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LMG3425R030RQZT

LMG3425R030RQZT

  • 厂商:

    BURR-BROWN(德州仪器)

  • 封装:

    VQFN54_EP

  • 描述:

    600-V 30-M GAN FET WITH INTEGRAT

  • 数据手册
  • 价格&库存
LMG3425R030RQZT 数据手册
LMG3422R030, LMG3425R030 SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 LMG342xR030 600-V 30-mΩ GaN FET With Integrated Driver, Protection, and Temperature Reporting 1 Features 3 Description • The LMG342xR030 GaN FET with integrated driver and protection enables designers to achieve new levels of power density and efficiency in power electronics systems. • • • Qualified for JEDEC JEP180 for hard-switching topologies 600-V GaN-on-Si FET with Integrated gate driver – Integrated high precision gate bias voltage – 200-V/ns CMTI – 2.2-MHz switching frequency – 30-V/ns to 150-V/ns slew rate for optimization of switching performance and EMI mitigation – Operates from 7.5-V to 18-V supply Robust protection – Cycle-by-cycle overcurrent and latched shortcircuit protection with < 100-ns response – Withstands 720-V surge while hard-switching – Self-protection from internal overtemperature and UVLO monitoring Advanced power management – Digital temperature PWM output – Ideal diode mode reduces third-quadrant losses in LMG3425R030 2 Applications • • • • • High density industrial power supplies Solar inverters and industrial motor drives Uninterruptable power supplies Merchant network and server PSU Merchant telecom rectifiers The LMG342xR030 integrates a silicon driver that enables switching speed up to 150 V/ns. TI’s integrated precision gate bias results in higher switching SOA compared to discrete silicon gate drivers. This integration, combined with TI's lowinductance package, delivers clean switching and minimal ringing in hard-switching power supply topologies. Adjustable gate drive strength allows control of the slew rate from 20 V/ns to 150 V/ns, which can be used to actively control EMI and optimize switching performance. The LMG3425R030 includes ideal diode mode, which reduces thirdquadrant losses by enabling adaptive dead-time control. Advanced power management features include digital temperature reporting and fault detection. The temperature of the GaN FET is reported through a variable duty cycle PWM output, which simplifies managing device loading. Faults reported include overtemperature, overcurrent, and UVLO monitoring. Device Information PART NUMBER LMG3422R030 LMG3425R030 (1) PACKAGE (1) BODY SIZE (NOM) VQFN (54) 12.00 mm × 12.00 mm For all available packages, see the orderable addendum at the end of the data sheet. DRAIN Slew Rate Direct-Drive GaN SOURCE RDRV IN VDD VNEG LDO5V LDO, BB OCP, SCP, OTP, UVLO Current TEMP FAULT OC SOURCE Simplified Block Diagram Switching Performance at > 100 V/ns An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 Table of Contents 1 Features............................................................................1 2 Applications..................................................................... 1 3 Description.......................................................................1 4 Revision History.............................................................. 2 5 Device Comparison......................................................... 3 6 Pin Configuration and Functions...................................4 7 Specifications.................................................................. 5 7.1 Absolute Maximum Ratings........................................ 5 7.2 ESD Ratings............................................................... 5 7.3 Recommended Operating Conditions.........................5 7.4 Thermal Information....................................................6 7.5 Electrical Characteristics.............................................6 7.6 Switching Characteristics............................................8 7.7 Typical Characteristics.............................................. 10 8 Parameter Measurement Information.......................... 12 8.1 Switching Parameters............................................... 12 9 Detailed Description......................................................15 9.1 Overview................................................................... 15 9.2 Functional Block Diagram......................................... 16 9.3 Feature Description...................................................17 9.4 Device Functional Modes..........................................26 10 Application and Implementation................................ 27 10.1 Application Information........................................... 27 10.2 Typical Application.................................................. 28 10.3 Do's and Don'ts.......................................................32 11 Power Supply Recommendations..............................33 11.1 Using an Isolated Power Supply............................. 33 11.2 Using a Bootstrap Diode......................................... 33 12 Layout...........................................................................35 12.1 Layout Guidelines................................................... 35 12.2 Layout Examples.................................................... 37 13 Device and Documentation Support..........................39 13.1 Documentation Support.......................................... 39 13.2 Receiving Notification of Documentation Updates..39 13.3 Support Resources................................................. 39 13.4 Trademarks............................................................. 39 13.5 Electrostatic Discharge Caution..............................39 13.6 Export Control Notice..............................................39 13.7 Glossary..................................................................39 14 Mechanical, Packaging, and Orderable Information.................................................................... 39 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision C (December 2021) to Revision D (March 2021) Page • Changed LMG3425R030 from Advance Information to Production Data...........................................................1 • Revised text and Figure 9-4 in Ideal-Diode Mode Operation section............................................................... 23 Changes from Revision B (April 2021) to Revision C (December 2021) Page • Changed the data sheet status from Advance Information to Production Data..................................................1 2 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 5 Device Comparison DEVICE NAME DUAL OVERCURRENT / SHORT-CIRCUIT PROTECTION TEMPERATURE REPORTING OPERATIONAL IDEAL-DIODE MODE LMG3422R030 Yes Yes No LMG3425R030 Yes Yes Yes Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 3 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 6 Pin Configuration and Functions 16 SOURCE NC2 NC1 NC1 DRAIN 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 17 54 NC2 18 53 LDO5V 19 52 RDRV 20 51 TEMP 21 50 OC 22 49 GND 23 48 FAULT 24 47 IN 25 46 VDD 26 45 GND 27 44 GND THERMAL PAD 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 BBSW 28 VNEG SOURCE Figure 6-1. RQZ Package 54-Pin VQFN (Top View) Table 6-1. Pin Functions PIN DESCRIPTION NO. NC1 1, 16 — Used to anchor QFN package to PCB. Pins must be soldered to PCB landing pads. The PCB landing pads are non-solder mask defined pads and must not be physically connected to any other metal on the PCB. Internally connected to DRAIN. DRAIN 2-15 P GaN FET drain. Internally connected to NC1. NC2 17, 54 — Used to anchor QFN package to PCB. Pins must be soldered to PCB landing pads. The PCB landing pads are non-solder mask defined pads and must not be physically connected to any other metal on the PCB. Internally connected to SOURCE, GND, and THERMAL PAD. SOURCE 18-40 P GaN FET source. Internally connected to GND, NC2, and THERMAL PAD. VNEG 41-42 P Internal buck-boost converter negative output. Used as the negative supply to turn off the depletion mode GaN FET. Bypass to ground with a 2.2-µF capacitor. BBSW 43 P Internal buck-boost converter switch pin. Connect an inductor from this point to ground. GND 44, 45, 49 G Signal ground. Internally connected to SOURCE, NC2, and THERMAL PAD. VDD 46 P Device input supply. IN 47 I CMOS-compatible non-inverting input used to turn the FET on and off. FAULT 48 O Push-pull digital output that asserts low during a fault condition. Refer to Fault Detection for details. OC 50 O Push-pull digital output that asserts low during overcurrent and short-circuit fault conditions. Refer to Fault Detection for details. TEMP 51 O Push-pull digital output that gives information about the GaN FET temperature. Outputs a fixed 9-kHz pulsed waveform. The device temperature is encoded as the duty cycle of the waveform. RDRV 52 I Drive strength selection pin. Connect a resistor from this pin to ground to set the turn-on drive strength to control slew rate. Tie the pin to GND to enable 150 V/ns and tie the pin to LDO5V to enable 100 V/ns. LDO5V 53 P 5-V LDO output for external digital isolator THERMAL PAD — — Thermal pad. Internally connected to SOURCE, GND, and NC2. The thermal pad can be used to conduct rated device current. (1) 4 TYPE(1) NAME I = input, O = output, P = power, G = ground Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 7 Specifications 7.1 Absolute Maximum Ratings Unless otherwise noted: voltages are respect to GND(1) MIN MAX UNIT VDS Drain-source voltage, FET off 600 V VDS(surge) Drain-source surge voltage, FET switching, surge condition(2) 720 V VDS(tr) Drain-source surge transient ringing peak voltage, FET off, surge condition(2) (3) 800 V (surge) VDD –0.3 20 V LDO5V –0.3 5.5 V –16 0.3 V VVNEG–1 VVDD+0.5 V VNEG BBSW Pin voltage ID(RMS) IN –0.3 20 V FAULT, OC, TEMP V +0. –0.3 LDO5V 3 V RDRV –0.3 5.5 V 55 A –120 Internally Limited A Drain RMS current, FET on ID(pulse) Drain pulsed current, FET on, tp < 10 µs(4) IS(pulse) Source pulsed current, FET off, tp < 1 µs 80 A TJ Operating junction temperature(5) –40 150 °C Tstg Storage temperature –55 150 °C (1) (2) (3) (4) (5) Stresses beyond those listed under Absolute Maximum Rating may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Condition. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. See Section 9.3.3 for an explanation of the switching cycle drain-source voltage ratings. t1 < 200 ns in Figure 9-1. The positive pulsed current must remain below the overcurrent threshold to avoid the FET being automatically shut off. The FET drain intrinsic positive pulsed current rating for tp < 10 µs is 120 A. Refer to the Electrical and Switching Characteristics Tables for junction temperature test conditions. 7.2 ESD Ratings PARAMETER V(ESD) (1) (2) Electrostatic discharge VALUE Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 Charged-device model (CDM), per ANSI/ESDA/JEDEC JS-002(2) ±500 UNIT V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. 