AAT4625IKS-T1 - AnalogicTech

SmartSwitch™

AAT4625

USB Single-Channel Power Switch

Preliminary Information

4625.2002.12.0.95 1

General Description

The AAT4625 SmartSwitch™ is part of

AnalogicTech's Application Specific Power

MOSFET™ (ASPM™) product family. It is a 1.0A

Current Limited P-channel, MOSFET power switch

designed for high-side load-switching applications.

This switch operates with inputs ranging from 2.7V

to 5.5V, making it ideal for both 3V and 5V systems.

An integrated current-limiting circuit protects the

input supply against large changes in load current

which may cause the supply to fall out of regulation.

The AAT4625 is also protected from thermal over-

load which limits power dissipation and junction

temperatures. The current limit threshold is factory

programmed at 1.5A, with a maximum of 2.0A. The

quiescent supply current is typically a low 16µA. In

shutdown mode, the supply current decreases to

less than 1µA.

The AAT4625 is available in 8 pin SOP, TSSOP, or

MSOP and is specified over a -40 to 85°C temper-

ature range.

The AAT4600 Series is a family of adjustable and

fixed SmartSwitch™ products with a range of cur-

rent handling capabilities. Single versions with

adjustable current limit (AAT4601) or fixed current

limit (AAT4625) as well as dual versions with fixed

current limit (AAT4626) are available.

Features

• Compliant with USB 1.1 and 2.0 specifications

• 2.7V to 5.5V Input voltage range

• 1.0A minimum continuous current

• 2.0A maximum current limit

• 60mΩtypical RDS(ON)

• Low quiescent current

• Typically 16µA

• 1µA max with Switch off

• Thermal shutdown

• Slew rate limited turn on

• Fault flag with 10ms blanking

• Undervoltage Lockout

• Temp range -40 to 85°C

• UL Approved—File No. E217765

• 8 pin SOP, TSSOP, or MSOP package

Applications

• USB ports and peripherals

• Notebook computers

• Hot swap supplies

• General purpose power switching

UL Recognized Component

Typical Application

120µF

GNDGND

OUTPUT

OUT

EN (EN)EN (EN)

0.1µF

VCC 5.0V

100k

FLG

AAT4625

Pin Descriptions

Pin Configuration

SOP-8

TSSOP-8

MSOP-8

(Top View)

1 2

OUT

EN (EN)

FLG

GND

Pin # Symbol Function

1 EN (EN) Enable Input: Logic-compatible enable input. High input > 2.1V typical. Low

input < 1.9V typical. Active high or active low option available; see Ordering

Information for details.

2 FLG Fault Flag Output: Active-low, open-drain output. Indicates over current,

UVLO and thermal shutdown.

3 GND Ground connection

4,5 NC Not internally connected.

6,8 OUT Switch Output: These pins are the P-channel MOSFET drain connection.

7 IN Supply Input: This pin is the P-channel MOSFET source connection. Also

supplies the IC's internal circuitry.

AAT4625

USB Single-Channel Power Switch

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Absolute Maximum Ratings (TA=25°C unless otherwise noted)

Note: Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at con-

ditions other than the operating conditions specified is not implied. Only one Absolute Maximum rating should be applied at any one time.

Thermal Information

Note 1: Mounted on an FR4 printed circuit board.

