HR1001C Enhanced LLC Controller with Adaptive Dead-Time Control, Capacitive Mode Protection and Enhanced Surge Protection DESCRIPTION The HR1001C is an enhanced LLC controller that provides adaptive dead-time adjustment (ADTA) and capacitive mode protection (CMP) features, as well as functional improvements on surge performance. ADTA inserts a dead time between the two complimentary gate outputs automatically. This is ensured by keeping the outputs off while sensing the dV/dt current of the half-bridge switching node. ADTA features easier design, lower EMI, and higher efficiency. The HR1001C incorporates anti-capacitive mode protection, which prevents potentially destructive capacitive mode switching if the output is shorted or has a severe overload. This feature protects the MOSFET during abnormal conditions, making the converter robust. The HR1001C has a programmable oscillator that sets both the maximum and minimum switching frequencies. It starts up at a programmed maximum switching frequency and decays until the control loop takes over to prevent excessive inrush current. The HR1001C enters a controlled burst mode at light load to minimize power consumption and tighten the output regulation. Full protection features include two-level overcurrent protection (OCP) with external latch shutdown, auto-recovery, brown-in and brownout, capacitive mode protection (CMP), and over-temperature protection (OTP), improving converter design safety with minimal extra components. HR1001C Rev.1.0 2/6/2017 FEATURES Over-Current Protection (OCP) with Programmable Delay for Enhanced Surge Performance Adaptive Dead-Time Adjustment (ADTA) Capacitive Mode Protection (CMP) 50% Duty Cycle, Variable Frequency Control for Resonant Half-Bridge Converter 600V High-Side Gate Driver with Integrated Bootstrap Diode with a High-Accuracy Oscillator of High dV/dt Immunity Operates up to 600kHz Two-Level Over-Current Protection (OCP): Frequency Shift and Latched Shutdown with Programmable Duration Time Latched Disable Input for Easy Protection Remote On/Off Control and Brown-Out Protection through BO Programmable Burst Mode Operation at Light Load Non-Linear Soft Start for Monotonic Output Voltage Rise Available in a SOIC-16 Package APPLICATIONS LCD and PDP TVs Desktop PCs and Servers Telecom SMPS AC/DC Adapter, Open-Frame SMPS Video Game Consoles Electronic Lighting Ballasts All MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. For MPS green status, please visit the MPS website under Quality Assurance. “MPS” and “The Future of Analog IC Technology” are registered trademarks of Monolithic Power Systems, Inc. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 1 HR1001C – ENHANCED LLC CONTROLLER Typical Application BO SS 16 1 TIMER 15 2 CT 14 3 CT FSET 4 HR1001C 13 Rfmax BURST 12 5 CS Rfmin 11 6 BO 10 7 LATCH 9 8 Rss Css BST Vdc Cbst HG S1 Lr SW NC VCC CHBVS D1 S2 Output Lm LG GND VCC HBVS Cr D2 Rf Cf Rs Cs TL431 HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 2 HR1001C – ENHANCED LLC CONTROLLER ORDERING INFORMATION Part Number* HR1001CGS Package SOIC-16 Top Marking See Below * For Tape & Reel, add suffix –Z (e.g. HR1001CGS–Z) TOP MARKING MPS: MPS prefix YY: Year code WW: Week code HR1001C: Part number LLLLLLLLL: Lot number PACKAGE REFERENCE TOP VIEW SS 1 16 BST TIMER 2 15 HG CT 3 14 SW FSET 4 13 NC BURST 5 12 VCC CS 6 11 LG BO 7 10 GND LATCH 8 9 HBVS HR1001C SOIC-16 HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 3 HR1001C – ENHANCED LLC CONTROLLER ABSOLUTE MAXIMUM RATINGS (1) BST voltage ................................. -0.3V to 618V SW voltage ..................................... -3V to 600V Max voltage slew rate of SW................... 50V/ns Supply voltage (VCC) ...................... Self-limited Sink current of HBVS .............................. ±65mA Voltage on HBVS ..................... -0.3V to self-limit Source current of FSET ..............................2mA Voltage rating LG .......................... -0.3V to VCC Voltage on CS .................................... -3V to 6V Other analog inputs and outputs ...... -0.3V to 6V Continuous power dissipation (TA = +25°C) (2) PIC ............................................................ 1.56W Junction temperature ............................... 150°C Lead temperature .................................... 260°C Storage temperature ................ -65°C to +150°C ESD immunity: BST, HG, SW passes HBM 2.5kV, other pins can pass HBM 4kV. THERMAL RESISTANCE (4) ΘJA ΘJC SOIC-16 ................................ 80 ....... 35 ... °C/W NOTES: 1) Exceeding these ratings may damage the device. 2) The maximum allowable power dissipation is a function of the maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature TA. The maximum allowable continuous power dissipation at any ambient temperature is calculated by PD (MAX) = (TJ (MAX)-TA)/θJA. Exceeding the maximum allowable power dissipation produces an excessive die temperature, causing the regulator to go into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. 3) The device is not guaranteed to function outside of its operating conditions. 4) Measured on JESD51-7, 4-layer PCB. RECOMMENDED OPERATING CONDITIONS (3) Supply voltage (VCC) ................... 