7.3 Recommended Operating Conditions Unless otherwise noted: voltages are respect to GND, SOURCE connected to GND ID(RMS) Supply voltage VDD (Maximum switching frequency derated for VVDD < 9 V) Input voltage IN MIN NOM MAX 7.5 12 18 V 0 5 18 V 40 A Drain RMS current Positive source current LDO5V UNIT 25 mA RRDRV RDRV to GND resistance from external slew-rate control resistor 0 500 kΩ CVNEG VNEG to GND capacitance from external bypass capacitor 1 10 uF Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 5 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 7.3 Recommended Operating Conditions (continued) Unless otherwise noted: voltages are respect to GND, SOURCE connected to GND LBBSW MIN NOM MAX 3 4.7 10 BBSW to GND inductance from external buck-boost inductor UNIT uH 7.4 Thermal Information LMG342xR030 THERMAL METRIC(1) RQZ (VQFN) UNIT 54 PINS RθJA Junction-to-ambient thermal resistance 16.6 °C/W RθJC(top) Junction-to-case (top) thermal resistance 4.2 °C/W RθJB Junction-to-board thermal resistance 3.1 °C/W ΨJT Junction-to-top characterization parameter 0.12 °C/W ΨJB Junction-to-board characterization parameter 3 °C/W RθJC(bot) Junction-to-case (bottom) thermal resistance 0.33 °C/W (1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report. 7.5 Electrical Characteristics Unless otherwise noted: voltage, resistance, capacitance, and inductance are respect to GND; –40℃ ≤ TJ ≤ 125℃; VDS = 480 V; 9 V ≤ VVDD ≤ 18 V; VIN = 0 V; RDRV connected to LDO5V; LBBSW = 4.7 µH PARAMETER TEST CONDITIONS MIN TYP MAX 26 35 UNIT GAN POWER TRANSISTOR RDS(on) VSD VIN = 5 V, TJ = 25°C Drain-source on resistance Third-quadrant mode source-drain voltage VIN = 5 V, TJ = 125°C 45 mΩ IS = 0.1 A 3.8 V IS = 20 A 3 VDS = 600 V, TJ = 25°C IDSS Drain leakage current COSS Output capacitance CO(er) Energy related effective output capacitance CO(tr) Time related effective output capacitance QOSS Output charge QRR Reverse recovery charge mΩ VDS = 600 V, TJ = 125°C VDS = 400 V 5 V 1 uA 10 uA 130 170 pF 230 276 VDS = 0 V to 400 V 160 335 pF 430 pF 175 nC 0 nC VDD – SUPPLY CURRENTS VDD quiescent current (LMG3422) VVDD = 12 V, VIN = 0 V or 5V 700 1200 uA VDD quiescent current (LMG3425) VVDD = 12 V, VIN = 0 V or 5V 780 1300 uA VDD operating current VVDD = 12 V, fIN = 140 kHz, soft-switching 13 18 mA BUCK BOOST CONVERTER VNEG output voltage VNEG sinking 50 mA Peak BBSW sourcing current at low peak current mode setting (Peak external buck-boost inductor current) 6 Submit Document Feedback –14 0.3 0.4 V 0.5 A Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 7.5 Electrical Characteristics (continued) Unless otherwise noted: voltage, resistance, capacitance, and inductance are respect to GND; –40℃ ≤ TJ ≤ 125℃; VDS = 480 V; 9 V ≤ VVDD ≤ 18 V; VIN = 0 V; RDRV connected to LDO5V; LBBSW = 4.7 µH MIN TYP MAX Peak BBSW sourcing current at high peak current mode setting (Peak external buck-boost inductor current) PARAMETER TEST CONDITIONS UNIT 0.8 1 1.2 A High peak current mode setting enable – IN positive-going threshold frequency 280 420 515 kHz LDO5V Output voltage 4.75 5 5.25 V Short-circuit current LDO5V sourcing 25 mA 25 50 100 mA VIN,IT+ Positive-going input threshold voltage 1.7 1.9 2.45 V VIN,IT– Negative-going input threshold voltage 0.7 1 1.3 V IN Input threshold hysteresis Input pulldown resistance VIN = 2 V 0.7 0.9 1.3 V 100 150 200 kΩ 0.16 0.4 V 0.2 0.45 V FAULT, OC, TEMP – OUPUT DRIVE Low-level output voltage Output sinking 8 mA High-level output voltage Output sourcing 8 mA, Measured as VLDO5V – VO VDD, VNEG – UNDER VOLTAGE LOCKOUT VVDD,T+ (UVLO) VDD UVLO – positive-going threshold voltage 6.5 7 7.5 V VDD UVLO – negative-going threshold voltage 6.1 6.5 7 V VDD UVLO – Input threshold voltage hysteresis 510 mV VNEG UVLO – negative-going threshold voltage –13.6 –13.0 –12.3 V VNEG UVLO – positive-going threshold voltage –13.2 –12.75 –12.1 V GATE DRIVER Turn-on slew rate From VDS < 320 V to VDS < 80 V, RDRV disconnected from LDO5V, RRDRV = 300 kΩ, TJ = 25℃, VBUS = 400 V, LHB current = 10 A, see Figure 8-1 20 V/ns From VDS < 320 V to VDS < 80 V, TJ = 25℃, VBUS = 400 V, LHB current = 10 A, see Figure 8-1 100 V/ns From VDS < 320 V to VDS < 80 V, RDRV disconnected from LDO5V, VRDRV = 0 V, TJ = 25℃, VBUS = 400 V, LHB current = 10 A, see Figure 8-1 150 V/ns VNEG rising to > –13.25 V, soft-switched, maximum switching frequency derated for VVDD < 9 V Maximum GaN FET switching frequency. 2.2 MHz FAULTS IT(OC) DRAIN overcurrent fault – threshold current 60 70 80 A IT(SC) DRAIN short-circuit fault – threshold current 80 95 110 A Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 7 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 7.5 Electrical Characteristics (continued) Unless otherwise noted: voltage, resistance, capacitance, and inductance are respect to GND; –40℃ ≤ TJ ≤ 125℃; VDS = 480 V; 9 V ≤ VVDD ≤ 18 V; VIN = 0 V; RDRV connected to LDO5V; LBBSW = 4.7 µH PARAMETER TEST CONDITIONS di/dt threshold between overcurrent and short-circuit faults MIN TYP MAX 150 UNIT A/µs Short-circuit current to overcurrent fault trip difference 25 A GaN temperature fault – postive-going threshold temperature 175 °C GaN Temperature fault – threshold temperature hysteresis 30 °C Driver temperature fault – positivegoing threshold temperature 185 °C 20 °C Driver Temperature fault – threshold temperature hysteresis TEMP Output Frequency 4.5 GaN TJ = 150℃ Output PWM Duty Cycle 9 14 82 kHz % GaN TJ = 125℃ 58.5 64.6 70 % GaN TJ = 85℃ 36.2 40 43.7 % GaN TJ = 25℃ 0.3 3 6 % –0.15 0 0.15 V –0.2 0 0.2 A –0.35 0 0.35 A IDEAL-DIODE MODE CONTROL VT(3rd) Drain-source third-quadrant detection – threshold voltage IT(ZC) Drain zero-current detection – threshold 0℃ ≤ TJ ≤ 125℃ current –40℃ ≤ TJ ≤ 0℃ 7.6 Switching Characteristics Unless otherwise noted: voltage, resistance, capacitance, and inductance are respect to GND; –40℃ ≤ TJ ≤ 125℃; VDS = 480 V; 9 V ≤ VVDD ≤ 18 V; VIN = 0 V; RDRV connected to LDO5V; LBBSW = 4.7 µH PARAMETER TEST CONDITIONS MIN TYP MAX UNIT SWITCHING TIMES Drain-current turn-on delay time From VIN > VIN,IT+ to ID > 1 A, VBUS = 400 V, LHB current = 10 A, see Figure 8-1 and Figure 8-2 28 42 ns td(on) Turn-on delay time From VIN > VIN,IT+ to VDS < 320 V, VBUS = 400 V, LHB current = 10 A, see Figure 8-1 and Figure 8-2 32 52 ns tr(on) Turn-on rise time From VDS < 320 V to VDS < 80 V, VBUS = 400 V, LHB current = 10 A, see Figure 8-1 and Figure 8-2 2.5 4 ns td(off) Turn-off delay time From VIN < VIN ,IT– to VDS > 80 V, VBUS = 400 V, LHB current = 10 A, see Figure 8-1 and Figure 8-2 44 65 ns tf(off) Turn-off fall time(1) From VDS > 80 V to VDS > 320 V, VBUS = 400 V, LHB current = 10 A, see Figure 8-1 and Figure 8-2 21 ns Minimum IN high pulse-width for FET turn-on VIN rise/fall times < 1 ns, VDS falls to < 200 V, VBUS = 400 V, LHB current = 10 A, see Figure 8-1 24 ns td(on) (Idrain) STARTUP TIMES 8 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 7.6 Switching Characteristics (continued) Unless otherwise noted: voltage, resistance, capacitance, and inductance are respect to GND; –40℃ ≤ TJ ≤ 125℃; VDS = 480 V; 9 V ≤ VVDD ≤ 18 V; VIN = 0 V; RDRV connected to LDO5V; LBBSW = 4.7 µH PARAMETER TEST CONDITIONS Driver start-up time TYP MAX UNIT From VVDD > VVDD,T+ (UVLO) to FAULT high, CLDO5V = 100 nF, CVNEG = 2.2 µF at 0-V bias linearly decreasing to 1.5 µF at 15-V bias MIN 310 470 us FAULT TIMES toff(OC) Overcurrent fault FET turn-off time, FET on before overcurrent VIN = 5 V, From ID > IT(OC) to ID < 50 A, ID di/dt = 100 A/µs 110 145 ns toff(SC) Short-circuit current fault FET turn-off time, FET on before short circuit VIN = 5 V, From ID > IT(SC) to ID < 50 A, ID di/dt = 700 A/µs 65 100 ns Overcurrent fault FET turn-off time, FET turning on into overcurrent From ID > IT(OC) to ID < 50 A 200 250 ns Short-circuit fault FET turn-off time, FET turning on into short circuit From ID > IT(SC) to ID < 50 A 80 180 ns IN reset time to clear FAULT latch From VIN < VIN,IT– to FAULT high 380 580 us 250 IDEAL-DIODE MODE CONTROL TIMES Ideal-diode mode FET turn-on time VDS < VT(3rd) to FET turn-on, VDS being discharged by half-bridge configuration inductor at 5 A 50 65 ns Ideal-diode mode FET turn-off time ID > IT(ZC) to FET turn-off, ID di/dt = 100 A/µs created with a half-bridge configuration 50 76 ns 230 360 ns Overtemperature-shutdown ideal-diode mode IN falling blanking time (1) 150 During turn-off, VDS rise time is the result of the resonance of COSS and loop inductance as well as load current. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 9 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 140 85 80 75 70 65 60 55 50 45 40 35 30 25 20 −40°C 0°C 25°C 85°C 125°C 50 100 150 200 250 300 350 RDRV Resistance (k) 400 450 80 60 20 500 Figure 7-1. Drain-Current Turn-On Delay Time vs Drive Strength Resistance 0 Turn-On Slew Rate (V/ns) 10 5 400 450 500 −40°C 0°C 25°C 85°C 125°C 80 60 40 20 0 0 50 100 150 200 250 300 350 RDRV Resistance (k) 400 450 Figure 7-3. Turn-On Rise Time vs Drive Strength Resistance 6.5 −40°C 0°C 25°C 85°C 125°C 5 4.5 4 3.5 3 5 10 15 20 Source Current (A) 25 30 0 500 35 50 100 150 200 250 300 350 RDRV Resistance (k) 400 450 500 Figure 7-4. Turn-On Slew Rate vs Drive Strength Resistance Normalized Drain-Source On Resistance (m) 0 0 150 200 250 300 350 RDRV Resistance (k) 100 15 5.5 100 120 −40°C 0°C 25°C 85°C 125°C 20 6 50 Figure 7-2. Turn-On Delay Time vs Drive Strength Resistance 25 Turn-On Rise Time (ns) 100 40 0 Source-Drain Voltage (V) −40°C 0°C 25°C 85°C 125°C 120 Turn-On Delay Time (ns) Drain-Current Turn-On Delay Time (ns) 7.7 Typical Characteristics 2.2 2 1.8 1.6 1.4 1.2 1 0.8 0.6 -40 -20 0 20 40 60 80 100 Junction Temperature (°C) 120 140 160 Figure 7-6. Normalized On-Resistance vs Junction Temperatue IN = 0 V Figure 7-5. Off-State Source-Drain Voltage vs Source Current 10 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 7.7 Typical Characteristics (continued) 250 VDS = 0 V VDS = 50 V VDS = 400 V 200 150 VDS = 400 V VDD Supply Current (mA) VDD Supply Current (mA) 250 VDS = 50 V 100 VDS = 0 V 50 0 VDS = 0 V VDS = 50 V VDS = 400 V 200 150 VDS = 50 V 100 VDS = 0 V 50 0 0 400 800 1200 1600 IN Switching Frequency (kHz) 2000 0 TJ = 25°C 400 800 1200 1600 IN Switching Frequency (kHz) 2000 TJ = 125°C Figure 7-7. VDD Supply Current vs IN Switching Frequency Figure 7-8. VDD Supply Current vs IN Switching Frequency 1750 120 1250 1000 750 500 100 Switching Energy (J) −40°C 0°C 25°C 85°C 125°C 1500 Output Capacitance (pF) VDS = 400 V 80 60 Turn-On Switching Energy (J) Turn-Off Switching Energy (J) 40 20 250 0 0 0 50 100 150 200 250 300 350 Drain-Source Voltage (V) 400 450 500 Figure 7-9. Output Capacitance vs Drain-Source Voltage 0 3 6 9 12 15 18 21 Inductive Load Current (A) 24 27 30 Figure 7-10. Half-Bridge Switching Energy vs Inductive Load Current Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 11 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 8 Parameter Measurement Information 8.1 Switching Parameters Figure 8-1 shows the circuit used to measure most switching parameters. The top device in this circuit is used to re-circulate the inductor current and functions in third-quadrant mode only. Only the LMG3422R030 must be used as the top device as it does not have the ideal-diode mode feature. Do not use the LMG3425R030 for the top device. If the top device has the ideal-diode mode feature, it will automatically turn on the GaN FET when the inductor current is re-circulating and cause a shoot-through current event when the bottom device turns on. The bottom device is the active device that turns on to increase the inductor current to the desired test current. The bottom device is then turned off and on to create switching waveforms at a specific inductor current. Both the drain current (at the source) and the drain-source voltage is measured. Figure 8-2 shows the specific timing measurement. TI recommends to use the half-bridge as double pulse tester. Excessive third-quadrant operation can overheat the top device. DRAIN RDRV Slew Rate Direct- Drive GaN SOURCE IN VDD VNEG OCP, OTP, Current LDO, UVLO, BB TEMP LDO5V LHB TEMP FAULT OC VBUS + SOURCE CPCB ± DRAIN RDRV Slew Rate Direct- Drive GaN SOURCE + IN VDD LDO5V VNEG OCP, OTP, Current LDO, UVLO, BB TEMP VDS _ TEMP PWM input FAULT OC SOURCE Figure 8-1. Circuit Used to Determine Switching Parameters 12 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 IN 50% 50% td(on)(Idrain) ID 1A td(on) td(off) tr(on) VDS tf(off) 80% 80% 20% 20% Figure 8-2. Measurement to Determine Propagation Delays and Slew Rates 8.1.1 Turn-On Times The turn-on transition has three timing components: drain-current turn-on delay time, turn-on delay time, and turn-on rise time . The drain-current turn-on delay time is from when IN goes high to when the GaN FET drain-current reaches 1 A. The turn-on delay time is from when IN goes high to when the drain-source voltage falls 20% below the bus voltage. Finally, the turn-on rise time is from when drain-source voltage falls 20% below the bus voltage to when the drain-source voltage falls 80% below the bus voltage. Note that the turn-on rise time is the same as the VDS 80% to 20% fall time. All three turn-on timing components are a function of the RDRV pin setting. 