Datasheet

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LTC1155

Dual High Side

Micropower MOSFET Driver

ITY

■

Fully Enhances N-Channel Power MOSFETs

■

8µA Standby Current

■

85µA ON Current

■

Short-Circuit Protection

■

Wide Power Supply Range: 4.5V to 18V

■

Controlled Switching ON and OFF Times

■

No External Charge Pump Components

■

Replaces P-Channel High Side MOSFETs

■

Compatible with Standard Logic Families

■

Available in 8-Pin SO Package

ESCRIPTIO

The LTC

1155 dual high side gate driver allows using low

cost N-channel FETs for high side switching applications.

An internal charge pump boosts the gate above the posi-

tive rail, fully enhancing an N-channel MOSFET with no

external components. Micropower operation, with 8µA

standby current and 85µA operating current, allows use in

virtually all systems with maximum efficiency.

Included on-chip is overcurrent sensing to provide auto-

matic shutdown in case of short circuits. A time delay can

be added in series with the current sense to prevent false

triggering on high in-rush loads such as capacitors and

incandescent lamps.

The LTC1155 operates off of a 4.5V to 18V supply input

and safely drives the gates of virtually all FETs. The

LTC1155 is well suited for low voltage (battery-powered)

applications, particularly where micropower “sleep” op-

eration is required.

The LTC1155 is available in both 8-pin PDIP and 8-pin SO

packages.

, LTC and LT are registered trademarks of Linear Technology Corporation.

■

Laptop Power Bus Switching

■

SCSI Termination Power Switching

■

Cellular Phone Power Management

■

P-Channel Switch Replacement

■

Relay and Solenoid Drivers

■

Low Frequency Half H-Bridge

■

Motor Speed and Torque Control

OUTPUT CURRENT (A)

0.00

VOLTAGE DROP (V)

0.05

0.10

0.15

0.20

0.25

123

1155 TA02

Switch Voltage Drop

1155 TA01

SEN



0.02Ω

DLY



0.1µF

10µF

5A

MAX

DLY



100k

POWER BUS

µP

SYSTEM

DISK

DRIVE

DISPLAY

PRINTER,

ETC.

LTC1155

TTL, CMOS INPUT

GND

IN1

IN2

DS2V

DS1

= 4.5V TO 5.5V

DLY



0.1µF

SEN



0.02Ω

DLY



100k

*SURFACE MOUNT

*IRLR034

5A

MAX

*IRLR034

Laptop Computer Power Bus Switch with Short Circuit Protection

Summary of content (16 pages)

