LTC4444 High Voltage Synchronous N-Channel MOSFET Driver FEATURES DESCRIPTION ■ The LTC®4444 is a high frequency high voltage gate driver that drives two N-channel MOSFETs in a synchronous DC/DC converter with supply voltages up to 100V. The powerful driver capability reduces switching losses in MOSFETs with high gate capacitance. The LTC4444’s pull-up for the top gate driver has a peak output current of 2.5A and its pull-down has an output impedance of 1.2Ω. The pull-up for the bottom gate driver has a peak output current of 3A and the pull-down has an output impedance of 0.55Ω. ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Bootstrap Supply Voltage to 114V Wide VCC Voltage: 7.2V to 13.5V Adaptive Shoot-Through Protection 2.5A Peak TG Pull-Up Current 3A Peak BG Pull-Up Current 1.2Ω TG Driver Pull-Down 0.55Ω BG Driver Pull-Down 5ns TG Fall Time Driving 1nF Load 8ns TG Rise Time Driving 1nF Load 3ns BG Fall Time Driving 1nF Load 6ns BG Rise Time Driving 1nF Load Drives Both High and Low Side N-Channel MOSFETs Undervoltage Lockout Thermally Enhanced 8-Pin MSOP Package APPLICATIONS ■ ■ ■ ■ The LTC4444 is configured for two supply-independent inputs. The high side input logic signal is internally level-shifted to the bootstrapped supply, which may function at up to 114V above ground. The LTC4444 contains undervoltage lockout circuits that disable the external MOSFETs when activated. The LTC4444 also contains adaptive shoot-through protection to prevent both MOSFETs from conducting simultaneously. Distributed Power Architectures Automotive Power Supplies High Density Power Modules Telecommunications The LTC4444 is available in the thermally enhanced 8-lead MSOP package. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 6677210. TYPICAL APPLICATION High Input Voltage Buck Converter LTC4444 Driving a 1000pF Capacitive Load BINP 5V/DIV BG 10V/DIV VIN 100V (ABS MAX) VCC 7.2V TO 13.5V BOOST VCC PWM1 (FROM CONTROLLER IC) PWM2 (FROM CONTROLLER IC) TG LTC4444 TINP TS VOUT TG-TS 10V/DIV BG BINP TINP 5V/DIV GND 4444 TA01a 20ns/DIV 4444 TA01b 4444f 1 LTC4444 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) Supply Voltage VCC......................................................... –0.3V to 14V BOOST – TS ........................................... –0.3V to 14V TINP Voltage ................................................. –2V to 14V BINP Voltage ................................................. –2V to 14V BOOST Voltage ........................................ –0.3V to 114V TS Voltage................................................... –5V to 100V Operating Temperature Range (Note 2) ... –40°C to 85°C Junction Temperature (Note 3) ............................. 125°C Storage Temperature Range................... –65°C to 150°C Lead Temperature (Soldering, 10 sec) .................. 