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NXP Semiconductors AN10881 Скачать руководство пользователя страница 59

AN10881

All information provided in this document is subject to legal disclaimers.

© NXP B.V. 2011. All rights reserved.

Application note

Rev. 2 — 26 September 2011

59 of 102

NXP Semiconductors

AN10881

TEA1713 resonant power supply control IC with PFC

8.7 HBC overcurrent protection and regulation

Measurement of the primary resonant current indicates the level of output power that is
generated by the converter. During a fault or output overload condition, this current often
increases considerable. By monitoring this current and then taking appropriate action, the
converter can remain operational during a temporary fault or overload condition.

The resonant controller of the TEA1713 has two functions when in an overcurrent
condition:

•

OverCurrent Regulation (OCR) slowly increases the frequency and the protection
timer is started

•

OverCurrent Protection (OCP) steps to maximum frequency

A boost voltage compensation function is included to reduce the variation in the preset
protection level of the resonant current.

8.7.1 HBC overcurrent regulation

The lowest comparator levels of



0.5 V at the SNSCURHBC pin belong to the

OverCurrent Regulation (OCR) level. There is a comparator for both the positive and
negative polarity. If either level is exceeded, the frequency is slowly increased. This is
accomplished by discharging the soft-start capacitor. Every time the OCR level is
exceeded, this state is latched until the next stroke and the soft-start discharge current is

Fig 36. SNSCURHBC

001aal046

BOOST

COMPENSATION

CONTROL

V

SNSBOOST

HBC operational

I

boost-compensation

±

I

boost-compensation

V

BOOST

over current protection

1 V

SNSCURHBC

17

1.8 V

V

SNSBOOST

0

μ

A

170

μ

A

2.5 V 2.63 V

COMP

Rcc

1 k

Ω

TEA1713

over current protection

−

1 V

COMP

over current regulation

0.5 V

COMP

over current regulation

−

0.5 V

COMP

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Содержание AN10881

Страница 1: ...e protection and a general purpose latched protection input In addition to the resonant controller the TEA1713 also contains a Power Factor Correction PFC controller The efficient operation of the PFC...

Страница 2: ...ber 2011 2 of 102 Contact information For more information please visit http www nxp com For sales office addresses please send an email to salesaddresses nxp com NXP Semiconductors AN10881 TEA1713 re...

Страница 3: ...iew of the TEA1713 pins with a summary of the functionality Section 4 Application diagram and block diagrams Section 5 Supply functions Sections 6 7 8 9 and 10 describe the main functions of the TEA17...

Страница 4: ...ights reserved Application note Rev 2 26 September 2011 4 of 102 NXP Semiconductors AN10881 TEA1713 resonant power supply control IC with PFC 1 2 Related documents Additional information and tools can...

Страница 5: ...forms cause turn on and turn off losses that limit the operating frequency The rectangular waveforms also generate broadband electromagnetic energy that can produce ElectroMagnetic Interference EMI A...

Страница 6: ...troller part of the IC includes a high voltage level shift circuit and several protection features such as overcurrent protection open loop protection Capacitive mode protection and a general purpose...

Страница 7: ...ction features Safe restart mode for system fault conditions General latched protection input for output overvoltage protection or external temperature protection Protection timer for time out and res...

Страница 8: ...is a 5 1 k series resistor to prevent damage of the input during surges e g lightning Open pin detection is included by an internal current source 33 nA 4 SNSCURPFC Current sense input for PFC This i...

Страница 9: ...ched 10 7 V UVP If SUPREG drops below 10 3 V after start the IC stops operating and the current from SUPIC is limited to 5 4 mA to allow recovery 10 GATELS Gate driver output for low side MOSFET of HB...

Страница 10: ...dis charging current is reduced to 30 A to slow down the charging temporarily An internal function limits the operating frequency to 670 kHz 20 RFMAX Oscillator frequency pin The value of the resistor...

Страница 11: ...out and restart The values of an externally connected resistor and capacitor determine the timing A 100 A charge current activates the timer during certain protection events Overcurrent regulation SN...

