LTC4444 High Voltage Synchronous N-Channel MOSFET Driver FEATURES DESCRIPTION AEC-Q100 Qualified for Automotive Applications nn Bootstrap Supply Voltage to 114V nn Wide V CC Voltage: 7.2V to 13.5V nn Adaptive Shoot-Through Protection nn 2.5A Peak TG Pull-Up Current nn 3A Peak BG Pull-Up Current nn 1.2 TG Driver Pull-Down nn 0.55 BG Driver Pull-Down nn 5ns TG Fall Time Driving 1nF Load nn 8ns TG Rise Time Driving 1nF Load nn 3ns BG Fall Time Driving 1nF Load nn 6ns BG Rise Time Driving 1nF Load nn Drives Both High and Low Side N-Channel MOSFETs nn Undervoltage Lockout nn Thermally Enhanced 8-Lead MSOP Package The LTC(R)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. This powerful driver reduces switching losses in MOSFETs with high gate capacitance. nn APPLICATIONS Distributed Power Architectures nn Automotive Power Supplies nn High Density Power Modules nn Telecommunications nn All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 6677210. The LTC4444 is configured for two supply-independent inputs. The high side input logic signal is internally levelshifted 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. Adaptive shoot-through protection prevents both MOSFETs from conducting simultaneously. For a similar driver in this product family, please refer to the chart below. PARAMETER LTC4444 LTC4446 LTC4444-5 Shoot-Through Protection Yes No Yes Absolute Max TS 100V 100V 100V MOSFET Gate Drive 7.2V to 13.5V 7.2V to 13.5V 4.5V to 13.5V VCC UV+ 6.6V 6.6V 4V VCC UV- 6.15V 6.15V 3.55V TYPICAL APPLICATION High Input Voltage Buck Converter LTC4444 Driving a 1000pF Capacitive Load VIN 100V (ABS MAX) VCC 7.2V TO 13.5V BINP 5V/DIV BG 10V/DIV BOOST VCC PWM1 (FROM CONTROLLER IC) PWM2 (FROM CONTROLLER IC) LTC4444 TINP TG TS VOUT BG BINP TINP 5V/DIV TG-TS 10V/DIV GND 4444 TA01a 20ns/DIV 4444 TA01b Rev. C Document Feedback For more information www.analog.com 1 LTC4444 ABSOLUTE MAXIMUM RATINGS (Note 1) PIN CONFIGURATION 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 Junction Temperature Range (Notes 2, 3)......................................... -55C to 150C Storage Temperature Range...................-65C to 150C Lead Temperature (Soldering, 10 sec).................... 300C TOP VIEW TINP BINP VCC BG 1 2 3 4 9 GND 8 7 6 5 TS TG BOOST NC MS8E PACKAGE 8-LEAD PLASTIC MSOP TJMAX = 125C, JA = 40C/W, JC = 10C/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 -40C to 125C LTC4444IMS8E#PBF LTC4444IMS8E#TRPBF LTDBF 8-Lead Plastic MSOP -40C to 125C LTC4444HMS8E#PBF LTC4444HMS8E#TRPBF LTDBF 8-Lead Plastic MSOP -40C to 150C LTC4444MPMS8E#PBF LTC4444MPMS8E#TRPBF LTDBF 8-Lead Plastic MSOP -55C to 150C LTC4444EMS8E#WPBF LTC4444EMS8E#WTRPBF LTDBF 8-Lead Plastic MSOP -40C to 125C LTC4444IMS8E#WPBF LTC4444IMS8E#WTRPBF LTDBF 8-Lead Plastic MSOP -40C to 125C LTC4444HMS8E#WPBF LTC4444HMS8E#WTRPBF LTDBF 8-Lead Plastic MSOP -40C to 150C AUTOMOTIVE PRODUCTS** Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix. **Versions of this part are available with controlled manufacturing to support the quality and reliability requirements of automotive applications. These models are designated with a #W suffix. Only the automotive grade products shown are available for use in automotive applications. Contact your local Analog Devices account representative for specific product ordering information and to obtain the specific Automotive Reliability reports for these models. ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at TA = 25C (Note 2). VCC = VBOOST = 12V, VTS = GND = 0V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS 13.5 V Gate Driver Supply, VCC VCC Operating Voltage 7.2 IVCC DC Supply Current TINP = BINP = 0V UVLO Undervoltage Lockout Threshold VCC Rising VCC Falling Hysteresis l l 6.00 5.60 350 550 A 6.60 6.15 450 7.20 6.70 V V mV 0.1 2 A Bootstrapped Supply (BOOST - TS) IBOOST 2 DC Supply Current TINP = BINP = 0V Rev. C For more information www.analog.com LTC4444 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at TA = 25C (Note 2). VCC = VBOOST = 12V, VTS = GND = 0V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Input Signal (TINP, BINP) VIH(BG) BG Turn-On Input Threshold BINP Ramping High l 2.25 2.75 3.25 V VIL(BG) BG Turn-Off Input Threshold BINP Ramping Low l 1.85 2.3 2.75 V VIH(TG) TG Turn-On Input Threshold TINP Ramping High l 2.25 2.75 3.25 V VIL(TG) TG Turn-Off Input Threshold TINP Ramping Low l 1.85 2.3 2.75 V ITINP(BINP) Input Pin Bias Current 0.01 2 A High Side Gate Driver Output (TG) VOH(TG) TG High Output Voltage ITG = -10mA, VOH(TG) = VBOOST - VTG 0.7 VOL(TG) TG Low Output Voltage ITG = 100mA, VOL(TG) = VTG -VTS IPU(TG) TG Peak Pull-Up Current l RDS(TG) TG Pull-Down Resistance l 120 l 1.7 V 250 2.5 1.2 mV A 2.5 Low Side Gate Driver Output (BG) VOH(BG) BG High Output Voltage IBG = -10mA, VOH(BG) = VCC - VBG 0.7 VOL(BG) BG Low Output Voltage IBG = 100mA IPU(BG) BG Peak Pull-Up Current l RDS(BG) BG Pull-Down Resistance l 55 l 2 V 125 3 mV A 0.55 1.25 Switching Time [BINP (TINP) is Tied to Ground While TINP (BINP) is Switching. Refer to Timing Diagrams] tPLH(TG) TG Low-High Propagation Delay l 25 50 ns tPHL(TG) TG High-Low Propagation Delay l 22 45 ns tPLH(BG) BG Low-High Propagation Delay l 19 40 ns tPHL(BG) BG High-Low Propagation Delay l 14 35 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 LTC4444 is tested under pulsed load conditions such that TJ TA. The LTC4444E is guaranteed to meet specifications from 0C to 85C junction temperature. Specifications over the -40C to 125C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LTC4444I is guaranteed over the -40C to 125C operating temperature range, the LTC4444H is guaranteed over the -40C to 150C operating temperature range and the LTC4444MP is tested and guaranteed over the full -55C to 150C operating junction temperature range. High junction temperatures degrade operating lifetimes; operating lifetime is derated for junction temperatures greater than 125C. Note that the maximum ambient temperature consistent with these specifications is determined by specific operating conditions in conjunction with board layout, the rated package thermal impedance and other environmental factors. Note 3: The junction temperature (TJ, in C) is calculated from the ambient temperature (TA , in C) and power dissipation (PD, in watts) according to the formula: TJ = TA + (PD * JA) where JA (in C/W) is the package thermal impedance. 