300°C TOP VIEW TINP BINP VCC BG 1 2 3 4 9 8 7 6 5 TS TG BOOST NC MS8E PACKAGE 8-LEAD PLASTIC MSOP TJMAX = 125°C, θJA = 40°C/W, θJC = 10°C/W (NOTE 4) EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC4444EMS8E#PBF LTC4444EMS8E#TRPBF LTDBF 8-Lead Plastic MSOP –40°C to 85°C LTC4444IMS8E#PBF LTC4444IMS8E#TRPBF LTDBF 8-Lead Plastic MSOP –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = VBOOST = 12V, VTS = GND = 0V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Gate Driver Supply, VCC VCC Operating Voltage IVCC DC Supply Current TINP = BINP = 0V 7.2 UVLO Undervoltage Lockout Threshold VCC Rising VCC Falling Hysteresis ● ● 6.00 5.60 13.5 V 350 550 μA 6.60 6.15 450 7.20 6.70 V V mV 0.1 2 μA Bootstrapped Supply (BOOST – TS) IBOOST DC Supply Current TINP = BINP = 0V Input Signal (TINP, BINP) VIH(BG) BG Turn-On Input Threshold BINP Ramping High ● 2.25 2.75 3.25 V VIL(BG) BG Turn-Off Input Threshold BINP Ramping Low ● 1.85 2.3 2.75 V VIH(TG) TG Turn-On Input Threshold TINP Ramping High ● 2.25 2.75 3.25 V TINP Ramping Low ● 1.85 2.3 2.75 V ±0.01 ±2 μA VIL(TG) TG Turn-Off Input Threshold ITINP(BINP) Input Pin Bias Current 4444f 2 LTC4444 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = VBOOST = 12V, VTS = GND = 0V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS 220 mV High Side Gate Driver Output (TG) VOH(TG) TG High Output Voltage ITG = –10mA, VOH(TG) = VBOOST – VTG VOL(TG) TG Low Output Voltage ITG = 100mA, VOL(TG) = VTG –VTS 0.7 IPU(TG) TG Peak Pull-Up Current ● RDS(TG) TG Pull-Down Resistance ● ● 120 1.7 V 2.5 1.2 A 2.2 Ω 110 mV Low Side Gate Driver Output (BG) VOH(BG) BG High Output Voltage IBG = –10mA, VOH(BG) = VCC – VBG VOL(BG) BG Low Output Voltage IBG = 100mA 0.7 IPU(BG) BG Peak Pull-Up Current ● RDS(BG) BG Pull-Down Resistance ● 0.55 1.1 Ω ● 55 2 V 3 A Switching Time (BINP (TINP) is Tied to Ground While TINP (BINP) is Switching. Refer to Timing Diagram) tPLH(TG) TG Low-High Propagation Delay ● 25 45 ns tPHL(TG) TG High-Low Propagation Delay ● 22 40 ns tPLH(BG) BG Low-High Propagation Delay ● 19 35 ns tPHL(BG) BG High-Low Propagation Delay ● 14 30 ns tr(TG) TG Output Rise Time 10% – 90%, CL = 1nF 10% – 90%, CL = 10nF 8 80 ns ns tf(TG) TG Output Fall Time 10% – 90%, CL = 1nF 10% – 90%, CL = 10nF 5 50 ns ns tr(BG) BG Output Rise Time 10% – 90%, CL = 1nF 10% – 90%, CL = 10nF 6 60 ns ns tf(BG) BG Output Fall Time 10% – 90%, CL = 1nF 10% – 90%, CL = 10nF 3 30 ns ns Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC4444E is guaranteed to meet specifications from 0°C to 85°C. Specifications over the –40°C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. The LTC4444I is guaranteed over the full –40°C to 85°C operating temperature range. Note 3: TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: TJ = TA + (PD • θJA°C/W) Note 4: Failure to solder the exposed back side of the MS8E package to the PC board will result in a thermal resistance much higher than 40°C/W. 4444f 3 LTC4444 TYPICAL PERFORMANCE CHARACTERISTICS 450 350 300 TINP(BINP) = 12V 250 200 150 100 VCC Supply Current vs Temperature 380 TA = 25°C VCC = 12V TS = GND 350 TINP = BINP = 0V QUIESCENT CURRENT (μA) QUIESCENT CURRENT (μA) 400 TA = 25°C BOOST = 12V TS = GND 400 BOOST-TS Supply Quiescent Current vs Voltage TINP = 12V, BINP = 0V 300 TINP = 0V, BINP = 12V 250 200 150 100 50 50 VCC = BOOST = 12V TS = GND 370 VCC SUPPLY CURRENT (μA) VCC Supply Quiescent Current vs Voltage 360 TINP = BINP = 0V 350 340 330 TINP(BINP) = 12V 320 310 TINP = BINP = 0V 0 0 4444 G01 Output