LM74610QDGKTQ1

Sample & Buy Product Folder Technical Documents Support & Community Tools & Software LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 LM74610-Q1 Zero IQ Reverse Polarity Protection Smart Diode Controller 1 Features 2 Applications • • • • • • • 1 • • • • • • • • • • • • Qualified for Automotive Applications AEC-Q100 Qualified With the Following Results: – Exceeds HBM ESD Classification Level 2 – Device CDM ESD Classification Level C4B Maximum reverse voltage of 45 V No Positive Voltage limitation to Anode Terminal Charge Pump Gate Driver for External N-Channel MOSFET Lower Power Dissipation than Schottky Diode/PFET Solutions Low Reverse Leakage Current Zero IQ Fast 2-µs Response to Reverse Polarity -40°C to +125°C Operating Ambient Temperature Can be Used in OR-ing Applications Meets CISPR25 EMI Specification Meets Automotive ISO7637 Transient Requirements with a Suitable TVS Diode No Peak Current Limit ADAS Infotainment Systems Power Tools (Industrial) Transmission Control Unit (TCU) Battery OR-ing Applications 3 Description The LM74610-Q1 is a controller device that can be used with an N-Channel MOSFET in a reverse polarity protection circuitry. It is designed to drive an external MOSFET to emulate an ideal diode rectifier when connected in series with a power source. A unique advantage of this scheme is that it is not referenced to ground and thus has Zero Iq. The LM74610-Q1 controller provides a gate drive for an external N-Channel MOSFET and a fast response internal comparator to discharge the MOSFET Gate in the event of reverse polarity. This fast pull-down feature limits the amount and duration of reverse current flow if opposite polarity is sensed. The device design also meets CISPR25 Class 5 EMI specifications and automotive ISO7637 transient requirements with a suitable TVS diode. Device Information(1) PART NUMBER LM74610-Q1 PACKAGE BODY SIZE (NOM) VSSOP (8) 3.00 mm x 5.00 mm (1) For all available packages, see the orderable addendum at the end of the datasheet. Smart Diode Configuration Application Diagram Q1 Source VIN S Drain Voltage Regulator VOUT D TVS+ Vout C Vbatt LM74610-Q1 TVS- G Vcap Gate Drive Anode Gate Pull Down LM74610-Q1 VCAPH Cathode VCAPL Vcap 1 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. LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 www.ti.com Table of Contents 1 2 3 4 5 6 7 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Pin Configuration and Functions ......................... Specifications......................................................... 1 1 1 2 3 4 6.1 6.2 6.3 6.4 6.5 6.6 4 4 4 4 5 6 Absolute Maximum Ratings ...................................... ESD Ratings.............................................................. Recommended Operating Conditions....................... Thermal Information .................................................. Electrical Characteristics........................................... Typical Characteristics .............................................. Detailed Description .............................................. 8 7.1 Overview ................................................................... 8 7.2 Functional Block Diagram ......................................... 8 7.3 Feature Description .................................................. 8 7.4 Device Functional Modes........................................ 11 8 Application and Implementation ........................ 13 8.1 Application Information............................................ 13 8.2 Typical Application ................................................. 13 9 Power Supply Recommendations...................... 21 10 Layout................................................................... 22 10.1 Layout Guidelines ................................................. 22 10.2 Layout Example .................................................... 23 11 Device and Documentation Support ................. 24 11.1 11.2 11.3 11.4 Community Resources.......................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 24 24 24 24 12 Mechanical, Packaging, and Orderable Information ........................................................... 24 4 Revision History Changes from Revision A (October 2015) to Revision B Page • Added No Peak Current Limit to Description ......................................................................................................................... 1 • Added Simplified Application Diagram to page 1 .................................................................................................................. 1 • Added Voltage Across Body Diode vs Vcap Charging Current to Typical Characteristics ................................................... 7 • Updated Gate Drive Pin ....................................................................................................................................................... 10 • Corrected Startup Relative to VIN figure ............................................................................................................................. 