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 40C/W. Rev. C For more information www.analog.com 3 LTC4444 TYPICAL PERFORMANCE CHARACTERISTICS 400 350 300 TINP(BINP) = 12V 250 200 150 100 200 150 100 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 VCC SUPPLY VOLTAGE (V) Boost Supply Current vs Temperature 350 TINP = 0V BINP = 12V 200 150 100 0 -55 TINP = BINP = 0V 100 80 40 -25 5 35 65 95 TEMPERATURE (C) 125 150 TA = 25C ITG(BG) = 100mA BOOST = VCC TS = GND 3.1 VIH(TG,BG) 2.8 2.7 2.6 2.5 2.4 VIL(TG,BG ) 2.3 12 11 10 SUPPLY VOLTAGE (V) 9 13 2.2 2.7 2.6 2.5 VIL(TG,BG) 2.3 8 11 10 9 12 SUPPLY VOLTAGE (V) 13 14 2.2 4444 G07 2.0 -55 -25 -10mA 10 -100mA 9 8 7 5 35 65 95 TEMPERATURE (C) 7 8 11 10 9 12 SUPPLY VOLTAGE (V) 13 14 4444 G06 Input Thresholds (TINP, BINP) Hysteresis vs Voltage VIH(TG,BG) 2.4 -1mA 11 4444 G05 2.1 7 12 5 14 VCC = BOOST = 12V 2.9 TS = GND 2.8 4444 G03 6 3.0 TG OR BG INPUT THRESHOLD (V) 2.9 8 125 150 TA = 25C BOOST = VCC TS = GND 13 Input Thresholds (TINP, BINP) vs Temperature TA = 25C BOOST = VCC TS = GND 3.0 7 4444 G04 Input Thresholds (TINP, BINP) vs Supply Voltage TG OR BG INPUT THRESHOLD (V) VOL(BG) 60 5 35 65 95 TEMPERATURE (C) Output High Voltage (VOH) vs Supply Voltage VOL(TG) 120 0 TINP(BINP) = 12V 320 14 20 50 330 15 140 300 250 340 300 -55 -25 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 BOOST SUPPLY VOLTAGE (V) 4444 G02 160 TINP = 12V BINP = 0V TINP = BINP = 0V 350 310 TINP = BINP = 0V TG OR BG OUTPUT VOLTAGE (V) VCC = BOOST = 12V TS = GND 360 Output Low Voltage (VOL) vs Supply Voltage OUTPUT VOLTAGE (mV) BOOST SUPPLY CURRENT (A) 400 4 TINP = 0V, BINP = 12V 250 VCC = BOOST = 12V TS = GND 370 300 4444 G01 2.1 TINP = 12V, BINP = 0V 50 50 0 380 TA = 25C VCC = 12V TS = GND 350 TINP = BINP = 0V VCC Supply Current vs Temperature TG OR BG INPUT THRESHOLD HYSTERESIS (mV) QUIESCENT CURRENT (A) 400 TA = 25C BOOST = 12V TS = GND QUIESCENT CURRENT (A) 450 BOOST-TS Supply Quiescent Current vs Voltage VCC SUPPLY CURRENT (A) VCC Supply Quiescent Current vs Voltage 125 150 500 TA = 25C VCC = BOOST = 12V TS = GND 475 450 425 400 375 7 8 11 9 12 10 SUPPLY VOLTAGE (V) 13 14 4444 G09 4444 G08 Rev. C For more information www.analog.com LTC4444 TYPICAL PERFORMANCE CHARACTERISTICS 6.7 VCC = BOOST = 12V TS = GND 6.6 475 450 425 400 RISING THRESHOLD 6.5 6.4 6.3 6.2 FALLING THRESHOLD 5 35 65 95 TEMPERATURE (C) 6.0 -55 125 150 3.4 PULL-UP CURRENT (A) tr(TG) 50 tr(BG) 40 30 tf(TG) 20 2 5 6 3 4 7 8 LOAD CAPACITANCE (nF) 2.4 2.0 -55 10 9 -25 4444 G13 5 35 65 95 TEMPERATURE (C) 125 150 30 28 tPLH(TG) 26 37 TA = 25C BOOST = VCC TS = GND tPHL(TG) 20 tPLH(BG) 18 16 tPHL(BG) 14 tf(BG) 7 11 9 12 10 SUPPLY VOLTAGE (V) 8 13 14 4444 G12 2.2 2.0 BOOST-TS = 12V 1.8 1.6 BOOST-TS = 7V 1.4 1.2 RDS(TG) BOOST-TS = 14V 1.0 VCC = 12V 0.8 VCC = 7V 0.6 0.4 0.2 -55 VCC = 14V RDS(BG) -25 5 35 65 95 TEMPERATURE (C) 125 150 4444 G15 32 VCC = BOOST = 12V TS = GND tPLH(TG) tPHL(TG) 27 tPLH(BG) 22 17 tPHL(BG) 12 7 12 10 tf(TG) Propagation Delay vs Temperature 24 22 tr(BG) 4444 G14 Propagation Delay vs VCC Supply Voltage PROPAGATION DELAY (ns) 1 IPU(TG) 2.2 tf(BG) 10 2.8 2.6 tr(TG) Output Driver Pull-Down Resistance vs Temperature IPU(BG) 3.0 TA = 25C BOOST = VCC TS = GND CL = 3.3nF 4444 G11 VCC = BOOST = 12V TS = GND 3.2 60 125 150 32 30 28 26 24 22 20 18 16 14 12 10 8 6 Peak Driver (TG, BG) Pull-Up Current vs Temperature TA = 25C VCC = BOOST = 12V TS = GND 70 5 35 65 95 TEMPERATURE (C) OUTPUT DRIVER PULL-DOWN RESISTACNE () 80 -25 4444 G10 PROPAGATION DELAY (ns) -25 Rise and Fall Time vs Load Capacitance RISE/FALL TIME (ns) BOOST = VCC TS = GND 6.1 375 -55 0 Rise and Fall Time vs VCC Supply Voltage RISE/FALL TIME (ns) 500 VCC Undervoltage Lockout Thresholds vs Temperature VCC SUPLLY VOLTAGE (V) TG OR BG INPUT THRESHOLD HYSTERESIS (mV) Input Thresholds (TINP, BINP) Hysteresis vs Temperature 7 8 11 10 9 12 SUPPLY VOLTAGE (V) 13 14 2 -55 4444 G16 -25 5 35 65 95 TEMPERATURE (C) 125 150 4444 G17 Rev. C For more information www.analog.com 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 = 25C 3.5 VCC = BOOST = 12V TS = GND IVCC (BG SWITCHING) 2.5 2.0 1.5 1.0 IVCC (TG SWITCHING) 0.5 0 IBOOST (BG SWITCHING) 0 200 400 800 600 SWITCHING FREQUENCY (kHz) 1000 IVCC (BG SWITCHING AT 1MHz) 100 IBOOST (TG SWITCHING AT 1MHz) 10 IVCC (BG SWITCHING AT 500kHz) IVCC IVCC (TG SWITCHING (TG SWITCHING AT 500kHz) AT 1MHz) 1 0.1 IBOOST (TG SWITCHING AT 500kHz) IBOOST (BG SWITCHING AT 1MHz OR 5OOkHz) 1 4444 G18 2 3 4 5 6 7 8 LOAD CAPACITANCE (nF) 9 10 4444 G19 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). GND (Exposed Pad Pin 9): Ground. Must be soldered to PCB ground for optimal thermal performance. NC (Pin 5): No Connect. No connection required. 6 Rev. C For more information www.analog.com LTC4444 BLOCK DIAGRAM 6 7.2V TO 13.5V 3 9 BOOST VCC GND TG HIGH SIDE LEVEL SHIFTER LDO 1 VIN UP TO 100V VCC UVLO VINT TS 8 ANTISHOOT-THROUGH PROTECTION TINP VCC 2 7 VCC BG LOW SIDE LEVEL SHIFTER BINP 4 NC 5 4444 BD TIMING DIAGRAMS Adaptive Shoot-Through Protection BINP BINP BG BG TINP TINP TG-TS TG-TS 4444 TD01 Switching Time INPUT RISE/FALL TIME < 10ns TINP (BINP) 90% 10% BINP (TINP) BG (TG) TG (BG) 90% 90% 10% tr tPHL 10% tf tPLH 4444 TD02 Rev. C For more information www.analog.com 7 LTC4444 OPERATION Overview Output Stage 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). 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 pulldown 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). 