Symbol Description Value Units

ΘJA Maximum Thermal Resistance (SOP-8)1120 °C/W

ΘJA Maximum Thermal Resistance (TSSOP-8)1150 °C/W

ΘJA Maximum Thermal Resistance (MSOP-8)1150 °C/W

PDMaximum Power Dissipation (SOP-8)11.0 W

PDMaximum Power Dissipation (TSSOP-8)1833 mW

PDMaximum Power Dissipation (MSOP-8)1833 mW

Symbol Description Value Units

VIN IN to GND -0.3 to 6 V

VFLG FLG to GND -0.3 to 6 V

IFLG FLG Current 50 mA

VOUT OUT to GND -0.3 to VIN+0.3 V

IOUT Output Current (Internally Limited) 2.0 A

VEN EN to GND -0.3 to 6 V

TSStorage Temperature 150 °C

TLEAD Maximum Soldering Temperature (at Leads) 300 °C

AAT4625

USB Single-Channel Power Switch

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

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

Symbol Description Conditions Min Typ Max Units

VIN Operation Voltage 2.7 5.5 V

IQQuiescent Current VIN=5V, EN=active 16 30 µA

IQ(OFF) Off Supply Current VIN=5.5V, EN (EN)=inactive 1µA

VEN-THRSH Enable Input Threshold Low-to-high transition 2.4 V

High-to-low transition 0.8 V

IEN Enable Input Current VEN = 0V to 5.5V 0.01 1µA

CEN Enable Input Capacitance 1 pF

Rds(ON) On-Resistance VIN =5V, TA= 25°C 60 100 mΩ

VIN =3.0V, TA= 25°C 70 115 mΩ

TON Output Turn-On Delay VIN =5V, RL=10Ω0.25 ms

TON-RISE Output Turn-On Rise Time VIN =5V, RL=10Ω0.2 ms

TOFF Output Turn-Off Delay VIN =5V, RL=10Ω520 µs

TOFF-FALL Output Turn-Off Fall Time VIN =5V, RL=10Ω20 µs

ISD(OFF) Output Leakage Current EN=inactive, VIN=5.5V, VOUT=0V 0.03 15 µA

ILIMIT Current Limit Threshold ramped load applied to enable 1.0 1.5 2.0 A

output, VOUT < 4.0V

OTMP Over Temperature Shut Down TJincreasing 125 °C

TJdecreasing 115 °C

RFLG Error Flag Output Resistance VIN =5V, IL= 1mA 30 Ω

ISINK Error Flag Off Current VFLG = 5.5V 0.05 1µA

VUVLO Under voltage Lockout VIN = increasing, 1% hysteresis 2.0 2.3 2.7 V

TBLANK FAULT blanking 10 ms

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USB Single-Channel Power Switch

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Typical Characteristics

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

Turn-ON/OFF Response with 10

Ohm 1µFload

EN (5V/div)

FAULT Vout (2V/

100µ/di

div)

Iin (200mA/div)

Off-Switch Current vs. Temperature

0.0000

0.0001

0.0010

0.0100

0.1000

1.0000

-40 -20 0 20 40 60 80 100 120

Off-Switch Current (µA)

Off-Supply Current vs. Temperature

0.0010

0.0100

0.1000

1.0000

-40 -20 0 20 40 60 80 100 120

Temperature (°C)

Off-Supply Current (µA)

Current Limit

0.2

0.4

0.6

0.8

1.2

1.4

1.6

1.8

012345

Output (A)

utput (V)

Quiescent Current

0123456

Input (V)

Input (µA)

Quiescent Current vs. Temperature

-40 -20 0 20 40 60 80 100 120

Temp

escen

urren

(

erature (°C)

AAT4625

USB Single-Channel Power Switch

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

Rds(ON) vs. Temperature

40.0

45.0

50.0

55.0

60.0

65.0

70.0

75.0

80.0

-40 -20 0 20 40 60 80 100 120

Temperature (°C)

VCC=3V

VCC=5V

Short Circuit Through 0.6 Ohm

-1012345

Input and Output (V)

Output (A)

me (µs)

-3

Input Voltage

Output Current

Output Voltage

Short Circuit Through 0.3 Ohm

-1012345

Tim

Input and Output (V)

Output (A)

e(µs)

-4

Input Voltage

Output Current

Output Voltage

Thermal Shutdown Response

50ms / div

EN (5V/div)

FAULT (5V/div)

Vout (1V/div)

Iin (500mA/div)

Start Into 1 Ohm load

1ms/div

EN (5V/div)

iv)

Vout (1V/div)

Iin (500mA/div)

AAT4625

USB Single-Channel Power Switch

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AAT4625

USB Single-Channel Power Switch

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Functional Description

The AAT4625 is an integrated MOSFET load

switch with a fixed current limit, over temperature

protection, level shifted input and a fault flag. The

current limit control is combined with an over tem-

perature thermal limit circuit to provide a compre-

hensive system to protect the load switch under

short circuit or other adverse operating conditions.