13V to 15.5V Analog inputs and outputs ............... -0.3V to 6V Operating junction temp (TJ) ... -40°C to + 125°C HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 4 HR1001C – ENHANCED LLC CONTROLLER ELECTRICAL CHARACTERISTICS VCC = 13V, CHG = CLG = 1nF, CT = 470pF, RFSET = 12kΩ, TJ = -40°C ~ 125°C, min and max values guaranteed by characterization, typical value tested under 25°C, unless otherwise specified. Parameter Symbol Condition Min Typ Max Units 15.5 11.7 8.9 V V V V IC Supply Voltage (VCC) VCC operating range VCC high threshold, IC switch on VCC low threshold, IC switch off Hysteresis IC Supply Current (VCC) VCCH VCCL VCC-hys Start-up current Istart-up Iq Quiescent current Iq-f Operating current ICC-nor 8.9 10.3 7.5 Before the device turns on, VCC = VCCH - 0.2V 250 320 μA Device on, VBurst < 1.23V, RFSET = 12kΩ, FMIN = 60kHz 1.2 1.5 mA 1.42 1.8 mA 3 5 mA 350 420 μA VBST = 600V, TJ = 25°C VSW = 582V, TJ = 25°C 14 14 µA µA VCS = 0 to VCS-OCP 2 µA Device on, VBurst < 1.23V, RFSET = 3.57kΩ, FBURST = 200kHz Device on, VBurst = VFSET VCC < 8.2V or VLATCH > 1.85V or VCS > 1.5V or VTIMER > 3.5V Residual consumption IFault or VBO < 1.81V or VBO > 5.5V or OTP High-Side Floating Gate Driver Supply (BST and SW) BST leakage current SW leakage current Current Sensing (CS) Input bias current ILK-BST ILK-SW ICS 11 8.2 2.8 240 Frequency shift threshold VCS-OCR 0.71 0.78 0.85 V OCP threshold VCS-OCP 1.41 1.5 1.59 V VCSPR 50 85 131 mV VCSNR -131 -85 -50 mV 2.30 2.40 V Current polarity comparator reference when HG turns off Current polarity comparator reference when LG turns off Line Voltage Sensing (BO) Start-up threshold voltage VBO-On Turn-off threshold voltage VBO-Off 1.72 1.81 Clamp level Latch Function (LATCH) VBO-Clamp 5.1 5.5 Input bias current (VLATCH = 0 to Vth) ILATCH LATCH threshold VLATCH HR1001C Rev.1.0 2/6/2017 1.72 1.85 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. V 5.9 V 1 µA 1.95 V 5 HR1001C – ENHANCED LLC CONTROLLER ELECTRICAL CHARACTERISTICS (continued) VCC = 13V, CHG = CLG = 1nF, CT = 470pF, RFSET = 12kΩ, TJ = -40°C ~ 125°C, min and max values guaranteed by characterization, typical value tested under 25°C, unless otherwise specified. Parameter Symbol Condition Min Typ Max Units 48 47 50 50 52 53 600 % % kHz V V 2.05 290 V ns µs ns µs Oscillator Output duty cycle D Oscillation frequency CT peak value CT valley value fosc VCFp VCFv Voltage reference at FSET VREF tDMIN tDMAX tD-float tCMP Dead time Timer for CMP Half-Bridge Voltage Sense (HBVS) TJ = 25°C TJ = -40 ~ 125°C CT ≤ 150pF, RFSET ≤ 2kΩ 3.8 0.9 CHBVS = 5pF typically 1.87 180 HBVS floating 250 VHBVS- Voltage clamp dvmin/dt Td Discharge resistance Threshold for OCP latch Standby Function (BURST) RSS VSS-OCP Disable threshold Hysteresis VBurst VBurst-hys 450 7.6 Clamp Minimum voltage change rate that can be detected Turn-on delay Soft-Start Function (SS) 2 235 1 350 52 CHBVS = 5pF, typically 180 Slope finish to turn-on delay VCS > VCS-OCR VCS > VCS-OCP V 100 V/µs ns 130 1.73 1.82 Ω V 1.17 1.23 30 1.28 100 V mV 80 130 180 µA 1.64 Delayed Shutdown (TIMER) Charge current ITIMER VTIMER = 1V, VCS = 0.85V, TJ = 25°C Threshold for forced operation at maximum frequency VTIMER-fmax 1.80 2 2.10 V Shutdown threshold VTIMER-SD 3.2 3.5 3.7 V Restart threshold VTIMER-R 0.21 0.28 0.35 V Low-Side Gate Driver (LG, Referenced to GND) Peak source current (5) ILG-source-pk 0.75 A Peak sink current (5) ILG-sink-pk 0.87 A Sourcing resistor Sinking resistor Fall time Rise time RLG-source LG_R @ Isrc = 0.01A RLG-sink LG_R @ Isnk = 0.01A tLG-f tLG-r 4 2 30 30 Ω Ω ns ns UVLO saturation HR1001C Rev.1.0 2/6/2017 VCC = 0 to VCCH, Isink = 2mA www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 1 V 6 HR1001C – ENHANCED LLC CONTROLLER ELECTRICAL CHARACTERISTICS (continued) VCC = 13V, CHG = CLG = 1nF, CT = 470pF, RFSET = 12kΩ, TJ = -40°C ~ 125°C, min and max values guaranteed by characterization, typical value tested under 25°C, unless otherwise specified. Parameter Symbol Condition Min Typ Max Units High-Side Gate Driver (HG, Referenced to SW) Peak source current (5) Peak sink current (5) Sourcing resistor Sinking resistor Fall time Rise time Thermal Shutdown Thermal shutdown threshold (5) Thermal shutdown recovery threshold (5) IHG-source-pk IHG-sink-pk RHG-source RHG-sink tHG-f tHG-r HG_R @ Isrc = 0.01A HG_R @ Isnk = 0.01A 0.74 0.87 4 2 30 A A Ω Ω ns 30 ns 150 °C 120 °C NOTE: 5) Guaranteed by design. HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 7 HR1001C – ENHANCED LLC CONTROLLER TYPICAL PERFORMANCE CHARACTERISTICS Performance waveforms are generated using the evaluation board built with the design example on page 22. VAC = 120V, VOUT = 24V, IOUT = 4.16A, TA = 25°C, unless otherwise noted. HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 8 HR1001C – ENHANCED LLC CONTROLLER TYPICAL PERFORMANCE CHARACTERISTICS (continued) Performance waveforms are generated using the evaluation board built with the design example on page 22. VAC = 120V, VOUT = 24V, IOUT = 4.16A, TA = 25°C, unless otherwise noted. HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 9 HR1001C – ENHANCED LLC CONTROLLER PIN FUNCTIONS Pin # Name 1 SS 2 TIMER 3 CT 4 FSET 5 BURST Description Soft start. Connect an external capacitor from SS to GND and a resistor to FSET to set the maximum oscillator frequency and the time constant for the frequency shift during start-up. An internal switch discharges the capacitor when the chip turns off (VCC < UVLO, BO < VBO-Off or > VBO-Clamp, LATCH > VLATCH, CS > VCS-OCP, TIMER > VTIMER-fmax, thermal shutdown) to guarantee a soft start. Period between over-current and