Low Voltage (VOL) vs Supply Voltage 200 150 100 VOL(TG) 120 100 80 VOL(BG) 60 40 TA = 25°C ITG(BG) = 100mA BOOST = VCC TS = GND 20 50 TINP = BINP = 0V 3.1 8 9 11 12 10 SUPPLY VOLTAGE (V) 13 VCC = BOOST = 12V 2.9 TS = GND TG OR BG INPUT THRESHOLD (V) 2.8 2.7 2.6 2.5 2.4 VIL(TG,BG ) 2.3 2.2 2.8 VIH(TG,BG) 2.7 2.6 2.5 2.4 VIL(TG,BG) 2.3 2.2 2.1 2.1 7 8 11 10 9 12 SUPPLY VOLTAGE (V) 13 14 4444 G07 –100mA 9 8 7 14 3.0 VIH(TG,BG) –10mA 10 7 8 11 10 9 12 SUPPLY VOLTAGE (V) 13 2.0 –40 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 4444 G08 14 4444 G06 Input Thresholds (TINP, BINP) vs Temperature TA = 25°C BOOST = VCC TS = GND –1mA 11 444343 G05 Input Thresholds (TINP, BINP) vs Supply Voltage 2.9 12 5 7 4444 G04 3.0 13 6 0 0 –40 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TG OR BG INPUT THRESHOLD (V) TG OR BG OUTPUT VOLTAGE (V) TINP = 0V BINP = 12V TA = 25°C BOOST = VCC TS = GND 14 140 300 250 15 Input Thresholds (TINP, BINP) Hysteresis vs Voltage TG OR BG INPUT THRESHOLD HYSTERESIS (mV) 350 Output High Voltage (VOH) vs Supply Voltage 160 TINP = 12V BINP = 0V OUTPUT VOLTAGE (mV) BOOST SUPPLY CURRENT (μA) VCC = BOOST = 12V TS = GND 4444 G03 4444 G02 Boost Supply Current vs Temperature 400 300 –40 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 BOOST SUPPLY VOLTAGE (V) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 VCC SUPPLY VOLTAGE (V) 500 TA = 25°C VCC = BOOST = 12V TS = GND 475 450 425 400 375 7 8 11 10 9 12 SUPPLY VOLTAGE (V) 13 14 4444 G09 4444f 4 LTC4444 TYPICAL PERFORMANCE CHARACTERISTICS 6.7 VCC = BOOST = 12V TS = GND BOOST = VCC TS = GND 6.6 475 450 425 400 Rise and Fall Time vs VCC Supply Voltage RISING THRESHOLD 6.5 RISE/FALL TIME (ns) 500 VCC Undervoltage Lockout Thresholds vs Temperature VCC SUPLLY VOLTAGE (V) 6.4 6.3 6.2 FALLING THRESHOLD 6.1 6.0 –40 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 375 –40 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) Rise and Fall Time vs Load Capacitance PULL-UP CURRENT (A) 50 tr(BG) 40 30 tf(TG) 20 1 2 5 6 3 4 7 8 LOAD CAPACITANCE (nF) 2.8 2.6 IPU(TG) 2.4 9 2.0 –40 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 10 4444 G13 Propagation Delay vs VCC Supply Voltage 30 28 tPLH(TG) 26 tf(BG) 11 10 9 12 SUPPLY VOLTAGE (V) 8 13 14 2.0 1.8 BOOST-TS = 12V 1.6 1.4 BOOST-TS = 7V RDS(TG) 1.2 BOOST-TS = 14V 1.0 VCC = 12V 0.8 VCC = 7V 0.6 0.4 0.2 VCC = 14V RDS(BG) 0 –40 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 4444 G15 Propagation Delay vs Temperature 37 TA = 25°C BOOST = VCC TS = GND 24 tPHL(TG) 22 tf(TG) 4444 G14 20 tPLH(BG) 18 16 tPHL(BG) 14 32 PROPAGATION DELAY (ns) 0 IPU(BG) 3.0 2.2 tf(BG) 10 tr(BG) Output Driver Pull-Down Resistance vs Temperature VCC = BOOST = 12V TS = GND 3.2 tr(TG) PROPAGATION DELAY (ns) RISE/FALL TIME (ns) 3.4 60 tr(TG) 4444 G12 Peak Driver (TG, BG) Pull-Up Current vs Temperature TA = 25°C VCC = BOOST = 12V TS = GND 70 TA = 25°C BOOST = VCC TS = GND CL = 3.3nF 4444 G11 4444 G10 80 32 30 28 26 24 22 20 18 16 14 12 10 8 6 7 OUTPUT DRIVER PULL-DOWN RESISTACNE (Ω) TG OR BG INPUT THRESHOLD HYSTERESIS (mV) Input Thresholds (TINP, BINP) Hysteresis vs Temperature VCC = BOOST = 12V TS = GND tPLH(TG) 27 tPHL(TG) 