8.1.2 Turn-Off Times The turn-off transition has two timing components: turn-off delay time, and turn-off fall time. The turn-off delay time is from when IN goes low to when the drain-source voltage rises to 20% of the bus voltage. The turn-off fall time is from when the drain-source voltage rises to 20% of the bus voltage to when the drain-source voltage rises to 80% of the bus voltage. Note that the turn-off fall time is the same as the VDS 20% to 80% rise time. The turn-off timing components are independent of the RDRV pin setting, but heavily dependent on the LHB load current. 8.1.3 Drain-Source Turn-On Slew Rate The drain-source turn-on slew rate, measured in volts per nanosecond, is the inverse of the turn-on rise time or equivalently the inverse of the VDS 80% to 20% fall time. The RDRV pin is used to program the slew rate. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 13 LMG3422R030, LMG3425R030 SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 www.ti.com 8.1.4 Turn-On and Turn-Off Switching Energy The turn-on and turn-off switching energy shown in Figure 7-10 represent the energy absorbed by the low-side device during the turn-on and turn-off transients of the circuit. As the circuit in Figure 8-1 represents a boost converter with input shorted to output, the switching energy is dissipated in the low-side device. The turn-on transition is lossy while the turn-off transition is essentially lossless with the output capacitance energy charged by the inductor current. The turn-on and turn-off losses have been calculated from experimental waveforms by integrating the product of the drain current with the drain-source voltage over the turn-on and turn-off times, respectively. The skew of probes for voltage and current are very important for accurate measurement of turn-on and turn-off energy. 14 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 www.ti.com LMG3422R030, LMG3425R030 SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 9 Detailed Description 9.1 Overview The LMG342xR030 is a high-performance power GaN device with integrated gate driver. The GaN device offers zero reverse recovery and ultra-low output capacitance, which enables high efficiency in bridge-based topologies. Direct Drive architecture is applied to control the GaN device directly by the integrated gate driver. This architecture provides superior switching performance compared to the traditional cascode approach and helps solve a number of challenges in GaN applications. The integrated driver ensures the device stays off for high drain slew rates. The integrated driver also protects the GaN device from overcurrent, short-circuit, undervoltage, and overtemperature. Regarding fault signal reporting, LMG342xR030 provides different reporting method which is shown in Table 9-1. Refer to Fault Detection for more details. The integrated driver is also able to sense the die temperature and send out the temperature signal through a modulated PWM signal. Unlike Si MOSFETs, GaN devices do not have a p-n junction from source to drain and thus have no reverse recovery charge. However, GaN devices still conduct from source to drain similar to a p-n junction body diode, but with higher voltage drop and higher conduction loss. Therefore, source-to-drain conduction time must be minimized while the LMG342xR030 GaN FET is turned off. The ideal-diode mode feature in the LMG3425R030 automatically minimizes the source-to-drain conduction loss that occur on the GaN FET soft-switched turn-on edge, similar to optimum dead-time control. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 15 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 9.2 Functional Block Diagram TEMP VDD LDO5V DRAIN Third-Quadrant Detection GaN LDO UVLO (+5V, VDD, VNEG) FAULT Thermal Shutdown Die Temp Sensing Series Si FET Short Circuit Protection OC Overcurrent Protection IN Gating logic control & level shifting BBSW Buck-Boost Controller VNEG RDRV 16 Submit Document Feedback SOURCE Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 9.3 Feature Description The LMG342xR030 includes advanced features to provide superior switching performance and converter efficiency. 9.3.1 GaN FET Operation Definitions For the purposes of this data sheet, the following terms are defined below. The SOURCE pin is assumed to be at 0 V for these definitions. First-Quadrant Current = Positive current flowing internally from the DRAIN pin to the SOURCE pin. Third-Quadrant Current = Positive current flowing internally from the SOURCE pin to the DRAIN pin. First-Quadrant Voltage = Drain pin voltage – Source pin voltage = Drain pin voltage Third-Quadrant Voltage = SOURCE pin voltage – DRAIN pin voltage = –DRAIN pin voltage FET On-State = FET channel is at rated RDS(on). Both first-quadrant current and third-quadrant current can flow at rated RDS(on). FET Off-State = FET channel is fully off for positive first-quadrant voltage. No first-quadrant current can flow. While first-quadrant current cannot flow in the FET Off-State, third-quadrant current still flows if the DRAIN voltage is taken sufficiently negative (positive third-quadrant voltage). For devices with an intrinsic p-n junction body diode, current flow begins when the DRAIN voltage drops enough to forward bias the p-n junction. GaN FETS do not have an intrinsic p-n junction body diode. Instead, current flows because the GaN FET channel turns back on. In this case, the DRAIN pin becomes the electrical source and the SOURCE pin becomes the electrical drain. To enhance the channel in third-quadrant, the DRAIN (electrical source) voltage must be taken sufficiently low to establish a VGS voltage greater than the GaN FET threshold voltage. The GaN FET channel is operating in saturation and only turns on enough to support the third-quadrant current as its saturated current. LMG342xR030 GaN FET On-State = GaN FET internal gate voltage is held at the SOURCE pin voltage to achieve rated RDS(on). The GaN FET channel is at rated RDS(on) with VGS = 0 V because the LMG342xR030 GaN FET is a depletion mode FET. LMG342xR030 GaN FET Off-State = GaN FET internal gate voltage is held at the VNEG pin voltage to block all first-quadrant current. The VNEG voltage is lower than the GaN FET negative threshold voltage to cut off the channel. To enhance the channel in off-state third quadrant, the LMG342xR030 DRAIN (electrical source) voltage must be taken sufficiently close to VNEG to establish a VGS voltage greater than the GaN FET threshold voltage. Again, because the LMG342xR030 GaN FET is a depletion mode FET with a negative threshold voltage, this means the GaN FET turns on with DRAIN (electrical source) voltage between 0 V and VNEG. The typical off-state third-quadrant voltage is 4.5 V for third-quadrant current at 20 A. Thus, the off-state third-quadrant losses for the LMG342xR030 are significantly higher than a comparable power device with an intrinsic p-n junction body diode. The ideal-diode mode function described in Ideal-Diode Mode Operation can help mitigate these losses in specific situations. 9.3.2 Direct-Drive GaN Architecture The LMG342xR030 uses a series Si FET to ensure the power IC stays off when VDD bias power is not applied. When the VDD bias power is off, the series Si FET is interconnected with the GaN device in a cascode mode, which is shown in the Functional Block Diagram. The gate of the GaN device is held within a volt of the series Si FET's source. When a high voltage is applied on the module and the silicon FET blocks the drain voltage, the VGS of the GaN device decreases until the GaN device passes the threshold voltage. Then, the GaN device is turned off and blocks the remaining major part of drain voltage. There is an internal clamp to make sure that the VDS does not exceed its maximum rating. This feature avoids the avalanche of the series Si FET when there is no bias power. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 17 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 When LMG342xR030 is powered up with VDD bias power, the internal buck-boost converter generates a negative voltage (VVNEG) that is sufficient to directly turn off the GaN device. In this case, the series Si FET is held on and the GaN device is gated directly with the negative voltage. During operation, this action removes the switching loss of the series Si FET. 9.3.3 Drain-Source Voltage Capability Due to the silicon FET’s long reign as the dominant power-switch technology, many designers are unaware that the headline drain-source voltage cannot be used as an equivalent point to compare devices across technologies. The headline drain-source voltage of a silicon FET is set by the avalanche breakdown voltage. The headline drain-source voltage of a GaN FET is set by the long term reliability with respect to data sheet specifications. Exceeding the headline drain-source voltage of a silicon FET can lead to immediate and permanent damage. Meanwhile, the breakdown voltage of a GaN FET is much higher than the headline drain-source voltage. For example, the breakdown voltage of the LMG342xR030 is more than 800 V. A silicon FET is usually the weakest link in a power application during an input voltage surge. Surge protection circuits must be carefully designed to ensure the silicon FET avalanche capability is not exceeded because it is not feasible to clamp the surge below the silicon FET breakdown voltage. Meanwhile, it is easy to clamp the surge voltage below a GaN FET breakdown voltage. In fact, a GaN FET can continue switching during the surge event which means output power is safe from interruption. The LMG342xR030 drain-source capability is explained with the assistance of Figure 9-1. The figure shows the drain-source voltage versus time for a GaN FET for a single switch cycle in a switching application. No claim is made about the switching frequency or duty cycle. VDS(tr) VDS(off) VDS(switching) t0 t1 t2 Figure 9-1. Drain-Source Voltage Switching Cycle The waveform starts before t0 with the FET in the on state. At t0 the GaN FET turns off and parasitic elements cause the drain-source voltage to ring at a high frequency. The peak ring voltage is designated VDS(tr). The high frequency ringing has damped out by t1. Between t1 and t2 the FET drain-source voltage is set by the characteristic response of the switching application. The characteristic is shown as a flat line, but other responses are possible. The voltage between t1 and t2 is designated VDS(off). At t2 the GaN FET is turned on at a non-zero drain-source voltage. The drain-source voltage at t2 is designated VDS(switching). Unique VDS(tr), VDS(off) and VDS(switching) parameters are shown because each can contribute to stress over the lifetime of the GaN FET. The LMG342xR030 drain-source surge voltage capability is seen with the absolute maximum ratings VDS(tr)(surge) and VDS(surge) in Absolute Maximum Ratings where VDS(tr)(surge) maps to VDS(tr) in Figure 9-1 and VDS(surge) maps to both VDS(off) and VDS(switching) in Figure 9-1. More information about the surge capability of TI GaN FETs is found in A New Approach to Validate GaN FET Reliability to Power-line Surges Under Use-conditions. 