PAGE 1
LTC1155 Dual High Side Micropower MOSFET Driver U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ The LTC®1155 dual high side gate driver allows using low cost N-channel FETs for high side switching applications. An internal charge pump boosts the gate above the positive rail, fully enhancing an N-channel MOSFET with no external components. Micropower operation, with 8µA standby current and 85µA operating current, allows use in virtually all systems with maximum efficiency.
PAGE 2
LTC1155 W W W AXI U U ABSOLUTE RATI GS (Note 1) Supply Voltage ........................................................ 22V Input Voltage ...................... (VS +0.3V) to (GND – 0.3V) Gate Voltage ......................... (VS +24V) to (GND – 0.3V) Current (Any Pin).................................................. 50mA Storage Temperature Range ................. – 65°C to 150°C Operating Temperature Range LTC1155C................................................ 0°C to 70°C LTC1155I.............
PAGE 3
LTC1155 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 4.5V to 18V, unless otherwise noted.
PAGE 4
LTC1155 U W TYPICAL PERFOR A CE CHARACTERISTICS Turn ON Time CGATE = 1000pF 900 800 40 700 35 600 500 400 VGS = 5V 300 200 VGS = 2V 100 0 Short-Circuit Turn OFF Delay Time 50 CGATE = 100pF TIME FOR VGATE < 1V 45 TURN OFF TIME (µs) TURN-ON TIME (µs) Turn OFF Time 50 40 30 25 20 15 30 25 15 10 5 0 15 5 10 SUPPLY VOLTAGE (V) 0 20 0 20 Standby Supply Current Supply Current Per Side (ON) Input ON Threshold 900 2.2 800 2.
PAGE 5
LTC1155 U U U PIN FUNCTIONS The supply pin of the LTC1155 should not be forced below ground as this may result in permanent damage to the device. A 300Ω resistor should be inserted in series with the ground pin if negative supply voltages are anticipated. This pin is also a high impedance CMOS gate with ESD protection and, therefore, should not be forced beyond the power supply rails. To defeat the over current protection, short the drain sense to supply.
PAGE 6
LTC1155 U OPERATIO Gate Charge Pump Gate drive for the power MOSFET is produced by an adaptive charge pump circuit that generates a gate voltage substantially higher than the power supply voltage. The charge pump capacitors are included on-chip and, therefore, no external components are required to generate the gate drive. Drain Current Sense The LTC1155 is configured to sense the drain current of the power MOSFET in high side applications.
PAGE 7
LTC1155 U W U UO APPLICATI S I FOR ATIO IPEAK = VSUPPLY/0.08Ω = 62.5A The drop across the drain sense resistor under these conditions is much larger than 100mV and is equal to the drain current times the sense resistance: VDROP = (IPEAK)(RSEN) = 1.88V By consulting the power MOSFET data sheet SOA graph, we note that the IRLZ34 is capable of delivering 62.5A at a drain-to-source voltage of 3.12V for approximately 10ms.
PAGE 8
LTC1155 W U U UO APPLICATI S I FOR ATIO VS = 5.0V CDLY 0.22µF RDLY 270k VS IN1 RSEN 0.025Ω DS1 D1 1N4148 LTC1155 IRLZ34 G1 GND If the MOSFET is turned ON and the power supply (battery) removed, the inductor current is delivered by the supply capacitor. The supply capacitor must be large enough to deliver the energy demanded by the discharging inductor. If the storage capacitor is too small, the supply lead of the LTC1155 may be pulled below ground, permanently destroying the device.
PAGE 9