Страница 12: ...o legal disclaimers NXP B V 2011 All rights reserved Application note Rev 2 26 September 2011 12 of 102 NXP Semiconductors AN10881 TEA1713 resonant power supply control IC with PFC 4 Application diagr...

Страница 13: ...V UV Clamp 3 0 V 0 89 V 1 15 V 1 25 V 3 5 V GatePfcDig Ton SoftStopEnd OCPfc I c V2 8 4 V demagnetized VRect N VRect VBoost VBoost VRect N Vaux demag 0 0 magnetized Demagnetization VALLEY SWITCHING lT...

Страница 14: ...V UV Clamp 3 0 V 0 89 V 1 15 V 1 25 V 3 5 V GatePfcDig Ton SoftStopEnd OCPfc I c V2 8 4 V demagnetized VRect N VRect VBoost VBoost VRect N Vaux demag 0 0 magnetized Demagnetization VALLEY SWITCHING lT...

Страница 15: ...ensation nominal OCP nominal VBoost no compensation nominal OCR VSNSCURHBC t t VSNSCURHBC Vocr HBC Vocr HBC Vocp HBC Vocp HBC 0 A 0 V 1 8 V VSNSBOOST Icompensation on SNSCURHBC 2 5 V Vregulation 170 A...

Страница 16: ...a new start up The internal regulator SUPREG generates a fixed voltage of 10 9 V to supply the internal MOSFET drivers GATEPFC GATELS and GATEHS A bootstrap function with an external diode is used to...

Страница 17: ...m a standby supply The IC starts operating when the SUPIC and SUPREG voltage have reached the start level The start level value of SUPIC depends on the condition of the SUPHV pin 5 2 1 1 SUPHV 25 Vmax...

Страница 18: ...igh and also during normal operation Initially the stored energy in the SUPIC capacitor delivers the SUPIC current After a short time the current supply is taken over by the supply source on SUPIC dur...

Страница 19: ...ing the output voltage to use the voltage from the auxiliary winding for IC supply and HBC output voltage measurement by SNSOUT Place this winding on the secondary output side to ensure good coupling...

Страница 20: ...input See Section 10 3 3 for more information In a combined function of SUPIC and SNSOUT by an auxiliary winding on the HBC transformer some issues must be addressed to obtain a good representation o...

Страница 21: ...with the SNSOUT function there can be an overlap in functionality in an over power or short circuit situation In such a situation often both the SNSOUT UVP and the OCP OCR on SNSCURHBC activate the p...

Страница 22: ...is state is reset by internal logic when the SUPIC voltage drops below 7 V 5 5 SUPREG SUPIC has a wide voltage range for easy application Because of this SUPIC cannot be directly used to supply the in...

Страница 23: ...is reduced to 5 4 mA In case of an overload at SUPREG in combination with an external DC supply for SUPIC this action reduces the dissipation in the series stabilizer It is important to realize that...

Страница 24: ...ated when SUPIC 22 V Using an external low voltage supply SUPREG is activated when SUPIC 17 V 5 5 3 Supply voltage for the output drivers SUPREG The TEA1713 has a powerful output stage for GATEPFC and...

Страница 25: ...nd or when switching at high frequencies Instead of using SUPREG as the power source for charging SUPHS another supply source can be used In such a construction it is important to check for correct st...

Страница 26: ...SUPHS During this time the circuit supplied by SUPHS slowly discharges the supply voltage capacitor When a new burst starts the SUPHS voltage is lower than during normal operation During the first swi...

Страница 27: ...G is a minimum of 40 mA How much current the IC is using must be determined to ensure how much current is available for an external circuit ISUPREG_for_external 40 mA ISUPREG_for_IC With respect to th...

Страница 28: ...jor part of the capacitance 5 6 1 2 Start up When the supply is initially provided by an HV source before being handled by an auxiliary winding a larger capacitor is needed The capacitor value must be...