15 • Corrected typo of revere to reverse in Response to Reverse Polarity ................................................................................ 15 • Updated Layout Guidelines ................................................................................................................................................. 22 Changes from Original (July 2015) to Revision A • 2 Page Product Preview to Production Data Release ....................................................................................................................... 1 Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 LM74610-Q1 www.ti.com SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 5 Pin Configuration and Functions DGK Package 8-Pin VSSOP Top View VCAPL 1 8 Cathode Gate Pull Down 2 7 VCAPH NC 3 6 Gate Drive Anode 4 5 NC LM74610-Q1 Pin Functions PIN NO. DESCRIPTION NAME 1 VcapL 2 Gate Pull Down 3 NC 4 Anode 5 NC 6 Gate Drive 7 VcapH 8 Cathode Charge Pump Output, connect to an external charge pump capacitor Connect to the gate of the external MOSFET for fast turn OFF in the case of reverse polarity No connect. Leave floating or connect to Anode pin Anode of the diode, connect to source of the external MOSFET No connect. Leave floating or connect to gate drive pin Gate Drive output, Connect to the Gate of the external MOSFET Charge Pump Output, connect to an external charge pump capacitor Cathode of the diode, connect to Drain of the external MOSFET Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 3 LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 www.ti.com 6 Specifications 6.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) Cathode to Anode (for a 2-ms time duration) Cathode to Anode (continuous) (1) (2) (3) , (3) MIN MAX UNIT -3 45 V -3 42 V VcapH to VcapL -0.3 7 V Anode to VcapL -0.3 3 V Gate drive, gate pull down to VcapL -0.3 7 V Ambient temperature, TA-MAX (4) -40 125 °C Case temperature, TC-MAX -40 125 °C Storage temperature, Tstg -65 150 °C (1) (2) (3) (4) Stresses beyond those listed under Absolute Maximum Ratings 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 Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. 42V continuous (and 45V transients for 2ms) absmax condition from Cathode to Anode. Suitable to use with TVS SMBJ28A and SMBJ14A at the anode. Reverse voltage rating only. There is no positive voltage limitation for the LM74610-Q1 Anode terminal. The device performance is ensured over this Ambient Temperature range as long the Case Temperature does not exceed the MAX value. 6.2 ESD Ratings VALUE V(ESD) (1) (2) Electrostatic discharge (1) Human body model (HBM), per AEC Q100-002 (2) ±4000 Charged-device model (CDM), per AEC Q100-011 ±750 UNIT V AEC Q100-002 indicates that HBM stressing shall be in accordance with the ANSI/ESDA/JEDEC JS-001 specification. The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. 6.3 Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted) MIN NOM MAX Cathode To Anode Ambient temperature, TA-MAX -40 Case temperature, TC-MAX UNIT 42 V 125 °C 125 °C 6.4 Thermal Information LM74610-Q1 THERMAL METRIC (1) VSSOP (DGK) UNIT 8 PINS RθJA 181 °C/W RθJC(top) Junction-to-case (top) thermal resistance 73 °C/W RθJB Junction-to-board thermal resistance 102 °C/W ψJT Junction-to-top characterization parameter 11 °C/W ψJB Junction-to-board characterization parameter 100 °C/W (1) 4 Junction-to-ambient thermal resistance For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953. Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 LM74610-Q1 www.ti.com SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 6.5 Electrical Characteristics TA= 25°C unless otherwise noted. Minimum and maximum limits are specified through test, design, validation or statistical correlation. Typical values represent the most likely parametric norm at TA= 25°C and are provided for reference purpose only. VAnode-Cathode= 0.55 V for all tests. (1) PARAMETER TEST CONDITIONS MIN TYP MAX VAnode to Cathode Vcap Threshold Charge pump capacitor drive thresholds Vcap Upper Threshold 6.3 Vcap Lower Threshold 5.15 V IGate up Gate drive pull up current VGate to Anode = 2 V 8.9 9.4 µA IGate Gate drive pull down current during forward voltage VGate to Anode = 4 V 6.35 6.8 µA down IGate pull down Gate drive pull down current when reverse voltage is sensed VGate Pull Down = VAnode + 2 V 160 mA ICharge Current Charging current for the charge pump capacitor VAnode to Cathode = 0.55 V 46 µA VCAP current consumption to power the controller when MOSFET is ON 0.95 µA IDischarge Current Vcap = 6.6 V TRecovery Time to shut off MOSFET when VAnode to Cathode = -20 mV voltage is reversed (Equivalent to Cgate = 4 nF diode reverse recovery time) D Duty cycle ILKG Reverse leakage current Iq Quiescent current to GND IAnode (1) V 40 2.2 Iload = 3 A, TA = 25°C 98% Iload = 3 A, TA = 125°C 92% V 5 (2) µs 110 (2) µA VAnode to Cathode = -13.5 V 60 0 µA Current into Anode pin when VAnode Cathode = 0.3V. 30 µA Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the table of Electrical Characteristics. Limit applies over the full Operating Temperature Range TA = -40°C to +125°C. VANODE ± VCATHODE (2) Current