shutdown. Connect a capacitor and a resistor from TIMER to GND to set both the maximum duration from an over-current condition before the IC stops switching and the delay before the IC resumes switching. Whenever the voltage on CS exceeds VCS-OCR, an internal current source (ITIMER) charges the capacitor. An external resistor discharges this capacitor slowly. If the voltage on TIMER reaches VTIMERfmax, the soft-start capacitor discharges completely, raising its switching frequency to its maximum value. ITIMER remains on. When the voltage exceeds VTIMER-SD, the IC stops switching, the internal current source turns off, and the voltage decays. The IC enters soft start when the voltage drops below VTIMER-R. This converter works intermittently with very low average input power under short-circuit conditions. Time set. An internal current source programmed by an external network connected to FSET charges and discharges a capacitor connected to GND. This determines the converter’s switching frequency. Switching frequency set. FEST provides a precise 2V reference. A resistor connected from FSET to GND defines a current that sets the minimum oscillator frequency. Connect the phototransistor of an optocoupler to FSET through a resistor to close the feedback loop that modulates the oscillator frequency, which regulates the converter’s output voltage. The value of this resistor sets the maximum operating frequency. An R-C series connected from FSET to GND sets the frequency shift at start-up to prevent excessive inrush energy. Burst mode operation threshold. BURST senses the voltage related to the feedback control, which is compared to an internal reference (VBurst). When the voltage on BURST is lower than this reference, the IC enters an idle state and reduces its quiescent current. When the feedback drives BURST above VBurst + 30mV (VBurst-hys), the chip resumes switching. There is no soft start. This function enables burst mode operation when the load falls below a programmed level determined by connecting an appropriate resistor to the optocoupler to FSET (see the Block Diagram on page 12). Connect BURST to FSET if burst mode is not used. Current sense of the half-bridge. CS uses a sense resistor or a capacitive divider to sense the primary current. CS has the following functions: Over-current regulation: If the voltage exceeds VCS-OCR, the soft-start capacitor on SS discharges internally. The frequency increases, limiting the power throughout. During an output short circuit, this normally results in a nearly constant peak primary current. TIMER limits the duration of this condition. 6 CS Over-current protection (OCP): If the current continues to build despite the frequency increase, when VCS > VCS-OCP, SS is discharged continuously, and OCP is not triggered immediately until VSS < VSS-OCP. If the condition for VCS > VCS-OCP remains once VSS drops below VSS-OCP, OCP is triggered in latch mode. This requires cycling the IC supply voltage to restart. The latch is removed once the VCC voltage drops below the UVLO threshold. This prevents OCP from mistriggering in surge tests or other transient tests. Capacitive mode protection (CMP): Once LG turns off, CS is compared to the VCSNR CMP threshold. If VCS > VCSNR, the HG gate is blocked from turning on until the slope is detected or the CMP timer is complete. Once HG turns off, CS is compared to the VCSPR CMP threshold. If VCS < VCSPR, the low-side gate is blocked from turning on until the slope is detected or the CMP timer is completed. If a capacitive mode status is detected, SS is not discharged immediately; there is a 1µs delay. After the blanking delay, SS is discharged if the fault condition in capacitive mode remains. This prevents the influence of CS noise. Connect CS to GND if the CMP function is not used. HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 10 HR1001C – ENHANCED LLC CONTROLLER PIN FUNCTIONS (continued) Pin # Name 7 BO 8 LATCH 9 HBVS 10 GND 11 LG 12 VCC 13 NC 14 SW 15 HG 16 BST HR1001C Rev.1.0 2/6/2017 Description Input voltage sense and brown-in/brown-out protection. If the voltage on BO is over VBO-On, the IC enables the gate driver. If the voltage on BO is below VBO-Off, the IC is disabled. IC latch off. When the voltage on LATCH exceeds VLATCH, the IC shuts down and lowers its bias current almost to its pre-start-up level. LATCH is reset when the voltage on VCC is discharged below its UVLO threshold. Connect LATCH to GND if the function is not used. Half-bridge dV/dt sense. To detect the dV/dt of the half-bridge, a high-voltage capacitor is connected between SW and HBVS. The dV/dt current through HVBS is used to adjust the dead-time adaptively between the high-side gate and the low-side gate. Ground. GND is the current return for both the low-side gate driver and the IC bias. Connect all external ground connections with a trace to GND—one for signals and a second for pulsed current return. Low-side gate driver output. The driver is capable of a 0.8A source/sink peak current to drive the lower MOSFET of the half-bridge. LG is pulled to GND during UVLO. Supply voltage. VCC supplies both the IC bias and the low-side gate driver. Use a small bypass capacitor (e.g.: 0.1µF) to achieve a clean bias voltage for the IC signal. High-voltage spacer. No internal connection. NC isolates the high-voltage pin (SW) and eases compliance with safety regulations (creepage-distance) on the PCB. High-side switch source. SW is the current return for the high-side gate drive current. SW requires careful layout to avoid large spikes below ground. High-side floating gate driver output. HG is capable of a 0.8A source/sink peak current to drive the upper MOSFET of the half-bridge. Connect an internal resistor to SW to ensure that HG does not float during UVLO. Bias for floating voltage supply of high-side gate driver. Connect a bootstrap capacitor between BST and SW. This capacitor is charged by an internal bootstrap diode driven inphase with the low-side gate driver. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 11 HR1001C – ENHANCED LLC CONTROLLER block diagram VCC VBUS VCC BST Internal circuit HSG DRIVER LEVEL SHIFTER HG CBOOT Lr SW DRIVING LOGIC BURST VDD STANDBY OTP 1.26V/ 1.23V LG LSG DRIVER Dtmin/ Dtada/ DTmax 2V RESONANT TANK CIRCUIT Cr GND ADTA Ifmin HBVS FSET Right Slope detected /52µs Timer out 1.73V SS OCP Control Logic OCR CMP wrong Current Polarity CS 1.5V 0.78V Disable LATCH Q S R Boost _OK VCC 1.85V UVLO 2.3V/1.81V CT VCLK TIMER BO Figure 1: Functional Block Diagram HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 12 HR1001C – ENHANCED LLC CONTROLLER APPLICATION INFORMATION Oscillator Figure 2 shows the oscillator block diagram. A modulated current charges and discharges the CT capacitor repeatedly between its peak valley thresholds, which determines the oscillator frequency. VREF Is-1 Fset Rss Iset Iset Rfmax Rfmin Css VCFv GND CT VCFp + - R + - S CT Is-2 Q 2Iset HR1001C Figure 2: Oscillator Block Diagram FSET sets the CT charging current, Iset (IS-1). When CT passes its peak threshold (VCFp), the flip-flop is set, and a discharge current source twice the charge current is enabled. The difference between these two currents forces the charge and discharge of CT to be equal. When the voltage on the CT capacitor falls below its valley threshold (VCFv), the flip-flop is reset and turns off IS-2. This starts a new switching cycle. Figure 3 shows the detailed waveform of the oscillator. HG SW TD t Under normal operation, the phototransistor adjusts the current flow through Rfmax to modulate the frequency for output voltage regulation. When the phototransistor is saturated, the current through Rfmax is at its maximum, which sets the frequency at its maximum. An R-C in series connected between FSET and GND shifts the frequency at start-up. Please see the Soft-Start Operation section on page 14 for details. Set the minimum and maximum frequencies with Equation (1) and Equation (2): 1 3 CT Rfmin (1) 1 3 CT (Rfmin || Rfmax ) (2) fmin fmax Rfmin 1 3 CT fmin (3) t Rfmax t t Figure 3: CT Waveform and Gate Signal HR1001C Rev.1.0 2/6/2017 Rfmin from FSET to GND contributes to the maximum resistance of the external R-C network when the phototransistor does not conduct. This sets the FSET minimum source current, which defines the minimum switching frequency. Typically, the CT capacitance is between 0.1nF and 1nF. Calculate the values of Rfmin and Rfmax with Equation (3) and Equation (4): CT LG An R-C network connected to FSET externally determines the normal switching frequency and the soft-start switching frequency. Rfmin fmax 1 fmin (4) It is recommended to use a CT capacitor (≤330pF) for best overall temperature performance. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 13 HR1001C – ENHANCED LLC CONTROLLER Soft-Start Operation (SS) For the resonant half-bridge converter, the power delivered is inversely proportional to its switching frequency. To ensure that the converter starts or restarts with safe currents, the soft start forces a high initial switching frequency until the value is controlled by the closed loop. Soft start is achieved by using an external R-C series circuit (see Figure 4). Fset 4 RSS Rfmin SS HR1001C 1 CSS Figure 4: Soft-Start Block When start-up begins, the SS voltage is 0V, so the soft-start resistor (RSS) is in parallel to Rfmin. Rfmin and RSS determine the initial frequency, which can be calculated with Equation (5): fstart 1 3 CT (Rfmin ||RSS ) (5) During start-up, CSS charges until its voltage reaches the reference (VREF), and the current through RSS decays to zero. This period takes about 5x(RSSxCSS). During this period, the switching frequency change follows an exponential curve. Initially, the CSS charge reduces the frequency relatively quickly, but the rate decreases gradually. Select an initial frequency (fstart) at least four times fmin. When selecting CSS, there is a tradeoff between the desired soft-start operation and the over-current protection (OCP) speed. See the Over-Current Protection section on page 17 for details. Adaptive Dead-Time Adjustment (ADTA) When operating in inductive mode, the soft switching of the power MOSFETs results in high efficiency of the resonant converter. A fixed dead time may result in hard switching in light load, especially if the magnetizing inductance (Lm) is too large. A dead time that is too long may lead to ZVS loss. The current may change polarity during the dead time, resulting in capacitive mode switching. The adaptive dead-time control adjusts the dead time automatically by detecting the dV/dt of the halfbridge switching node (SW). The HR1001C incorporates an intelligent adaptive dead-time adjustment (ADTA) logic circuit, which detects SW’s dV/dt and inserts a proper dead time automatically. For the external circuit, connect a capacitor (CHBVS, typically 