NCP3418, NCP3418A Dual Bootstrapped 12 V MOSFET Driver with Output Disable The NCP3418 and NCP3418A are dual MOSFET gate drivers optimized to drive the gates of both high−side and low−side power MOSFETs in a synchronous buck converter. Each of the drivers is capable of driving a 3000 pF load with a 25 ns propagation delay and a 20 ns transition time. With a wide operating voltage range, high or low side MOSFET gate drive voltage can be optimized for the best efficiency. Internal, adaptive nonoverlap circuitry further reduces switching losses by preventing simultaneous conduction of both MOSFETs. The floating top driver design can accommodate VBST voltages as high as 30 V. Both gate outputs can be driven low by applying a low logic level to the Output Disable (OD) pin. An Undervoltage Lockout function ensures that both driver outputs are low when the supply voltage is low, and a Thermal Shutdown function provides the IC with overtemperature protection. The NCP3418A is identical to the NCP3418 except that there is no internal charge pump diode. The NCP3418 is pin−to−pin compatible with Analog Devices ADP3418 with the following advantages: • Faster Rise and Fall Times • Internal Charge Pump Diode Reduces Cost and Parts Count • Thermal Shutdown for System Protection • Integrated OVP • Internal Pulldown Resistor Suppresses Transient Turn On of Either MOSFET Anti Cross−Conduction Protection Circuitry Floating Top Driver Accommodates Boost Voltages of up to 30 V One Input Signal Controls Both the Upper and Lower Gate Outputs Output Disable Control Turns Off Both MOSFETs Complies with VRM 10.x Specifications Undervoltage Lockout Thermal Shutdown Pb−Free Package is Available Semiconductor Components Industries, LLC, 2004 January, 2004 − Rev. 8 MARKING DIAGRAM 8 8 1 3418 ALYW SO−8 D SUFFIX CASE 751 1 8 A L Y W = Assembly Location = Wafer Lot = Year = Work Week 3418A ALYW 1 PIN CONNECTIONS BST 1 8 DRVH IN OD SW PGND VCC DRVL ORDERING INFORMATION Features • • • • • • • • http://onsemi.com 1 Package Shipping† NCP3418D SO−8 98 Units/Rail NCP3418DR2 SO−8 2500 Tape & Reel NCP3418ADR2 SO−8 2500 Tape & Reel NCP3418ADR2G SO−8 2500 Tape & Reel Device †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specification Brochure, BRD8011/D. Publication Order Number: NCP3418/D NCP3418, NCP3418A VCC 4 Not present in the NCP3418A IN 1 BST 8 DRVH 7 SW 5 DRVL 6 PGND 2 100 k − + Nonoverlap 1.5 V 4V − + 120 k OD 3 Figure 1. NCP3418/A Block Diagram PACKAGE PIN DESCRIPTION Pin Pin Symbol Description 1 BST 2 IN Logic−Level Input. This pin has primary control of the drive outputs. 3 OD Output Disable. When low, normal operation is disabled forcing DRVH and DRVL low. 4 VCC Input Supply. A 1.0 F ceramic capacitor should be connected from this pin to PGND. 5 DRVL Output drive for the lower MOSFET. 6 PGND Power Ground. Should be closely connected to the source of the lower MOSFET. 7 SW 8 DRVH Upper MOSFET Floating Bootstrap Supply. A capacitor connected between BST and SW pins holds this bootstrap voltage for the high−side MOSFET as it is switched. The recommended capacitor value is between 100 nF and 1.0 F. An external diode will be needed with the NCP3418A. Switch Node. Connect to the source of the upper MOSFET. Output drive for the upper MOSFET. http://onsemi.com 2 NCP3418, NCP3418A MAXIMUM RATINGS* Rating Value Unit Operating Ambient Temperature, TA 0 to 85 °C Operating Junction Temperature, TJ (Note 1) 0 to 150 °C 45 123 °C/W °C/W −65 to 150 °C 230 °C 1 − Package Thermal Resistance: Junction−to−Case, RJC Junction−to−Ambient, RJA (2−Layer Board) Storage Temperature Range, TS Lead Temperature Soldering (10 Sec): Reflow: (SMD styles only) (Note 2) JEDEC Moisture Sensitivity Level 1. Internally limited by thermal shutdown, 150°C min. 2. 