LTC1155 W U U UO APPLICATI S I FOR ATIO VS = 4.5V TO 18V 18.6V and pulls the drain sense pin 0.6V below the supply pin voltage. RSEN CDLY RDLY VS DS1 + IN1 The supply voltage is limited to 18.6V and the gate drive is immediately removed from the MOSFET to ensure that it cannot conduct during the overvoltage period. The gate of the MOSFET will be latched OFF until the supply transient is removed and the input turned OFF and ON again. 10µF 25V LTC1155 100k G1 GND VS = 4.
PAGE 10
LTC1155 UO TYPICAL APPLICATI S High Side Driver with VDS Sense Short-Circuit Shutdown X-NOR Fault Detection 4.5V TO 6V 4.5V TO 6V + + 10µF VS 5V IN1 * 10µF 30k 0.1Ω VS DS1 1/2 LTC1155 GND IN1 IRLZ24 G1 DS1 1/2 LTC1155 GND 10k IRLD024 G1 100k 0.01µF 270k FAULT LOAD 74C266 LOAD 1155 TA05 *ANY 74C OR 74HC LOGIC GATE.
PAGE 11
LTC1155 UO TYPICAL APPLICATI S Automotive High Side Driver with Reverse-Battery and High Voltage Transient Protection 5V/3A Extremely Low Voltage Drop Regulator with 10µA Standby Current and Short-Circuit Protection 5.2V TO 6V 9V TO 16V + 100k* IN1 10µF 0.02Ω 5% 0.1µF RDLY** VS 5V + CDLY** 10µF 18V 1N4746A 1/2 LTC1155 300k VS DS1 IN1 ON/OFF 0.02Ω DS1 1/2 LTC1155 100k MTP50N05E G1 GND IRLR024 G1 GND 18V 1N4746A 200pF FAULT 10k 0.1µF 300Ω 1/4W VALVE, ETC.
PAGE 12
LTC1155 UO TYPICAL APPLICATI S Logic Controlled Boost Mode Switching Regulator with Short-Circuit Protection and 8µA Standby Current 4.75V TO 5.25V + 0.33µF 100µF 100k VS FROM µP, ETC. 0.02Ω DS1 1/2 LTC1155 IN1 MTM25N05L G1 GND 5V SWITCHED FAULT 1N5820 50µH* 1N4148 12V/1A 5 4 1 + LT1170 68µF 10.7k 1% 2 + 2200µF 1k 3 1.24k 1% 1µF *COILTRONICS CTX-7-52 1155 TA12 High Efficiency 60Hz Full-Wave Synchronous Rectifier ** 18V 1N4746A S 1N4148 IRFZ44* 9V/3A DC D 100k 10k 12.
PAGE 13
LTC1155 UO TYPICAL APPLICATI S High Efficiency 60Hz Full-Wave Synchronous Rectifier 9V/3A DC 10k 110V AC 6.3V AC 2 100k 1N4148 – DS2 IN1 7 6 LT1006 3 4 × IRFZ44* + VS DS1 G1 ** LTC1155 1N4148 IN2 4 ** 18V 1N4746A 100k 10Ω D S D S S S D ** + 4700µF 16V G2 GND 10k D ** 18V 1N4746A 0.
PAGE 14
LTC1155 UO TYPICAL APPLICATI S Full H-Bridge Driver with Shoot-Through Current Lockout and Stall Current Shutdown (fO < 100Hz) 4.5V TO 6V 10µF 0.01Ω 0.1µF 100k 5V DIRECTION 74HC02 DS1 IN1 VS DS2 G1 IRLZ44 IRLZ44 * LTC1155 IN2 VN2222L G2 M GND DISABLE * IRFZ44 IRFZ44 VN2222L 1155 TA16 *OPPOSING GATES ARE HELD OFF UNTIL OTHER GATES DROP BELOW 1.5V DC Motor Speed and Torque Control for Cordless Tools and Appliances + 100Ω 6V + 0.1µF 1.1k 47µF 16V 300k 1M 0.
PAGE 15
LTC1155 U PACKAGE DESCRIPTIO Dimensions in inches (milimeters) unless otherwise noted. J8 Package 8-Lead CERDIP (Narrow 0.300, Hermetic) (LTC DWG # 05-08-1110) 0.300 BSC (0.762 BSC) CORNER LEADS OPTION (4 PLCS) 0.015 – 0.060 (0.381 – 1.524) 0.023 – 0.045 (0.584 – 1.143) HALF LEAD OPTION 0.008 – 0.018 (0.203 – 0.457) 0° – 15° 0.045 – 0.068 (1.143 – 1.727) FULL LEAD OPTION 0.405 (10.287) MAX 0.005 (0.127) MIN 0.200 (5.080) MAX 8 0.220 – 0.310 (5.588 – 7.874) 2 3 4 J8 1197 0.125 3.175 0.
PAGE 16
LTC1155 UO TYPICAL APPLICATI S Isolated High Voltage High Side Switch with Circuit Breaker 6V TO 12V 1N5817 1N4148 1/6 74C14 1k C 0.1µF 200V 10mA CONTROL 1k B 100k + 90V 4N28 E DS1 IN1 10µF 25V 1N4148 100pF VS DS2 G1 6A MAX LTC1155 1N5817 IN2 1k G2 2N2222 GND 18V 1N4746A 1M 0.1Ω MUR420 M 1155 TA18 Isolated Solid-State AC Relay with Circuit Breaker 18V 1N4746A 18V 1N4746A IN/OUT IRFZ24 5V 0.1µF 1/6 74C14 0.01µF 5.6V 1N4690A 1N5817 100k 0.