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. LTC4444 BOOST 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 VIN UP TO 100V 6 Q1 Rise/Fall Time TG CGD 7 M1 TS VCC CGS 8 HIGH SIDE POWER MOSFET LOAD INDUCTOR 3 Q2 BG CGD 4 M2 GND CGS LOW SIDE POWER MOSFET 9 4444 FO1 Figure 1. Capacitance Seen by BG and TG During Switching 8 Rev. C For more information www.analog.com LTC4444 OPERATION of cross- conduction 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 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. If both TINP and BINP are high at the same time, BG will be kept off and TG will be turned on (refer to the Timing Diagrams). If BG is still high when TINP turns on, TG will not be turned on until BG goes low. When TINP turns off, the adaptive shoot-through protection circuitry monitors the level of the TS pin. BG can be turned on if the TS pin goes low. If the TS pin stays high, BG will be turned on 150ns after TINP turns off. 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 (JA) 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 where: PQG = Loss due turning on and off the external MOSFET with gate charge QG at frequency fIN TJ = Junction temperature TA = Ambient temperature PD = Power dissipation JA = Junction-to-ambient thermal resistance The LTC4444 consumes very little quiescent current. The DC power loss at VCC = 12V and VBOOST-TS = 12V is only (350A)(12V) = 4.2mW. Rev. C For more information www.analog.com 9 LTC4444 APPLICATIONS INFORMATION 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: PCLOAD = (CLOAD)(f)[(VBOOST-TS)2 + (VCC)2] 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 160C. Normal operation will resume when the junction temperature cools to less than 135C. 10 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. 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. D. Keep the copper trace between the driver output pin and the load short and wide. E. Be sure to solder the Exposed Pad on the back side of the LTC4444 package to the board. Correctly soldered to a 2500mm2 double sided 1oz copper board, the LTC4444 has a thermal resistance of approximately 40C/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 40C/W. Rev. C For more information www.analog.com LTC4444 TYPICAL APPLICATION LTC3780 High Efficiency 36V to 72V VIN to 48V/6A Buck-Boost DC/DC Converter 6V 10k 0.022F 1000pF SENSE+ 100 220k 100pF 0.1F 100V 1 68pF SENSE- VOS+ 487k 1% 100 2 3 4 5 8.25k 1% 47pF 6 7 8 D5 15k VIN 9 10 220k 11 12 PGOOD SS LTC3780EG TG1 SENSE+ SW1 SENSE- VIN ITH EXTVCC VOSENSE INTVCC SGND BG1 RUN PGND FCB BG2 PLLFLTR SW2 PLLIN TG2 STBYMD VBIAS 10V TO 12V D2 BOOST1 BOOST2 D1 1 VCC 6 BOOST LTC4444 2 7 BINP TG 23 22 21 4 0.1F 16V 20 19 6V 18 10F 10V 17 2.2F 100V x4 3 24 TINP BG TS 8 + VIN C1 100F 100V 0.22F 16V VOS+ GND 1F 16V 10 9 L1 10H 16 D3 15 D4 2.2F 100V x8 + VOUT C2,C3 220F 63V x2 14 13 6V D6 0.1F 16V 0.1F 16V 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- 10 10 R1 0.025 1W R2 0.025 1W 4444 TA02a Efficiency 98 VIN = 36V EFFICIENCY (%) 2.2F, 100V, TDK C4532X7R2A225MT C1: SANYO 100ME100HC +T C2, C3: SANYO 63ME220HC + T D1: ON SEMI MMDL770T1G D2: DIODES INC. 1N5819HW-7-F VBIAS 10V TO 12V 1F 16V VIN = 48V 97 VIN = 72V 96 95 1 2 3 4 LOAD CURRENT (A) 5 6 4444 TA02b Rev. C For more information www.analog.com 11 LTC4444 PACKAGE DESCRIPTION MS8E Package 8-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1662 