5pF) between SW and HBVS to sense dV/dt. Figure 5 shows the simplified block diagram of ADTA. Figure 6 shows the operation waveform of ADTA. Vbus BST HSG Driver HG CBOOT HG Lr SW VDD LG LG LSG Driver After the soft-start period, the switching frequency is dominated by the feedback loop to regulate the output voltage. With the soft start, the current of the resonant tank increases during the start-up gradually. Select the soft-start R-C network with Equation (6) and Equation (7): RSS CSS HR1001C Rev.1.0 2/6/2017 Rfmin fstart 1 fmin 3 10-3 RSS CHBVS GND Cr HG LG ADTA Logic CLK id HBVS D1 CLKN Figure 5: Block Diagram of ADTA (6) (7) www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 14 HR1001C – ENHANCED LLC CONTROLLER Dead time adaptively adjusted Then design CHBVS with Equation (10): LG HG HG CHBVS im ir 700uA Coss Im 2 (10) Where Coss is the output capacitance when drain-source voltage on the MOSFET is almost zero volts (refer to the Coss characteristics curve in the MOSFET’s datasheet). VSW VHBVS In a typical design, Lm = 870µH, VIN = 450Vdc, and fmax = 140kHz. CHBVS is calculated at 4.5pF, indicating that 5pF is suitable for most MOSFETs. TDmin Current of C HBVS id CLK Figure 6: Operation Waveform of ADTA When HG switches off, SW voltage swings from high to low due to the resonant tank current (ir). Accordingly, this negative dV/dt pulls current from HBVS via CHBVS. If the dV/dt current is higher than the internal comparison current, the voltage on HBVS (VHBVS) is pulled down and clamped at zero. When SW stops slewing and differential current stops, VHBVS starts to ramp up. LG turns on after a delay (minimum dead time). Dead time is the duration between the moment HG turns off and the moment LG turns on. When LG switches off, the SW voltage swings from low to high, and a positive dV/dt current is detected via CHBVS. The dead time between LG turning off and HG turning on is maintained automatically by sensing the dV/dt current. To avoid damaging HBVS, CHBVS should be selected carefully. Keep the dV/dt current below 65mA using Equation (8): id CHBVS dv 65mA dt Figure 7 illustrates a possible dead time by ADTA logic. Note that there are three kinds of dead time: minimum dead time (tDmin), maximum dead time (tDmax), and adjusted dead time (tDadj), which is between tDmin and tDmax. ADTA logic sets tDmin = 235ns. When the SW transition time is smaller than tDmin, the logic does not let the gate turn on, which prevents a shoot-through between the low-side and high-side MOSFETs. A maximum dead time (tDmax = 1µs) forces the gate to turn on, preventing duty cycle losses or soft switching. ADTA adjusts the dead time automatically and ensures zero-voltage switching (ZVS), which enables more flexibility in the MOSFET and Lm selection. ADTA also prevents hard switching if the design does not carefully account for light load or no load. At light load, the switching frequency goes high, and the magnetizing current goes low, risking hard switching that can lead to a thermal or reliability issue. DTmin DTmax t VCLK t (8) If CHBVS is designed too low to sense the dV/dt, the minimum voltage change rate (dVmin/dt) must be accounted for to design a proper CHBVS value. Vgate LG HG First, calculate the peak magnetizing current (Im) with Equation (9): Vin (9) Im 8 Lm fmax LG HG t VSW t VDT t t1 t2 t3 HR1001C Rev.1.0 2/6/2017 DTmin Vosc t4 t5 t6 t7 t8 Figure 7: Dead Time in ADTA www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 15 HR1001C – ENHANCED LLC CONTROLLER If HBVS is not connected, the internal circuit cannot detect the differential current from HBVS, so the dead time remains fixed at 350ns. Figure 8 shows the dead-time waveform when HG turns off, and Figure 9 shows the dead-time waveforms when LG turns off. ADTA logic inserts the dead time automatically according to the transition shape of SW. If VHBVS is pulled down too low by the negative current of CHBVS, the dead time from HG turning off to LG turning on may be too long. To clamp HBVS at zero and ensure an optimum dead time, connect a Schottky diode (D1) (such as BAT54) on HBVS to GND. VSW VLG VHG VHBVS Capacitive Mode Protection (CMP) When the resonant HB converter output is in an overload or short circuit, it may cause the converter to run into a capacitive region. In capacitive mode, the voltage applied to the resonant tank causes the current of the resonant tank to lag. Under this condition, the body diode of one of the MOSFETs is conducting. The other MOSFET should not be turned on to prevent device failure. The functional block diagram of capacitive mode protection (CMP) is shown in Figure 10. Figure 11 shows the operating current principle of CMP. CSPOS and CSNEG stand for the current polarity, which is generated by comparing the voltage on CS with the internal VCSNR and VCSPR voltage reference. At t0, LG turns off. CSNEG is high, which means the current is in the correct direction and is operating in inductive mode. At t1, HG turns off. CSPOS is high, which means the current is in the correct direction and is operating in inductive mode. Figure 8: Dead Time at High-to-Low Transition VSW VLG VHBVS VHG At t2, LG turns off for the second time. CSNEG is low, indicating the current is in the wrong direction (the low-side MOSFET body diode is conducting), and the converter is operating in capacitive mode. SW does not swing high until the current returns to the correct polarity. DT stays high and VOSC