22 tPLH(BG) 17 tPHL(BG) 12 7 12 10 7 8 11 10 9 12 SUPPLY VOLTAGE (V) 13 14 4444 G16 2 –40 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 4444 G17 4444f 5 LTC4444 TYPICAL PERFORMANCE CHARACTERISTICS Switching Supply Current vs Input Frequency Switching Supply Current vs Load Capacitance 4.0 IBOOST (TG SWITCHING) 3.0 SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) TA = 25°C = BOOST = 12V 3.5 VCC TS = GND IVCC (BG SWITCHING) 2.5 2.0 1.5 1.0 IVCC (TG SWITCHING) IVCC (BG SWITCHING AT 1MHz) 100 IBOOST (TG SWITCHING AT 500kHz) IBOOST (TG SWITCHING IVCC AT 1MHz) (BG SWITCHING AT 500kHz) IVCC IVCC (TG SWITCHING (TG SWITCHING AT 500kHz) AT 1MHz) 10 1 0.5 0 IBOOST (BG SWITCHING AT 1MHz OR 5OOkHz) IBOOST (BG SWITCHING) 0 200 400 800 600 SWITCHING FREQUENCY (kHz) 1000 4444 G18 0.1 1 2 3 4 5 6 7 8 LOAD CAPACITANCE (nF) 9 10 """" /' PIN FUNCTIONS TINP (Pin 1): High Side Input Signal. Input referenced to GND. This input controls the high side driver output (TG). BINP (Pin 2): Low Side Input Signal. This input controls the low side driver output (BG). VCC (Pin 3): Supply. This pin powers input buffers, logic and the low side gate driver output directly and the high side gate driver output through an external diode connected between this pin and BOOST (Pin 6). A low ESR ceramic bypass capacitor should be tied between this pin and GND (Pin 9). BG (Pin 4): Low Side Gate Driver Output (Bottom Gate). This pin swings between VCC and GND. BOOST (Pin 6): High Side Bootstrapped Supply. An external capacitor should be tied between this pin and TS (Pin 8). Normally, a bootstrap diode is connected between VCC (Pin 3) and this pin. Voltage swing at this pin is from VCC – VD to VIN + VCC – VD, where VD is the forward voltage drop of the bootstrap diode. TG (Pin 7): High Side Gate Driver Output (Top Gate). This pin swings between TS and BOOST. TS (Pin 8): High Side MOSFET Source Connection (Top Source). Exposed Pad (Pin 9): Ground. Must be soldered to PCB ground for optimal thermal performance. NC (Pin 5): No Connect. No connection required. 4444f 6 LTC4444 BLOCK DIAGRAM 6 7.2V TO 13.5V 3 9 VCC BOOST GND VINT TS 7 8 ANTISHOOT-THROUGH PROTECTION TINP VCC 2 TG HIGH SIDE LEVEL SHIFTER LDO 1 VIN UP TO 100V VCC UVLO VCC BG LOW SIDE LEVEL SHIFTER BINP 4 NC 5 4444 BD TIMING DIAGRAM INPUT RISE/FALL TIME < 10ns TINP (BINP) 90% 10% BINP (TINP) BG (TG) 90% TG (BG) 90% 10% tr tPHL 10% tf tPLH 4444 TD OPERATION Overview The LTC4444 receives ground-referenced, low voltage digital input signals to drive two N-channel power MOSFETs in a synchronous buck power supply configuration. The gate of the low side MOSFET is driven either to VCC or GND, depending on the state of the input. Similarly, the gate of the high side MOSFET is driven to either BOOST or TS by a supply bootstrapped off of the switching node (TS). Input Stage The LTC4444 employs CMOS compatible input thresholds that allow a low voltage digital signal to drive standard power MOSFETs. The LTC4444 contains an internal voltage regulator that biases both input buffers for high side and low side inputs, allowing the input thresholds (VIH = 2.75V, VIL = 2.3V) to be independent of variations in VCC. The 450mV hysteresis between VIH and VIL eliminates false triggering due to noise during switching transitions. However, care should be taken to keep both input pins (TINP and BINP) from any noise pickup, especially in high frequency, high voltage applications. The LTC4444 input buffers have high input impedance and draw negligible input current, simplifying the drive circuitry required for the inputs. 