IRS25411STRPBF

IRS25411S Synchronous buck LED driver Features IRS25411S Synchronous buck LED driver Features  600 V high side/low side gate drive outputs  Switching frequency up to 500kHz  500mA source/700mA sink gate drive outputs  Hysteretic or slave mode operation  Logic level enable input  PWM dimmable  SO8 package Potential applications  High voltage current regulated synchronous buck LED drivers Product validation Qualified for applications listed above based on the test conditions in the relevant tests of JEDEC20/22 Description The IRS25411 is a half-bridge driver for current regulated synchronous buck regulators typically used in high voltage output non-isolated LED drivers. VBUS RS1 DBOOT VOUT+ CBUS1 CBUS2 DCLAMP CVCC2 ENABLE/ DISABLE COM 2 IFB 3 ENN 4 VB 8 IRS25411 VCC 1 CVCC1 HO 7 RG1 VS 6 CBOOT LBUCK LO 5 RG2 RF M1 COUT M2 CF VOUT- RCS COM Figure 1 Typical schematic Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 1 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Table of contents Table of contents Contents Features ........................................................................................................................................ 1 Potential applications ..................................................................................................................... 1 Product validation .......................................................................................................................... 1 Description .................................................................................................................................... 1 Table of contents ............................................................................................................................ 2 1 1.1 1.2 Maximum ratings ................................................................................................................... 3 Absolute maximum ratings ..................................................................................................................... 3 Recommended operating conditions..................................................................................................... 3 2 Electrical characteristics ......................................................................................................... 4 3 Functional description ............................................................................................................ 6 3.1 Internal block diagram and pin functions .............................................................................................. 6 3.2 Operation ................................................................................................................................................. 7 3.2.1 Basic operation .................................................................................................................................. 7 3.2.2 ZVS operation ..................................................................................................................................... 8 3.2.3 Enable/disable input (ENN) ............................................................................................................... 9 3.2.4 Slave mode operation ...................................................................................................................... 12 3.2.5 IRS25411 state diagram ................................................................................................................... 13 3.3 PCB layout guidelines ........................................................................................................................... 14 4 Package and marking ............................................................................................................ 15 Revision history............................................................................................................................. 18 Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 2 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Maximum ratings 1 Maximum ratings 1.1 Absolute maximum ratings Table 1 Maximum electrical ratings Symbol Definition Minimum Maximum Units VB Floating high side bias supply voltage -0.3 625 V VS Floating high side reference voltage -0.3 VB + 0.3V V VHO Floating gate drive output voltage VB - 0.3V VB + 0.3V V VLO Low side output voltage -0.3 VCC+0.3 V VIFB Feedback input voltage -0.3 VCC+0.3 V VENN Enable input voltage -0.3 VCC+0.3 V VCC Bias supply voltage -0.3 VCLAMP V ICC Supply current -20 20 mA dVS/dt Half-bridge node slew rate -50 50 V/ns Minimum Maximum Units Table 2 1 Maximum thermal ratings Symbol Definition PD Package power dissipation at TA ≤ 25°C (SO8) PD = (TJMAX – TA)/RTHJA 0.625 W RθJA Thermal resistance, junction to ambient (SO8) 200 °C/W TJ Junction temperature -55 150 °C TS Storage temperature -55 150 °C TL Lead temperature during soldering (10 seconds) 300 °C 1.2 Recommended operating conditions Table 3 Recommended operating conditions Symbol Definition Minimum Maximum Units VBS High side floating supply voltage VCC – 0.7 VCLAMP V VS Steady state floating high side offset voltage -1 600 V VCC Bias supply voltage VCCUV+ VCLAMP V ICC Supply current 10 mA fS Switching frequency 10 500 kHz TJ Junction temperature -25 125 °C 1 This IC contains an internal zener diode clamp from VCC to COM. The clamp voltage is referred to as VCLAMP. Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 3 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Electrical characteristics 2 Electrical characteristics VCC = VBS = 14 V +/- 0.25 V, CLO=CHO=1000 pF, CVCC=CVBS=0.1 μF, TA=25 °C unless otherwise specified. Table 4 Bias supply characteristics Symbol Definition Minimum Typical Maximum Units VCLAMP VCC clamp voltage 14.6 15.6 16.6 V VCCUV+ VCC turn on threshold 8.0 9.0 10.0 V VCCUV- VCC turn off threshold 6.5 7.5 8.5 V VCCUVHYS VCC threshold hysteresis 1.0 1.5 2.0 V IQCCUV Low VCC bias current 50 150 μA IQCCENN Disabled (sleep) mode bias current 1.0 2.0 mA IQCC VCC quiescent current (no switching) 1.0 2.0 mA IQCC50k Supply current at 50kHz switching 2.0 3.0 mA Table 5 Floating bias supply characteristics Symbol Definition Minimum Typical Maximum Units VCLAMPHS VB-VS clamp voltage 24.4 26.0 27.6 V VBSUV+ VBS turn on threshold 6.5 7.5 8.5 V VBSUV- VBS turn off threshold 6.0 7.0 8.0 V IQBS0 VBS supply current, VHO low 0.05 1.0 mA IQBS1 VBS supply current, VHO high (VIFB = 0 V) 1.0 2.0 mA ILK Offset leakage current (VB = VS = 600 V) 1 50 μA Table 6 Control characteristics Symbol Definition Minimum Typical Maximum Units VENNTH+ Enable input positive threshold (disable) 2.5 2.7 3.0 V VENNTH- Enable input negative threshold (enable) 1.7 2.0 2.3 V V0.5 Internal voltage reference 490 500 510 mV VIFBTH IFB input threshold 455 500 540 mV tLO-ON Propagation delay, VIFB>VIFBTH to LO high 320 ns tLO-OFF Propagation delay, VIFB tWD. This ensures that the capacitor does not discharge, which would prevent the high side output from operating. Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 5 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Functional description 3 Functional description 3.1 Internal block diagram and pin functions DELAY LEVEL SHIFT PULSE FILTER & LATCH 3 IFB 8 VB 7 HO 6 VS 1 VCC UVN DELAY UVLO 15.6 V 5 LO ENN 4 100 K VNNTH BANDGAP REFERENCE VIFBTH Re-start Timer (t WD) Pulse Generator (tWDCH) 2 COM Figure 2 Internal block diagram VCC VB 8 COM 2 IFB 3 ENN IRS25411 1 4 Figure 3 Pin assignments Table 9 Pin functions HO 7 VS 6 LO 5 Pin Symbol Description 1 VCC Supply voltage 2 COM 0 V return 3 IFB Current feedback (hysteretic) 4 ENN Enable/disable input (high to disable, LO=High and HO=Low) 5 LO Low side gate drive output 6 VS Half bridge node, floating high side return 7 HO High side gate drive output 8 VB High side gate drive floating supply Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 6 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Functional description 3.2 Operation The IRS25411 is a time-delayed hysteretic current regulated synchronous1 buck controller. The output current is sensed through a 0V referenced shunt resistor from which the voltage (VIFB) is fed back to the IFB pin voltage and compared to an internal high precision bandgap voltage reference (VIFBTH). The high and low side gate drive outputs (HO and LO) change state as VIFB rises above and falls below VIFBTH. A fixed dead time (tDT) is provided to prevent shoot though due to overlapping switching transitions of the MOSFETs. Once the VCC supply to the IC rises above the under-voltage lockout positive threshold (VCCUV+), the LO output transitions high while the HO output is low for a predetermined period of time to pre-charge the bootstrap capacitor (CBOOT) connected externally between the VB and VS pins. This establishes the VBS floating supply voltage required for the high-side gate driver, without which the buck regulator would never be able to start up. The recommended capacitor type for CBOOT is a 0.1 μF at 25 V ceramic. The bootstrap diode DBOOT must be rated at 600 V, 1 A and must be a fast recovery type, trr < 50 ns is recommended. In this configuration the high side MOSFET (M1) in the on state delivers power from the input to the output via the buck inductor. The low side MOSFET (M2) is switched on when M1 is off to provide a low resistance path for the re-circulating inductor current thus eliminating the diode conduction losses that occur in a standard buck converter. CBOOT is replenished every switching cycle while LO is high connecting VS to 0V/COM through M2. It is not permissible for HO to be high continuously because if that were the case the charge on CBOOT would eventually leak away and VBS would fall below the minimum threshold required for high side gate drive operation. To prevent this from occurring the IRS25411 includes an internal re-charge timer that forces HO to switch off and LO to switch on for a short pulse after a period of tWD despite VIFB being below VIFBTH. The length of this bootstrap re-charge pulse is tWDCH after which HO and LO revert to their previous states. This process is repeated indefinitely thereby preventing the buck regulator to operate at 100% duty cycle. 