Datasheet AAT4250IJS-T1, AAT4250 Datasheet (Analogic Technologies)

SmartSwitch

™

General Description

The AAT4250 SmartSwitch™ is a member of
AATI's Application Specific Power MOSFET™
(ASPM™) product family. It is a Slew Rate
Controlled P-channel MOSFET power switch
designed for high-side load-switching applications.
This switch operates with an input voltage range
from 1.8V to 5.5V, making it ideal for 2.5V, 3.3V or
5V systems. The part features 1.5ms turn on and
10µs turn off time. The AAT4250 has an under volt­age lock out which turns off the switch when an
under-voltage condition exists. Input logic levels
are TTL compatible. The quiescent supply current
is very low, typically 2µA. In shutdown mode, the
supply current is typically reduced to 0.1µA or less.

The AAT4250 is available in a 5-pin SOT23 and 8­pin SC70JW specified over -40 to 85°C.

Features

• 1.8V to 5.5V Input voltage range

• 120mΩ (5V) typical R

DS(ON)

• Low quiescent current

• Typical 2µA

• Typical 0.1µA with Enable off

• Only 2.0V needed for ON/OFF Control

• Temperature range -40º to 85°C

• 5kV ESD rating

• 5-pin SOT23 or SC70JW-8 package

Applications

• Hot swap supplies

• Notebook computers

• Personal communication devices

AAT4250

Slew Rate Controlled Load Switch

Typical Application

AAT4250

SOT23

ON/OFF

IN OUT

GND

ON

1µF0.1µF

INPUT

GND GND

C

IN

C

OUT

OUTPUT

Preliminary Information

4250.2001.12.0.94 1

Pin Descriptions

Pin Configuration

SOT23-5

(Top View)

SC70JW-8
(Top View)

GND
GND
GND

1 2

IN
IN
ON/OFF
GND

OUT

1

2

3

4

8

7

6

5

1

2

3

NC

OUT

4

5

GND

IN

ON/OFF

Pin #

SOT23-5 SC70JW Symbol Function

1 1 OUT P-channel MOSFET drain

2 2, 3, 4, 5 GND Ground connection

3 n/a NC Not internally connected

4 6 ON/OFF Active-High Enable Input (Logic high turns the switch on)

5 7, 8 IN P-channel MOSFET source

AAT4250

Slew Rate Controlled Load Switch

2 4250.2001.12.0.94

Absolute Maximum Ratings (T

A

=25°C unless otherwise noted)

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.

Thermal Characteristics

Note 2: Mounted on an AAT4250 demo board in still 25ºC air.

Electrical Characteristics (V

IN

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

are at TA=25°C)

Note 3: For VINoutside this range consult typical ON/OFF threshold curve.

Symbol Description Conditions Min Typ Max Units

V

IN

Operation Voltage 1.8 5.5 V

I

Q

Quiescent Current VIN= 5V, ON/OFF = VIN, I

OUT

= 0 2 4 µA

I

Q(OFF)

Off Supply Current ON/OFF = GND, VIN= 5V, OUT open 1 µA

I

SD(OFF)

Off Switch Current ON/OFF = GND, VIN= 5V, V

OUT

= 0 0.1 1 µA

V

UVLO

Undervoltage Lockout VINfalling 1.5 V

V

UVLO(hys)

Undervoltage Lockout hysteresis 250 mV

V

IN

= 5V 120 175 mΩ

R

DS(ON)