4444f 7 LTC4444 OPERATION Output Stage A simplified version of the LTC4444’s output stage is shown in Figure 1. The pull-up devices on the BG and TG outputs are NPN bipolar junction transistors (Q1 and Q2). The BG and TG outputs are pulled up to within an NPN VBE (~0.7V) of their positive rails (VCC and BOOST, respectively). Both BG and TG have N-channel MOSFET pull-down devices (M1 and M2) which pull BG and TG down to their negative rails, GND and TS. The large voltage swing of the BG and TG output pins is important in driving external power MOSFETs, whose RDS(ON) is inversely proportional to the gate overdrive voltage (VGS − VTH). LTC4444 BOOST VIN UP TO 100V 6 Q1 TG CGD 7 M1 TS CGS 8 HIGH SIDE POWER MOSFET LOAD INDUCTOR VCC 3 Q2 BG CGD 4 M2 GND CGS LOW SIDE POWER MOSFET 9 Rise/Fall Time The LTC4444’s rise and fall times are determined by the peak current capabilities of Q1 and M1. The predriver that drives Q1 and M1 uses a nonoverlapping transition scheme to minimize cross-conduction currents. M1 is fully turned off before Q1 is turned on and vice versa. Since the power MOSFET generally accounts for the majority of the power loss in a converter, it is important to quickly turn it on or off, thereby minimizing the transition time in its linear region. An additional benefit of a strong pull-down on the driver outputs is the prevention of crossconduction current. For example, when BG turns the low side (synchronous) power MOSFET off and TG turns the high side power MOSFET on, the voltage on the TS pin will rise to VIN very rapidly. This high frequency positive voltage transient will couple through the CGD capacitance of the low side power MOSFET to the BG pin. If there is an insufficient pull-down on the BG pin, the voltage on the BG pin can rise above the threshold voltage of the low side power MOSFET, momentarily turning it back on. With both the high side and low side MOSFETs conducting, significant cross-conduction current will flow through the MOSFETs from VIN to ground and will cause substantial power loss. A similar effect occurs on TG due to the CGS and CGD capacitances of the high side MOSFET. The powerful output driver of the LTC4444 reduces the switching losses of the power MOSFET, which increase with transition time. The LTC4444’s high side driver is Figure 1. Capacitance Seen by BG and TG During Switching capable of driving a 1nF load with 8ns rise and 5ns fall times using a bootstrapped supply voltage VBOOST-TS of 12V while its low side driver is capable of driving a 1nF load with 6ns rise and 3ns fall times using a supply voltage VCC of 12V. Undervoltage Lockout (UVLO) The LTC4444 contains an undervoltage lockout detector that monitors VCC supply. When VCC falls below 6.15V, the output pins BG