into Anode pin External MOSFET VGS = 0V 0.48 UNIT Minimum startup voltage across external MOSFET's body diode 30 mV 0 mV -20 mV VANODE > VCATHODE VCATHODE > VANODE tTRECOVERYt VGATE ± VANODE VGATE 0V Figure 1. Gate Shut Down Timing in the Event of Reverse Polarity Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 5 LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 www.ti.com 6.6 Typical Characteristics 300 0.465 Anode to Cathode Voltage (V) V_Reverse = 13.5 V V_Reverse = 37 V Leakage Current (PA) 250 200 150 100 50 -40 -20 0 20 40 60 80 Temperature (qC) 100 120 0.46 0.455 0.45 0.445 0.44 0.435 -40 140 Figure 2. Reverse Leakage at Negative Voltages 0 20 40 60 80 Temperature (qC) 100 120 140 D002 Figure 3. Anode to Cathode Startup Voltage 3.25 Vcap High and Low Voltage (V) 6.5 3 Trecovery (µs) -20 D001 2.75 2.5 2.25 2 -40 -20 0 20 40 60 80 Temperature (°C) 100 120 VCAP H VCAP L 6.25 6 5.75 5.5 5.25 5 -40 140 -20 0 20 D009 Figure 4. Reverse Recovery Time (TRecovery) 40 60 80 Temperature (qC) 100 120 140 D003 Figure 5. VcapH and VcapL Voltage Threshold 100 100 90 80 70 Duty Cycle (%) Duty Cycle (%) 80 60 50 40 30 -40qC 25qC 85qC 125qC 20 10 40 20 -40qC 25qC 85qC 125qC 0 0 -20 0 0.1 0.2 0.3 0.4 0.5 0.6 Current (A) 0.7 0.8 0.9 1 0 1 D005 Figure 6. Duty Cycle of the Output Voltage at Startup 6 60 2 3 4 5 6 Current (A) 7 8 9 10 D004 Figure 7. Duty Cycle of the Output Voltage Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 LM74610-Q1 www.ti.com SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 Typical Characteristics (continued) 175 ICharge Current 150 125 100 75 50 25 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 VAnode to Cathode 1 1.05 D010 Figure 8. Voltage Across Body Diode vs Vcap Charging Current Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 7 LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 www.ti.com 7 Detailed Description 7.1 Overview Most systems in automotive or industrial applications require fast response reverse polarity protection at the input stage. Schottky diodes or P-Channel MOSFETs are typically used in most power systems to protect the load in the case of negative polarity. The main disadvantage of using diodes is voltage drop during forward conduction, which reduces the available voltage and increases the associated power losses. PFET solutions are inefficient for handling high load current at low input voltage. The LM74610-Q1 is a zero Iq controller that is combined with an external N-channel MOSFET to replace a diode or PFET reverse polarity solution in power systems. The voltage across the MOSFET source and drain is constantly monitored by the LM74610-Q1 ANODE and CATHODE pins. An internal charge pump is used to provide the GATE drive for the external MOSFET. . This stored energy is used to drive the gate of MOSFET. The voltage drop depends on the RDSON of a particular MOSFET in use, which is significantly smaller than a PFET. The LM74610-Q1 has no ground reference which makes it identical to a diode. 7.2 Functional Block Diagram Input S Output D G ANODE GATE DRIVE GATE PULL DOWN CATHODE 11.5 V VCAPL LOGIC VCAPH Charge Pump Reverse Batt Shut Off 7.3 Feature Description 7.3.1 During T0 When power is initially applied, the load current (ID) will flow through the body diode of the MOSFET and produce a voltage drop (Vf) during T0 in Figure 9. This forward voltage drop (Vf) across the body diode of the MOSFET is used to charge up the charge pump capacitor Vcap. During this time, the charge pump capacitor Vcap is charged to a higher threshold of 6.3V (typical). 8 Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 LM74610-Q1 www.ti.com SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 Feature Description (continued) VOUT Body Diode Voltage Drop T0 tT1t FET is ON VGS FET is OFF 0V Figure 9. Output Voltage and VGSOperation at 1A Output Current 7.3.2 During T1 Once the voltage on the capacitor reaches the higher voltage level of 6.3V (typical), the charge pump is disabled and the MOSFET turns ON. The energy stored in the capacitor is used to provide the gate drive for the MOSFET (T1 in Figure 9). When the MOSFET is ON, it provides a low resistive path for the drain current to flow and minimizes the power dissipation associated with forward conduction. The power losses during the MOSFET ON state depend primarily on the RDSON of the selected MOSFET and load current. At the time when the capacitor voltage reaches its lower threshold VcapL 5.15V (typical), the MOSFET gate turns OFF. The drain current ID will then begin to flow through the body diode of the MOSFET, causing the MOSFET body diode voltage drop to appear across Anode and Cathode pins. The charge pump circuitry is re-activated and begins charging the charge pump capacitor. The LM74610-Q1 operation keeps the MOSFET ON at approximately 98% duty cycle (typical) regardless of the external charge pump capacitor value. This is the key factor to minimizing the power losses. The forward voltage drop during this time is determined by the RDSON of the MOSFET. 