Datasheet AAT4680 Datasheet (Analogic Technologies)

AAT4680

Electronic Resettable Fuse

General Description

The AAT4680 Electronic Resettable Fuse is part of
the AnalogicTech Application Specific Power MOS­FET (ASPM™) line of products. It is a 1A current
limited P-channel MOSFET power device that
remains fully enhanced as long as the input power
supply is above an under voltage lockout thresh­old, and the load is below the current limit setting.
If the load increases above the current limit setting,
as is the case during a short circuit, the MOSFET
effectively becomes a constant current source
equal to the current limit. If the current limit condi­tion persists long enough to heat the MOSFET to
an extreme temperature, the device will thermal
cycle off and on until the current limit condition is
removed. An open drain FAULT flag signals an
over current or over temperature condition.
Quiescent current is typically a low 10µA.

The AAT4680 is available in a 5-pin SOT-23, spec­ified over a -40 to 85°C temperature range.

SmartSwitch

Features

• 500mA steady state load current

• 600mA minimum current limit trip point

• Low quiescent current, typically 10µA

• Over temperature protection

• Fast transient response:

• < 1µs response to short circuit

• 400mΩ typical R

• Undervoltage Lockout

• Temp range -40 to 85°C

• FAULT flag with 3ms blanking

•5-pin SOT23 package

Applications

• USB ports

• Peripheral ports

• Desktop PCs

• Cell phone ports

DS(ON)

™

Preliminary Information

Typical Application

5

INPUT

IN

AAT4680

FAULT

C

IN

1µF

GND

4680.2001.11.0.91 1

GND

2

OUT

1

3

FAULT

C

1µF

OUT

OUT

GND

Electronic Resettable Fuse

Pin Descriptions

Pin # Symbol Function

1 OUT P-channel MOSFET drain

2 GND Ground connection

3 FAULT Open drain output signals over-current and over-temperature condition

4 NC Not internally connected

5 IN P-channel MOSFET source

Pin Configuration

SOT23-5

AAT4680

OUT

GND

FAULT

1

2

3

5

IN

4

NC

2 4680.2001.11.0.9

AAT4680

Electronic Resettable Fuse

Absolute Maximum Ratings (T

=25°C unless otherwise noted)

A

Symbol Description Value Units

V

IN

V

OUT

V

FLG

I

OUT

T

J

V

ESD

T

LEAD

Note: Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at con­ditions other than the operating conditions specified is not implied. Only one Absolute Maximum rating should be applied at any one time.

Note 1: Human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.

IN to GND -0.3 to 6 V
OUT to GND -0.3 to 6 V
FAULT to GND -0.3 to 6 V
Output Current Internally Limited A
Operating Junction Temperature Range -40 to 150 °C
ESD Rating1- HBM 5000 V
Maximum Soldering Temperature (at Leads) 300 °C

Thermal Characteristics

Symbol Description Value Units

Θ

JA

P

D

Note 2: Mounted on a demo board.

Maximum Thermal Resistance
Maximum Power Dissipation

2

2

150 °C/W
667 mW

Electrical Characteristics (V

= 5V, TA= -40 to 85°C unless otherwise noted. Typical values

IN

are at TA=25°C; bold values designate full temperature range)

Symbol Description Conditions Min Typ Max Units

V

IN

I

Q

V

UVLO

V

UVLO(hys)

R

DS(ON)

I

LIM

t

RESP

V

FAULTLOW

I

SINK

T

blank

T

SD

Operation Voltage 1.8 5.5 V
Quiescent Current VIN= 5V, I

= 0 10 20 µA

OUT

Undervoltage Lockout VINfalling 1.5 1.8 V
Undervoltage Lockout Hysteresis 0.3 V

V

= 5.0V,TA= 25°C 400 500

On-Resistance

IN

VIN= 3.V,TA= 25°C 525 650
Current Limit OUT < IN - 0.5V 0.6 0.875 1.25 A
Current Loop Response VIN= 5V 500 ns
FAULT Logic Output Low I
FAULT Logic Output High V

