Linear Technology LTC1477, LTC1478 Datasheet

FEATURES

■

Extremely Low R

■

No Parasitic Body Diode

■

Built-In Short-Circuit Protection: 2A

■

Built-In Thermal Overload Protection

■

Operates from 2.7V to 5.5V

■

Inrush Current Limited

■

Ultralow Standby Current: 0.01µA

■

Built-In Charge Pump

■

Controlled Rise and Fall Times: tR = 1ms

■

Single Switch in 8-Pin SO Package

■

Dual Switch in Narrow 16-Pin SO Package

Switch: 0.07

DS(ON)

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APPLICATIONS

■

Notebook Computer Power Management

■

Power Supply/Load Protection

■

Supply/Battery Switch-Over Circuits

■

Circuit Breaker Function

■

"Hot Swap" Board Protection

■

Peripheral Power Protection

Ω

LTC1477/LTC1478

Single and Dual Protected

High Side Switches

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DESCRIPTION

The LTC®1477/LTC1478 protected high side switches
provide extremely low R

DS(ON)

protection against short-circuit and thermal overload con­ditions. A built-in charge pump generates gate drive
higher than the supply voltage to fully enhance the internal
NMOS switch. This switch has no parasitic body diode and
therefore no current flows through the switch when it is
turned off and the output is forced above the input supply
voltage. (DMOS switches have parasitic body diodes that
become forward biased under these conditions.)

Two levels of protection are provided by the
LTC1477/LTC1478. The first level of protection is short­circuit current limit which is set at 2A. The short-circuit
current can be reduced to as low as 0.85A by disconnect­ing portions of the power device (see Applications Infor­mation). The second level of protection is provided by
thermal overload protection which limits the die tempera­ture to approximately 130°C.

The LTC1477 single is available in 8-lead SO packaging.
The LTC1478 dual is available in 16-lead SO packaging.

switching with built-in

SI PLIFIED BLOCK DIAGRAM

EN

GATE CHARGE

AND

DISCHARGE

CONTROL LOGIC

CHARGE

PUMP

*NMOS SWITCHES WITH NO PARASITIC BODY DIODES

V

INS

CURRENT LIMIT

AND THERMAL

SHUTDOWN

V

IN1

***

V

IN2

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

WW

V

IN3

V

OUT

LTC1477/1478 • TA01

5.20

5.10

5.00

4.90

4.80

OUTPUT VOLTAGE (V)

4.70

4.60

Switch Output Voltage

TA = 25°C

= V

V

0

= V

IN1

IN2

0.5 0.75 1.00

0.25
OUTPUT CURRENT (A)

IN3

= V

INS

= 5V

1.25 1.50

LTC1477/1478 • TP02

1

LTC1477/LTC1478

WW

W

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ABSOLUTE MAXIMUM RATINGS

Supply Voltage .......................................................... 7V

Enable Input Voltage...................... (7V) to (GND –0.3V)

Output Voltage (OFF) (Note 1) .......(7V) to (GND –0.3V)

Output Short-Circuit Duration.......................... Indefinite

Junction Temperature...........................................110°C

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PACKAGE/ORDER INFORMATION

ORDER PART

NUMBER

LTC1477CS8

S8 PART MARKING

1477

V

1



OUT

V



2

IN1

V



3

INS

EN

4

8-LEAD PLASTIC SO

T

= 110°C, θJA = 120°C/W

JMAX

TOP VIEW

S8 PACKAGE

V

8

OUT

V



7

IN2

V



6

IN3

GND

5

Operating Temperature

LTC1477C/LTC1478C ..............................0°C to 70°C

Storage Temperature Range ................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec)..................300°C

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1

AV



OUT

2

AV



IN

3

AV



INS

4

AEN

5

GND

6

BV



IN3

7

BV



IN2

8

BV



OUT



16-LEAD PLASTIC SO

T

JMAX

TOP VIEW

16
15
14
13
12
11
10

9

S PACKAGE

= 110°C, θJA = 100°C/ W

AV
AV
AV
GND
BEN
BV
BV
BV


OUT

IN2

IN3

INS

IN1

OUT










ORDER PART

NUMBER

LTC1478CS

Consult factory for Industrial and Military grade parts.

ELECTRICAL CHARACTERISTICS

V

= V

= V

= V

INS

IN1

IN2

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IN

I

VIN

R

ON

I

LKG

I

SC

V

ENH

V

ENL

I

EN

t

D+R

The

Supply Voltage Range 2.7 5.5 V
Supply Current Switch OFF, Enable = 0V ● 0.01 10 µA

ON Resistance V

Output Leakage Current OFF Switch OFF, Enable = 0V ● ±20 µA
Short-Circuit Current Limit V

Enable Input High Voltage 3.0V ≤ V
Enable Input Low Voltage 3.0V ≤ V
Enable Input Current 0V ≤ VEN ≤ 5.5V ● ±1 µA
Delay and Rise Time R

● denotes specifications which apply over the full operating

temperature range.

Note 1: The V
Note 2: The V

pins are typically connected to V

V

IN3

pins must be connected together.

OUT

and V

INS

selectively disconnected to reduce the short-circuit current limit and

= 5V (Note 2), TA = 25°C, unless otherwise noted. Each channel of the LTC1478 is tested separately (Note 3).

