TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
N-Channel MOSFET Driver
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.
bootstrapped
The LTC4444 is confi gured 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. The LTC4444 is available in the thermally enhanced 8-lead MSOP package.
■
Bootstrap Supply Voltage to 114V ■ Wide V CC
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
■
Distributed Power Architectures ■ Automotive Power Supplies ■ High Density Power Modules ■ Telecommunications
Protected by U.S. Patents, including 6677210.
High Input Voltage Buck Converter
V OUT
LTC4444 Driving a 1000pF Capacitive Load
BINP 5V/DIV
BG 10V/DIV TINP 5V/DIV TG-TS 10V/DIV
20ns/DIV
4444 TA01b
PIN CONFIGURATION
ABSOLUTE MAXIMUM RATINGS
Supply Voltage
V CC
.........................................................–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
(Note 1)
1234
TINP BINP V CC BG
8765TS TG BOOST NC
TOP VIEW
9
MS8E PACKAGE 8-LEAD PLASTIC MSOP
T JMAX  = 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
ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER CONDITIONS
MIN TYP
MAX UNITS
Gate Driver Supply, V CC
V CC Operating Voltage 7.2
13.5V I VCC DC Supply Current
TINP = BINP = 0V 350
550μA UVLO
Undervoltage Lockout Threshold
V CC  Rising
V CC  Falling Hysteresis ●●
6.00
5.60
6.606.15450
7.206.70
V V mV Bootstrapped Supply (BOOST – TS)I BOOST DC Supply Current TINP = BINP = 0V 0.1
2μA Input Signal (TINP , BINP)
V IH(BG)BG Turn-On Input Threshold BINP Ramping High ●  2.25  2.75  3.25V V IL(BG)BG Turn-Off Input Threshold BINP Ramping Low ●  1.85  2.3  2.75V V IH(TG)TG Turn-On Input Threshold TINP Ramping High ●  2.25  2.75  3.25V V IL(TG)TG Turn-Off Input Threshold TINP Ramping Low
●  1.85
2.3  2.75V I TINP(BINP)
Input Pin Bias Current
±0.01±2
μA
The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T A  = 25°C. V CC  = V BOOST  = 12V, V TS  = GND = 0V, unless otherwise noted.
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 specifi ed with wider operating temperature ranges.  *The temperature grade is identifi ed by a label on the shipping container.Consult LTC Marketing for information on non-standard lead based fi nish parts.For more information on lead free part marking, go to: www.linear/leadfree/ For more information on tape and reel specifi cations, go to: www.linear/tapeandreel/
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 specifi cations from 0°C to 85°C. Specifi cations 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.
ELECTRICAL CHARACTERISTICS  The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T A  = 25°C. V CC  = V BOOST  = 12V, V TS  = GND = 0V, unless otherwise noted.
SYMBOL PARAMETER CONDITIONS
MIN TYP MAX UNITS
High Side Gate Driver Output (TG)
V OH(TG)TG High Output Voltage I TG  = –10mA, V OH(TG) = V BOOST  – V TG 0.7V
V OL(TG)TG Low Output Voltage I TG  = 100mA, V OL(TG) = V TG  –V TS
●120
220mV I PU(TG)TG Peak Pull-Up Current ●  1.7  2.5A R DS(TG)TG Pull-Down Resistance ●
1.2
2.2
ΩLow Side Gate Driver Output (BG)
V OH(BG)BG High Output Voltage I BG  = –10mA, V OH(BG) = V CC  – V BG 0.7V
V OL(BG)BG Low Output Voltage I BG  = 100mA
●55
110mV I PU(BG)BG Peak Pull-Up Current ●23A R DS(BG)BG Pull-Down Resistance ●
0.55  1.1ΩSwitching Time (BINP (TINP) is Tied to Ground While TINP (BINP) is Switching. Refer to Timing Diagram)
t PLH(TG)TG Low-High Propagation Delay ●2545ns t PHL(TG)TG High-Low Propagation Delay ●2240ns t PLH(BG)BG Low-High Propagation Delay ●1935ns t PHL(BG)BG High-Low Propagation Delay ●
1430
ns t r(TG)TG Output Rise Time 10% – 90%, C L  = 1nF
10% – 90%, C L  = 10nF 880ns
ns t f(TG)TG Output Fall Time 10% – 90%, C L  = 1nF 10% – 90%, C L  = 10nF 550ns ns t r(BG)BG Output Rise Time 10% – 90%, C L  = 1nF 10% – 90%, C L  = 10nF 660ns ns t f(BG)
BG Output Fall Time
10% – 90%, C L  = 1nF 10% – 90%, C L  = 10nF
330
ns ns
Note 3: T J  is calculated from the ambient temperature T A  and power dissipation P D  according to the following formula:  T J  = T A  + (P D  • 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.