The AAT4625 is ideally suited for control and pro-

tection of peripheral ports such as USB, RS232

and parallel ports.

The current limit and over temperature circuits will

act independently. The device current limit is acti-

vated when the output load current exceeds a pre-

set internal threshold level. The minimum current

limit threshold characteristic is specified by ILIM(MIN).

If the load switch ambient temperature becomes

excessive or if a short circuit condition persists, the

die temperature will rise causing the over tempera-

ture protection circuit to activate.

If the current limit or over temperature protection

circuits are active for more then two milliseconds,

the system will be informed via the FAULT Flag. A

ten millisecond fault blanking delay allows the

AAT4625 to be turned on into large capacitive

loads without activating the FAULT Flag. The open

drain FAULT output can be connected directly to

system controllers driven by voltage levels less

than the IN pin voltage without additional level

shifting circuitry.

The load switch is turned on and off by applying a

logic level signal to the EN pin. The AAT4625

enable function is available in both active high and

active low logic level versions. The AAT4625 typi-

cally consumes 16µA when operating, when off, the

device draws less then 1µA. In the off state, current

is prevented from flowing between the input and out-

put. The EN function has logic level thresholds that

allow the AAT4625 to be TTL compatible and may

also be controlled by 2.5V to 5.0V CMOS circuits.

The voltage level on either EN or FAULT should not

exceed the input supply level present on the IN pin.

Functional Block Diagram

1.2V

Reference

Current

Limit

Over-Temp

Protection

Under-

voltage

Lockout

EN (EN)

GND

FLG

OUT

AAT4625

USB Single-Channel Power Switch

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Applications Information

Operation in Current Limit

If an excessive load is applied to the output of an

AAT4625, the load current will be limited by the

AAT4625's current limit circuitry. Refer to the

"Current Limit" figure in the typical characteristics

section of this data sheet. If a short circuit were to

occur on the load, there would be a demand for more

current than what is allowed by the internal current

limiting circuit and the voltage at the device output will

drop. This causes the AAT4625 to dissipate more

power than in normal operation, causing the die tem-

perature to increase. When die temperature exceeds

the internal over temperature threshold, the AAT4625

will shut down. After shutting down, the AAT4625

cools to a level below the over temperature thresh-

old, at which point it will start up again. The AAT4625

will continue to cycle off and on until one of the fol-

lowing events occurs; the load current is reduced to

a level below the AAT4625's current limit setting, the

input power is removed, or until the output is turned

off by a logic high level applied to the EN pin.

Thermal Considerations

Since the AAT4625 has internal current limit and

over temperature protection, junction temperature

is rarely a concern. If an application requires a

large load current in a high temperature operating

environment, there is the possibility that the over

temperature protection circuit rather than the cur-

rent limit circuit will regulate the current available to

the load. In these applications, the maximum cur-

rent available without risk of activation of the over

temperature circuit can be calculated. The maxi-

mum internal temperature while current limit is not

active can be calculated using Equation 1.

TJ(MAX) = IMAX2× RDS(ON)(MAX) × RθJA + TA(MAX)

In Equation 1, IMAX is the maximum current

required by the load. RDS(ON)(MAX) is the maxi-

mum rated RDS(ON) of the AAT4625 at high temper-

ature. RθJA is the thermal resistance between the

device die and the board onto which it is mounted.

TA(MAX) is the maximum ambient temperature for

the printed circuit board assembly under the

AAT4625 when the load switch is not dissipating

power. Equation 1 can be transformed to provide

IMAX; Refer to Equation 2.