and TG are pulled down to GND and TS, respectively. This turns off both external MOSFETs. When VCC has adequate supply voltage, normal operation will resume. Adaptive Shoot-Through Protection Internal adaptive shoot-through protection circuitry monitors the voltages on the external MOSFETs to ensure that they do not conduct simultaneously. This feature improves efficiency by eliminating cross-conduction current from flowing from the VIN supply through both of the MOSFETs to ground during a switch transition. The adaptive shootthrough protection circuitry also monitors the level of the TS pin. If the TS pin stays high, BG will be turned on 150ns after TG is turned off. 4444f 8 LTC4444 APPLICATIONS INFORMATION Power Dissipation To ensure proper operation and long-term reliability, the LTC4444 must not operate beyond its maximum temperature rating. Package junction temperature can be calculated by: TJ = TA + PD (θJA) where: TJ = Junction temperature TA = Ambient temperature PD = Power dissipation θJA = Junction-to-ambient thermal resistance Power dissipation consists of standby and switching power losses: PD = PDC + PAC + PQG where: PDC = Quiescent power loss PAC = Internal switching loss at input frequency, fIN PQG = Loss due turning on and off the external MOSFET with gate charge QG at frequency fIN The LTC4444 consumes very little quiescent current. The DC power loss at VCC = 12V and VBOOST-TS = 12V is only (350μA)(12V) = 4.2mW. At a particular switching frequency, the internal power loss increases due to both AC currents required to charge and discharge internal node capacitances and cross-conduction currents in the internal logic gates. The sum of the quiescent current and internal switching current with no load are shown in the Typical Performance Characteristics plot of Switching Supply Current vs Input Frequency. The gate charge losses are primarily due to the large AC currents required to charge and discharge the capacitance of the external MOSFETs during switching. For identical pure capacitive loads CLOAD on TG and BG at switching frequency fIN, the load losses would be: In a typical synchronous buck configuration, VBOOST-TS is equal to VCC – VD, where VD is the forward voltage drop across the diode between VCC and BOOST. If this drop is small relative to VCC, the load losses can be approximated as: PCLOAD = 2(CLOAD)(fIN)(VCC)2 Unlike a pure capacitive load, a power MOSFET’s gate capacitance seen by the driver output varies with its VGS voltage level during switching. A MOSFET’s capacitive load power dissipation can be calculated using its gate charge, QG. The QG value corresponding to the MOSFET’s VGS value (VCC in this case) can be readily obtained from the manufacturer’s QG vs VGS curves. For identical MOSFETs on TG and BG: PQG = 2(VCC)(QG)(fIN) To avoid damage due to power dissipation, the LTC4444 includes a temperature monitor that will pull BG and TG low if the junction temperature rises above 160°C. Normal operation will resume when the junction temperature cools to less than 135°C. Bypassing and Grounding The LTC4444 requires proper bypassing on the VCC and VBOOST-TS supplies due to its high speed