Rev K) BOTTOM VIEW OF EXPOSED PAD OPTION 1.88 (.074) 1 1.88 0.102 (.074 .004) 0.29 REF 1.68 (.066) 0.889 0.127 (.035 .005) 0.05 REF 5.10 (.201) MIN DETAIL "B" CORNER TAIL IS PART OF DETAIL "B" THE LEADFRAME FEATURE. FOR REFERENCE ONLY NO MEASUREMENT PURPOSE 1.68 0.102 3.20 - 3.45 (.066 .004) (.126 - .136) 8 3.00 0.102 (.118 .004) (NOTE 3) 0.65 (.0256) BSC 0.42 0.038 (.0165 .0015) TYP 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 0.53 0.152 (.021 .006) DETAIL "A" 1 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) NOTE: BSC 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 6. EXPOSED PAD DIMENSION DOES INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD SHALL NOT EXCEED 0.254mm (.010") PER SIDE. 12 0.1016 0.0508 (.004 .002) MSOP (MS8E) 0213 REV K Rev. C For more information www.analog.com LTC4444 REVISION HISTORY REV DATE DESCRIPTION A 06/10 MP-grade part added. Reflected throughout the data sheet. PAGE NUMBER 1 to 14 B 01/11 H-grade part added. Reflected throughout the data sheet. 1 to 14 C 12/18 Added AEC-Q100 approval and product information. 1 and 2 Rev. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license For is granted implication or otherwise under any patent or patent rights of Analog Devices. more by information www.analog.com 13 LTC4444 TYPICAL APPLICATION LTC3780 High Efficiency 8V to 80V VIN to 12V/5A Buck-Boost DC/DC Converter 6V 10k 0.1F 0.01F SENSE+ SENSE- VOS+ 113k 1% 0.1F 1 68pF 20k 100pF 100 100 2 3 4 5 8.06k 1% 47pF 6 7 8 9 D4 VIN 150k 10 11 2.2F, 100V, TDK C4532X7R2A225MT 100F, 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 12 PGOOD SS 0.22F 16V D2 BOOST1 LTC3780EG TG1 SENSE+ SW1 SENSE- VIN ITH EXTVCC VOSENSE INTVCC SGND BG1 RUN PGND FCB BG2 PLLFLTR SW2 PLLIN TG2 STBYMD BOOST2 1F 16V VBIAS 12V 22 21 1 TG1 18 17 4 0.1F 16V 20 19 2 SW1 6V 10F 10V D1 3 24 23 VBIAS 12V 6 BOOST LTC4444 7 BINP TG TINP BG TS 8 + 2.2F 100V x5 VCC 0.22F 16V VOS+ 10 GND 1F 16V VIN 8V TO 80V 100F 100V x2 9 TG1 L1 8H 16 D3 22F 16V x3 + VOUT 12V, 5A C1 330F x2 SW1 15 14 13 6V D5 0.1F 16V 0.1F SENSE+ SENSE- 10 10 0.005 1W 4444 TA03 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC4446 High Voltage Synchronous N-Channel MOSFET Driver without Shoot-Through Protection Up to 100V Supply Voltage, 7.2V VCC 13.5V, 3A Peak Pull-Up/ 0.55 Peak Pull-Down LTC4440/LTC4440-5 High Speed, High Voltage, High Side Gate Driver Up to 80V Supply Voltage, 8V VCC 15V, 2.4A Peak Pull-Up/ 1.5 Peak Pull-Down LTC4442 High Speed Synchronous N-Channel MOSFET Driver Up to 38V Supply Voltage, 6V VCC 9.5V, 3.2A Peak Pull-Up/ 4.5A Peak Pull-Down LTC4449 High Speed Synchronous N-Channel MOSFET Driver Up to 38V Supply Voltage, 4.5V VCC 6.5V, 3.2A Peak Pull-Up/ 4.5A Peak Pull-Down LTC4441/LTC4441-1 N-Channel MOSFET Gate Driver Up to 25V Supply Voltage, 5V VCC 25V, 6A Peak Output Current LTC1154 High Side Micropower MOSFET Driver Up to 18V Supply Voltage, 85A Quiescent Current, H-Grade Available 14 Rev. C 12/18 www.analog.com For more information www.analog.com ANALOG DEVICES, INC. 2017-2018