60 seconds maximum above 183°C. *The maximum package power dissipation must be observed. NOTE: This device is ESD sensitive. Use standard ESD precautions when handling. MAXIMUM RATINGS Pin Symbol Pin Name VMAX VMIN VCC Main Supply Voltage Input 15 V −0.3 V BST Bootstrap Supply Voltage Input 30 V wrt/PGND 15 V wrt/SW −0.3 V wrt/SW SW Switching Node (Bootstrap Supply Return) 30 V −1.0 V DC −10 V < 200 ns DRVH High−Side Driver Output BST + 0.3 V −0.3 V wrt/SW DRVL Low−Side Driver Output VCC + 0.3 V −0.3 V DC −2.0 V < 200 ns IN DRVH and DRVL Control Input VCC + 0.3 V −0.3 V OD Output Disable VCC + 0.3 V −0.3 V PGND Ground 0V 0V NOTE: All voltages are with respect to PGND except where noted. http://onsemi.com 3 NCP3418, NCP3418A NCP3418−SPECIFICATIONS (Note 3) (VCC = 12 V, TA = 0°C to +85°C, TJ = 0°C to +125°C unless otherwise noted.) Parameter Symbol Conditions Min Typ Max Unit Supply Voltage Range VCC − 4.6 − 13.2 V Supply Current ISYS BST = 12 V, IN = 0 V − 2.0 6.0 mA Input Voltage High − − 2.0 − − V Input Voltage Low − − − − 0.8 V Input Current − − −1.0 − +1.0 A tpdlOD tpdhOD See Figure 2 − − 40 40 60 60 ns ns Input Voltage High − − 2.0 − − V Input Voltage Low − − − − 0.8 V Input Current − − −1.0 − +1.0 A Output Resistance, Sourcing Current − VBST − VSW = 12 V (Note 6) − 1.8 3.0 Output Resistance, Sinking Current − VBST − VSW = 12 V (Note 6) − 1.0 2.5 trDRVH tfDRVH VBST − VSW = 12 V, CLOAD = 3.0 nF, See Figure 3 − − 18 10 25 15 ns ns tpdhDRVH tpdlDRVH VBST − VSW = 12 V − − 30 25 60 45 ns ns Output Resistance, Sourcing Current − VCC = 12 V (Note 6) − 1.8 3.0 Output Resistance, Sinking Current − VCC − VSW = 12 V (Note 6) − 1.0 2.5 trDRVL tfDRVL CLOAD = 3.0 nF, See Figure 3 − − 16 11 25 15 ns ns tpdhDRVL tpdlDRVL See Figure 3 − − 30 20 60 30 ns ns UVLO − − 3.9 4.3 4.6 V Hysteresis − (Note 6) − (Note 6) Supply OD Input Propagation Delay Time (Note 4) PWM Input High−Side Driver Transition Times (Note 4) Propagation Delay (Notes 4 & 5) Low−Side Driver Transition Times Propagation Delay Undervoltage Lockout 0.5 V 170 °C 20 °C Thermal Shutdown Over Temperature Protection Hysteresis 3. 4. 5. 6. (Note 6) 150 All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC). AC specifications are guaranteed by characterization, but not production tested. For propagation delays, “tpdh’’ refers to the specified signal going high; “tpdl’’ refers to it going low. GBD: Guaranteed by design; not tested in production. Specifications subject to change without notice. http://onsemi.com 4 NCP3418, NCP3418A OD tpdlOD tpdhOD 90% DRVH or DRVL 10% Figure 2. Output Disable Timing Diagram IN tpdlDRVL tfDRVL DRVL tpdlDRVH trDRVL 90% 90% 1.5 V 10% 10% tpdhDRVH tfDRVH trDRVH 90% DRVH−SW 90% 10% 10% tpdhDRVL SW 4V Figure 3. Nonoverlap Timing Diagram (Timing is Referenced to the 90% and 10% Points Unless Otherwise Noted) http://onsemi.com 5 NCP3418, NCP3418A APPLICATIONS INFORMATION IN IN DRVH DRVH DRVL DRVL Figure 4. DRVH Rise and DRVL Fall Times Figure 5. DRVH Fall and DRVL Rise Times 15 40 FALL TIME (ns) trTG 20 trBG 10 0 1 trTG 10 trBG 5 0 2 4 3 1 5 2 3 LOAD CAPACITANCE (nF) Figure 7. Fall Time vs. Load Capacitance 60 50 40 ICC 30 20 TA = 25 °C VCC = 12 V Cload = 3.3 nF 10 0 0 4 LOAD CAPACITANCE (nF) Figure 6. Rise Time vs. Load Capacitance SUPPLY CURRENT (mA) RISE TIME (ns) 30 200 400 600 800 1000 1200 IN FREQUENCY (kHz) Figure 8. VCC Supply Current vs. IN Frequency http://onsemi.com 6 5 NCP3418, NCP3418A APPLICATIONS INFORMATION Theory of Operation The NCP3418 and NCP3418A are single phase MOSFET drivers optimized for driving two N−channel MOSFETs in a synchronous buck converter topology. The NCP3418 features an internal diode, while the NCP3418A requires an external BST diode for the floating top gate driver. A single PWM input signal is all that is required to properly drive the high−side and the low−side MOSFETs. Each driver is capable of driving a 3.3 nF load at frequencies up to 500 kHz. turn on, the overlap protection circuit waits for the voltage at the SW pin to fall below 4 V. Once SW falls below the 4 V threshold, DRVL will go high after a propagation delay (tpdhDRVL), turning the low−side MOSFET on. However, if SW does not fall below 4 V in 300 ns, the safety timer circuit will override the normal control scheme and drive DRVL high. This will help insure that if the high−side MOSFET fails to turn off it will not produce an over−voltage at the output. Similarly, to prevent cross conduction during the low−side MOSFET’s turn−off and the high−side MOSFET’s turn−on, the overlap circuit monitors the voltage at the gate of the low−side MOSFET through the DRVL pin. When the PWM signal goes high, DRVL will go low after a propagation delay (tpdlDRVL), turning the low−side MOSFET off. However, before the high−side MOSFET can turn on, the overlap protection circuit waits for the voltage at DRVL to drop below 1.5 V. Once this has occurred, DRVH will go high after a propagation delay (tpdhDRVH), turning the high−side MOSFET on. Low−Side Driver The low−side driver is designed to drive a ground−referenced low RDS(on) N−Channel MOSFET. The voltage rail for the low−side driver is internally connected to the VCC supply and PGND. When the NCP3418 is enabled, the low−side driver’s output is 180 out of phase with the PWM input. When the device is disabled, the low−side gate is held low. High−Side Driver Application Information The high−side driver is designed to drive a floating low RDS(on) N−channel MOSFET. The bias voltage for the high side driver is developed by a bootstrap circuit referenced to SW. The bootstrap capacitor should be connected between the BST and SW pins. The bootstrap circuit comprises an internal or external diode, D1 (in which the anode is connected to VCC), and an external bootstrap capacitor, CBST. When the NCP3418 is starting up, the SW pin is at ground, so the bootstrap capacitor will charge up to VCC through D1. When the PWM input goes high, the high−side driver will begin to turn on the high−side MOSFET by pulling charge out of CBST. As the high−side MOSFET turns on, the SW pin will rise to VIN, forcing the BST pin to VIN + VCC, which is enough gate−to−source voltage to hold the MOSFET on. To complete the cycle, the high−side MOSFET is switched off by pulling the gate down to the voltage at the SW pin. When low−side MOSFET turns on, the SW pin is held at ground. This allows the bootstrap capacitor to charge up to