IMAX=TSD(MIN) - TA(MAX)

RDS(ON)(MAX) × RθJA

TSD(MIN) is the minimum temperature required to

activate the device over temperature protection.

The typical thermal limit temperature specification

is 125°C for the AAT4625, for calculations, 115°C is

a safe minimum value to use.

For example, a portable device is specified to oper-

ate in a 50°C environment. The printed circuit

board assembly will operate at temperatures as

high as 85°C. This portable device has a sealed

case and the area of the printed board assembly is

relatively small causing RθJA to be approximately

120°C/W. Using Equation 2,

IMAX=115 - 85 = 1.4 A

130 ×120

If this system requires less than 1.4 A, the thermal

limit will not activate during normal operation.

Input Capacitor

The input capacitor serves two purposes. First, it

protects the source power supply from transient

current effects generated by the application load

circuit. If a short circuit is suddenly applied to the

output of an AAT4625, there is a microsecond long

period during which a large current can flow before

the current limit circuit becomes active. Refer to

the characteristic curve named "Short Circuit

Through 0.3Ω." A properly sized input capacitor

can dramatically reduce the load switch input tran-

sient response effects seen by the power supply

and other circuitry upstream from the AAT4625.

The second purpose of the input capacitor is to pre-

vent transient events generated by the load circuit

from effecting the operation of the AAT4625. For

example, if an AAT4625 is used in a circuit that oper-

ates from a 5 volt power supply with poor step load

response, it is possible that turning on the load switch

could cause the input power supply to droop below

the AAT4625's under voltage lockout threshold. This

drop in voltage would cause the AAT4625 to turn off

until the input power supply voltage levels recovers.

Since this cycle would be self-perpetuating, the entire

circuit could be seen to be unstable. In the very rare

case where capacitor cost is prohibitive and the input

capacitor is omitted, the output load circuit should be

slew rate limited when turned on.

Output Capacitor

In order to insure stability while the device current

limit is active, a small capacitance of approximately

1µF should be used. When the AAT4625 is activat-

ed using the ON function, there are no momentary

current transients as in the case of when a short cir-

cuit suddenly applied to a device that is already on.

Refer to the characteristic curve named "Turn-

On/OFF Response". Regardless of output capaci-

tor size, output current is limited to the value

allowed by the threshold determined by the internal

current limiting circuitry. Refer to the internal cur-

rent limit threshold specifications stated in the elec-

trical characteristics section of this datasheet. This

permits very large output capacitors to be used.

For example, USB ports are specified to have at

least 120µF of down stream capacitance from their

controlling power switch. An output capacitance as

large as 1000µF would not disturb the input power

supply to an AAT4625 used to control a USB port.

EN Input

The AAT4625 is available in both active high EN

enable and active low (EN) enable versions. For

specific part numbers, refer to the ordering infor-

mation section. When the AAT4625 is in the off

state, the output is an open circuit and the device

quiescent current consumption is reduced to less

than 1µA. The EN threshold voltage is set to allow

the AAT4625 to be controlled by 5 volt TTL levels

as well as CMOS compatible levels ranging from

2.5 volts to 5 volts. The EN function control voltage

level should not exceed the input supply level

applied to the IN pin.

Fault Flag Output

The AAT4625 features an active low fault flag out-

put. The fault flag is provided to alert the system if

the over current or over temperature circuits

become active or if the load switch is not receiving

a sufficient voltage level to operate properly. If

either the current limit or over temperature circuits

in any combination are constantly active for more

than approximately ten milliseconds, the FAULT pin

is pulled to ground internally through an open drain

device. The 10 millisecond delay on the FAULT

function is intended to prevent capacitive loads

connected to the load switch output from activating

FAULT flag when the device is turned on. The

placement of a pull up resistor between the FAULT

pin and the IN pin is recommended. Reasonable

values for the pull up resistor should range from

10kΩto 100kΩ. Since FAULT flag is an open drain

terminal, it may be pulled up to any voltage that is

not greater than the level present on the IN pin.