On-Resistance V

IN

= 3V 135 200 mΩ

V

IN

=1.8V 165 mΩ

TC

RDS

On-Resistance Temp-Co 2800 ppm/ºC

V

IL

ON/OFF Input Logic Low Voltage V

IN

= 2.7V to 5.5V

3

0.8 V

V

IH

ON/OFF Input Logic High Voltage

V

IN

= 2.7V to ≤ 4.2V 2.0

V

V

IN

= > 4.2V to 5.5V 2.4

I

SINK

ON Input leakage VON= 5V 0.01 1 µA

T

D

Output Turn-On Delay Time 300 µs

T

OFF

Turn-Off Fall Time VIN=5V, R

LOAD

=10Ω 10 µs

T

OFF

Turn-Off Fall Time VIN=3V, R

LOAD

=5Ω 10 µs

T

ON

Turn-On Rise Time VIN=5V, R

LOAD

=16.5Ω , TA=0 to 50º C 1000 µs

T

ON

Turn-On Rise Time VIN=5V, R

LOAD

=10Ω , C

OUT

=0.1µF 1500 µs

T

ON

Turn-On Rise Time VIN=3V, R

LOAD

=5Ω , C

OUT

=0.1µF 1500 µs

Symbol Description Value Units

Θ

JA

Thermal Resistance (SOT23-5 or SC70JW-8)

2

150 °C/W

P

D

Power Dissipation (SOT23-5 or SC70JW-8)

2

667 mW

Symbol Description Value Units

V

IN

IN to GND -0.3 to 6 V

V

ON

ON/OFF to GND -0.3 to 6 V

V

OUT

OUT to GND -0.3 to VIN+0.3 V

I

MAX

Maximum Continuous Switch Current 1.7 A

I

DM

Maximum Pulsed Current

IN ≥ 2.5V 4 A
IN < 2.5V 2 A

T

J

Operating Junction Temperature Range -40 to 150 °C

T

LEAD

Maximum Soldering Temperature (at Leads) 300 °C

V

ESD

ESD Rating1- HBM 5000 V

AAT4250

Slew Rate Controlled Load Switch

4250.2001.12.0.94 3

Typical Characteristics

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

Turn-On Time vs. Temperature

0.5

1.0

1.5

2.0

2.5

3.0

-40 -20 0 20 40 60 80 100

Temperature (°C)

Turn-ON Time (ms)

CIN=1µF, C

OUT

=0.1µF

VIN=5V
R

LOAD

=10Ω

VIN=3V
R

LOAD

=5Ω

Turn-OFF Time vs. Temperature

5

6

7

8

9

10

-40 -20 0 20 40 60 80 100

Temperature (°C)

C

IN

=1µF, C

OUT

=0.1µF

Turn-OFF Time (µs)

VIN=5V
R

LOAD

=10Ω

VIN=3V
R

LOAD

=5Ω

Off-Switch Current vs. Temperature

1

10

100

1000

10000

-40 -20 0 20 40 60 80 100

Temperature (°C)

Off-Switch Current (nA)

Off-Supply Current vs. Temperature

1

10

100

1000

-40 -20 0 20 40 60 80 100

Temperature (°C)

Off-Supply Current (nA)

Quiescent Current vs. V

IN

0

0.5

1

1.5

2

2.5

3

3.5

4

0 123456

Quiescent Current (µA)

V

IN

Quiescent Current vs. Temperature

0

0.5

1

1.5

2

2.5

3

3.5

4

-40 -20 0 20 40 60 80 100

Temperature (°C)

Quiescent Current (µA)

VIN=3V

VIN=5V

AAT4250

Slew Rate Controlled Load Switch

4 4250.2001.12.0.94

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

1

3

5

CIN=1µF,C

OUT

=1µF,VIN=5V

Turn Off Waveforms

Time (µs)

-1

-1 1 3 5 7 9 11 13 15

V(out)

Volt

V(ON/OFF)

0

1

2

3

4

CIN=1µF,C

OUT

=1µF,VIN=3V

Turn Off Waveforms

Time (µs)

-1

-1 1 3 5 7 9 11 13 15

V(out)

Volt

V(ON/OFF)

-1 0 1 2 3 4

0

1

1.2

Time (ms)

C

IN

=1µF,C

OUT

=10µF,VIN=5V

Turn On Waveforms

V(out)

0.8

0.6

0.4

0.2

5

6

I(in)

Volt

4

3

2

1

0

A

V(ON/OFF)

Volt

-1 0 1 2 3 4

0

1

2

3

4

0

0.5

1

1.5

2

Time (ms)