7.3.3 Pin Operation 7.3.3.1 Anode and Cathode Pins The LM74610-Q1 Anode and Cathode pins are connected to the source and drain of the external MOSFET. The current into the Anode pin is 30 µA (typical). When power is initially applied, the load current flows through the body diode of the external MOSFET, the voltage across Anode and Cathode pins is equal to the forward diode drop (Vf). The minimum value of Vf required to enable the charge pump circuitry is 0.48V. Once the MOSFET is turned ON, the Anode and Cathode pins constantly sense the voltage difference across the MOSFET to determine the magnitude and polarity of the voltage across it. When the MOSFET is on, the voltage difference across Anode and Cathode pins depends on the RDSON and load current. If voltage difference across source and drain of the external MOSFET becomes negative, this is sensed as a fault condition by Anode and Cathode pins and gate is turned off by Gate Pull Down pin as shown in Figure 1. The reverse voltage threshold across Anode and Cathode to detect the fault condition is -20 mV. The consistent sensing of voltage polarity across the MOSFET enables the LM74610-Q1 to provide a fast response to the power source failure and limit the amount and duration of the reverse current flow. 7.3.3.2 VcapH and VcapL Pins VcapH and VcapL are high and low voltage thresholds respectively that the LM74610-Q1 uses to detect when to turn the charge pump circuitry ON and OFF. The capacitor charging and discharging time can be correlated to the duty cycle of the MOSFET gate. Figure 10 shows the voltage behavior across the Vcap. During the time period T0, the capacitor is storing energy from the charge pump. The MOSFET is turned off and current flow is only through the body diode during this time period. The conduction though body diode of the MOSFET is for a Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 9 LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 www.ti.com Feature Description (continued) very small period of time (2% typical) which rules out the chances of overheating the MOSFET, regardless of the output current. Once the capacitor voltage reaches its high threshold, the MOSFET is turned ON and charge pump circuity is deactivated until the Vcap reaches its lower voltage threshold again (T1). The voltage difference between Vcap high and low threshold is typically 1.15V. The LM74610-Q1 charge pump has 46µA charging capability with 5-8MHz frequency. VCAPH 1.1 V VCAPL VOUT Body Diode Voltage Drop T0 tT1t Figure 10. Vcap Charging and Discarding by the Charge Pump The Vcap current consumption is 1 µA (typical) to drive the gate. The MOSFET OFF time (T0) and ON time (T1) can be calculated using the following expression dV 'T C dI (1) Where: • C = Vcap Capacitance • dV = 1.15V • dI = 46 µA for charging • dI = 0.95 µA for discharging Note: Temperature dependence of these parameters – The duty cycle is dependent on temperature since the capacitance variation over temperature has a direct correlation to the MOSFET OFF and ON periods and the frequency. If the capacitor varies 20% the periods and the frequency will also vary by 20% so it is recommended to use a quality X7R/COG cap and not to place the cap in close proximity to high temperature devices. The variation of the capacitor does not have a thermal impact in the application as the duty cycle does not change. 7.3.3.3 Gate Drive Pin When the charge pump capacitor is charged to the high voltage level of 6.3 V (typical), the Gate Drive pin provides a 6.8 µA (typical) of drive current. When the charge pump capacitor reaches its lower voltage threshold of 5.15 V (typical), Gate is pulled down to the Anode voltage (Vin). During normal operation, the gate turns ON and OFF with a slow 2msec slew rate in order to avoid switching noise and EMI issues. To protect the gate of the MOSFET, a built-in internal 11.5V Zener clamp the maximum gate to source voltage (VGS(MAX)). 7.3.3.4 Gate Pull Down Pin The Gate Pull Down pin is connected to the Gate Drive pin in a typical application circuit. When the controller detects negative polarity, possibly due to failure of the input supply or voltage ripple, the Pull-Down quickly discharges the MOSFET gate through a discharge transistor. The Gate Pull Down pin can discharge the MOSFET gate capacitance with 160-mA pull down current to speed up the MOSFET turn OFF time. This fast pull down reacts regardless of the Vcap charge level. If the input supply abruptly fails, as would happen if the supply gets shorted to ground, a reverse current will temporarily flow through the MOSFET. This reverse current can be due to parallel connected supplies and load capacitance and is dependent upon the RDSON of the MOSFET. 