This is done to allow the AAT4625 to signal ancil-

lary circuitry that is powered by voltage levels less

than the level on the IN pin.

If a fault flag delay greater then 10ms is required,

addition delay may be added by use of an RC filter.

Referencing to Figure 1, an RC filter can be added

to the fault flag output.

AAT4625

USB Single-Channel Power Switch

4625.2002.12.0.95 9

Figure 1: Fault Flag delay RC filter

10k

100k

0.1µF

AAT4625

FLG

GND

NC NC

OUT

V+

USB Controller

Over Current

Flag Input

AAT4625

USB Single-Channel Power Switch

10 4625.2002.12.0.95

Reverse Voltage

The AAT4625 is designed to control current flowing

from IN to OUT. If a voltage is applied to OUT

which is greater than that on IN, a large resulting

reverse current may flow, potentially damaging the

AAT4625.

Under Voltage Lockout

The AAT4625 has been designed with an under

voltage lockout (UVLO) control circuit. The under

voltage lockout prevents the output MOSFET

device from turning on until the VIN exceeds the

typical UVLO threshold of 2.3 volts. During opera-

tion, the device will automatically shutdown if VIN

falls below the UVLO threshold and the fault flag

will be toggled.

Hot-Plug Applications

Application circuit cards with a high in-rush current

potential can be limited by use of the AAT4625. The

AAT4625 has both slew rate limited turn on charac-

teristics and a current limit controlled output which

make it ideally suited for power port hot-plug appli-

cations. A host power back plane or hot plug recep-

tacle may be sensitive to short duration high power

surges. The AAT4625 will turn on in a linear ramp-

ing fashion and regulate the inrush current with in the

specified current limit for the device. The error flag

usually will not be effected during application turn on

since the 10ms Flag blanking time is intended for

these types of events. If an application turn on cur-

rent surge exceeds 10ms, an RC delay filter may be

added to the Flag output to prevent the system from

receiving an error during the start up sequence.

Figure 2: AAT4625 Inrush Current Protected Application

0.1µF

AAT4625

FLG

GND

NC NC

OUT

BULK

(120µF)

Card

Application

Circuit

GND Inrush Current Protected

Application Card

Cable / Connector

to Hot-Plug Port

BUS

GND

Hot-Plug

Receptacle

PCB Layout Information

In order to obtain the maximum performance from

the AAT4625, very careful attention must be con-

sidered in regard to the printed circuit board layout.

In most port power switch and port protection appli-

cations, high voltage and current transient events

will occur. Proper PCB layout can help reduce the

effects of transient events. PCB trace resistance

will effect over all circuit transient response, in addi-

tion small voltage drops will be incurred.

Refer to the following guide lines for power port

PCB layout:

1. PCB traces should be kept as short and direct

as possible to minimize the effects of the PCB

on circuit performance.

2. Make component solder pads large to mini-

mize contact resistance

3. The AAT4625 output bulk capacitor and ferrite

beads should be placed as close to the

device as possible. PCB traces to the output

connector should be kept as short as possible

to minimized trace resistance and the associ-

ated voltage drop (I2R loss).

4. If ferrite beads are used in the circuit, select

ferrite beads with a minimum series resistance.

5. The use of PCB trace vias should be avoided

on all traces that conduct high currents. If

vias are necessary, make the vias as large as

possible and use multiple vias connected in

parallel to minimize their effect.

AAT4625

USB Single-Channel Power Switch

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Figure 3: Summary of typical circuit voltage drops caused by AAT4625 circuit components and PCB

trace resistance.

Trace Resistance

0.01ohms

(5mV)

CBULK 0.1µF CBULK 0.1µF

Cable, Connector

and Contact

Resistance

0.03ohms

(15mV)

V+

GND

Input

Power Supply

4.50V to 5.25V

P-Channel Mosfet

Switch On Resistance

0.06ohms

(30mV)

AAT4625

Ferrite Bead

and PCB trace

resistance

0.02ohms

(10mV)

VBUS

GND

Downstream

Peripheral Port

500mA Max.

