecting RvsenseL) Vsense terminal monitors the input voltage for halting gate drive pulse and varying the frequency. UVLO function avoids below-resonant state caused by supplying Vbulk remaining Vc1 is applied, brown-out (quick decrease of input voltage) or black-out (instantaneous interruption). Timing diagram of brown-out protection is shown in Fig.12. High side resistor of voltage divider is RvsenseH :greater than 3Mohm is recommended. Required minimum sink current of Vsense terminal is 1uA. Low side resistor, RvsenseL(init) is obtained from formula(3) and correct value of Vbulkreset threshold is obtained from formula(4) by using actual value of RvsenseL. This 1.4V threshold is for Css resetting without hysterisis,and 1.1V is for ON/OFF with 0.4V hysterisis.Vsense pin can be simply used for ON/OFF function. Vsense 1.4V 1.1V 0.7V 13.5V Vc1 Css Ct VG(H) VG(L) Fig.11 Vsense internal block R vsenseL (init) Vbulkreset Fig.12 Vsense brown out timing diagram 1.4 R vsenseH Vbulkreset - 1.4 [ohm] ---(3) R vsenseH R vsenseL 1.4 R vsenseL [Vdc] ---(4) RvsenseH of 3Mohm as an example consumes 40mW constantly at AC240V (without PFC operating). In the case where PFC converter with independent OVP function is installed, the voltage divider (associated power consumption) can be eliminated by obtaining Vsense voltage from OVP detector of the PFC converter. Connect filtering capacitor of around 3.3-10nF between Vsense terminal and GND. 3.3 Soft start (selecting Css) Tentative value of soft start timing capacitor Css(init) is obtained from approximate formula(5). tss is the time period of which the frequency stabilizes at fmin after VCss reaches around 0.8V. Correct value of tss, soft start time period, is obtained from formula(6) using actual value of Css. Characteristics of Css voltage vs operating frequency at Css = 4.7uF (tss = 200ms) is shown in Fig.13. C ss(init ) t ss 23 10 6 t ss C ss [F] ---(5) [sec] ---(6) 23 10 6 SHINDENGEN ELECTRIC MFG.CO.,LTD - 12 - Confidential S S tim e vs f re qu e n c y an d te rm in al vo ltag e Ct=1000pF Rt=13.2kΩ Css=4.7uF 250 2.0 f s s [ k H z] V s s [V ] 200 1.5 fss [kHz] 1.0 100 SS terminal voltage [V] 150 0.5 50 0 0.0 0 50 100 150 200 250 Time [ms] Fig.13. fss characteristics 3.4 Over-current Protection（selecting Rocpdet / RocpL） OCP(over current protection) operates by detecting positive peak current of resonant tank (drain current of high-side MOSFET) beyond the threshold of +0.345V. The current is detected by sensing resistor Rocpdet and its detected voltage is applied to OCP terminal through R/C filter. When the voltage applied to OCP terminal reaches +0.345V, timing capacitor Ct is charged rapidly and consequently the frequency is increased to limit the current / MOSFET drain current. Threshold level is low enough to minimize ineffective power loss of sensing resistor. Filter capacitor is connected between OCP and SGND to eliminate the influence of parasitic inductance of sensing resistor or parasitic inductance. The capacitance value of 1000pF to 10000pF is recommended. Fig.14. OCP Timing diagram SHINDENGEN ELECTRIC MFG.CO.,LTD - 13 - Confidential Rocpdet is obtained from formula(7) with desired OCP threshold Ipk. Tentative value of RocpL(init) is obtained from formula(8) and correct value of Ipk(th) is calculated from formula(9) using actual value of RocpL. 10-47 ohm is recommended as RocpH considering OCP terminal sourcing current (180uA typ.)。 