Страница 29: ...an SMD ceramic capacitor supported by an electrolytic capacitor This is necessary to provide sufficient capacitance to prevent voltage drop during high current loads The value of the capacitor on SUPR...

Страница 30: ...ver is referenced to pin PGND and is supplied from SUPREG The high side driver is floating referenced to HB the connection to the midpoint of the external half bridge The high side driver is supplied...

Страница 31: ...to be discharged The voltage on the gate just before discharge The gate threshold voltage for the MOSFET to switch off The external circuit to the gate Because the timing for switching off the MOSFET...

Страница 32: ...alue of the sink current is highest when the gate voltage is highest The supply voltage provided by SUPREG for GATEPFC and GATELS is constant at 10 9 V The supply voltage for GATEHS is lower and depen...

Страница 33: ...nd HBC are independently driven in time Due to these current peaks being high they can give disturbance on control and sense signals As both the PFC controller and the HBC controller are integrated in...

Страница 34: ...C is switched on first when the mains voltage is present The HBC is switched on after the boost capacitor is charged to approximately 90 of its normal value The system can be operated in Burst mode fo...

Страница 35: ...ing until the voltage on SNSBOOST is above 0 4 V This serves as short circuit protection for the boost voltage and SNSBOOST pin itself An internal current source draws a small amount of current from S...

Страница 36: ...ing on time A compensation network typically comprising one resistor and two capacitors at pin COMPPFC is used to stabilize the PFC control loop The transfer function has a pole at 0 Hz a zero by Rcom...

Страница 37: ...s input voltage influence SNSMAINS measures the average mains voltage which is used for internal compensation Figure 18 shows the relationship between the SNSMAINS voltage COMPPFC voltage and the on t...

Страница 38: ...3 1 PFC auxiliary sensing circuit Add a 5 k series resistor to SNSAUXPFC to protect the internal circuit of the IC against excessive voltage for example during lightning surges In the PCB layout plac...

Страница 39: ...nant operation is above the 125 kHz limit the system switches over to Discontinuous conduction mode The PFC MOSFET is only switched on at a minimum voltage across the switch valley switching One or mo...

Страница 40: ...reached At start up the current source is stopped and the voltage on SNSCURPFC drops as RSS discharges CSS During this discharge the peak current of each cycle increases until CSS is discharged compl...

Страница 41: ...th the following equation 15 In the example a design value of 394 V is used for nominal VBOOST 7 6 PFC mains UnderVoltage Protection brownout protection The voltage on the SNSMAINS pin is sensed conti...

Страница 42: ...NS brownout protection RMS voltage level is calculated with Equation 17 17 18 Example Required VBO 66 V AC with VSNSMAINS UVP 0 89 V R1 R2 2 M RV 1 M 19 20 R3 560 k R4 47 k The time constant for a rec...

Страница 43: ...F The time constant equals tdischarge Rdischarge C 2465 k 220 nF 542 ms 7 6 3 SNSMAINS open pin detection The SNSMAINS pin which senses the mains input voltage has an integrated protection circuit to...

Страница 44: ...side and low side MOSFET for every oscillator cycle 2 The adaptive non overlap see Section 8 3 sensing on HB determines the switch on moment 3 The oscillator see Section 8 4 determines the switch off...

Страница 45: ...of the TEA1713 provides an automatic measurement and control function that decides when to switch on As it uses actual measurement input the control adapts for operation changes in time Because of th...

Страница 46: ...itching This limitation of the maximum non overlap time ensures that at high switching frequency the on time of the MOSFET is at least 25 of the HB switching period 8 3 2 Capacitive mode During error...

Страница 47: ...reaches the high level The Capacitive Mode Regulation CMR function increases the oscillation frequency to bring the converter from Capacitive mode to Inductive mode operation again 8 3 3 Capacitive Mo...

Страница 48: ...apacitive Inductive HBC operating frequencies 001aal035 load independent point series resonance f0 Vimax Qmax Qnom Qmin Vinom Vimin Mmin Mnom 1 Mmax resistive inductive capactive fl fr fmax f M Vi a V...