3.2.1 Basic operation Figure 4 Synchronous buck operation During normal operation VIFB rises and falls above and below VIFBTH to regulate the output current through the buck inductor. An RC filter (RF and CF) is required at the IFB input to avoid false triggering, which can occur due to noise coupling. This filter also introduces a delay (tRC) that limits the switching frequency. As VIFB rises above VIFBTH, HO switches high to low (M1 off) after a propagation delay of tHO-OFF plus tRC. When M1 switches off, LO switches low to high (M2 on) after the dead-time (DT). The buck inductor then releases stored energy into the load as the current falls and VIFB decreases. When VIFB drops below VIFBTH again LO switches low 1 A synchronous buck converter utilizes a second MOSFET in place of the buck diode in order to eliminate diode conduction losses. Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 7 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Functional description after a delay of tHO-ON plus tRC and HO switches high after a delay of tHO-ON plus tRC plus tDT. The hysteretic buck converter operates in continuous conduction mode (CCM). This hysteretic switching operation continues to regulate the average current as follows: 𝐼𝑂𝑈𝑇(𝐴𝑉𝐺) = 𝑉𝐼𝐹𝐵𝑇𝐻 [1] 𝑅𝐶𝑆 The high and low gate drive and feedback are illustrated below: HO 50% 50% 50% t_HO_off t_HO_on t tDT2 DT DT1 DT 50% 50% LO t_LO_on t_LO_off VIFB(t) IFB VIFBTH IFBTH Figure 5 Hysteretic operation 3.2.1.1 Switching frequency and duty cycle Since the IRS25411 operates hysteretically without a built in oscillator, the switching frequency and duty cycle will vary as the feedback signal VIFB(t) rises and falls across the threshold VIFBTH. The rise and fall slopes of the sensed current depend on the input voltage, the output voltage and the inductor value (LBUCK). The IFB input RC filter delay tRC combined with the internal propagation delays will determine the amount of overshoot and undershoot and therefore the peak to peak current ripple. Higher ripple occurs with lower inductor values since the effect of these delays increases. With higher ripple the average output current will vary more with line and load changes. Higher switching frequency offers better regulation accuracy but reduced efficiency. The standard current sensing arrangement is shown in figure 1. In this case the current sensed is not equal to the inductor since some of the ripple bypasses the load through the output capacitor. It is also possible to locate RCS differently to also include the ripple component from the output capacitor effectively sensing the inductor current. The switching frequency varies depending on input and voltages as well as inductance and load current. This is not easy to calculate accurately and therefore a design approach based on simulation and physical circuit optimization in a lab is required. 3.2.2 ZVS operation In order to realize an efficient high voltage buck regulator, it becomes necessary to implement zero voltage switching of the MOSFETs (ZVS). Buck regulators operating in CCM exhibit hard switching during switch on of the MOSFETs. This results in switching losses that increase with bus voltage and frequency. In a back end Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 8 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Functional description converter stage operating from a front end PFC DC bus voltage in the region of 400 V the efficiency is limited by switching losses, which can only be reduced so far by limiting the frequency. To get around this, it is possible to operate the converter in discontinuous mode, which can be done by reducing the inductor value and/or increasing the feedback RC filter delay so that the inductor current falls to zero during the off period. The downside is that, since the inductor ripple is now very high, it becomes necessary to add an electrolytic capacitor at the output to remove the ripple component from the output current driving the LED load. 3.2.3 Enable/disable input (ENN) The ENN input when raised above the VENNTH+ threshold forces the IRS25411 into the disabled/standby state where HO is low and LO is high regardless of the voltage level at VIFB. LO remains high to ensure that CBOOT remains fully charged ready for the controller to re-start when the ENN input is reduced below VENNTH-. The ENN input is internally pulled down to zero so that the controller remains enabled if the ENN pin is left floating. 