9.3.4 Internal Buck-Boost DC-DC Converter An internal inverting buck-boost converter generates a regulated negative rail for the turn-off supply of the GaN device. The buck-boost converter is controlled by a peak current mode, hysteretic controller. In normal operation, the converter remains in discontinuous-conduction mode, but can enter continuous-conduction mode 18 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 during start-up and overload the conditions. The converter is controlled internally and requires only a single surface-mount inductor and output bypass capacitor. The LMG342xR030 supports the GaN operation up to 2.2 MHz. As power consumption is very different in a wide switching frequency range enabled by the GaN device, two peak current limits are used to control the buck-boost converter. The two ranges are separated by IN positive-going threshold frequency. When switching frequency is in the lower range, the peak current is set to the lower value (around 0.4 A) so a smaller inductor can be selected. When switching frequency is in the higher range, the peak current is raised to the higher value (around 1 A) and requires a larger inductor. There is a filter on this frequency detection logic, therefore the LMG342xR030 requires five consecutive cycles at the higher frequency before it is set to the higher buck-boost peak current limit. The current limit does not go down again until power off after the higher limit is set. Even if the switching frequency returns to the lower range, the current limit does not decrease to the lower limit. 9.3.5 VDD Bias Supply Wide VDD voltage ranges from 7.5 V to 18 V are supported by an internal LDO which regulates supplies the internal low voltage and buck-boost converter circuits. If the VDD input voltage is less than 9 V, then the maximum switching frequency is de-rated. TI recommends to use a 12-V unregulated power supply to supply VDD, otherwise no external LDO is needed. 9.3.6 Auxiliary LDO There is a 5-V voltage regulator inside the part used to supply external loads, such as digital isolators for the high-side drive signal. The digital outputs of the part use this rail as their supply. No capacitor is required for stability, but transient response is poor if no external capacitor is provided. If the application uses this rail to supply external circuits, TI recommends to have a capacitor of at least 0.1 μF for improved transient response. A larger capacitor can be used for further transient response improvement. The decoupling capacitor used here must be a low-ESR ceramic type. Capacitances above 0.47 μF will slow down the start-up time of the LMG342xR030 due to the ramp-up time of the 5-V rail. 9.3.7 Fault Detection The GaN power IC integrates overcurrent protection (OCP), short-circuit protection (SCP), overtemperature protection (OTP) and undervoltage lockout (UVLO). 9.3.7.1 Overcurrent Protection and Short-Circuit Protection There are two types of current faults which can be detected by the driver: overcurrent fault and short-circuit fault. The overcurrent protection (OCP) circuit monitors drain current and compares that current signal with an internally set limit. Upon detection of the overcurrent, the LMG342xR030 conducts cycle-by-cycle overcurrent protection as shown in Figure 9-2. In this mode, the GaN device is shut off when overcurrent happens, but the overcurrent signal clears after the input PWM goes low. In the next cycle, the GaN device can turn on as normal. The cycle-by-cycle function can be used in cases where steady-state operation current is below the OCP level but transient response can still reach current limit, while the circuit operation cannot be paused. The cycle-by-cycle function also prevents the GaN device from overheating by overcurrent induced conduction losses. The short-circuit protection (SCP) monitors drain current and compares that current signal with a internally set limit higher than that of OCP as shown in Figure 9-3. The short-circuit protection is designed to protect the GaN device from high-current short-circuit fault. If a short-circuit fault is detected, the driver turn-off is intentionally slowed down to obtain lower di/dt so that a lower overshoot voltage and ringing can be achieved during the turn-off event. On detection of an overcurrent fault, LMG342xR030 latches off. This fast response circuit helps protect the GaN device even under a hard short-circuit condition. In this protection, the GaN device is shut off and held off until the fault is reset by either holding the IN pin low for a period of time defined in the Specifications or removing power from VDD. During OCP or SCP in a half bridge, after the current reaches the upper limit and the device is turned off by protection, the PWM input of the device could still be high and the PWM input of the complementary device could still be low. In this case, the load current can flow through the third quadrant of the complementary device Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 19 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 with no synchronous rectification. The extra high negative voltage drop (–6 V to –8 V) from drain to source could lead to high third-quadrant loss, similar to dead-time loss but for a longer time. For safety considerations, OCP allows cycle-by-cycle operation while SCP latches the device until reset. By reading the FAULT and OC pins, the exact current fault type can be determined. Refer to Fault Reporting for detailed information. IT(OC) Inductor current VSW Input PWM Figure 9-2. Cycle-by-Cycle OCP Operation 20 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 toff(SC) toff(OC) IT(SC) IT(OC) ID IN OC Cycle by cycle OCP Latched SCP Figure 9-3. Overcurrent Detection vs Short-Circuit Detection 9.3.7.2 Overtemperature Shutdown The LMG342xR030 implements two overtemperature-shutdown (OTSD) functions, the GaN OTSD and the Driver OTSD. Two OTSD functions are needed to maximize device protection by sensing different locations in the device and protecting against different thermal-fault scenarios. The GaN OTSD senses the GaN FET temperature. The GaN FET can overheat from both first-quadrant current and third-quadrant current. As explained in GaN FET Operation Definitions, a FET can prevent first-quadrant current by going into the off-state but is unable to prevent third-quadrant current. FET third-quadrant losses are a function of the FET technology, current magnitude, and if the FET is operating in the on-state or off-state. As explained in GaN FET Operation Definitions, the LMG342xR030 has much higher GaN FET third-quadrant losses in the off-state. When the GaN FET is too hot, the best protection is to turn off the GaN FET when first-quadrant current tries to flow and turn on the GaN FET when third-quadrant current is flowing. This type of FET control is known as ideal-diode mode (IDM). When the GaN OTSD trip point is exceeded, the GaN OTSD puts the GaN FET into overtemperature-shutdown ideal-diode mode (OTSD-IDM) operation to achieve this optimum protection. OTSD-IDM is explained in Ideal-Diode Mode Operation. The Driver OTSD senses the integrated driver temperature and trips at a higher temperature compared to the GaN OTSD. This second OTSD function exists to protect the LMG342xR030 from driver thermal-fault events while allowing sufficient temperature difference for OTSD-IDM to operate. These driver thermal events include shorts on the LD05V, BBSW, and VNEG device pins. When the Driver OTSD trip point is exceeded, the Driver OTSD shuts off the LDO5V regulator, the VNEG buck-boost converter, and the GaN FET. Note that OTSD-IDM does not function in Driver OTSD. This is why the Driver OTSD must trip higher than the GaN OTSD function. Otherwise, GaN FET third-quadrant overheating cannot be addressed. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 21 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 Besides the temperature difference in the GaN OTSD and Driver OTSD trip points, further temperature separation is obtained due to the thermal gradient difference between the GaN OTSD and Driver OTSD sense points. The GaN OTSD sensor is typically at least 20°C hotter than the driver OTSD sensor when the device is in GaN OTSD due to GaN FET power dissipation. The FAULT pin is asserted for either or both the GaN OTSD state and the Driver OTSD state. FAULT de-asserts and the device automatically returns to normal operation after both the GaN OTSD and Driver OTSD fall below their negative-going trip points. During cool down, when the device exits the Driver OTSD state but is still in the GaN OTSD state, the device automatically resumes OTSD-IDM operation. 9.3.7.3 UVLO Protection The LMG342xR030 supports a wide range of VDD voltages. However, when the device is below UVLO threshold, the GaN device stops switching and is held off. The FAULT pin is pulled low as an indication of UVLO. The LDO is turned on by the rising-edge of the VIN UVLO and shuts off around 5 V to 6 V. 9.3.7.4 Fault Reporting The FAULT and OC outputs form a fault reporting scheme together. The FAULT and OC outputs are both push-pull outputs indicating the readiness and fault status of the driver. These two pins are logic high in normal operation, and change logic according to Table 9-1. Table 9-1. Fault Types and Reporting NORMAL UVLO, OT, and RDRV-OPEN OVERCURRENT SHORT-CIRCUIT FAULT 1 0 1 0 OC 1 1 0 0 FAULT is held low when starting up until the series Si FET is turned on. During operation, if the power supplies go below the UVLO thresholds or the device temperature go above the OT thresholds, power device is disabled and FAULT is held low until a fault condition is no longer detected. If RDRV is open, FAULT is also held low. In a short-circuit or overtemperature fault condition, FAULT is held low until the fault latches are reset or fault is cleared. The OC pin is held low if there is a short-circuit or overcurrent fault. The signals help notify the controller the exact type of faults by reading the truth table. If a combined reporting of the faults on a single pin is desired, one can short the OC pin to ground during power up. All faults assert the FAULT pin then and the OC pin is not used. Please note: internal protection happens regardless of the connection of the pin outputs, which means that the protection features continue to operate even if fault reporting is ignored.. 