= 1mA 0.4 V

SINK

= 5.5V 0.5 1 µA

FAULT

Leakage Current
FAULT Blanking Time 3 ms
Over-temperature threshold 125 °C

mΩ

4680.2001.11.0.91 3

Typical Characteristics

(Unless otherwise noted, VIN= 5V, TA= 25°C)

AAT4680

Electronic Resettable Fuse

Quiescent Current vs. Temperature

20

18

A)

µ

16

14

12

10

8

6

4

Quiescent Current (

2

0

-40 -20 0 20 40 60 80 100 120

Temperature (°C)

Current Limit vs. Output Voltage

1

0.8

0.6

0.4

Output (A)

0.2

0

012345

Output (V)

Quiescent Current vs. Input Voltage

12

10

8

6

4

2

Quiescent Current (µA)

0

0123456

Input (V)

RDS(ON) vs. Temperature

700

650

600

550

500

(ON) (mΩ)

450

DS

R

400

350

300

-40 -20 0 20 40 60 80 100 120

Temperature (°C)

VIN=3V

VIN=5V

Short Circuit Through 0.3Ω

6

4

2

0

Input and Output (V)

-2

-0.5 0.0 0.5 1.0 1.5 2.0

Time (µs)

Input Voltage

Output Voltage

Output Current

7

5

3

1

-1

Output (A)

Input and Output (V)

Short Circuit Through 0.6Ω

6

4

2

0

-0.5 0.0 0.5 1.0 1.5 2.0

Time (µs)

Input Voltage

Output Current

Output Voltage

5

3

1

-1

4 4680.2001.11.0.9

Output (A)

Typical Characteristics

(Unless otherwise noted, VIN= 5V, TA= 25°C)

AAT4680

Electronic Resettable Fuse

Thermal Shutdown Response

FAULT (5V/div)

V

(2V/div)

OUT

IIN (500mA/div)

50ms/div

Fault Delay

FAULT (5V/div)

V

(2V/div)

OUT

IIN (500mA/div)

2ms/div

4680.2001.11.0.91 5

Functional Block Diagram

IN OUT

Under-Voltage

Lockout

AAT4680

Electronic Resettable Fuse

Over-Temp

Protection

Current

Limit

FAULT

Functional Description

The AAT4680 is a single channel electronic reset­table fuse that protects against short circuit condi­tions by current limiting to a preset level. A patent­ed fast acting current limit loop limits load current in
a fraction of a microsecond, and instantly resets to
low impedance once the short circuit condition is
removed. A current limit condition is reported by the
open drain FAULT output after a three millisecond
blanking interval. The blanking prevents false
reporting during the charging of a capacitive load,
which typically occurs when a load is connected.
The AAT4680 is internally protected from thermal
damage by an over temperature detection circuit. If

3ms Blanking

GND

the die temperature reaches the internal thermal
limit, the power device is switched off until the die
temperature cools to a level below the thermal limit
threshold. The device will thermal cycle indefinitely
until the over current condition is removed. The
AAT4680 operates with input voltages ranging from

1.8V to 5.5V which, along with extremely low oper­ating current, makes it ideal for battery-powered
applications. In cases where the input voltage
drops below 1.8V, the AAT4680 internal MOSFET is
protected from entering the saturated region of
operation by being automatically shut down by an
under voltage lockout circuit.

The AAT4680 is ideally suited for protection of peri­pheral ports such as USB, RS232 and parallel ports.

6 4680.2001.11.0.91

AAT4680

Electronic Resettable Fuse

Applications Information

Input Capacitor

The input capacitor, CIN, protects the power supply
from current transients generated by the load
attached to the AAT4680. If a short circuit is sud­denly applied to the output of the AAT4680, there is
a 500 nanosecond long period during which a large
current can flow before current limit circuitry acti­vates. (See characteristic curve "Short Circuit

Through 0.3Ω.") In this event, a properly sized input

capacitor can dramatically reduce the voltage tran­sient seen by the power supply and other circuitry
upstream from the AAT4680.