3.2.3.1 PWM dimming through the ENN input For PWM burst mode dimming operation a signal with constant frequency and adjustable duty cycle may be applied to the ENN input. An inverse linear relationship exists between the average load current and duty cycle of this input, i.e. if the ratio is 50% then 50% of the maximum set light output will be realized. A frequency of at least 2 kHz is recommended for the dimming control signal to avoid noticeable flicker/strobe effects and to meet flicker index limits. When utilizing the IRS25411 in this way a diode and optional series resistor should be connected from the ENN input to the IFB input (cathode to IFB) so that when ENN is high and the converter is disabled the IFB input is held above VIFBTH. This is required to properly clear the re-charge timer and eliminate possible flicker at very low dimming levels. VBUS RS1 DBOOT VOUT+ VCC 1 CBUS1 DCLAMP CBUS2 CVCC2 PWM DIM INPUT COM 2 IFB 3 ENN 4 VB 8 IRS25411 CVCC1 HO 7 RG1 VS 6 CBOOT RDIM LBUCK LO 5 RG2 RF DDIM M1 COUT M2 CF VOUT- RCS COM Figure 6 Burst mode/PWM dimming circuit configuration In practice the minimum dimming level possible is limited by the length of the dimming burst in relation to the switching frequency. To prevent flicker there should be several switching cycles within the on burst at the minimum dimming level. This may require a PWM frequency below 2 kHz or a higher switching frequency than desired. Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 9 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Functional description PWM dimming is further limited in designs with an electrolytic capacitor at the output because the hold up from this capacitor tends to limit the minimum possible dimming level. For these reasons the IRS25411 is not recommended for dimming to very low levels except in low voltage applications where CCM operation is used. Enable Duty Cycle Relationship to Light Output 100 90 Enable Pin Duty Cycle 80 70 60 50 40 30 20 10 0 0 10 20 30 40 50 60 70 80 90 100 Percentage of Light Output Figure 7 Light output vs ENN input duty cycle and waveforms Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 10 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Functional description 3.2.3.2 Adjustable output current In applications where different values of output current are desired by external selection. The recommended method is to use various options for the current sense resistor (RCS), which can be connected as needed. 3.2.3.3 Linear current dimming As an alternative to PWM/burst mode dimming, the IRS25411 may also be used in linear dimming mode. In this case the output current remains continuous with a level adjustable from an analog control voltage. The output current level is reduced as the voltage at the analog dimming input is increased. This provides a DC offset to the feedback signal, which is dependent on the ratio of RF and RDIM. A control voltage of 0V will allow the output current to regulate at maximum and when the voltage is increased to a certain level, will reduce the output current to zero. The output current will be linearly controlled according to the input current introduced into the RDIM/RFB (IFB) node. This analog dimming input may be used separately or in conjunction with the PWM dimming control in order to achieve wider dimming range. An input control voltage range of 0V to 3.3V would enable the output current to be controlled by a PWM output from an XMC microcontroller and converted to DC through an RC integrator. VBUS RS1 DBOOT VOUT+ VCC 1 CBUS1 DCLAMP CBUS2 CVCC2 ENABLE/ DISABLE ANALOG DIMMING INPUT COM 2 IFB 3 ENN 4 DDIM IRS25411 CVCC1 VB 8 HO 7 RG1 VS 6 CBOOT RF LBUCK LO 5 RG2 RDIM M1 COUT M2 CF VOUT- RCS COM Figure 8 Linear dimming circuit Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 11 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Functional description 3.2.4 Slave mode operation Should the application require more precise control of the switching frequency, the IRS25411 may also be used in slave mode. This is done by supplying the IFB input from an externally generated fixed frequency oscillating voltage signal with a DC offset. This signal may be triangular, sinusoidal or rectangular provided that it rises above and below VIFBTH. As the DC offset is increased HO will become shorter and LO will become longer thus reducing the converter duty cycle while the frequency remains fixed. When the offset is reduced the opposite will occur increasing the converter duty cycle. The figure below illustrates a triangular waveform with a DC offset intersecting VIFBTH to produce LO and HO gate drive outputs. Slave mode operation may be used to more accurately regulate the output current or voltage by means of external control circuitry. In this configuration a feedback circuit produces an error voltage that can added to the oscillating signal that sets the switching frequency, which can be connected to the IFB input. VIFB VIFBTH t LO t HO t Figure 9 External switching control Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 12 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Functional description 3.2.5 IRS25411 state diagram POWER ON UVLO LO and HO Low IQCC < IQCCUV VCC > VCCUV + ENERGY STORING PHASE HO=High, LO=Low IFB Increasing Start recharge timer VCC < VCCUV- IFB < IFBTH AND ENN < VENNTH- End of pulse BOOTSTRAP CAPCITOR RECHARG E PULSE HO=Low, LO=High IFB > IFBTH OR ENN > VENNTH+ ENERGY TRANSFER PHASE VCC < VCCUV- t > tWD ENN > VENNTH+ HO=Low, LO=High IFB Decreasing ENN < VENNTH- DISABLED MODE VCC < VCCUV- Figure 10 HO=Low, LO=High State diagram Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 13 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Functional description 3.3 PCB layout guidelines To operate correctly the IRS25411 requires careful placement of components and layout of PCB traces. The following guidelines must be followed: 1. A decoupling capacitor (typically 0.1 μF, 25 V SMD ceramic) must be placed between the VCC and COM pins (1 and 2) as shown by CVCC in the layout example below. 