Страница 49: ...voltage on RFMAX is 2 5 V when the oscillator frequency is maximum The value of the resistor on RFMAX determines the relationship between VRFMAX and the frequency It also determines the maximum frequ...

Страница 50: ...d the other one on is adaptive adaptive non overlap time or dead time This non overlap time has no influence on the oscillator signal The frequency control by oscillator frequency consists of determin...

Страница 51: ...rification of the result is advised 8 4 4 RFMAX and High Frequency Protection HFP Normally the converter does not operate continuously at the preset maximum frequency This maximum frequency is only us...

Страница 52: ...e secondary mains insulated side the output voltage is compared to a reference and amplified The TEA1713 is normally placed on the primary side The output of the error amplifier is transferred to the...

Страница 53: ...al operating conditions the OPTO coupler current is between 0 66 mA and 2 2 mA which pulls down the voltage at pin SNSFB Due to an error in the feedback loop the current can become less than 260 A whi...

Страница 54: ...A 40 A Capacitive mode regulation high low discharge 1800 A 440 A General bias discharge 5 mA 8 6 1 Switching ON and OFF using an external control function The SSHBC EN can be used to switch the conv...

Страница 55: ...C EN pin HBC only active The TEA1713 is not designed to provide this operation mode but it can be realized by forcing a voltage higher than 2 63 V but below 5 V on SNSBOOST This way the output overvol...

Страница 56: ...d at 8 4 V and remains at that level during normal operation When the voltage on SSHBC EN is reduced during protection or regulation the voltage is clamped at 3 0 V This is to provide a quick response...

Страница 57: ...ed soft start The fast dis charge speed is used for the upper frequency range where VSSHBC EN is below 5 6 V In the upper frequency range the current and power in the converter do not react strongly t...

Страница 58: ...he overcurrent protection is an example see Table 4 When this protection is activated the control input of the oscillator is disconnected internally from the soft start capacitor at pin SSHBC EN and t...

Страница 59: ...protection timer is started OverCurrent Protection OCP steps to maximum frequency A boost voltage compensation function is included to reduce the variation in the preset protection level of the reson...

Страница 60: ...current within the limits 8 7 2 HBC overcurrent protection In most cases the OverCurrent Regulation is able to keep the current below the set maximum values However the OCR can not be fast enough to l...

Страница 61: ...the voltage amplitude at the pin resulting in a higher effective current protection level The value of Rcc sets the amount of compensation 8 7 4 Current measurement circuits 8 7 5 SNSCURHBC layout Be...

Страница 62: ...fter interruption no soft start is applied as the system is still in regulation close to the regular working point the regulation loop of the system normally by the output voltage determines the timin...

Страница 63: ...op The HBC is already paused Above this level the PFC resumes operation with a soft start A current 100 A from the SNSOUT pin keeps the voltage at an internal clamp voltage of 1 5 V which is above bot...

Страница 64: ...tching resumes When the power delivered during a burst is larger than needed for the output the regulation voltage SNSFB quickly decreases stopping the switching at BURST The time needed for the regul...

Страница 65: ...rst period the power is transferred directly from the input to the output The HBC determines the repetition time of the burst and the PFC follows In the burst period the PFC operates in normal regulat...

Страница 66: ...circuit with hysteresis The basic choice for the voltage level at which the comparator must be active BURST can be made experimentally It is important to realize that the input voltage of the resonant...

Страница 67: ...voltage to start bursting With this kind of characteristic there is a risk that due to spread the system can either remain in Burst mode or never reach Burst mode operation at all The dimensioning of...

Страница 68: ...d when the output power is low the converted energy does not contribute much to generate audible noise The magnetization current however is still present during low loads and is the dominant energy du...

Страница 69: ...st mode is chosen at a higher output power the level of audible noise is larger Overshoot on feedback voltage When the output load is increased the system reverts to normal operation The transition fr...