10 Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 LM74610-Q1 www.ti.com SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 Feature Description (continued) When the negative voltage across the Anode and Cathode pins reaches -20mV (typical), the LM74610-Q1 immediately reacts and discharges the MOSFET gate capacitance as shown in Figure 11 . A MOSFET with 5nF of effective gate capacitance can be turned off by the LM74610-Q1 within 2µs (typical). The fast turnoff time minimizes the reverse current flow from MOSFET drain by opening the circuit. The reverse leakage current does not exceed 110µA for a constant 13.5V reverse voltage across Anode and Cathode pins. The reverse leakage current for a Schottky diode is 15mA under the same voltage and temperature conditions. Figure 11. Gate Pull Down in the Event of Reverse Polarity 7.4 Device Functional Modes The LM74610-Q1 operates in two modes: • Body Diode Conduction Mode The LM74610-Q1 solution works like a conventional diode during this time with higher forward voltage drop. The power dissipation during this time can be given as: PDissipation VForward Drop u IDrain Current (2) However, the current only flows through the body diode while the MOSFET gate is being charged to VGS(TH). This conduction is only for 2% duty cycle, therefore it does not cause any thermal issues. Body Diode ON Time • C u (VcapH VcapL) ICharge Current (3) The MOSFET Conduction Mode The MOSFET is turned on during this time and current flow is only through the MOSFET. The forward voltage drop and power losses are limited by the RDSON of the specific MOSFET used in the solution. The LM74610Q1 solution output is comprised of the MOSFET conduction mode for 98% of its duty cycle. This time period is given by the following expression: C u (VcapH VcapL) MOSFET ON Time IDischarge Current (4) Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 11 LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 www.ti.com Device Functional Modes (continued) 7.4.1 Duty Cycle Calculation The LM74610-Q1 has an operating duty cycle of 98% at 25 ̊C and >90% at 125 ̊C. The duty cycle doesn’t depend on the Vcap capacitance value. However, the variation in capacitance value over temperature has direct correlation to the switching frequency between the MOSFET and body diode. If the capacitance value decreases, the charging and discharging time will also decrease, causing more frequent switching between body diode and the MOSFET condition. The following expression can be used to calculate the duty cycle of the LM74610-Q1: Duty Cycle (%) 12 (MOSFET ON Time) u 100 (MOSFET ON Time Body Diode ON Time) Submit Documentation Feedback (5) Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 LM74610-Q1 www.ti.com SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 8 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. Customers should validate and test their design implementation to confirm system functionality. 8.1 Application Information The LM74610-Q1 is used with N-Channel MOSFET controller in a typical reverse polarity protection application. This device is connected to the N-Channel MOSFET as shown in Figure 12 . The schematic for the typical application is shown in Figure 13 where the LM74610-Q1 is used in series with a battery to drive the MOSFET Q1. The TVS+ and TVS- are not required for the LM74610-Q1. However, they are typically used to clamp the positive and negative voltage surges respectively. The output capacitor Cout is recommended to protect the immediate output voltage collapse as a result of line disturbance. 8.2 Typical Application Anode Cathode TVS+ Voltage Regulator Vout Cout Vbatt LM74610-Q1 TVS- Vcap Figure 12. Typical System Application Q1 ANODE CATHODE 2.2 µF TVS+ VCAP VBatt Cout 1 2 Cin 100 pf 3 TVS- 4 VCAPL CATHODE 8 Vout Voltage Regulator GATE PULL DOWN NC VCAPH GATE DRIVE ANODE NC 7 6 5 LM74610QDGKRQ1 GND Figure 13. Typical Application Schematic Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 13 LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 www.ti.com Typical Application (continued) 8.2.1 Design Requirements For this design example, use the parameters listed in Table 1 as the input parameters Table 1. Design Parameters DESIGN PARAMETER EXAMPLE VALUE Input voltage range Max VDS of the MOSFET Output Voltage Max VDS of the MOSFET Maximum Negative Voltage -45V Output Current Range Maximum drain current Output Capacitance 47µF Transient Response, 3A Load Step ΔVo = ± 5% 8.2.2 Detailed Design Procedure To begin the design process, determine the following: 8.2.2.1 Design Considerations • Input voltage range • Output current range • Body Diode forward voltage drop for the selected MOSFET • MOSFET Gate threshold voltage 8.2.2.2 Startup Voltage The LM74610-Q1 will not initiate the charge pump operation if a closed loop system is in standby mode or the drain current is smaller than 1mA (typical). This is due to a minimum body diode voltage requirement of the LM74610-Q1 controller. If the drain current is too small to produce a minimum voltage drop of 0.48V at 25 ͦC, the charge pump circuitry will remain off and the MOSFET will act just like a diode. It is very important to know the body diode voltage parameter of a MOSFET before implementing it into the Smart Diode solution. Some Nchannels MOSFETs have very low body diode voltage at higher temperature. This makes their drain current requirement higher to achieve 0.48V across the body diode in order to initiate the LM74610-Q1 controller at higher temperatures. 