is stopped, preventing the other MOSFET from turning on. This prevents capacitive switching. At t3, the current returns to the correct polarity, and the other MOSFET turns on after the dV/dt current is detected. Between t2 to t5, the correct current polarity cannot be detected, or there is so little current that SW cannot be pulled up or down. Figure 9: Dead Time at Low-to-High Transition HR1001C Rev.1.0 2/6/2017 Eventually, the timer (tCMP) for CMP expires, and the other MOSFET is forced to switch on (see Figure 11). www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 16 HR1001C – ENHANCED LLC CONTROLLER Vbus BST HSG DRIVER 2V CBOOT HG HG FSET Lr SW Iset VDD Discharge: OCR SS CMP LG LG Restart LSG DRIVER SET Q D Q V 3.5 Timer V G VS W D 85mV CLK CMP 2.0 Protection G CS SET Q TIMER VL CLR detected 130uA VH -85mV CLK Capacitive Cr GND Q CLR ir Latch off Control Logic 0.3 Q S QN R 1.5 UVLO V OCP V Protection OCR 0.8 Timer V HR1001C Figure 12: Capacitive Mode Protection Waveform Figure 10: Block Diagram of CMP and OCP DTmin DTmin Timer out Vosc DTmax t VCLK Vgate t LG HG LG VSW HG HG t Slope Missing t Vcs t CSNEG t CSPOS Figure 12 shows CMP behavior when the output is shorted. The current polarity goes in the wrong direction when LG switches off. The CMP logic detects this capacitive mode immediately and prevents HG from turning on. This prevents destructive capacitive switching. Once the current (ir) returns to the correct polarity, SW ramps up, the dV/dt current is detected, and HG turns on at the ZVS condition. Over-Current Protection (OCP) The HR1001C provides two levels of overcurrent protection (see Figure 13). t tOC Vss tOP tSTOP tSS VCC t VCCH VCCL DT SS t t0 t1 t2 t3 t4 t5 t VSS VSS-OCP t6 t Figure 11: Operating Principle of CMP ICr t VCS-OCP When capacitive mode operation is detected, the VSS control signal goes high, turning on an internal transistor to discharge CSS after a 1µs blanking delay. This causes the frequency to increase to a very high level quickly to limit the output power. The VSS control is reset, and soft start is activated when the first gate driver is switched off after CMP. The switching frequency decreases smoothly until the control loop takes over. HR1001C Rev.1.0 2/6/2017 VCS-OCR VCS TIMER t VTIMER-SD VTIMER-fmax VTIMER-R t Vout Normal operation Over load Shutdown Soft-start OCP(Latch-off mode) Pmin t Soft-start Figure 13: OCP Timing Sequence The first level of protection occurs when the voltage on CS (VCS) exceeds VCS-OCR. Once this occurs, two actions take place. First, the internal transistor connected between SS and GND turns on for at least 10µs, which discharges CSS. This creates a sharp increase in the oscillator frequency, reducing the energy transferred to the output. Second, an internal current source (ITIMER) turns on to charge CTIMER, ramping the TIMER voltage. www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 17 HR1001C – ENHANCED LLC CONTROLLER If VCS drops below VCS-OCR before the voltage on TIMER (VTIMER) reaches VTIMER-fmax, both the discharge of CSS and the charge of CTIMER are stopped. The converter resumes normal operation. VSS tOC is the time for VTIMER to rise from 0V to VTIMER-fmax. tOC is also a delay time for overcurrent regulation. There is no simple relationship between tOC and CTIMER. Select CTIMER based on experimental results. Based on experiments, CTIMER may increase the operating time by 100ms. If VCS is still larger than VCS-OCR after VTIMER rises to VTIMER-fmax, CSS is discharged completely. Simultaneously, ITIMER continues to charge CTIMER until VTIMER reaches VTIMER-SD and then turns off all gate drivers. Calculate the time VTIMER takes to rise from VTIMER-fmax to VTIMER-SD with Equation (11): tOP 104 CTIMER (11) The IC maintains the condition until VTIMER decreases to VTIMER-R, and then the IC restarts. Calculate this time period with Equation (12): t OFF =RTIMER CTIMER ln 3.5 2.5RTIMER CTIMER (12) 0.3 The second level of over-current protection is triggered when VCS rises to VCS-OCP. Typically, this condition occurs when VCS continues to rise during a short circuit. Once VCS reaches VCS-OCP, the HR1001C does not stop switching immediately, and CSS is discharged by an internal transistor continuously. If VCS remains above VCS-OCP until VSS drops below VSS-OCP, the IC shuts down in latch-off mode (see Figure 14). While VSS is dropping, the converter resumes normal operation if VCS decreases below VCSOCR. This is a particular characteristic of the HR1001C and prevents instantaneous interference on CS to trigger any protection when the converter suffers a surge or other transient waves. Once the latch is triggered, it is not reset until VCC drops below UVLO. VCS VLG Figure 14: SCP Waveform OCP limits the energy transferred from the primary side to the secondary side during an overload or short-circuit condition. Excessive power consumption due to high continuous currents can damage the secondary-side windings and rectifiers. TIMER provides additional protection to reduce the average power consumption. When OCP is triggered (except in a VCS > VCS-OCP condition), the converter enters a hiccup-like protection mode that operates intermittently. Current Sensing There are two current sensing methods: lossless current sensing and current sensing with a sense resistor. Generally, a lossless current sensing solution is used in high-power applications (see Figure 15). Lr CS R1 C1 