C

IN

=1µF,C

OUT

=10µF,VIN=3V

Turn On Waveforms

V(out)

I(in)

A

V(ON/OFF)

Volt

-1 0 1 2 3 4

0

1

2

3

4

0

1

1.2

Time (ms)

C

IN

=1µF,C

OUT

=0.1µF,VIN=5V

Turn On Waveforms

V(out)

0.8

0.6

0.4

0.2

5

6

I(in)

A

V(ON/OFF)

Volt

-1 0 1 2 3 4

0

1

2

3

4

0

0.5

1

1.5

2

Time (ms)

C

IN

=1µF,C

OUT

=0.1µF,VIN=3V

Turn On Waveforms

V(ON/OFF)

V(out)

I(in)

A

AAT4250

Slew Rate Controlled Load Switch

4250.2001.12.0.94 5

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

Typical ON/OFF Threshold vs. V

IN

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

V

IN

ON/OFF Threshold

V

IH

V

IL

R

DS(ON)

vs. V

IN

110

120

130

140

150

160

170

180

190

1.5 2 2.53 3.54 4.55 5.5

V

IN

R

DS(ON)

(mΩ)

I

OUT

= 100mA

R

DS(ON)

vs. Temperature

80

120

160

-40 -20 0 20 40 60 80 100

Temperature (°C)

R

DS(ON)

(mΩ)

VIN=3V

VIN=5V

AAT4250

Slew Rate Controlled Load Switch

6 4250.2001.12.0.94

Functional Description

The AAT4250 is a slew rate controlled P-channel
MOSFET power switch designed for high-side load­switching applications. It operates with input volt­ages ranging from 1.8V to 5.5V which, along with its
extremely low operating current, makes it ideal for
battery-powered applications. In cases where the
input voltage drops below 1.8V, the AAT4250 MOS­FET is protected from entering the saturated region
of operation by automatically shutting down. In
addition, the TTL compatible ON/OFF pin makes
the AAT4250 an ideal level shifted load-switch. The
slew rate controlling feature eliminates in-rush cur-

rent when the MOSFET is turned on, allowing the
AAT4250 to be implemented with a small input
capacitor, or no input capacitor at all. During slew­ing, the current ramps linearly until it reaches the
level required for the output load condition. The
proprietary control method works by careful control
and monitoring of the MOSFET gate voltage. When
the device is switched ON, the gate voltage is quick­ly increased to the threshold level of the MOSFET.
Once at this level, the current begins to slew as the
gate voltage is slowly increased until the MOSFET
becomes fully enhanced. Once it has reached this
point, the gate is quickly increased to the full input
voltage and R

DS(ON)

is minimized.

AAT4250

Slew Rate Controlled Load Switch

4250.2001.12.0.94 7

Functional Block Diagram

Under-

voltage

Lockout

Level

Shift

Slew Rate

Control

IN

ON/OFF

GND

OUT

Applications Information

Input Capacitor

Typically a 1µF or larger capacitor is recommend­ed for CINin most applications. A CINcapacitor is
not required for basic operation, however, it is use­ful in preventing load transients from affecting up
stream circuits. 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

For proper slew operation, a 0.1µF capacitor or
greater between VOUT and GND is required.

Likewise, with the output capacitor, there is no spe­cific capacitor ESR requirement. If desired, C

OUT

maybe increased without limit to accommodate any
load transient condition without adversely affecting
the slew rate.

Enable Function

The AAT4250 features an enable / disable function.
This pin (ON) is active high and is compatible with
TTL or CMOS logic. To assure the load switch will
turn on, the ON control level must be greater than

2.0 volts. The load switch will go into shutdown
mode when the voltage on the ON pin falls below

0.8 volts. When the load switch is in shutdown
mode, the OUT pin is tristated, and quiescent cur­rent drops to leakage levels below 1µA.

Reverse Output to Input Voltage
Conditions and Protection

Under normal operating conditions a parasitic
diode exists between the output and input of the
load switch. The input voltage should always
remain greater than the output load voltage main­taining a reverse bias on the internal parasitic
diode. Conditions where V

OUT

might exceed V

IN

should be avoided since this would forward bias
the internal parasitic diode and allow excessive
current flow into the V

OUT

pin and possibly damage

the load switch.