2. The filter capacitor (CF) should be located as close as possible to the IFB input (pin 3) and COM (pin 2) with the shortest possible traces. 3. Traces connecting to the IFB pin must be kept as far as possible from the VS, HO and VB pins. It is recommended not to pass these traces under the IC. 4. The filter resistor (RF) should also be located close to the IFB pin if possible, however this is less critical. 5. The VS, HO and VB pins (6, 7 and 8) carry high voltage switching signals with fast rise and fall times, therefore traces connected to these pins need to be appropriately distanced from other circuit traces for clearance and to avoid noise propagation that could interfere with correct circuit operation. 6. Since the LO and VS pins are close together designers may choose to include extra HV isolation by routing a narrow slot in the PCB between these pins, adding coating or potting. 7. Under no circumstances should traces be routed between the VS, HO, VB and LO pins! This is also not recommended for the VCC, COM, IFB and ENN pins. 8. The bootstrap capacitor (CB) should be located close to the VB and VS pins allowing sufficient high voltage clearance from other circuit traces. 9. The bootstrap diode (DB) should be located close to the VCC and VB pins allowing sufficient high voltage clearance between the cathode and other circuit traces. 10. Traces should not be passed under DB as this reduces clearance distances. Figure 11 IRS25411 correct layout example Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 14 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Package and marking 4 Package and marking Figure 12 Package details Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 15 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Package and marking LOADED TAPE FEED DIRECTION A B H D F C NOTE : CONTROLLING DIM ENSION IN M M E G CARRIER TAPE DIMENSION FOR Metric Code Min Max A 7.90 8.10 B 3.90 4.10 C 11.70 12.30 D 5.45 5.55 E 6.30 6.50 F 5.10 5.30 G 1.50 n/a H 1.50 1.60 8SOICN Imperial Min Max 0.311 0.318 0.153 0.161 0.46 0.484 0.214 0.218 0.248 0.255 0.200 0.208 0.059 n/a 0.059 0.062 F D C B A E G H REEL DIMENSIONS FOR 8SOICN Metric Code Min Max A 329.60 330.25 B 20.95 21.45 C 12.80 13.20 D 1.95 2.45 E 98.00 102.00 F n/a 18.40 G 14.50 17.10 H 12.40 14.40 Figure 13 Imperial Min Max 12.976 13.001 0.824 0.844 0.503 0.519 0.767 0.096 3.858 4.015 n/a 0.724 0.570 0.673 0.488 0.566 Tape and reel details Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 16 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Package and marking S25411 Part number YWW ? Date code Pin 1 Identifier ? XXXX ? MARKING CODE P Lead Free Released Non-Lead Free Released Figure 14 Logo (may be present) Lot Code (Prod mode – 4 digit SPN code) Assembly site code Per SCOP 200-002 Part marking information Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 17 of 19 2 0.0 2019-02-06 IRS25411S Synchronous buck LED driver Package and marking Revision history Document version Date of release Description of changes 2.0.0 Feb 8, 2019 Updated datasheet replaces original IR version Datasheet www.infineon.com Please read the Important Notice and Warnings at the end of this document page 18 of 19 2 0.0 2019-02-06 Trademarks All referenced product or service names and trademarks are the property of their respective owners. Edition 2019-02-06 Published by Infineon Technologies AG 81726 München, Germany © 2019 Infineon Technologies AG. All Rights Reserved. Do you have a question about this document? Email: erratum@infineon.com Document reference ifx1 IMPORTANT NOTICE The information given in this document shall in no event be regarded as a guarantee of conditions or characteristics (“Beschaffenheitsgarantie”) . For further information on the product, technology, delivery terms and conditions and prices please contact your nearest Infineon Technologies office (www.infineon.com). With respect to any examples, hints or any typical values stated herein and/or any information regarding the application of the product, Infineon Technologies hereby disclaims any and all warranties and liabilities of any kind, including without limitation warranties of non-infringement of intellectual property rights of any third party. WARNINGS Due to technical requirements products may contain dangerous substances. For information on the types in question please contact your nearest Infineon Technologies office. 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