9.3.8 Drive Strength Adjustment The LMG342xR030 allows users to adjust the drive strength of the device and obtain a desired slew rate, which provides flexibility when optimizing switching losses and noise coupling. To adjust drive strength, a resistor can be placed between the RDRV pin and GND pin. The resistance determines the slew rate of the device, from 30 V/ns to 150 V/ns, during turn-on. On the other hand, there are two dv/dt values that can be selected without the resistor: shorting the RDRV pin to ground sets the slew rate to 150 V/ns, and shorting the RDRV pin to LDO5V sets the slew rate to 100 V/ns. The device detects the short to LDO5V one time at power up. Once the short to LDO5V condition is detected, the device no longer monitors the RDRV pin. Otherwise, the RDRV pin is continuously monitored and the dv/dt setting can be changed by modulating the resistance during device operation. The modulation must be fairly slow since there is there is significant internal filtering to reject switching noise. 9.3.9 Temperature-Sensing Output The integrated driver senses the GaN die temperature and outputs the information through a modulated PWM signal on the TEMP pin. The typical PWM frequency is 9 kHz with the same refresh rate. The minimum PWM duty cycle is around 1%, which can be observed at temperature below 25°C. The target temperature range is from 25°C to 150°C, and the corresponding PWM duty cycle is typically from 3% to 82%. At temperatures above 150°C, the duty cycle continues to increase linearly until overtemperature fault happens. When overtemperature happens, the TEMP pin is pulled high to indicate this fault until the temperature is reduced to the normal range. There is a hysteresis to clear overtemperature fault. 22 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 9.3.10 Ideal-Diode Mode Operation Off-state FETs act like diodes by blocking current in one direction (first quadrant) and allowing current in the other direction (third quadrant) with a corresponding diode like voltage drop. FETs, though, can also conduct third-quadrant current in the on-state at a significantly lower voltage drop. Ideal-diode mode (IDM) is when an FET is controlled to block first-quadrant current by going to the off-state and conduct third-quadrant current by going to the on-state, thus achieving an ideal lower voltage drop. FET off-state third-quadrant current flow is commonly seen in power converters, both in normal and fault situations. As explained in GaN FET Operation Definitions, GaN FETs do not have an intrinsic p-n junction body diode to conduct off-state third-quadrant current. Instead, the off-state third-quadrant voltage drop for the LMG342xR030 is several times higher than a p-n junction voltage drop, which can impact efficiency in normal operation and device ruggedness in fault conditions. To mitigate efficiency degradation, the LMG3425R030 implements an operational ideal-diode mode (OP-IDM) function. Meanwhile, to improve device ruggedness in a GaN FET overtemperature fault situation, all devices in the LMG342xR030 family implement a GaN FET overtemperature-shutdown ideal-diode mode (OTSD-IDM) function as referenced in Overtemperature Shutdown. Both OP-IDM and OTSD-IDM are described in more detail below. Operational Ideal-Diode Mode (LMG3425R030) Operational ideal-diode mode (OP-IDM) is implemented in the LMG3425R030 but not in the LMG3422R030. Understand that the OP-IDM function is not a general-purpose ideal-diode mode function which allows the LMG342xR030 to autonomously operate as a diode, including as an autonomous synchronous rectifier. Furthermore, the OP-IDM function is not intended to support an ideal-diode mode transition from the on-state to the off-state in a high-voltage, hard-switched application. Exposing the LMG342xR030 to this situation is akin to operating a half-bridge power stage with negative dead time with corresponding high shoot-through current. Instead, as described below, the LMG342xR030 OP-IDM function is narrowly implemented to address a specific off-state third-quadrant current flow situation while minimizing situations where the ideal-diode mode can create a dangerous shoot-through current event. OP-IDM is intended to minimize GaN FET off-state third-quadrant losses that occur in a zero-voltage switched (ZVS) event. ZVS events are seen in applications such as synchronous rectifiers and LLC converters. The ZVS event occurs at the FET off-state to on-state transition when an inductive element discharges the FET drain voltage before the FET is turned-on. The discharge ends with the inductive element pulling the FET drain-source voltage negative and the FET conducting off-state third-quadrant current. Power supply controllers use dead-time control to set the time for the ZVS event to complete before turning on the FET. Both the ZVS time and resulting FET off-state third-quadrant current are a function of the power converter operation. Long ZVS time and low third-quadrant current occur when the inductive element is slewing the FET with low current and short ZVS time and high third-quadrant current occur when the inductive element is slewing at the FET with high current. Sophisticated controllers optimally adjust the dead time to minimize third-quadrant losses. Simpler controllers use a fixed dead time to handle the longest possible ZVS time. Thus, in a fixed dead-time application, the highest possible off-state third-quadrant losses occur for the longest possible time. OP-IDM mitigates the losses in a fixed dead-time application by automatically turning on the GaN FET as soon as third-quadrant current is detected. In this sense, OP-IDM can be described as providing a turn-on assist function with optimum dead-time control. Meanwhile, OP-IDM is not intended to be used to turn-off the GaN FET in normal operation. OP-IDM turnoff capability is only provided as a protection mechanism to guard against shoot-through current. OP-IDM works within the confines of normal LMG342xR030 switching operation as controlled by the IN pin. The key consideration for the OP-IDM operation is to ensure the turn-on assist function is only activated on the ZVS edge. For example, third-quadrant current is seen in a LMG342xR030 used as a synchronous rectifier both before the IN pin goes high to turn on the GaN FET and after the IN pin goes low to turn off the GaN FET. OP-IDM turns on the GaN FET before the IN pin goes high when OP-IDM detects third-quadrant current. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 23 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 But it would be a mistake for OP-IDM to turn the GaN FET back on right after IN has turned it off because OP-IDM detects third-quadrant current. If OP-IDM were to turn on the GaN FET in this situation, it would create a shoot-through current event when the opposite-side power switch turns on. OP-IDM avoids this shoot-through current problem on the turn-off edge by requiring the drain voltage to first go positive before looking for the ZVS event. The OP-IDM state machine is shown in Figure 9-4. Each state is assigned a state number in the upper right side of the state box. 1 FET OFF IN low FET ON OP-IDM looking for positive VDS 5 OP-IDM idle IN high Positive VDS IN high IN high 2 FET OFF OP-IDM looking for negative VDS Power Up IN high FET ON Negative VDS due to third-quadrant drain current OP-IDM looking for firstquadrant drain current 4 3 FET Off First-quadrant drain current OP-IDM locks FET off Exit OTSD Figure 9-4. Operational Ideal-Diode Mode (OP-IDM) State Machine 1. A new OP-IDM cycle begins in OP-IDM state #1 after the IN pin goes low in OP-IDM state #5. OP-IDM turns off the GaN FET in OP-IDM state #1. OP-IDM monitors the GaN FET drain voltage, looking for a positive drain voltage to know it can now start looking for a ZVS event. After a positive GaN FET drain voltage is detected, the device moves to OP-IDM state #2. 2. OP-IDM keeps the GaN FET off in OP-IDM state #2. OP-IDM continues monitoring the GaN FET drain voltage. But this time it is looking for a negative drain voltage which means third-quadrant current is flowing after a ZVS event. This is also the starting state when the device powers up or exits OTSD. After a negative GaN FET drain voltage is detected, the device moves to OP-IDM state #3. 3. OP-IDM turns on the GaN FET in OP-IDM state #3. OP-IDM monitors the drain current in this state. Ideally, the device simply stays in this state until IN goes high. The drain current is monitored to protect against an unexpected shoot-through current event. If first-quadrant drain current is detected, the device moves to OP-IDM state #4. 4. OP-IDM locks the GaN FET off in OP-IDM state #4. The GaN FET only turns back on when the IN pin goes high. 5. The device moves to OP-IDM state #5 from any other state when the IN pin goes high. The GaN FET is commanded on in OP-IDM state #5. OP-IDM is idle in this state. A new OP-IDM switching cycle begins when IN goes low moving the device into OP-IDM state #1. OP-IDM can only turn on the GaN FET once per IN cycle. If an unexpected shoot-through current is detected between OP-IDM turning on the GaN FET and the IN pin going high, OP-IDM locks the GaN FET off for the remainder of the IN cycle. Understand that the OP-IDM function turns on the GaN FET, after IN goes low, if it sees a positive drain voltage followed by a negative drain voltage. A design using the LMG3425R030 must be analyzed for any situations where this sequence of events creates a shoot-through current event. The analysis must include all power system corner cases including start-up, shutdown, no load, overload, and fault events. Note that discontinuous 24 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 mode conduction (DCM) operation can easily create an OP-IDM shoot-through current event when the ringing at the end of a DCM cycle triggers OP-IDM to turn on the GaN FET. Overtemperature-Shutdown Ideal-Diode Mode Overtemperature-shutdown ideal-diode mode (OTSD-IDM) is implemented in all devices in the LMG342xR030 family. As explained in Overtemperature Shutdown, ideal-diode mode provides the best GaN FET protection when the GaN FET is overheating. OTSD-IDM accounts for all, some, or none of the power system operating when OTSD-IDM is protecting the GaN FET. The power system may not have the capability to shut itself down, in response to the LMG342xR030 asserting the FAULT pin in a GaN OTSD event, and just continue to try to operate. Parts of the power system can stop operating due to any reason such as a controller software bug or a solder joint breaking or a device shutting off to protect itself. At the moment of power system shutdown, the power system stops providing gate drive signals but the inductive elements continue to force current flow while they discharge. The OTSD-IDM state machine is shown in Figure 9-5. Each state is assigned a state number in the upper right side of the state box. The OTSD-IDM state machine has a similar structure to the OP-IDM state machine. Similar states use the same state number. 