IN3

Switch ON, Enable = 5V, VIN = 5V ● 120 180 µA
Switch ON, Enable = 3.3V, VIN = 3.3V ● 80 120 µA

= V

= V

= V

INS

V

INS

V

INS

V

INS

INS

V

INS

OUT

IN1

= V
= V
= V

= V
= V

IN2

= V

IN1

IN2

= 5V, V

IN1

= 3.3V, V

IN1

= V

IN1

IN2

= 5V, V

IN1

≤ 5.5V ● 2.0 V

INS

≤ 5.5V ● 0.8 V

INS

= 100Ω, C

= 5V, I

IN3

= V

= 3.3V, I

IN3

= V

IN2

IN3

= V

IN2

= V

= 5V, V

IN3

= V

IN2

IN3

= 1µF, to 90% of Final Value 0.50 1.00 2.00 ms

OUT

= 1A 0.07 0.12 Ω

OUT

= 1A 0.08 0.12 Ω

OUT

= NC, I

= NC, I

IN3

= NC, V

= 0.5A 0.12 0.20 Ω

OUT

= 0.5A 0.13 0.20 Ω

OUT

= 0V, (Note 4) 1.60 2.00 2.40 A

OUT

= 0V, (Note 4) 0.68 0.85 1.02 A

OUT

increase the ON resistance of the switch. The LTC1478 GND pins must be
connected together. (See Pin Functions and Block Diagram for more detail.)

Note 3: Other channel turned OFF, i.e. AEN and BEN = 0V.

pins must be connected together. The V

IN1

INS

and V

pins but can be

IN1

IN2

and

Note 4: The output is protected with fold-back current limit which reduces
the short-circuit (0V) currents below peak permissible current levels at
higher output voltages. (See Typical Performance Characteristics for
further detail on output current versus output voltage).

2

W

JUNCTION TEMPERATURE (°C)

0

0

SWITCH RESISTANCE (Ω)

0.05

0.10

0.15

0.20

0.25

0.30

25 50 75 100

LTC1477/1478 • TPC03

125

V

INS

= V

IN1

= 5V

V

IN2

= V

IN3

= NC

ALL VIN PINS = 5V

OUTPUT VOLTAGE (V)

0

0

OUTPUT CURRENT (A)

1

2

3

4

6

1

234

LTC1477/1478 • TPC06

56

5

TA = 25°C

ALL VIN PINS = 5V

V

IN2

= V

IN3

= NC

TIME (ms)

–0.4

INRUSH CURRENT (A)OUTPUT VOLTAGE (V)



0

1

2.8

LTC1477/1478 • TPC09

6

4

0

0.4

1.2

2.0

2

3

2

0

0.8

1.6

2.4

C

OUT

= 470µF

R

OUT

= 10Ω

C

OUT

= 10µF

R

OUT

= 10Ω

CURRENT
LIMITED

TJ = 25°C
ALL V

IN

PINS = 3.3V

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TYPICAL PERFORMANCE CHARACTERISTICS

LTC1477/LTC1478

Supply Current (ON) Switch Resistance

300

TA = 25°C
OUTPUT TURNED ON, NO LOAD

250

200

150

100

SUPPLY CURRENT (µA)

50

0

0

1

SUPPLY VOLTAGE (V)

234

LTC1477/1478 • TPC01

56

SWITCH RESISTANCE (Ω)

0.30

0.25

0.20

0.15

0.10

0.05

0

TA = 25°C

1

2

Switch Resistance (3.3V) Short-Circuit Current

SWITCH RESISTANCE (Ω)

0.30

0.25

0.20

0.15

0.10

0.05

V

= V

= 3.3V

INS

IN1

= V

V

= NC

IN2

IN3

ALL VIN PINS = 3.3V

3.0
TJ = 25°C

2.5

2.0

1.5

1.0

SHORT-CIRCUIT CURRENT (A)

0.5

V

= V

IN2

ALL VIN PINS 
CONNECTED

345

INPUT VOLTAGE (V)

ALL VIN PINS
CONNECTED

V

= V

IN2

IN3

= NC

IN3

67

LTC1477/1478 • TPC02

= NC

Switch Resistance (5V)

Output Current (5V)

0

6

5

4

3

2

OUTPUT CURRENT (A)

1

0

0

25 50 75 100

JUNCTION TEMPERATURE (°C)

125

LTC1477/1478 • TPC04

0

0

234

1

SUPPLY VOLTAGE (V)

Output Current (3.3V) Inrush Current (5V)

TA = 25°C

ALL VIN PINS = 3.3V

V

= V

= NC

IN2

IN3

0

234

1

OUTPUT VOLTAGE (V)

56

LTC1477/1478 • TPC07

3

2

1

0

INRUSH CURRENT (A)OUTPUT VOLTAGE (V)

6

4

2

0

–0.4

C

= 10µF

OUT



= 10Ω

R

OUT

0

0.4

1.2

0.8
TIME (ms)

C

OUT

R

OUT

LTC1477/1478 • TPC05

CURRENT
LIMITED

= 470µF

= 10Ω

TJ = 25°C
ALL V

IN

1.6

56

PINS = 5V

2.0

2.4

LTC1477/1478 • TPC08

Inrush Current (3.3V)

2.8

3