Load Current

Total Voltage Drop = 60mV

Evaluation Board Layout

The AAT4625 evaluation layout follows the recom-

mend printed circuit board layout procedures and

can be used as an example for good application

layouts. Note that ferrite beards are not used on

this simple device evaluation board. The board

layout shown is not to scale.

Figure 4: Evaluation board Figure 5: Evaluation board Figure 6: Evaluation board

component side layout solder side layout top side silk screen layout /

assembly drawing

AAT4625

USB Single-Channel Power Switch

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Application Circuits

Figure 7: Typical USB Host Port Application

Figure 8: Self-Powered Single Port USB Hub

Figure 9: USB Bus Powered Single Port USB Hub

120µF0.01µF

100k

1µF1µF

AAT3220-3.3 3.3V USB Controller AAT4625 Ferrite Beads

Data Data

BUS

D+

D-

GND

BUS

D+

D-

GND

USB PortUSB Host

VIN ON/OFF

Over Current

Flag

IN OUT

GND

EN OUT

FLG

GND

NC NC

OUT

120µF0.1µF

100k

1µF1µF

AAT3220-3.3 3.3V USB Controller AAT4625 Ferrite Beads

Vcc

5.0V

Data Data

BUS

D+

D-

GND

BUS

D+

D-

GND

USB Port

4.50V to 5.25V

Upstream V

BUS

100mA Maximum

VIN ON/OFF

Over Current

Flag

IN OUT

GND

EN OUT

FLG

GND

NC NC

OUT

CIN

0.1µF

100k

On/Off

Error Flag

USB Controller

AAT4625

VBUS = 5.0V IN OUT

FLG

EN(EN)

6,8

4,5

COUT1

0.1µF

COUT2

120µF

DATA

D+

D-

VBUS

GND

Ferrite Beads

Ordering Information

Package Information

SOP-8

0.175 ± 0.075 6.00 ± 0.20

3.90 ± 0.10

1.55 ± 0.20

1.27 BSC0.42 ± 0.09 × 8

4.90 ± 0.10

4° ± 4°

45°

0.375 ± 0.125

0.235 ± 0.045

0.825 ± 0.445

Package Enable Marking Part Number

Bulk Tape and Reel

SOP8 EN (Active-high) N/A AAT4625IAS-1-T1

SOP8 EN (Active-low) N/A AAT4625IAS-T1

TSSOP8 EN (Active-high) N/A AAT4625IHS-1-T1

TSSOP8 EN (Active-low) N/A AAT4625IHS-T1

MSOP8 EN (Active-high) N/A AAT4625IKS-1-T1

MSOP8 EN (Active-low) N/A AAT4625IKS-T1

AAT4625

USB Single-Channel Power Switch

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AAT4625

USB Single-Channel Power Switch

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TSSOP-8

DETAIL A

4.40 ± 0.10

6.40 ± 0.20



0.65 BSC

3.00 ± 0.10

0.245 ± 0.055 × 8 0.10 ± 0.05

0.60 ± 0.15

0.145 ± 0.055

1.05 MAX

1.20 MAX

4° ± 4°

12°

12° REF × 4

1.00

REF

MSOP-8

PIN 1

1.95 BSC

0.254 BSC

0.155 ± 0.075

0.60 ± 0.20

3.00 ± 0.10

0.95 ± 0.15

0.95 REF

0.85 ± 0.10

3.00 ± 0.10

10° ± 5°

4° ± 4°

0.65 BSC 0.30 ± 0.08

0.075 ± 0.075

4.90 ± 0.10

GAUGE PLANE

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USB Single-Channel Power Switch

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USB Single-Channel Power Switch

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Advanced Analogic Technologies, Inc.

830 E. Arques Avenue, Sunnyvale, CA 94085

Phone (408) 737-4600

Fax (408) 737-4611