8.2.2.3 Capacitor Selection A ceramic capacitor should be placed between VcapL and VcapH. The capacitor acts as a holding tank to power up the control circuitry when the MOSFET is on. When the MOSFET is off, this capacitor is charged up to higher voltage threshold of ~6.3 V. Once this voltage is reached, the Gate Drive of LM74610-Q1 will provide drive for the external MOSFET. When the MOSFET is ON, the voltage across its body diode is collapsed because the forward conduction is through the MOSFET. During this time, the capacitor acts as a supply for the Gate Drive to keep the MOSFET ON. The capacitor voltage will gradually decay when the MOSFET is ON. Once the capacitor voltage reaches a lower voltage threshold of 5.15V, the MOSFET is turned off and the capacitor gets recharged again for the next cycle. A capacitor value of 220nF to 4.7uF with X7R/COG characteristic and 16V rating or higher is recommended for this application. A higher value capacitor sets longer MOSFET ON time and OFF time; however, the duty cycle remains at ~98% for MOSFET ON time irrespective of capacitor value. If the Vcap value is 2.2µF, the MOSFET ON time and OFF time can be calculated using Equation 1 : MOSFET ON Time = (2.2 µF × 1.15 V)/0.95 µA = 2.66 seconds Body Diode ON Time = (2.2 µF × 1.15 V)/46 µA = 55 miliseconds (6) (7) The duty cycle can be calculated using Equation 5 : Duty Cycle % = 2.66 sec / (2.66 sec + 0.055 sec) = 98% 14 Submit Documentation Feedback (8) Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 LM74610-Q1 www.ti.com SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 8.2.2.4 MOSFET Selection The LM74610-Q1 can provide up to 5V of gate to source voltage (VGS). The important MOSFET electrical parameters are the maximum continuous Drain current ID, the maximum drain-to-source voltage VDS(MAX), and the drain-to-source On resistance RDSON. The maximum continuous drain current, ID, rating must exceed the maximum continuous load current. The rating for the maximum current through the body diode, IS, is typically rated the same as, or slightly higher than the drain current, but body diode current only flows for a small period when the charge pump capacitor is being charged. The voltage across the MOSFET's body diode must be higher than 0.48 V at low current. The body diode voltage for a MOFET typically decreases as the ambient temperature increases. This will increase the source current requirement to achieve the minimum body diode drain-to-source voltage for the charge pump to initiate. The maximum drain-to-source voltage, VDS(MAX), must be high enough to withstand the highest differential voltage seen in the application. This would include any anticipated fault conditions. The LM74610-Q1 does not have positive voltage limitation, however, it is recommended to use MOSFETs with voltage rating up to 45 V for automotive applications. Table 2 shows the examples of recommended MOSFETs to be used with the LM74610Q1. 8.2.3 Application Curves VIN (5 V/DIV) VOUT (5 V/DIV) Gate Drive (5 V/DIV) Time (50 ms/DIV) Figure 15. Shutdown Relative to VIN Figure 14. Startup Relative to VIN VIN (10 V/DIV, 12 V to -20 V) VIN (10 V/DIV, 12 V to -20 V, 60 Hz) VOUT (10 V/DIV, 12 V to 0 V) VOUT (10 V/DIV, 12 V to 0 V) Gate Drive (10 V/DIV) Gate Drive (10 V/DIV) Time (100 µs/DIV) Time (10 ms/DIV) Figure 16. Response to Reverse Polarity Figure 17. Response to a 60Hz AC Input Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 15 LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 www.ti.com VIN (10 V/DIV, 12 V to -20 V) TVS Clamping at -20 V VOUT (5 V/DIV) 0V Figure 18. ISO Pulse 1 Test Setup Time (1 ms/DIV) Figure 19. Response to ISO 1 Pulse 8.2.4 Selection of TVS Diodes in Automotive Reverse Polarity Applications TVS diodes can be used in automotive systems for protection against transients. There are 2 types of TVS diode, one that offers bi-directional clamping and one that is uni-directional. In the application circuit show in Figure 12, 2 unidirectional TVS diodes are used. TVS + does the clamping for positive pulses as seen in load dump and TVS- does the clamping for negative pulses such as seen in the ISO specs. There are two important specs to be aware of: breakdown voltage and clamping voltage. Breakdown voltage is the voltage at which the TVS diode goes into avalanche similar to a zener diode and is specified at a low current value typ 1mA. Clamping voltage is the voltage the TVS diode clamps to in high current pulse situations. In the case of an ISO 7637-2 pulse 1, the voltages go to -150V with a generator impedance of 10Ω. This translates to 15A flowing through the TVS - and the voltage across the TVS would be close to its clamping voltage. A rule of thumb with TVS diode voltage selection is that the breakdown voltage should be higher than worst case steady state voltages seen in the system. TVS diodes are meant to clamp pulses and not meant for steady state voltages. The value of the TVS + is selected such that the breakdown voltage of the TVS is higher than 24V which is a commonly used battery for jump start. LM74610-Q1 does not have a positive voltage limit so the selection of the voltage rating of TVS + is determined by the max voltage tolerated by