Rs Cs Cr Figure 15: Current Sensing with a Lossless Network Design a lossless current sensing network with Equation (13) and Equation (14): Cs HR1001C Rev.1.0 2/6/2017 Cr 100 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. (13) 18 HR1001C – ENHANCED LLC CONTROLLER Choose Rs with Equation (14): Rs< C 0.8 (1 r ) ICrpk CS (14) Where ICrpk is the peak current of the resonant tank at a low input voltage and full load. Calculate ICrpk with Equation (15): ICrpk ( NVO 2 IO 2 ) ( ) 4Lm fs 2N (15) Where N is the turns ratio of the transformer, lo is the output current, Vo is the output voltage, fS is the switching frequency, and Lm is the magnetizing inductance. For capacitive mode detection in no load or tiny-load conditions, Rs should fulfill the condition in Equation (16): C 85mV RS (1 r ) Im CS (16) In some conditions, especially where a large Lm is used, it can be difficult to fulfill both Equation (14) and Equation (16). The IC operates without a CMP function at light load if it does not have the restriction of Equation (16). The R1 and C1 network is used to attenuate switching noise on CS. The time constant should be in the range of 100ns. An alternate solution uses a sense resistor in series with the resonant tank (see Figure 16). This method is simple but causes unnecessary power loss on the sense resistor. Input Voltage Sensing (BI/BO) The HR1001C stops switching when the input voltage drops below a specified value and restarts when the input voltage returns to normal. This function guarantees that the resonant half-bridge converter always operates within the specified input voltage range. The IC senses the voltage on BO (VBO) through the tap of a resistor divider connected to the rectified AC voltage or the PFC output. Figure 17 shows the line-sensing internal block diagram. Shutdown VBO-Clamp RH BO 7 RL VinOK VBO-On/ VBO-Off HR1001C Figure 17: Input Voltage Sensing Block If VBO is higher than VBO-On, the IC provides the gate driver outputs. The IC does not stop the gate driver until VBO drops below VBO-Off. For a minimum operation input voltage of the half-bridge (VIN-min), select a value for RH that is large enough to reduce power consumption at no load. Then calculate RL with Equation (18): RL RH 1.81 VIN-min 1.81 (18) For additional protection, the IC shuts down when VBO exceeds the internal clamp voltage (VBO-Clamp). When VBO is between VBO-On and VBOClamp, the IC operates normally. CS R1 Cr C1 Rs Figure 16: Current Sensing with a Sense Resistor Design the sense resistor using Equation (17): RS HR1001C Rev.1.0 2/6/2017 0.8 ICrpk Burst Mode Operation At light load or in the absence of a load, the maximum frequency limits the resonant halfbridge switching frequency. To control the output voltage and limit power consumption, the HR1001C enables compatible converters to operate in burst mode. This reduce the average switching frequency greatly, thus reducing the average residual magnetizing current and associated losses. (17) www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 19 HR1001C – ENHANCED LLC CONTROLLER Operating in burst mode requires setting BURST. If the voltage on BURST (VBURST) drops below the internal threshold (VBurst), the HR1001C shuts down the HG and LG gate drive outputs, leaving only the 2V reference voltage on FSET and SS to retain the previous state and minimize the power consumption. When VBURST exceeds VBurst over 30mV (VBursthys), the HR1001C resumes normal operation. Based on the burst mode operating principle, BURST must be connected to the feedback loop. Figure 18 shows a typical circuit connecting BURST to the feedback signal for narrow input voltage range applications. Fset 4 Rfmin Rfmax Burst HR1001C 5 Figure 18: Burst Mode Operation Set-Up In addition to setting the oscillator maximum frequency at start-up, Rfmax and determines the maximum burst mode frequency. After confirming fmax, calculate Rfmax with Equation (19): Rfmax 3 Rfmin 8 fmax 1 fmin (19) Here, fmax corresponds to a load point (PBurst), where the peak current flow through the transformer is too low to cause audible noise. So far, this section has been based on a narrow input voltage range. As a property of the resonant circuit, the input voltage determines the switching frequency. This means PBurst has a large variance over the wide input voltage range. To stabilize PBurst over the input range, use the circuit in Figure 19 to insert the input voltage signal into the feedback loop. HR1001C Rev.1.0 2/6/2017 Vin FSET Rss Rfmin Css Rfmax BURST HR1001C BO RH RL RB1 Cburst RB2 Figure 19: Burst Mode Operation Set-Up for a Wide Input Voltage Range RB1 and RB2 in Figure 19 correct against the wide input voltage range. Select both resistors based on experimental results. The total resistance of RB1 and RB2 should be much larger than RH to minimize the effect on VBO. During burst mode operation, when the load is lower than PBurst, the switching frequency is clamped at the maximum frequency. The output voltage must rise over the setting value, which increases the current flowing through the optocoupler. Therefore, the voltage on Rfmax rises due to the increased phototransistor current. Then VBURST drops below VBurst, triggering the gate signal off state. Until the output voltage falls below the setting value, the current flow through the optocoupler decreases, causing VBURST to rise. When VBURST exceeds VBurst over 30mV, the IC restarts to generate