Страница 70: ...SNSBOOST is too low This can cause an unacceptable voltage decrease in the output of the resonant converter 9 9 2 PFC burst duration Normally a square SNSOUT pulse leads to equal operation time for P...

Страница 71: ...eresis System and component tolerances play a significant role in variations of performance in production The regulation feedback loop can be optimized for Normal mode Any additional filtering can be...

Страница 72: ...otection Action Link IC UVP SUPIC undervoltage protection SUPIC IC disable Section 5 2 2 IC UVP SUPREG undervoltage protection SUPREG IC disable Section 5 5 IC UVP supplies undervoltage protection sup...

Страница 73: ...tage is discharged fast shutdown reset When resetting by interrupting the mains input some time is still required to lower the SNSMAINS voltage below 0 8 V The time depends on the component values use...

Страница 74: ...detecting OVP the TEA1713 enters the latched protection shutdown state 10 3 1 3 Connecting external measurement circuits When latched protection is needed for other detection circuits it can be added...

Страница 75: ...th a series diode 10 3 3 OVP and UVP combinations 10 3 3 1 Circuit configurations The following list contains examples of configurations for which certain functionality on the SNSOUT pin is disabled O...

Страница 76: ...UT can be prevented from exceeding the preset voltage by externally adding a low impedance resistive divider with a fixed voltage and connecting it to SNSOUT via a diode This simple circuit is not acc...

Страница 77: ...plied to SNSOUT This can be obtained from a resistive divider that is referenced to the SUPREG Fig 51 Example of disabling the OVP function of SNSOUT 001aal060 100 A 1 5 V SNSOUT SUPREG 10 9 V 1N4148...

Страница 78: ...mer is used in two ways As a protection timer As a restart timer The values for both types of timer can be independently preset by an external resistor and capacitor connected to RCPROT 10 4 1 Block d...

Страница 79: ...quency protection RFMAX Open loop protection SNSFB Undervoltage protection SNSOUT The activation of protection and restart can be forced by increasing the RCPROT voltage to above the 4 V but no higher...

Страница 80: ...n The required restart time trestart determines the time constant tRCPROT made by the values of R and C 38 With this time constant and the required protection time tprotection the value of R and C can...

Страница 81: ...d HBC circuits on the PCB to avoid mutual interference 11 1 2 Grounding Connect SGND PGND directly under the IC on the ground plane if possible to avoid false signal detection by driver current distur...

Страница 82: ...the SNSCURHBC connection as close as possible to pin 17 This is important for avoiding disturbance pickup Also avoid capacitive coupling between the connection to pin 17 and the HB track to pin 15 tha...

Страница 83: ...ce for debugging 1 HBC only with protection disabled 2 HBC only with protection disabled and variable DC input voltage 3 HBC only with protection enabled 4 PFC only 5 PFC HBC complete application The...

Страница 84: ...he external supply voltage of 2 7 V on SNSMAINS and SNSBOOST to a value below 2 5 V This allows the gate drive pulses on GATEPFC to be seen By varying the voltage changes are shown in on time After th...

Страница 85: ...non protection sense voltage if needed COMPPFC 1 24 SNSBOOST TEA1713 SNSMAINS 2 23 RCPROT SNSAUXPFC 3 22 SSHBC EN SNSCURPFC 4 21 SNSFB SNSOUT 5 20 RFMAX SUPIC 6 19 CFMIN GATEPFC 7 18 SGND PGND 8 17 SN...

Страница 86: ...tor signal cannot observe proper detection of HB slope or a possible Capacitive mode detection PGND and SGND If the TEA1713 detects HB operation while there is zero input voltage it indicates that the...

Страница 87: ...ion setup but for extra safety the VBOOST connection to the high side switch of the HBC can be disconnected In addition a small load can be connected on VBOOST to prevent voltage overshoot and control...

Страница 88: ...resistor from SNSBOOST to ground can be temporarily increased in value This leads to a lower output voltage regulation setting Supply a DC voltage to the mains input instead of the usual AC voltage t...

