Datasheet

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LTC4444

4444fb

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

High Voltage Synchronous

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. This

powerful driver reduces switching losses in MOSFETs with

high gate capacitance.

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. 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

6.6V 6.6V 4V

–

6.15V 6.15V 3.55V

Bootstrap Supply Voltage to 114V

Wide V

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

High Input Voltage Buck Converter LTC4444 Driving a 1000pF Capacitive Load

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and

No R

SENSE

is a trademark of Linear Technology Corporation. All other trademarks are the

property of their respective owners. Protected by U.S. Patents, including 6677210.

BOOST

100V

(ABS MAX)

GND

TINP

LTC4444

PWM2

(FROM CONTROLLER IC)

PWM1

(FROM CONTROLLER IC)

7.2V TO 13.5V

BINP

OUT

4444 TA01a

BINP

5V/DIV

10V/DIV

TINP

5V/DIV

TG-TS

10V/DIV

20ns/DIV

4444 TA01b

Summary of content (14 pages)

PAGE 1
LTC4444 High Voltage Synchronous N-Channel MOSFET Driver FEATURES DESCRIPTION n 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. This powerful driver reduces switching losses in MOSFETs with high gate capacitance. n n n n n n n n n n n n n 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.
PAGE 2
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 ..................................................
PAGE 3
LTC4444 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VCC = VBOOST = 12V, VTS = GND = 0V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS 250 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.
PAGE 4
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 250 200 150 100 360 TINP = BINP = 0V 350 340 330 TINP(BINP) = 12V 320 310 50 50 VCC = BOOST = 12V TS = GND 370 VCC SUPPLY CURRENT (μA) VC
PAGE 5
LTC4444 TYPICAL PERFORMANCE CHARACTERISTICS 6.7 VCC = BOOST = 12V TS = GND 6.6 475 450 425 400 BOOST = VCC TS = GND RISING THRESHOLD 6.5 6.4 6.3 6.2 FALLING THRESHOLD 6.1 5 35 65 95 TEMPERATURE (°C) 6.0 –55 125 150 80 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) 2.8 2.6 IPU(TG) 2.4 2.
PAGE 6
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 3.5 VCC = BOOST = 12V 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 AT 1MHz) 10 IVCC (BG SWITCHING AT 500kHz) IVCC IVCC (TG SWITCHING (TG SWITCHING AT 500kHz) AT 1MHz) 1 0.
PAGE 7
LTC4444 BLOCK DIAGRAM 6 7.2V TO 13.
PAGE 8
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.
PAGE 9
LTC4444 OPERATION 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.
PAGE 10
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.
PAGE 11
LTC4444 TYPICAL APPLICATION LTC3780 High Efficiency 36V to 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 s4 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.
PAGE 12
LTC4444 PACKAGE DESCRIPTION MS8E Package 8-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1662 Rev I) BOTTOM VIEW OF EXPOSED PAD OPTION 1.88 (.074) 1 1.88 t 0.102 (.074 t .004) 0.29 REF 1.68 (.066) 0.889 t 0.127 (.035 t .005) 0.05 REF 5.23 (.206) MIN DETAIL “B” CORNER TAIL IS PART OF DETAIL “B” THE LEADFRAME FEATURE. FOR REFERENCE ONLY NO MEASUREMENT PURPOSE 1.68 t 0.102 3.20 – 3.45 (.066 t .004) (.126 – .136) 8 3.00 t 0.102 (.118 t .004) (NOTE 3) 0.65 (.0256) BSC 0.42 t 0.038 (.
PAGE 13
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 4444fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use.
PAGE 14
LTC4444 TYPICAL APPLICATION LTC3780 High Efficiency 8V to 80V VIN to 12V/5A Buck-Boost DC/DC Converter VBIAS 12V 6V 10k 0.1μF 0.01μF SENSE+ 100pF VOS+ 113k 1% 0.1μF 1 68pF SENSE– 100Ω 2 SW1 – VIN 6 7 10 11 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.