the gate signal. The IC operates in this mode under no load or light load to decrease average power consumption. Latch Operation The HR1001C provides a simple latch-off function through LATCH. Applying an external voltage over VLATCH causes the IC to enter a latched shutdown. After the IC is latched, its consumption drops, as shown by the residual current in the Electrical Characteristics table on page 5. Resetting the IC requires dropping the VCC voltage below the UVLO threshold (see the latch internal block diagram in Figure 20). www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 20 HR1001C – ENHANCED LLC CONTROLLER Low-Side Gate Driver LG provides the gate driver signal for the lowside MOSFET. The maximum absolute rating table shows the maximum voltage on LG is 16V. Under some conditions, a large voltage spike occurs on LG due to oscillations from the long gate driver wire, the MOSFET parasitic capacitance, and the small gate driver resistor. This voltage spike is dangerous to LG, so a 15V Zener diode close to LG and GND is recommended (see Figure 22). HR1001C LATCH 8 + S VLATCH Q Disable UVLO R Figure 20: Latch Function Block High-Side Gate Driver The external BST capacitor provides energy to the high-side gate driver. An integrated bootstrap diode charges this capacitor through VCC. This diode simplifies the external driving circuit for the high-side switch, allowing the BST capacitor to charge when the low-side MOSFET is on (see the high-side gate driver internal block diagram in Figure 21). To provide enough gate driver energy (considering the BST capacitor charge time), use a 100nF to 470nF capacitor for the BST capacitor. SW Vs Cgd Low-Side Driver Cds Rg 11 LG Cgs 15V HR1001C 10 GND Figure 22: Low-Side Gate Driver VCC 12 16 BST High-Side Driver Level Shifter 15 CBST HG 14 SW HR1001C Figure 21: High-Side Gate Driver HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 21 HR1001C – ENHANCED LLC CONTROLLER Design Example A 100W LED driver is designed with the specifications below (see Table 1). Table 1: Design Example Input AC Voltage Output Voltage Output Current 90-305VAC 24V 4.16A Figure 23 shows the detailed application schematic. The typical performance and circuit waveforms are shown in the Typical Performance Characteristics section. The HR1001C has passed 4kV surge test for 30s duration on the EV44010-S + HR1001 - S - 00A evaluation board built with the design example. PFC Stage LLC Stage Figure 23: Design Example for a 24V/4.16A Output HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 22 HR1001C – ENHANCED LLC CONTROLLER CONTROL FLOW CHARTS START VCC capacitor is charged by external circuit N VCC>11V & BO>2.3V? Y Soft Start Slope detected? Y N Fixed DT=350ns ADTA Normal operation, IFset controls fs Latched Shutdown CMP Monitor CS Vcs>85mV or Vcs<-85mV Monitor LATCH N N LATCH>1.85V Y 1. Latch off the switching pulse 2. Soft-start capacitor is fully discharged Polarity is wrong? TIMER>2V 1. Discharge softstart capacitor (10µs), increasing switching frequency 2. TIMER capacitor is charged (10µs) by an internal 130µA current source Y Monitor current polarity at the moment of gate driver turning off Y Burst Mode Monitor Thermal Monitor BO Monitor VCC Monitor Burst CS>0.8V N Y VCC<8.2V 1. Discharge SS cap after 1µs delay. 2. VCLK is held. 3. Both HSG and LSG are turned off Y Y CMP timer out? Y 1. Stop discharging soft-start capacitor 2. Stop charging TIMER capacitor 3. Continue normal operation CS>1.5V Y N BO>5.5V or BO<1.81V N VCC<8.2V Y Y Burst<1.23V Y 1. Stop the switching pulse 2. Soft-start capacitor is fully discharged 1. Stop the switching pulse 2. Soft start capacitor is fully discharged 1. Stop the switching pulse 2. Soft-start capacitor is fully discharged 1. Switching frequency is pushed to maximum 2. Soft-start capacitor is fully discharged 3. TIMER capacitor is charged by an internal 130µA current source Stop the switching pulse Burst>1.26V <120ºC Y N 2.3V<BO<5.5V Y N VCC>11V Y N N Y Resume the switching pulse Y N SS<1.73V Y(Latch) N 1. Stop the switching pulse 2. Soft start capacitor is fully discharged 3. Stop charging TIMER capacitor Y Turn on the other gate driver N N >150ºC N Y N CMP timer à 52µs No slope detected? UVLO CS>0.8V Enable CMP N Brown-Out Monitor TIMER Y N OTP OCP N TIMER>3.5V N Y 1. Stop the switching pulse 2. TIMER capacitor is discharged by external resistor VCC<8.2V Y TIMER<0.3V N Y Figure 24: Control Flow Chart HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 23 HR1001C – ENHANCED LLC CONTROLLER TYPICAL APPLICATION CIRCUIT PFC Pre-Regulator MP44010/ MP44014 Resonant Half-Bridge HR1001C Figure 25: Application Circuit HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 24 HR1001C – ENHANCED LLC CONTROLLER SYSTEM TIMING Unplug from main input Over temperature VCC VCCH VCCL LG/HG Soft Start VSS-OCP VLATCH LATCH CS VCS-OCP VCS-OCR TIMER VTIMER-SD VTIMER-fmax VTIMER-R BO VBO-On VBO-Off Burst VBurst UVLO Brown- Normal OCP In Soft Latch OCP Latch Shutdown Start HR1001C Rev.1.0 2/6/2017 OCP BrownOut OTP www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. Burst Mode 25 HR1001C – ENHANCED LLC CONTROLLER PACKAGE INFORMATION SOIC-16 NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not assume any legal responsibility for any said applications. HR1001C Rev.1.0 2/6/2017 www.MonolithicPower.com MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited. © 2017 MPS. All Rights Reserved. 26