In applications where there is a possibility of V

OUT

exceeding VINfor brief periods of time during nor­mal operation, the use of a larger value CINcapaci­tor is highly recommended. A larger value of C

IN

with respect to C

OUT

will effect a slower CINdecay

rate during shutdown, thus preventing V

OUT

from
exceeding VIN. In applications where there is a
greater danger of V

OUT

exceeding VINfor extended
periods of time, it is recommended to place a schot­tky diode from VINto V

OUT

(connecting the cathode

to VINand anode to V

OUT

). The Schottky diode for-

ward voltage should be less then 0.45 volts.

Thermal Considerations and High
Output Current Applications

The AAT4250 is designed to deliver a continuous
output load current. The limiting characteristic for
maximum safe operating output load current is
package power dissipation. In order to obtain high
operating currents, careful device layout and circuit
operating conditions need to be taken into account.

The following discussions will assume the load
switch is mounted on a printed circuit board utiliz­ing the minimum recommended footprint as stated
in the layout considerations section.

At any given ambient temperature (TA) the maxi­mum package power dissipation can be deter­mined by the following equation:

P

D(MAX)

= [T

J(MAX)

- TA] / Θ

JA

Constants for the AAT4250 are maximum junction
temperature, T

J(MAX)

= 125°C, and package thermal
resistance, ΘJA= 150°C/W. Worst case conditions
are calculated at the maximum operating tempera­ture where TA= 85°C. Typical conditions are cal­culated under normal ambient conditions where T

A

= 25°C. At TA= 85°C, P

D(MAX)

= 267mW. At TA=

25°C, P

D(MAX)

= 667mW.

The maximum continuous output current for the
AAT4250 is a function of the package power dissi­pation and the RDSof the MOSFET at T

J(MAX)

. The

maximum RDSof the MOSFET at T

J(MAX)

is calcu­lated by increasing the maximum room tempera­ture RDSby the RDStemperature coefficient. The
temperature coefficient (TC) is 2800ppm/°C.
Therefore, at 125°C

R

DS(MAX)

= R

DS(25°C)

× (1 + TC × ∆ T)

R

DS(MAX)

= 175mΩ × (1 + .002800 × (125°C - 25°C))

R

DS(MAX)

= 224mΩ

AAT4250

Slew Rate Controlled Load Switch

8 4250.2001.12.0.94

For maximum current, refer to the following equation:

I

OUT(MAX)

< ( P

D(MAX)

/ RDS)

1/2

For example, if V

IN

= 5V, R

DS(MAX)

=224mΩ and T

A

= 25°C, I

OUT(MAX)

= 1.7A. If the output load current
were to exceed 1.7A or if the ambient temperature
were to increase, the internal die temperature will
increase, and the device will be damaged.

Higher peak currents can be obtained with the
AAT4250. To accomplish this, the device thermal
resistance must be reduced by increasing the heat
sink area or by operating the load switch in a duty
cycle manner. Duty cycles with peaks less than
2ms in duration can be considered using the
method below.

High Peak Output Current Applications

Some applications require the load switch to oper­ate at a continuous nominal current level with short
duration high current peaks. Refer to the IDMspec­ification in the Absolute Maximum table to ensure
the AAT 4250’s maximum pulsed current rating is
not exceeded. The duty cycle for both output cur­rent levels must be taken into account. To do so,
first calculate the power dissipation at the nominal
continuous current level, and then add in the addi­tional power dissipation due to the short duration
high current peak scaled by the duty factor.

For example, a 4V system using an AAT4250 oper­ates at a continuous 100mA load current level and
has short 2A current peaks, as in a GSM applica­tion. The current peak occurs for 576µs out of a

4.61ms period.