CINshould be located as close to the device VINpin
as practically possible. Ceramic, tantalum or alu­minum electrolytic capacitors may be selected for
CIN. There is no specific capacitor ESR requirement
for CIN. However, for higher current operation,
ceramic capacitors are recommended for CINdue to
their inherent capability over tantalum capacitors to
withstand input current surges from low impedance
sources such as batteries in portable devices.

Output Capacitor

In order to insure stability while current limit is
active, a small output capacitance of approximately
1µF is required. No matter how big the output
capacitor, output current is limited to the value set
by the AAT4680 current limiting circuitry, allowing
very large output capacitors to be used.

For example, USB ports are specified to have at
least 120µF of capacitance down stream from their
controlling power switch. The current limiting circuit
will allow an output capacitance of 1000µF or more
without disturbing the upstream power supply.

Attaching Loads

Capacitive loads attached to the AAT4680 will charge
at a rate no greater than the current limit setting.

FAULT Output

A FAULT flag is provided to alert a system if the
AAT4680 load is not receiving sufficient voltage to
operate properly. If current limit or over tempera­ture circuits in any combination are active for more
than approximately three milliseconds, FAULT is

pulled to ground through approximately 100Ω .

Removal of voltage or current transients of less

than two milliseconds prevents capacitive loads
connected to the AAT4680 output from activating
the FAULT flag when they are initially attached.

Pull up resistances of 1kΩ to 100kΩ are recom-

mended. Since FAULT is an open drain terminal, it
may be pulled up to any voltage rail less than the
maximum operating voltage of 5.5V, allowing for
level shifting between circuits.

Thermal Considerations

Since the AAT4680 has internal current limit and
over temperature protection, junction temperature is
rarely a concern. However, if the application
requires large currents in a hot environment, it is
possible that temperature rather than current limit will
be the dominant regulating condition. In these appli­cations, the maximum current available without risk
of an over temperature condition must be calculated.
The maximum internal temperature while current
limit is not active can be calculated using Equation 1.

TJ(MAX) = I

In Equation 1, I
required by the load. R
mum rated R
ature. R
AAT4680 die and the board onto which it is mount­ed. TA(MAX) is the maximum temperature that the
PCB under the AAT4680 would be if the AAT4680
were not dissipating power. Equation 1 can be
rearranged to solve for I

TSD(MIN) is the minimum temperature required to
activate the AAT4680 over temperature protection.
With typical specification of 125°C, 115°C is a safe
minimum value to use.

For example, if an application is specified to oper­ate in 50°C environments, the PCB operates at
temperatures as high as 85°C. The application is
sealed and its PCB is small, causing R
approximately 150°C/W. Using Equation 2,

To prevent thermal limiting, the operating load cur­rent in the application must be less than 575mA.

2

× R

MAX

MAX

DS(ON)

is the thermal resistance between the

θJA

I

=

MAX

I

=

MAX

DS(ON)

(MAX) × R

+ TA(MAX)

θJA

is the maximum current

(MAX) is the maxi-

DS(ON)

of the AAT4680 at high temper-

; Equation 2.

MAX

(MIN) - TA(MAX)

T

SD

R

600 × 150

DS(ON)

115 - 8 5

(MAX) × R

= 575 mA

θJA

θJA

to be

4680.2001.11.0.91 7

Ordering Information

c

AAT4680

Electronic Resettable Fuse

Package Marking

SOT23-5 N/A AAT4680IGV-T1

Package Information

e

S1

H

E

D

A

A1

S

b

Part Number

Bulk Tape and Reel

Dim

Millimeters Inches

Min Max Min Max

A 0.95 1.45 0.037 0.057
A1 0.05 0.15 0.002 0.006
A2 0.90 1.30 0.035 0.051

b 0.35 0.50 0.014 0.019

c 0.08 0.20 0.003 0.078
D 2.84 3.00 0.112 0.112
E 1.50 1.70 0.059 0.067
e 1.90 0.0748
H 2.60 3.00 0.102 0.118
L 0.35 0.55 .0137 .0216
S 0.47 0.55 0.019 .0216

S1 .95 0.037

L

Θ 0° 10° 0° 10°

Advanced Analogic Technologies, Inc.

1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086
Phone [phone]
Fax [phone]

8 4680.2001.11.0.9