1 FET OFF OTSD-IDM waiting for IN falling-edge blank time to expire IN falling-edge blank time expired IN falling edge FET OFF 2 IN falling edge First-quadrant drain current 3 FET ON OTSD-IDM looking for negative VDS OTSD-IDM looking for firstquadrant drain current Negative VDS due to third-quadrant drain current Enter OTSD Figure 9-5. Overtemperature-Shutdown Ideal-Diode Mode (OTSD-IDM) State Machine 1. The LMG342xR030 GaN FET always goes to state #1 if a falling edge is detected on the IN pin. OTSD-IDM turns off the GaN FET in OTSD-IDM state #1. OTSD-IDM is waiting for the IN falling edge blank time to expire. This time gives the opposite-side FET time to switch to create a positive drain voltage. After the blank time expires, the device moves to OTSD-IDM state #2. 2. For OTSD-IDM state #2, OTSD-IDM keeps the GaN FET off if it is coming from OTSD-IDM state #1 and turns the GaN FET off if it is coming from OTSD-IDM state #3. OTSD-IDM is monitoring the GaN FET drain voltage in OP-IDM state #2. It is looking for a negative drain voltage which means third-quadrant current is flowing. This is also the starting state when the device enters OTSD. After a negative GaN FET drain voltage is detected, the device moves to OTSD-IDM state #3 3. OP-IDM turns on the GaN FET in OTSD-IDM state #3. OP-IDM monitors the drain current in this state. If first-quadrant drain current is detected, the device moves to OP-IDM state #2. State #1 is used to protect against shoot-through current in a similar manner to OP-IDM state #1. The difference is that state #1 in the OTSD-IDM state machine simply waits for a fixed time period before proceeding to state #2. The fixed time period is to give the opposite-side switch time to switch and create a positive drain voltage. A fixed time is used to avoid a stuck condition for cases where a positive drain voltage is not created. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 25 LMG3422R030, LMG3425R030 SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 www.ti.com State #1 will help protect against shoot-through currents if the converter continues switching when the LMG342xR030 enters OTSD. Meanwhile, if the converter initiates switching with the LMG342xR030 already in OTSD, shoot-through current protection can be obtained by switching the OTSD device first to force it to progress though state #1. For example, the synchronous rectifier in a boost PFC can go into OTSD during initial input power application as the inrush current charges the PFC output cap. A shoot-through current event can be avoided if converter switching begins by switching the synchronous rectifier FET before switching the boost PFC FET. If there is no IN signal, the state machine only moves between states #2 and #3 as a classic ideal-diode mode state machine. This allows all the inductive elements to discharge, when the power system shuts off, with minimum discharge stress created in the GaN FET. Note that the OTSD-IDM state machine has no protection against repetitive shoot-through current events. There are degenerate cases, such as the LMG342xR030 losing its IN signal during converter operation, which can expose the OTSD-IDM to repetitive shoot-through current events. There is no good solution in this scenario. If OTSD-IDM did not allow repeated shoot-thru current events, the GaN FET would instead be exposed to excessive off-state third-quadrant losses. 9.4 Device Functional Modes The device has one mode of operation that applies when operated within the Recommended Operating Conditions. 26 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 10 Application and Implementation Note Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes, as well as validating and testing their design implementation to confirm system functionality. 10.1 Application Information The LMG342xR030 is a power IC targeting hard-switching and soft-switching applications operating up to 480V bus voltages. GaN devices offer zero reverse-recovery charge enabling high-frequency, hard-switching in applications like the totem-pole PFC. Low Qoss of GaN devices also benefits soft-switching converters, such as the LLC and phase-shifted full-bridge configurations. As half-bridge configurations are the foundation of the two mentioned applications and many others, this section describes how to use the LMG342xR030 in a half-bridge configuration. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 27 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 10.2 Typical Application CAUTION For applications where the drain slew rate is programmed for greater than a typical 100 V/ns (RRDRV < 10 kΩ or VRDRV = 5 V), the following application design modifications must be implemented to minimize the risk of LDO5V pin damage. 1. Remove C2. 2. Put a 10-Ω resistor between the U1 LDO5V pin and C10. No other components must be between the resistor and the U1 LDO5V pin. 3. Remove C12. 4. Put a 10-Ω resistor between the U2 LDO5V pin and C27. No other components must be between the resistor and the U2 LDO5V pin. ISO_12V _L R2 DNP 2.05 PGND i D1 VHV i VHV i U1 ISO_12V_H GB01SLT06-214 5V_H R1 0 LMG342x Half-Bridge GaN Daughter Card 46 53 C1 10uF D6 5V_H AGND 20k 100V/ns 70k 50V/ns U3 15 9 INGND i GND2 GND2 8 2 GND1 GND1 R7 Top_FET_PWM 11 49.9 Top_FET_FAULT C6 68pF R8 Top_FET_OC 300 R9 12 300 C24 C25 68pF 68pF 13 Top_FET_TEMP 16 5V AGND PGND 14 EN1 IND OUTD OUTC INC OUTB INB OUTA INA VCC2 C26 1uF AGND AGND TP3 EN2 42 41 25V 2.2uF DNP R3 0 SW 43 L1 SDEM20161T-4R7MS LDO5V VNEG VNEG BBSW RDRV_H SW 20.0k C7 50V R6 100pF Have R6 close to GaN FET SW 7 VNEG_H C3 C2 SW 0.22µF SW R5 SW 5V_H 10 5V 16V VDD 6 52 C5 22pF 300 IN_H 47 5 TEMP_H 51 4 FAULT_H 48 OC_H 50 3 5V_H RDRV IN TEMP FAULT OC 1 VCC1 C10 0.1uF ISO7741FDBQR SW AGND TP4 PGND HV TP5 TH1 SW NC1 VSWNET i Power Connector HVBUS TH2 TH3 NC3 SW SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE U1NC1 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 U1NC17 i VSWNET SW HVBUS U1NC16 i VHV TH4 NC4 TP6 NC2 PGND DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 HS push-pin LMG342x GND GND GND GND PAD 44 SW 45 49 54 U1NC54 55 i VSWNET VSWNET i PGND U2 12V R10 0 INGND i TSW-106-08-G-D-RA J1 1 2 Top_FET_TEMP 3 4 Top_FET_OC 5 6 Top_FET_FAULT 7 8 Top_FET_PWM 9 11 AGND 3 C14 68pF 5V AGND AGND ISO7762FQDBQRQ1 10 11 Bot_FET_FAULT 12 Bot_FET_OC 13 Bot_FET_TEMP 14 OUTA 15 5V 16 AGND TP11 GND2 GND1 INF OUTF PGND R18 7 INE OUTE OUTD IND OUTC INC OUTB INB OUTA INA VCC2 VCC1 20.0k 46 5V_L 53 VDD LDO5V OC_L 3 TEMP_L 2 INA 5V_L 42 41 25V 2.2uF PGND PGND 43 L2 SDEM20161T-4R7MS PGND Have R15 close to GaN FET FAULT_L 4 C13 5V_L C8 50V 100pF PGND 6 5 C12 0.22µF PGND R12 0 DNP R14 20.0k Q1 MGSF1N02LT1G 1 8 10.0 Bot_FET_PWM TP10 U4 9 Top_FET_FAULT 49.9 R16 20k 100V/ns 70k 50V/ns R17 DNP AGND 10 12 12V C11 10uF ISO_12V_L DNP VNEG_L 2 Bot_FET_PWM Bot_FET_FAULT Bot_FET_OC Bot_FET_TEMP R15 52 C23 22pF IN_L 47 VNEG VNEG BBSW RDRV IN TEMP_L 51 TEMP FAULT_L 48 FAULT OC_L OC 50 TP2 PGND C27 0.1uF AGND PGND AGND TP8 Top_FET_FAULT i PGND 1 U2NC1 i VSWNET 2 3 4 5 6 7 8 TP1 9 10 5016 11 12 13 14 15 16 U2NC16 TP9 Bot_FET_FAULT LMG342x SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE SOURCE GND GND GND GND PAD C15 0.022µF C16 0.022µF C17 0.022µF C18 0.022µF C19 0.1uF C20 0.1uF C21 0.1uF C38 0.1uF i VSWNET 300 1 C9 1uF DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN DRAIN 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 U2NC17 i PGND PGND 44 PGND 45 49 54 U2NC54 i PGND 55 Figure 10-1. Typical Half-Bridge Application 28 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 10.2.1 Design Requirements This design example is for a hard-switched boost converter which is representative of PFC applications. Table 10-1 shows the system parameters for this design. Table 10-1. Design Parameters DESIGN PARAMETER EXAMPLE VALUE Input voltage 200 VDC Output voltage 400 VDC Input (inductor) current 20 A Switching frequency 100 kHz 10.2.2 Detailed Design Procedure In high-voltage power converters, circuit design and PCB layout are essential for high-performance power converters. As designing a power converter is out of the scope of this document, this data sheet describes how to build well-behaved half-bridge configurations with the LMG342xR030. 10.2.2.1 Slew Rate Selection The slew rate of LMG342xR030 can be adjusted between approximately 20 V/ns and 150 V/ns by connecting a resistor, RDRV, from the RDRV pin to GND. The slew rate affects GaN device performance in terms of: • • • • Switching loss Voltage overshoot Noise coupling EMI emission Generally, high slew rates provide low switching loss, but high slew rates can also create higher voltage overshoot, noise coupling, and EMI emissions. Following the design recommendations in this data sheet helps mitigate the challenges caused by a high slew rate. The LMG342xR030 offers circuit designers the flexibility to select the proper slew rate for the best performance of their applications. 10.2.2.1.1 Start-Up and Slew Rate With Bootstrap High-Side Supply Using a bootstrap supply introduces additional constraints on the start-up of the high-side LMG342xR030. Prior to powering up, the GaN device operates in cascode mode with reduced performance. In some circuits, a proper slew rate can be required for the start-up of a bootstrap-supplied half-bridge configuration. 10.2.2.2 Signal Level-Shifting In half-bridges, high-voltage level shifters or digital isolators must be used to provide isolation for signal paths between the high-side device and control circuit. Using an isolator is optional for the low-side device. However, using and isolator equalizes the propagation delays between the high-side and low-side signal paths, and provides the ability to use different grounds for the GaN device and the controller. If an isolator is not used on the low-side device, the control ground and the power ground must be connected at the device and nowhere else on the board. For more information, see Layout Guidelines. With fast-switching devices, common ground inductance can easily cause noise issues without the use of an isolator. Choosing a digital isolator for level-shifting is important for improvement of noise immunity. As GaN device can easily create high dv/dt, > 50 V/ns, in hard-switching applications, TI highly recommends to use isolators with high common-mode transient immunity (CMTI). Isolators with low CMTI can easily generate false signals, which could cause shoot-through. Additionally, TI strongly encourages to select isolators which are not edgetriggered. In an edge-triggered isolator, a high dv/dt event can cause the isolator to flip states and cause circuit malfunction. Generally, ON/OFF keyed isolators are preferred, such as the TI ISO77xxF series, as a high CMTI event would only cause a very short false pulse, a few nanoseconds, which can be filtered out. To filter these false pulses, TI recommends a low pass filter, like 1 kΩ and 22 pF R-C filter, to be placed at the driver input. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 29 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 10.2.2.3 Buck-Boost Converter Design The buck-boost converter generates the negative voltage to turn off the direct-drive GaN device. While the buck-boost converter is controlled internally, it requires an external power inductor and output capacitor. The converter is designed to use a 4.7-µH inductor and a 2.2-µF output capacitor. As the peak current of the buck-boost is subject to two different peak current limits which are 0.4 A and 1 A for low and high frequency operation (see Internal Buck-Boost DC-DC Converter), so the inductor must have a saturation current well above the rated peak current limit. After the higher limit is established by switching at a higher frequency, the current limit does not go back to the lower level even when GaN device is then switched at a lower frequency. Therefore, select an inductor according to the higher 1-A limit if higher frequency GaN operation is anticipated. The buck-boost converter uses a peak current hysteretic control. As shown in Figure 10-2, the inductor current increases at the beginning of a switching cycle until the inductor reaches the peak current limit. The inductor current goes down to zero. The idle time between each current pulse is determined automatically by the output current, and can be reduced to zero. Therefore, the maximum output current happens when the idle time is zero, and is decided by the peak current but independent of the inductor value. A minimum inductance value of 3 µH is preferred for the buck-boost converter so that the di/dt across the inductor is not too high. This leaves enough margin for the control loop to respond. As a result, the maximum di/dt of the inductor is limited to 6 A/µs. On the other hand, large inductance also limits the transient response for stable output voltage, and it is preferred to have inductors less than 10 µH. VNEG_avg ûVNEG VNEG IDCDC,PK Smaller inductor Buck-boost inductor current Larger inductor Idle time 1/(buck-boost frequency) Figure 10-2. Buck-Boost Converter Inductor Current 30 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 10.2.3 Application Curves VDS (50 V/div) ID (2.5 A/div) VDS (50 V/div) ID (1.25 A/div) VOUT = 400V IL = 5 A RDRV = 40 k: VBUS = 400 V IL = 5 A RDRV = 40 k: Time (5 ns/div) Time (5 ns/div) D006 Figure 10-3. Turn-On Waveform in Application Example D007 Figure 10-4. Turn-Off Waveform in Application Example Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 31 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 10.3 Do's and Don'ts The successful use of GaN devices in general, and LMG342xR030 in particular, depends on proper use of the device. When using the LMG342xR030, DO: • • • • • • Read and fully understand the data sheet, including the application notes and layout recommendations. Use a four-layer board and place the return power path on an inner layer to minimize power-loop inductance. Use small, surface-mount bypass and bus capacitors to minimize parasitic inductance. Use the proper size decoupling capacitors and locate them close to the IC as described in Layout Guidelines. Use a signal isolator to supply the input signal for the low-side device. If not, ensure the signal source is connected to the signal GND plane which is tied to the power source only at the LMG342xR030 IC. Use the FAULT pin to determine power-up state and to detect overcurrent and overtemperature events and safely shut off the converter. To avoid issues in your system when using the LMG342xR030, DON'T: • • • • • 32 Use a single-layer or two-layer PCB for the LMG342xR030 as the power-loop and bypass capacitor inductances is excessive and prevent proper operation of the IC. Reduce the bypass capacitor values below the recommended values. Allow the device to experience drain transients above 600 V as they can damage the device. Allow significant third-quadrant conduction when the device is OFF or unpowered, which can cause overheating. Self-protection features cannot protect the device in this mode of operation. Ignore the FAULT pin output. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 11 Power Supply Recommendations The LMG342xR030 only requires an unregulated 12-V supply. The low-side supply can be obtained from the local controller supply. The supply of the high-side device must come from an isolated supply or a bootstrap supply. 11.1 Using an Isolated Power Supply Using an isolated power supply to power the high-side device has the advantage that it works regardless of continued power-stage switching or duty cycle. Using an isolated power supply can also power the high-side device before power-stage switching begins, eliminating the power-loss concern of switching with an unpowered LMG342xR030 (see Start-Up and Slew Rate With Bootstrap High-Side Supply for details). Finally, a properlyselected isolated supply introduces less parasitics and reduces noise coupling. The isolated supply can be obtained with a push-pull converter, a flyback converter, a FlyBuck™ converter, or an isolated power module. When using an unregulated supply, the input of LMG342xR030 must not exceed the maximum supply voltage. A 16-V TVS diode can be used to clamp the VDD voltage of LMG342xR030 for additional protection. Minimizing the inter-winding capacitance of the isolated power supply or transformer is necessary to reduce switching loss in hard-switched applications. Furthermore, capacitance across the isolated bias supply inject high currents into the signal-ground of the LMG342xR030 and can cause problematic groundbounce transients. A common-mode choke can alleviate most of these issues. 11.2 Using a Bootstrap Diode In half-bridge configuration, a floating supply is necessary for the high-side device. To obtain the best performance of LMG342xR030, Ti highly recommends Using an Isolated Power Supply. A bootstrap supply can be used with the recommendations of this section. In applications like a boost converter, the low side LMG342xR030 always start switching while high side LMG342xR030 is unpowered. If the low side is adjusted to achieve very high slew rate before the high side bias is fully settled, there can be unintentional turn-on at the high side due to parasitic coupling at high slew rate. The start-up slew rate must be slowed down to 30 V/ns by changing the resistance of RDRV pin of the low side. This slow down can be achieved by controlling the low side RDRV resistance with the high side FAULT as given in Figure 10-1. 11.2.1 Diode Selection The LMG342xR030 offers no reverse-recovery charge and very limited output charge. Hard-switching circuits using the LMG342xR030 also exhibit high voltage slew rates. A compatible bootstrap diode must not introduce high output charge and reverse-recovery charge. A silicon carbide diode, like the GB01SLT06-214, can be used to avoid reverse-recovery effects. The SiC diode has an output charge of 3 nC. Althought there is additional loss from its output charge, it does not dominate the losses of the switching stage. 11.2.2 Managing the Bootstrap Voltage In a synchronous buck or other converter where the low-side switch occasionally operates in third-quadrant, the bootstrap supply charges through a path that includes the third-quadrant voltage drop of the low-side LMG342xR030 during the dead time as shown in Figure 11-1. This third-quadrant drop can be large, which can over-charge the bootstrap supply in certain conditions. The VDD supply of LMG342xR030 must be kept below 18 V. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 33 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 VDD DRAIN VF SOURCE + ± DRAIN VDD VF SOURCE Figure 11-1. Charging Path for Bootstrap Diode As shown in Figure 11-2, the recommended bootstrap supply includes a bootstrap diode, a series resistor, and a 16-V TVS or zener diode in parallel with the VDD bypass capacitor to prevent damaging the high-side LMG342xR030. The series resistor limits the charging current at start-up and when the low-side device is operating in third-quadrant mode. This resistor must be selected to allow sufficient current to power the LMG342xR030 at the desired operating frequency. At 100-kHz operation, TI recommends a value of approximately 2 Ω . At higher frequencies, this resistor value must be reduced or the resistor omitted entirely to ensure sufficient supply current. +12 V VDD DRAIN VF SOURCE Figure 11-2. Suggested Bootstrap Regulation Circuit 34 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 12 Layout 12.1 Layout Guidelines The layout of the LMG342xR030 is critical to its performance and functionality. Because the half-bridge configuration is typically used with these GaN devices, layout recommendations are considered with this configuration. A four-layer or higher layer count board is required to reduce the parasitic inductances of the layout to achieve suitable performance. 12.1.1 Solder-Joint Reliability Large QFN packages can experience high solder-joint stress. TI recommends several best practices to ensure solder-joint reliability. First, the instructions for the NC1 and NC2 anchor pins found in Table 6-1 must be followed. Second, all the LMG342xR030 board solder pads must be non-solder-mask defined (NSMD) as shown in the land pattern example in Mechanical, Packaging, and Orderable Information. Finally, any board trace connected to an NSMD pad must be less than 2/3 the width of the pad on the pad side where it is connected. The trace must maintain this 2/3 width limit for as long as it is not covered by solder mask. After the trace is under solder mask, there are no limits on the trace dimensions. All these recommendations are followed in the Layout Example. 12.1.2 Power-Loop Inductance The power loop, comprising the two devices in the half bridge and the high-voltage bus capacitance, undergoes high di/dt during switching events. By minimizing the inductance of this loop, ringing and electro-magnetic interference (EMI) can be reduced, as well as reducing voltage stress on the devices. Place the power devices as close as possible to minimize the power-loop inductance. The decoupling capacitors are positioned in line with the two devices. They can be placed close to either device. In Layout Examples, the decoupling capacitors are placed on the same layer as the devices. The return path (PGND in this case) is located on second layer in close proximity to the top layer. By using inner layer and not bottom layer, the vertical dimension of the loop is reduced, thus minimizing inductance. A large number of vias near both the device terminal and bus capacitance carries the high-frequency switching current to inner layer while minimizing impedance. 