TYPICAL PERFORMANCE CHARACTERISTICS
V CC  Supply Quiescent Current vs Voltage
BOOST-TS Supply Quiescent Current vs Voltage
V CC  Supply Current vs Temperature
Boost Supply Current vs Temperature
Output Low Voltage (V OL ) vs Supply Voltage
Output High Voltage (V OH ) vs Supply Voltage
Input Thresholds (TINP , BINP) vs Supply Voltage
Input Thresholds (TINP , BINP) vs Temperature
Input Thresholds (TINP , BINP) Hysteresis vs Voltage
V CC  SUPPLY VOLTAGE (V)
00
Q U I E S C E N T  C U R R E N T  (μA )501502002506789101112134504444 G01
1001234514
300350400
BOOST SUPPLY VOLTAGE (V)
00
Q U I E S C E N T  C U R R E N T  (μA )50
1502002506789101112134004444 G02
1001234514
300350
TEMPERATURE (°C)
V C C  S U P P L Y  C U R R E N T  (μA )
350360
3704444 G03
330
300
–40–25–105203550658095110
125
380340320310
TEMPERATURE (°C)
B O O S T  S U P P L Y
C U R R E N T  (μA )
2503003504444 G04
1500
–40–25–105203550658095110125
400200
10050
SUPPLY VOLTAGE (V)7
O U T P U T  V O L T A G E  (m V )
14010
444343 G0580408
9
1120
0160
120100601213
14
SUPPLY VOLTAGE (V)
75
T G  O R  B G  O U T P U T  V O L T A G E  (V )
6
8910151291112
4444 G06
713
14118
101314
SUPPLY VOLTAGE (V)
7
2.1
T G  O R  B G  I N P U T  T H R E S H O L D  (V )
2.22.42.52.6
3.12.891112
4444 G072.32.93.02.78
1013
14
SUPPLY VOLTAGE (V)
78
375
T G  O R  B G  I N P U T  T H R E S H
O L D  H Y S T E R E S I S  (m V )
425
500
91112
4444 G09
400
475
450
101314
TEMPERATURE (°C)
–25T G  O R  B G  I N P U T  T H R E S H O L D  (V )
2.62.8
3.0
954444 G08
2.42.22.52.7
2.92.32.1
2.0
53565–10–40110205080125
TYPICAL PERFORMANCE CHARACTERISTICS
Input Thresholds (TINP , BINP) Hysteresis vs Temperature
V CC  Undervoltage Lockout Thresholds vs Temperature
Rise and Fall Time vs V CC  Supply Voltage
Rise and Fall Time vs Load Capacitance
Peak Driver (TG, BG) Pull-Up Current vs Temperature
Output Driver Pull-Down Resistance vs Temperature
Propagation Delay vs V CC  Supply Voltage
Propagation Delay vs Temperature
TEMPERATURE (°C)
–40–25375
T G  O R  B G  I N P U T  T H R E S H O L D  H Y S T E R E S I S  (m V )425
500
–105205065804444 G10
400
475
450
3511095125
TEMPERATURE (°C)
–406.0
V C C  S U P L L Y  V O L T A G E  (V )
6.1
6.36.46.56.7–2535654444 G11
6.26.62095125
110–10550
80SUPPLY VOLTAGE (V)
7
R I S E /F A L L  T I M E  (n s )
12283022263291112
4444 G12
8201610246
18148
1013
14
LOAD CAPACITANCE (nF)
1
R I S E /F A L L  T I M E  (n s )
4050609
4444 G13
302003572
10
46
8
108070TEMPERATURE (°C)
–402.0
P U L L -U P  C U R R E N T  (A )
2.2
2.6
2.8
3.03.4–2535654444 G14
2.4
3.22095125
110–1055080TEMPERATURE (°C)
–25O U T P U T  D R I V E R  P U L L -D O W N  R E S I S T A C N E  (Ω)
1.21.6
2.0954444 G15
0.80.41.01.41.80.60.2
53565–10–40110205080125
SUPPLY VOLTAGE (V)
7
10P R O P A G A T I O N  D E L A Y  (n s )
12161820302491112
4444 G16
142628228
1013
14
TEMPERATURE (°C)
–402
P R O P A G A T I O N  D E L A Y  (n s )
7
1722
2737–2535654444 G17
12322095125
110
–1055080
PIN FUNCTIONS
TYPICAL PERFORMANCE CHARACTERISTICS
Switching Supply Current vs Input Frequency
Switching Supply Current vs Load Capacitance
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).
V CC  (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 con-nected 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 V CC  and GND.NC (Pin 5): No Connect. No connection required.
BOOST (Pin 6): High Side Bootstrapped Supply. An ex-ternal capacitor should be tied between this p
in and TS (Pin 8). Normally, a bootstrap diode is connected between V CC  (Pin 3) and this pin. Voltage swing at this pin is from V CC  – V D  to V IN  + V CC  – V D , where V D  is the forward volt-age 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.
SWITCHING FREQUENCY (kHz)
S U P P L Y  C U R R E N T  (m A )
1.5
2.02.5600
1000
4444 G18
1.00.50200
400
8003.03.54.0
LOAD CAPACITANCE (nF)
1
S U P P L Y  C U R R E N T  (m A )
10
100
1
3450.1
2
789
610
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