Страница 89: ...10881 TEA1713 resonant power supply control IC with PFC 12 Application examples and topologies 12 1 Examples of IC evaluation and test setup Examples of a test evaluation setup are provided in Figure...

Страница 90: ...4 SNSBOOST TEA1713 SNSMAINS SUPIC SUPIC 2 23 RCPROT SUPIC SUPIC SNSAUXPFC 3 22 SSHBC EN SNSCURPFC 4 21 SNSFB SNSOUT 5 20 RFMAX SUPIC SUPIC 6 19 CFMIN GATEPFC 7 18 SGND PGND 8 17 SNSCURHBC SUPREG 9 16...

Страница 91: ...ENSING ENABLE SENSING PFC HALF BRIDGE 1 0 V 0 4 V BURST SENSING PFC HBC 3 5 V OUTPUT OVER VOLTAGE SENSING 1 V 1 V OVER CURRENT PROTECTION SENSING CAPACITIVE MODE SENSING ADAPTIVE NON OVERLAP SENSING S...

Страница 92: ...September 2011 92 of 102 NXP Semiconductors AN10881 TEA1713 resonant power supply control IC with PFC 12 2 Example of a 250 W LCD TV application Fig 65 Example of a 250 W LCD TV application part 1 of...

Страница 93: ...C306 680 nF C321 10 nF C365 150 nF C360 150 nF C361 10 nF C362 3 3 nF IC102A LM393 IC302 SFH615 IC303 TL431 IC102B LM393 C300 4 7 F C304 100 F C307 10 F R302 150 k D312 R303 C305 330 pF 27 k R352 10 R...

Страница 94: ...P B V 2011 All rights reserved Application note Rev 2 26 September 2011 94 of 102 NXP Semiconductors AN10881 TEA1713 resonant power supply control IC with PFC Fig 67 Example of a 250 W LCD TV applicat...

Страница 95: ...ptember 2011 95 of 102 NXP Semiconductors AN10881 TEA1713 resonant power supply control IC with PFC 12 3 Example of a 90 W notebook adapter application Fig 68 Example of a 90 W notebook adapter applic...

Страница 96: ...F C302 220 pF C301 220 pF C306 680 nF C321 10 nF C365 150 nF C360 150 nF C361 10 nF C362 3 3 nF IC102A LM393 IC302 SFH615 IC303 TL431 IC102B LM393 C300 4 7 F C304 100 F C307 10 F R302 150 k D312 R303...

Страница 97: ...1713LT the open loop protection on SNSFB leads to a latched protection after the protection timer RCPROT has triggered the protection In the TEA1713T the system continues with a safe restart RFMAX HFP...

Страница 98: ...mpatibility EMI ElectroMagnetic Interference or Immunity HB Half Bridge HBC Half Bridge Converter or Controller HFP High Frequency Protection HV High Voltage IC Integrated Circuit LCD Liquid Crystal D...

Страница 99: ...heir applications and products using NXP Semiconductors products and NXP Semiconductors accepts no liability for any assistance with applications or customer product design It is customer s sole respo...

Страница 100: ...d SNSCURHBC OCP OCR 21 5 4 SUPIC supply by external voltage 22 5 4 1 Start up 22 5 4 2 Stop 22 5 5 SUPREG 22 5 5 1 Block diagram of SUPREG regulator 24 5 5 2 SUPREG during start up 24 5 5 3 Supply vol...

Страница 101: ...RHBC layout 61 9 Burst mode operation 62 9 1 Burst mode controlled by SNSOUT 62 9 2 External comparator for Burst mode implementation 63 9 3 Advantages of Burst mode for HBC 64 9 4 Advantages of Burst...

Страница 102: ...ng layout example 82 11 1 5 Miscellaneous 82 11 1 5 1 Connecting SNSCURHBC pin 17 82 11 1 5 2 CFMIN pin 19 and RFMAX pin 20 82 11 2 Starting debugging partial circuits 83 11 2 1 HBC only 84 11 2 2 PFC...

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