the downstream electronics. If the downstream parts can withstand at least 37V (suppressed load dump) then there is no need to use the TVS+. In this case it can be replaced with a diode as seen in Figure 20. A 1A diode with a 30A surge current rating and at least 40V reverse voltage rating is recommended. In case positive clamping voltage is desired then SMBJ24A/SMBJ26A is recommended for TVS + as seen in Figure 12. Anode Cathode TVS- Voltage Regulator Vout Cout Vbatt LM74610-Q1 Diode Vcap Figure 20. Typical Application without Positive Voltage Clamping The value of the TVS – is selected such that 2 criteria are met. The breakdown voltage of the TVS should be higher than the max reverse battery voltage which is typically 15V. The second criterion is that the abs max rating for reverse voltage of the LM74610 is not exceeded (-45V). 16 Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 LM74610-Q1 www.ti.com SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 In case of reverse voltage pulses such as in ISO specs, the LM74610 turns the MOSFET off. When the MOSFET turns off the voltage seen by the LM74610, Anode to Cathode is - (clamping voltage of TVS- (plus) the output capacitor voltage). If the max voltage on output capacitors is 16V, then the clamping voltage of the TVS- should not exceed, 45V – 16V = 29V. SMBJ14A/SMBJ15A/SMBJ16A TVS diodes can be used for TVS-. The breakdown voltage of SMBJ14A is 15.6V and SMBJ16A is 17.8V. This meets criteria one. The clamping voltage of SMBJ14A is 23.2V and SMBJ16A is 26V. This meets the second criteria. Bi-directional TVS diodes are not recommended due to their symmetrical clamping specs. SMBJ24CA has a breakdown voltage of 26.7V and a clamping voltage of 38.9V. The breakdown voltage meets the criteria for being higher than 24V. However the clamping voltage is 38.9V. The high clamping voltage is not an issue for the positive pulses however for a negative ISO pulse, the abs max of the LM74610 can be violated. Voltage across Anode to Cathode in this case is –(38.9V + 16V) = -54.9V which violates abs max rating of -45V. As far as power levels for TVS diodes the ‘B’ in the SMBJ stands for 600W peak power levels. This is sufficient for ISO 7637-2 pulses and suppressed load dump case (ISO-16750-2 pulse B). For unsuppressed load dumps (ISO-16750-2 pulse A) higher power TVS diodes such as SMCJ or SMDJ may be required. 8.2.5 OR-ing Application Configuration Basic redundant power architecture comprises of two or more voltage or power supply sources driving a single load. In its simplest form, the OR-ing solution for redundant power supplies consists of Schottky OR-ing diodes that protect the system against an input power supply fault condition. A diode OR-ing device provides effective and low cost solution with few components. However, the diodes forward voltage drops affects the efficiency of the system permanently, since each diode in an OR-ing application spends most of its time in forward conduction mode. These power losses increase the requirements for thermal management and allocated board space. The LM74610-Q1 ICs combined with external N-Channel MOSFETs can be used to in OR-ing Solution as shown in Figure 21 . The source to drain voltage VDS for each MOSFET is monitored by the Anode and Cathode pins of the LM74610-Q1. The forward conduction is through MOSFETs 98% of the time which avoids the diode forward voltage drop. The body diode of each MOSFET only conducts the remaining 2% of the time to allow the charge pump capacitor to be fully charged. This is essential for an OR-ing device to quickly detect the reverse current and instantly pull-down the MOSFET gate to block the reverse current flow. An effective OR-ing solution needs to be extremely fast to limit the reverse current amount and duration. The LM74610-Q1 devices in OR-ing configuration constantly sense the voltage difference between Anode and Cathode pins, which are the voltage levels at the power sources (PS1, PS2) and the common load point respectively. When either of the power sources operates at lower voltage, the LM74610Q1 detects a negative polarity and shuts down the Gate Drive through a fast Pull-Down within 2μsec (typical). Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 17 LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 www.ti.com + PS1 Gate Drive Anode ± Pull Down LM74610-Q1 Cathode CLOAD VCAPH RLOAD VCAPL Vcap + PS2 Gate Drive Anode ± Pull Down LM74610-Q1 VCAPH Cathode VCAPL Vcap Figure 21. Typical OR-ing Application If one of the power supplies fails in LM74610-Q1 OR-ing controller application, the output remains uninterrupted. This behavior is similar to diode OR-ing. Figure 22 18 Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 LM74610-Q1 www.ti.com SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 VOUT (5 V/DIV, 12 V) VIN 1 (5 V/DIV, 12 V) VIN 2 (5 V/DIV, 12 V to 0 V) Time (1 s/DIV) Figure 22. LM74610-Q1 OR-ing waveform 8.2.6 Design Requirements NOTE Startup voltage is the voltage drop is needed for the controller to turn ON. It directly influences the Minimum output current at which the MOSFET turns ON. Table 