switching (nanoseconds) and large AC currents (Amperes). Careless component placement and PCB trace routing may cause excessive ringing. To obtain the optimum performance from the LTC4444: A. Mount the bypass capacitors as close as possible between the VCC and GND pins and the BOOST and TS pins. The leads should be shortened as much as possible to reduce lead inductance. B. Use a low inductance, low impedance ground plane to reduce any ground drop and stray capacitance. Remember that the LTC4444 switches greater than 3A peak currents and any significant ground drop will degrade signal integrity. PCLOAD = (CLOAD)(f)[(VBOOST-TS)2 + (VCC)2] 4444f 9 LTC4444 APPLICATIONS INFORMATION C. Plan the power/ground routing carefully. Know where the large load switching current is coming from and going to. Maintain separate ground return paths for the input pin and the output power stage. E. Be sure to solder the Exposed Pad on the back side of the LTC4444 package to the board. Correctly soldered to a 2500mm2 doublesided 1oz copper board, the LTC4444 has a thermal resistance of approximately 40°C/W for the MS8E package. Failure to make good thermal contact between the exposed back side and the copper board will result in thermal resistances far greater than 40°C/W. D. Keep the copper trace between the driver output pin and the load short and wide. TYPICAL APPLICATION LTC3780 High Efficiency 36V-72V VIN to 48V/6A Buck-Boost DC/DC Converter 6V 0.022μF SENSE+ 1000pF 100pF 0.1μF 100V 1 68pF SENSE– VOS+ 487k 1% D1 2.2μF + 100V ×4 3 100Ω 220k VBIAS 10V TO 12V D2 10k VBIAS 10V TO 12V 1μF 16V 100Ω 2 47pF 15k SENSE+ SW1 SENSE– VIN 6 7 9 10 220k VIN LTC3780EG TG1 4 8 D5 SS BOOST1 3 5 8.25k 1% PGOOD 11 12 ITH EXTVCC VOSENSE INTVCC SGND BG1 RUN PGND FCB BG2 PLLFLTR SW2 PLLIN TG2 STBYMD BOOST2 24 1 23 2 22 21 20 19 6V 18 10μF 10V 17 6 BOOST LTC4444 7 BINP TG TINP BG TS 8 0.22μF 16V VOS+ GND 1μF 16V 10Ω 9 L1 10μH D3 16 15 D4 2.2μF + 100V ×8 VOUT C2,C3 220μF 63V ×2 14 13 6V D6 0.1μF 16V 0.1μF 16V 2.2μF, 100V, TDK C4532X7R2A225MT C1: SANYO 100ME100HC +T C2, C3: SANYO 63ME220HC + T D1: ON SEMI MMDL770T1G D2: DIODES INC. 1N5819HW-7-F 4 0.1μF 16V VCC VIN C1 100μF 100V SENSE+ D3, D4: DIODES INC. PDS560-13 D5: DIODES INC. MMBZ5230B-7-F D6: DIODES INC. B1100-13-F L1: SUMIDA CDEP147NP-100MC-125 R1, R2: VISHAY DALE WSL2512R0250FEA SENSE– 10Ω 10Ω R1 0.025Ω 1W R2 0.025Ω 1W 4444 TA02a Efficiency 98 VIN = 36V EFFICIENCY (%) VIN = 48V 97 VIN = 72V 96 95 1 2 3 4 LOAD CURRENT (A) 5 6 4444 TA02b 4444f 10 LTC4444 PACKAGE DESCRIPTION MS8E Package 8-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1662 Rev D) BOTTOM VIEW OF EXPOSED PAD OPTION 2.06 ± 0.102 (.081 ± .004) 1 5.23 (.206) MIN 1.83 ± 0.102 (.072 ± .004) 0.889 ± 0.127 (.035 ± .005) 2.794 ± 0.102 (.110 ± .004) 2.083 ± 0.102 3.20 – 3.45 (.082 ± .004) (.126 – .136) 8 0.42 ± 0.038 (.0165 ± .0015) TYP 3.00 ± 0.102 (.118 ± .004) (NOTE 3) 0.65 (.0256) BSC 8 7 6 5 0.52 (.0205) REF RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 4.90 ± 0.152 (.193 ± .006) DETAIL “A” 0° – 6° TYP GAUGE PLANE 1 0.53 ± 0.152 (.021 ± .006) DETAIL “A” 2 3 4 1.10 (.043) MAX 0.86 (.034) REF 0.18 (.007) SEATING PLANE 0.22 – 0.38 (.009 – .015) TYP 0.65 (.0256) BSC 0.1016 ± 0.0508 (.004 ± .002) MSOP (MS8E) 0307 REV D NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 4444f Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 11 LTC4444 TYPICAL APPLICATION LTC3780 High Efficiency 8V-80V VIN to 12V/5A Buck-Boost DC/DC Converter VBIAS 12V 6V 0.1μF 0.01μF SENSE+ 100pF VOS+ 113k 1% 0.1μF 1 68pF SENSE– 100Ω SS SENSE+ SW1 4 SENSE– VIN 6 7 2.2μF, 100V, TDK C4532X7R2A225MT 100μF, 100V SANYO 100ME 100AX C1: SANYO 16ME330WF D1: DIODES INC. BAV19WS D2: DIODES INC. 1N5819HW-7-F D3: DIODES INC. B320A-13-F D4: DIODES INC. MMBZ5230B-7-F D5: DIODES INC. B1100-13-F L1: SUMIDA CDEP147-8R0 ITH EXTVCC VOSENSE INTVCC SGND 9 150k LTC3780EG TG1 3 8 VIN BOOST1 PGOOD 2 5 8.06k 1% 47pF D4 1μF 16V VBIAS 12V D1 10 11 12 BG1 RUN PGND FCB BG2 PLLFLTR SW2 PLLIN TG2 STBYMD BOOST2 24 23 1 TG1 22 2 SW1 21 0.1μF 16V 20 19 6V 18 10μF 10V 17 4 1μF 16V VCC 6 BOOST LTC4444 7 BINP TG TINP BG TS 8 VIN 100μF 100V ×2 2.2μF + 100V ×5 3 100Ω 20k 0.22μF 16V D2 10k 0.22μF 16V VOS+ 10Ω GND 9 22μF 16V ×3 TG1 L1 8μH D3 16 + VOUT C1 330μF ×2 SW1 15 14 13 6V D5 0.1μF 16V 0.1μF SENSE+ SENSE– 10Ω 10Ω 0.005Ω 1W 4444 TA03 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1693 Family High Speed Dual MOSFET Drivers 1.5A Peak Output Current, 4.5V ≤ VIN ≤ 13.2V LT 1952/LTC3900 36V to 72V Input Isolated DC/DC Converter Chip Sets Synchronous Rectification; Overcurrent, Overvoltage, UVLO Protection; Power Good Output Signal; Compact Solution LT3010/LT3010-5 50mA, 3V to 80V Low Dropout Micropower Regulators Low Quiescent Current (30μA), Stable with Small (1μF) Ceramic Capacitor LTC3703 100V Synchronous Switching Regulator Controller No RSENSE™, Synchronizable Voltage Mode Control LTC3722-1/ LTC3722-2 Synchronous Dual Mode Phase Modulated Full-Bridge Controllers Adaptive Zero Voltage Switching, High Output Power Levels (Up to Kilowatts) LTC3723-1/ LTC3723-2 Synchronous Push-Pull PWM Controllers Current Mode or Voltage Mode Push-Pull Controllers LTC3780 High Power Buck-Boost Controller Four Switch, 4V ≤ VIN ≤ 36V, 0.8V ≤ VOUT ≤ 30V, High Efficiency LTC3785 Buck-Boost Controller High Efficiency, Four Switch, 2.7V ≤ VIN ≤ 10V, 2.7V ≤ VOUT ≤ 10V LTC3810 100V Current Mode Synchronous Step-Down Switching No RSENSE, Synchronizable Tracking, Power Good Signal Regulator Controller LTC3813 100V Current Mode Synchronous Step-Up Controller No RSENSE, On-Board 1Ω Gate Drivers, Synchronizable LT3845 High Power Synchronous DC/DC Controller Current Mode Control, VIN Up to 60V, Low IQ LTC3901 Secondary Side Synchronous Driver for Push-Pull and Full-Bridge Converters Programmable Time Out, Reverse Inductor Current Sense LTC4440/ LTC4440-5 High Speed, High Voltage, High Side Gate Drivers Wide Operating VIN Range: Up to 80V DC, 100V Transient LTC4441 6A MOSFET Driver Adjustable Gate Drive from 5V to 8V, 5V ≤ VIN ≤ 28V ® LTC4442/LTC4442-1 High Speed Synchronous N-Channel MOSFET Drivers 5A Peak Output Current, 6V to 9.5V Gate Drive Supply, 38V Max Input Supply No RSENSE is a trademark of Linear Technology Corporation. 4444f 12 Linear Technology Corporation LT 1107 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2007