12.1.3 Signal-Ground Connection The LMG342xR030's SOURCE pin is internally connected to GND pins of the power IC, the signal-ground reference. Local signal-ground planes must be connected to GND pins with low impedance star connection. In addition, the return path for the passives associated to the driver (for example, bypass capacitance) must be connected to the GND pins. In Layout Example, local signal-ground planes are located on second layer to act as the return path for the local circuitry. The local signal-ground planes are not connected to the high-current SOURCE pins except the star connection at GND pins. 12.1.4 Bypass Capacitors The gate drive loop impedance must be minimized to obtain good performance. Although the gate driver is integrated on package, the bypass capacitance for the driver is placed externally. As the GaN device is turned off to a negative voltage, the impedance of the path to the external VNEG capacitor is included in the gate drive loop. The VNEG capacitor must be placed close to VNEG and GND pins. The VDD pin bypass capacitors, C1 and C11, must also be placed close to the VDD pin with low impedance connections. 12.1.5 Switch-Node Capacitance GaN devices have very low output capacitance and switch quickly with a high dv/dt, yielding very low switching losses. To preserve this low switching losses, additional capacitance added to the output node must be minimized. The PCB capacitance at the switch node can be minimized by following these guidelines: • • • Minimize overlap between the switch-node plane and other power and ground planes. Make the GND return path under the high-side device thinner while still maintaining a low-inductance path. Choose high-side isolator ICs and bootstrap diodes with low capacitance. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 35 LMG3422R030, LMG3425R030 SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 • • • • www.ti.com Place the power inductor as close to the GaN device as possible. Power inductors must be constructed with a single-layer winding to minimize intra-winding capacitance. If a single-layer inductor is not possible, consider placing a small inductor between the primary inductor and the GaN device to effectively shield the GaN device from the additional capacitance. If a back-side heat-sink is used, use the least amount of area of the switch-node copper coverage on the bottom copper layer to improve the thermal dissipation. 12.1.6 Signal Integrity The control signals to the LMG342xR030 must be protected from the high dv/dt caused by fast switching. Coupling between the control signals and the drain can cause circuit instability and potential destruction. Route the control signals (IN, FAULT and OC) over a ground plane placed on an adjacent layer. In Layout Example, for example, all the signals are routed on layers close to the local signal ground plane. Capacitive coupling between the traces for the high-side device and the static planes, such as PGND and HVBUS, could cause common mode current and ground bounce. The coupling can be mitigated by reducing overlap between the high-side traces and the static planes. For the high-side level shifter, ensure no copper from either the input or output side extends beneath the isolator or the CMTI of the device can be compromised. 12.1.7 High-Voltage Spacing Circuits using the LMG342xR030 involve high voltage, potentially up to 600 V. When laying out circuits using the LMG342xR030, understand the creepage and clearance requirements for the application and how they apply to the GaN device. Functional (or working) isolation is required between the source and drain of each transistor, and between the high-voltage power supply and ground. Functional isolation or perhaps stronger isolation (such as reinforced isolation) can be required between the input circuitry to the LMG342xR030 and the power controller. Choose signal isolators and PCB spacing (creepage and clearance) distances which meet your isolation requirements. If a heat sink is used to manage thermal dissipation of the LMG342xR030, ensure necessary electrical isolation and mechanical spacing is maintained between the heat sink and the PCB. 12.1.8 Thermal Recommendations The LMG342xR030 is a lateral device grown on a Si substrate. The thermal pad is connected to the source of device. The LMG342xR030 can be used in applications with significant power dissipation, for example, hard-switched power converters. In these converters, cooling using just the PCB can not be sufficient to keep the part at a reasonable temperature. To improve the thermal dissipation of the part, TI recommends a heat sink is connected to the back of the PCB to extract additional heat. Using power planes and numerous thermal vias, the heat dissipated in the LMG342xR030 can be spread out in the PCB and effectively passed to the other side of the PCB. A heat sink can be applied to bare areas on the back of the PCB using an thermal interface material (TIM). The solder mask from the back of the board underneath the heat sink can be removed for more effective heat removal. Refer to the High Voltage Half Bridge Design Guide for LMG3410 Smart GaN FET application note for more recommendations and performance data on thermal layouts. 36 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 www.ti.com LMG3422R030, LMG3425R030 SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 12.2 Layout Examples Correct layout of the LMG342xR030 and its surrounding components is essential for correct operation. The layouts shown here reflect the GaN device schematic in Figure 10-1 . These layouts are shown to produce good results and is intended as a guideline. However, it can be possible to obtain acceptable performance with alternate layout schemes. Additionally, please refer to the land pattern example in Mechanical, Packaging, and Orderable Information for the latest recommended PCB footprint of the device. The the top-layer layout and mid-layer layout are shown. The layouts are zoomed in to the LMG342xR030 U1 and U2 component placements. The mid-layer layout includes the outlines of the top level components to assist the reader in lining up the top-layer and mid-layer layouts. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 37 LMG3422R030, LMG3425R030 SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 www.ti.com Figure 12-1. Half-Bridge Top-Layer Layout Figure 12-2. Half-Bridge Mid-Layer Layout 38 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 13 Device and Documentation Support 13.1 Documentation Support 13.1.1 Related Documentation • • Texas Instruments, High Voltage Half Bridge Design Guide for LMG3410 Smart GaN FET application note. Texas Instruments, A New Approach to Validate GaN FET Reliability to Power-line Surges Under Useconditions. 13.2 Receiving Notification of Documentation Updates To receive notification of documentation updates, navigate to the device product folder on ti.com. Click on Subscribe to updates to register and receive a weekly digest of any product information that has changed. For change details, review the revision history included in any revised document. 13.3 Support Resources TI E2E™ support forums are an engineer's go-to source for fast, verified answers and design help — straight from the experts. Search existing answers or ask your own question to get the quick design help you need. Linked content is provided "AS IS" by the respective contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of Use. 13.4 Trademarks FlyBuck™ is a trademark of Texas Instruments. TI E2E™ is a trademark of Texas Instruments. All trademarks are the property of their respective owners. 13.5 Electrostatic Discharge Caution This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. 13.6 Export Control Notice Recipient agrees to not knowingly export or re-export, directly or indirectly, any product or technical data (as defined by the U.S., EU, and other Export Administration Regulations) including software, or any controlled product restricted by other applicable national regulations, received from disclosing party under nondisclosure obligations (if any), or any direct product of such technology, to any destination to which such export or re-export is restricted or prohibited by U.S. or other applicable laws, without obtaining prior authorization from U.S. Department of Commerce and other competent Government authorities to the extent required by those laws. 13.7 Glossary TI Glossary This glossary lists and explains terms, acronyms, and definitions. 14 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 39 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 PACKAGE OUTLINE RQZ0054A-C01 VQFN - 1 mm max height SCALE 1.100 PLASTIC QUAD FLATPACK - NO LEAD 12.1 11.9 B A PIN 1 ID INDEX AREA 12.1 11.9 1.0 0.8 C SEATING PLANE 0.08 C 0.05 0.00 7.8 0.1 (2.75) PKG 54X (2.65) 4X 0.975 0.65 0.55 16 28 4X 10.2 0.1 2X 8.45 26X 0.65 PIN 1 ID (45 X 0.3) 46X 43 1 4X (0.2) 1.1 1.0 0.1 0.05 C A B C 55 PKG SYMM 4X (0.25) (0.1) TYP 27 17 54 44 2X 1.285 4X 16X 0.65 2X 5.2 0.45 0.35 0.1 0.05 0.65 0.55 0.1 0.05 C A B C C A B C 4X 0.75 4228230/A 11/2021 NOTES: 1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance. www.ti.com 40 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 EXAMPLE BOARD LAYOUT RQZ0054A-C01 VQFN - 1 mm max height PLASTIC QUAD FLATPACK - NO LEAD (7.8) (4.906) (2.65) (4.449) TYP 54X (0.8) (0.914) TYP 54 4X (1.05) 44 (0.508) TYP 43 1 ( 0.2) TYP VIA (4.572) (4.826) 46X (0.4) (10.2) 55 PKG SYMM (11.6) (R0.05) TYP 42X (0.65) 4X (0.975) 28 16 27 17 4X (0.75) (1.25) 2X (2.035) PAD 4X (0.6) PKG (11.6) LAND PATTERN EXAMPLE 0.07 MAX ALL AROUND EXPOSED METAL SHOWN SCALE:8X METAL EDGE EXPOSED METAL SOLDER MASK OPENING NON SOLDER MASK DEFINED SOLDER MASK DETAIL 4228230/A 11/2021 NOTES: (continued) 4. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature number SLUA271 (www.ti.com/lit/slua271). 5. All pads must be NSMD for mechanical performance, refer to the device datasheet for trace connection recommendations to the pads. 6. Filling the thermal pad with thermal vias is recommended for thermal performance, refer to the device datasheet. Vias must be filled and planarized. www.ti.com Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 41 LMG3422R030, LMG3425R030 www.ti.com SNOSDA7D – SEPTEMBER 2020 – REVISED MARCH 2022 EXAMPLE STENCIL DESIGN RQZ0054A-C01 VQFN - 1 mm max height PLASTIC QUAD FLATPACK - NO LEAD (4.225) 50X (0.8) 4X (0.76) (1.19) TYP 54 44 43 1 4X (1) 48X ( 0.99) (1.19) TYP (4.165) 46X (0.4) 55 PKG SYMM (11.6) (R0.05) TYP 42X (0.65) 4X (0.975) 28 16 17 4X (0.75) PKG 27 4X (0.6) 2X (2.035) (11.6) SOLDER PASTE EXAMPLE BASED ON 0.125 mm THICK STENCIL PRINTED SOLDER COVERAGE BY AREA UNDER PACKAGE PADS 1, 16, 28 & 43: 90% PAD 55: 60% SCALE:8X 4228230/A 11/2021 NOTES: (continued) 7. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate design recommendations. www.ti.com 42 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated Product Folder Links: LMG3422R030 LMG3425R030 PACKAGE OPTION ADDENDUM www.ti.com 23-Jun-2023 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) Samples (4/5) (6) LMG3422R030RQZR ACTIVE VQFN RQZ 54 2000 RoHS-Exempt & Green NIPDAU Level-3-260C-168 HR -40 to 150 LMG3422 R030 Samples LMG3422R030RQZT ACTIVE VQFN RQZ 54 250 RoHS-Exempt & Green NIPDAU Level-3-260C-168 HR -40 to 150 LMG3422 R030 Samples LMG3425R030RQZR ACTIVE VQFN RQZ 54 2000 RoHS-Exempt & Green NIPDAU Level-3-260C-168 HR -40 to 150 LMG3425 R030 Samples LMG3425R030RQZT ACTIVE VQFN RQZ 54 250 RoHS-Exempt & Green NIPDAU Level-3-260C-168 HR -40 to 150 LMG3425 R030 Samples (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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