2. Recommended MOSFET Examples (1) Part No Voltage (V) Current Drain Current at 25C CSD17313Q2 Q1 30 5 26 1.8 0.65 SON; 2 x 2 Auto Rdson mΩ @ 4.5V Vgs Diode voltage @ 2A at Threshold( Package; Footprint 125C/175C V) Qual SQJ886EP 40 60 5.5 2.5 0.5 PowerPAK SO-8L; 5 x 6 Auto SQ4184EY 40 29 5.6 2.5 0.5 SO-8; 5 x 6 Auto Si4122DY 40 23.5 6 2.5 0.5 SO-8; 5 x 6 Auto RS1G120MN 40 12 20.7 2.5 0.6 HSOP8; 5 x 6 Auto RS1G300GN 40 30 2.5 2.5 0.5 HSOP8; 5 x 6 Auto CSD18501Q5 A 40 22 3.3 2.3 0.53 SON; 5 x 6 Industrial SQD40N0614L 60 40 17 2.5 0.5 TO-252; 6 x 10 Auto SQ4850EY 60 12 31 2.5 0.55 SO-8; 5 x 6 Auto CSD18532Q5 B 60 23 3.3 2.2 0.53 SON;5 x 6 Industrial IPG20N04S4 L-07A 40 20 7.2 2.2 0.48 PG-TDSON-8-10; 5 x 6 Auto IPB057N06N 60 45 5.7 3.3 0.55 PG-TO263-3; 10 x 15 Auto IPD50N04S4 L 40 50 7.3 2.2 0.50 PG-TO252-3-313; 6 x10 Auto (1) The LM74610-Q1 solution is not limited to the MOSFETs included in this table. It only shows examples of compatible MOSFETs. Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 19 LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 www.ti.com Table 2. Recommended MOSFET Examples(1) (continued) Part No Voltage (V) Current Drain Current at 25C BUK9Y3R540E 40 100 3.8 2.1 0.48 LFPAK56; Power-SO8 (SOT669); 5 x 6 Auto IRF7478PbF1 60 7 30 3 0.55 SO-8; 5 x 6 Industrial SQJ422EP 40 75 4.3 2.5 0.50 PowerPAK SO-8L; 5 x 6 Auto IRL1004 40 130 6.5 1 0.60 TO-220AB Auto AUIRL7736 40 112 2.2 3 0.65 DirectFET®; 5 x 6 Auto Rdson mΩ @ 4.5V Vgs Diode voltage @ 2A at Threshold( Package; Footprint 125C/175C V) Qual Table 3. Recommended TVS Combination to meet ISO7637 Specifications (Note 4) TVS + TVS- SMA6T33AY SMBJ14A/ SMA6T15AY SMA6T30AY SMBJ14A/ SMA6T15AY SMA6T28AY SMBJ14A/ SMA6T15AY 20 Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 LM74610-Q1 www.ti.com SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 9 Power Supply Recommendations While testing the LM74610-Q1 solution, it is important to use low impedance power supply which allows current sinking. If the power supply does not allow current sinking, it would prevent the current flow in the reverse direction in the event of reverse polarity. The MOSFET gate won't get pulled down immediately due to the absence of reverse current flow. Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 21 LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 www.ti.com 10 Layout 10.1 Layout Guidelines • • • • • • • • • 22 The VIN terminal is recommended to have a low-ESR ceramic bypass-capacitor. The typical recommended bypass capacitance is a 10-μF ceramic capacitor with a X5R or X7R dielectric. The VIN terminal must be tied to the source of the MOSFET using a thick trace or polygon. The Anode pin of the LM74610-Q1 is connected to the Source of the MOSFET for sensing. The Cathode pin of the LM74610-Q1 is connected to the drain of the MOSFET for sensing. The high current path of for this solution is through the MOSFET, therefor it is important to use thick traces for source and drain of the MOSFET. The charge pump capacitor Vcap must be kept away from the MOSFET to lower the thermal effects on the capacitance value. The Gate Drive and Gate pull down pins of the LM74610-Q1 must be connected to the MOSFET gate without using vias. Avoid excessively thin traces to the Gate Drive. Obtaining acceptable performance with alternate layout schemes is possible, however this layout has been shown to produce good results and is intended as a guideline. Keep the Drive pin close to the MOSFET to avoid further reduce MOSFET turn-on delay. Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 LM74610-Q1 www.ti.com SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 10.2 Layout Example 1. VcapL 2. PullDown 3. NC 4. Anode 8. Cathode 7. VcapH 6. Gate Drive 5. NC Figure 23. Layout Example Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 23 LM74610-Q1 SNOSCZ1B – JULY 2015 – REVISED JUNE 2016 www.ti.com 11 Device and Documentation Support 11.1 Community Resources The following links connect to TI community resources. Linked contents are 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. TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help solve problems with fellow engineers. Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and contact information for technical support. 11.2 Trademarks E2E is a trademark of Texas Instruments. All other trademarks are the property of their respective owners. 11.3 Electrostatic Discharge Caution These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 11.4 Glossary SLYZ022 — TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 12 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. 24 Submit Documentation Feedback Copyright © 2015–2016, Texas Instruments Incorporated Product Folder Links: LM74610-Q1 PACKAGE OPTION ADDENDUM www.ti.com 6-Feb-2020 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) LM74610QDGKRQ1 ACTIVE VSSOP DGK 8 2500 Green (RoHS & no Sb/Br) NIPDAUAG Level-2-260C-1 YEAR -40 to 125 ZDSK LM74610QDGKTQ1 ACTIVE VSSOP DGK 8 250 Green (RoHS & no Sb/Br) NIPDAUAG Level-2-260C-1 YEAR -40 to 125 ZDSK (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