VCC again. The high−side driver’s output is in phase with the PWM input. When the device is disabled, the high side gate is held low. Supply Capacitor Selection For the supply input (VCC) of the NCP3418, a local bypass capacitor is recommended to reduce noise and supply peak currents during operation. Use a 1 to 4.7 F, low ESR capacitor. Multilayer ceramic chip (MLCC) capacitors provide the best combination of low ESR and small size. Keep the ceramic capacitor as close as possible to the VCC and PGND pins. Bootstrap Circuit The bootstrap circuit uses a charge storage capacitor (CBST) and the internal (or an external) diode. Selection of these components can be done after the high−side MOSFET has been chosen. The bootstrap capacitor must have a voltage rating that is able to withstand twice the maximum supply voltage. A minimum 50 V rating is recommended. The capacitance is determined using the following equation: CBST QGATE VBST (eq. 1) where QGATE is the total gate charge of the high−side MOSFET, and VBST is the voltage droop allowed on the high−side MOSFET drive. For example, a NTD60N03 has a total gate charge of about 30 nC. For an allowed droop of 300 mV, the required bootstrap capacitance is 100 nF. A good quality ceramic capacitor should be used. If an external Schottky diode will be used for bootstrap, it must be rated to withstand the maximum supply voltage plus any peak ringing voltages that may be present on SW. The average forward current can be estimated by: Safety Timer & Overlap Protection Circuit The overlap protection circuit prevents both the high−side MOSFET and the low−side MOSFET from being on at the same time, and minimizes the associated off times. This will reduce power losses in the switching elements. The overlap protection circuit accomplishes this by controlling the delay from turning off the high−side MOSFET to turning on the low−side MOSFET. To prevent cross conduction during the high−side MOSFET’s turn−off and the low−side MOSFET’s turn−on, the overlap circuit monitors the voltage at the SW pin. When the PWM input signal goes low, DRVH will go low after a propagation delay (tpdlDRVH), turning the high−side MOSFET off. However, before the low−side MOSFET can IF(AVG) QGATE fMAX (eq. 2) where fMAX is the maximum switching frequency of the controller. The peak surge current rating should be checked http://onsemi.com 7 NCP3418, NCP3418A in−circuit, since this is dependent on the source impedance of the 12 V supply and the ESR of CBST. http://onsemi.com 8 NCP3418, NCP3418A PACKAGE DIMENSIONS SOIC−8 D SUFFIX CASE 751−07 ISSUE AA NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSION A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. 6. 751−01 THRU 751−06 ARE OBSOLETE. NEW STANDARD IS 751−07 −X− A 8 5 0.25 (0.010) S B 1 M Y M 4 K −Y− G C N X 45 SEATING PLANE −Z− 0.10 (0.004) H D 0.25 (0.010) M Z Y S X M J S DIM A B C D G H J K M N S MILLIMETERS MIN MAX 4.80 5.00 3.80 4.00 1.35 1.75 0.33 0.51 1.27 BSC 0.10 0.25 0.19 0.25 0.40 1.27 0 8 0.25 0.50 5.80 6.20 INCHES MIN MAX 0.189 0.197 0.150 0.157 0.053 0.069 0.013 0.020 0.050 BSC 0.004 0.010 0.007 0.010 0.016 0.050 0 8 0.010 0.020 0.228 0.244 SOLDERING FOOTPRINT* 1.52 0.060 7.0 0.275 4.0 0.155 0.6 0.024 1.270 0.050 SCALE 6:1 mm inches Figure 9. SOIC−8 *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. 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