Ipk(th) value should be determined carefully to have enough margins in low input voltage / Pomax or switching load condition. Rocp det 0.345 Ipk Ipk ( th ) Rocpdet Cr RocpL C116 10000pF RocpL (init ) [ohm] (7) 0.345 10 Ipk R ocp det 0.345 10 R ocpL RocpL R ocp det 0.345 [ohm] (8) [ A ] (9) Fig.15. Main resonant current detecting configuration OCP function of MCZ5203 activates by detecting positive current (drain current of high-side MOSFET) so keep suitable winding direction if half-wave rectification is applied in multiple output converter usage. If OCP activates (in the period of high-side driven), succeeding period of low-side driven is limited to 1/ (2 x fmin x 1.8). Large negative voltage applied to OCP terminal may cause OCP malfunction. If OCP terminal negative voltage is greater than -0.8V , add 40V 1A SBD to clamp the negative voltage. Fig.16. OCP protection 3.5 di/dt mode protection MCZ5203 adopts pulse by pulse bidirectional didt protection to avoid below resonant mode operation. This function helps to avoid hard switching of main switches in below ZVS boundary operation. When OCP terminal voltage (Vocp) exceeds 60mV during the period of Ct voltage going bottom to 2.1V (Ct masking period), didt protection is ready to activate. In identical Ct saw tooth period, Vocp decreasing to 60mV again results in instantaneous Ct discharging and gate drive turns off. In negative current direction, threshold voltage is -60mV. During didt protection is operating , CTimer is not charged. Please note didt threshold is about 1/6 of OCP threshold. Fig.17. di/dt protection SHINDENGEN ELECTRIC MFG.CO.,LTD - 14 - Confidential 3.6 Timer Protection （selecting CTimer ） TIMER terminal has 2 threshold, 3V and 0.3V. When OCP or F/B loop open protection operates, CTimer charging starts and continuous abnormal condition keeps charging CTimer with constant 215uA until V(CTimer) reaches 3.0V. Once V(CTimer) reached 3V, gate output stops and CTimer discharging with constant 10uA sinking starts and continues until V(CTimer) decreases to 0.3V. At the moment V(CTimer) reaches 0.3V, CTimer 215uA charging restarts and Gate output also restarts with soft starting function.TIMER counter counts the number of times of 3V charging.If count is twice, output will be latched off. When abnormal condition is eliminated and converter enters in normal operation before abnormal 2 counts, CTIMER is rapidly discharged with 2mA sinking and the counting result is reset. To release latching , restart with supplying Vc1 of less than 8V Timing chart is shown in Fig.18. CTIMER tTIMER 215 10 6 [F] 3 ----(10) TIMER burst timing ratio is tTimer1 : tb = 1 : (20+tss), In case of CTimer=4.7uF / Css=2.2uF, tTimer=70msec , tb=1.5sec. 3V refresh PROT abnormal signal reset Latch counter Vss latch 2.5V Gate out (1) (2) Fig.18. Timer delayed burst and latching timing chart SHINDENGEN ELECTRIC MFG.CO.,LTD - 15 - Confidential 3.7 High side floating Vcc (VB) Floating High side gate drive voltage source (VB) is produced by bootstrapping configuration from stabilized Vc2 10V. 600V soft recovery type UFRD (ultra fast recovery diode) is recommended like D1NK60 (Shindengen). VB = Vc2 – Vf (Dboot) VS terminal is the reference potential for VB, so if negative spike voltage due to turn off current of low side switch and pattern parasitic inductance is too large,VB will be over charged. In case of VB max exceeds 15V , zener diode clamping is recommended to avoid high side logic malfunction. Np Cboot 22 0.1 uF 16V 21 20 VG(H)VS VB Dboot D1NK60 D1FK60 15 14 13 VG(L) PGND Vc2 MCZ Fig.19. Boot Strapping configuration 3.8 Gate driver The gate drivers have 0.18A sourcing and 0.53A sinking current capability at Vc2=10V. Typical configurations are shown in Fig.20a) b). If using small low Qg MOSFET like 30nC or less, R122/125 and D112/113 will not be required like Fig.20 C) due to optimized unbalanced drive capability of MCZ5203. Fig.20. Gate driving configuration SHINDENGEN ELECTRIC MFG.CO.,LTD - 16 - Confidential 4 Circuit diagram 4.1 circuit example T101 F101 Vin Q101 C110 D201 C120 GND R121 R123 V1 8 1 7 Q102 R101 4 C121 R124 C119 R102 GND D203 9 C122 R126 C201 C202 10 D205 C123 D110 R103 VGH VS VB (NC) (NC) (NC) R111 (NC) VGL PGND SS (NC) Vc2 OCP R112 IC101 Vsen FB Ct Rt GND (NC) Timer Vc1 (NC) C116 12 R110 C205 GND 13 R107 C126 C112 R131 V2 11 C113 C114 D206 R210 C115 C111 R203 R211 R108 CN102 C231 R231 PC101 VCC ON/OFF R202 IC201 C117 Q113 GND Fig.21. dual output LLC SHINDENGEN ELECTRIC MFG.CO.,LTD - 17 - R213 Confidential 5 Dimensions 5.1 SOP22 (MCZ5203SE) Units : mm SHINDENGEN ELECTRIC MFG.CO.,LTD - 18 -