First, the current duty cycle is calculated:

% Peak Duty Cycle: X/100 = 576µs/4.61ms
% Peak Duty Cycle = 12.5%

The load current is 100mA for 87.5% of the 4.61ms
period and 2A for 12.5% of the period. Since the
Electrical Characteristics do not report R

DS MAX

for 4

volts operation, it must be calculated approximated

by consulting the chart of R

DSON

vs. VIN. The Rds
reported for 5 volt RDScan be scaled by the ratio
seen in the chart to derive the Rds for 4 volt V

IN

:
175mΩ x 120mΩ/115mΩ = 183mΩ. Derated for
temperature: 183mΩ x (1 + .002800 x (125°C ­25°C)) = 235mΩ . The power dissipation for a
100mA load is calculated as follows:

P

D(MAX)

= I

2

OUT

x R

DS

P

D(100mA)

= (100mA)2 x 235mΩ

P

D(100mA)

= 2.35mW

P

D(87.5%D/C)

= %DC x P

D(100mA)

P

D(87.5%D/C)

= 0.875 x 2.35mW

P

D(87.5%D/C)

= 2.1mW

The power dissipation for 100mA load at 87.5%
duty cycle is 2.1mW. Now the power dissipation for
the remaining 12.5% of the duty cycle at 2A is cal­culated:

P

D(MAX)

= I

2

OUT

x R

DS

P

D(2A)

= (2A)2 x 235mΩ

P

D(2A)

= 940mW

P

D(12.5%D/C)

= %DC x P

D(2A)

P

D(12.5%D/C)

= 0.125 x 940mW

P

D(12.5%D/C)

= 117.5mW

The power dissipation for 2A load at 12.5% duty
cycle is 117mW. Finally, the two power figures are
summed to determine the total true power dissipa­tion under the varied load.

P

D(total)

= P

D(100mA)

+ P

D(2A)

P

D(total)

= 2.1mW + 117.5mW

P

D(total)

= 120mW

The maximum power dissipation for the AAT4250
operating at an ambient temperature of 85°C is
267mW. The device in this example will have a
total power dissipation of 120mW. This is well with
in the thermal limits for safe operation of the
device, in fact, at 85°C, the AAT4250 will handle a
2A pulse for up to 28% duty cycle. At lower ambi­ent temperatures the duty cycle can be further
increased.

AAT4250

Slew Rate Controlled Load Switch

4250.2001.12.0.94 9

AAT4250

Slew Rate Controlled Load Switch

10 4250.2001.12.0.94

Figure 1: Evaluation board Figure 2: Evaluation board Figure 3: Evaluation board
top side silk screen layout / component side layout solder side layout
assembly drawing

Printed Circuit Board Layout
Recommendations

For proper thermal management, and to take
advantage of the low R

DSON

of the AAT4250, a few
circuit board layout rules should be followed: Vin
and Vout should be routed using wider than normal
traces, and GND should be connected to a ground
plane. For best performance, CINand C

OUT

should

be placed close to the package pins.

Evaluation Board Layout

The AAT4250 evaluation layout follows the printed
circuit board layout recommendations, and can be
used for good applications layout.

Note: Board layout shown is not to scale.

AAT4250

Slew Rate Controlled Load Switch

4250.2001.12.0.94 11

Ordering Information

Package Information

SOT23-5

E

A

c

b

D

e

S1

L

Θ

H

A2

S

Package Marking

Part Number

Bulk Tape and Reel

SOT23-5 N/A AAT4250IGV-T1

SC70JW-8 N/A AAT4250IJS-T1

Dim

Millimeters Inches

Min Max Min Max

A 1.00 1.30 0.039 0.051
A1 0.00 0.10 0.000 0.004
A2 0.70 0.90 0.028 0.035

b 0.35 0.50 0.014 0.020

c 0.10 0.25 0.004 0.010
D 2.70 3.10 0.106 0.122
E 1.40 1.80 0.055 0.071

e 1.90 0.075
H 2.60 3.00 0.102 0.118

L 0.37 0.015
S 0.45 0.55 0.018 0.022

S1 0.85 1.05 0.033 0.041

Θ 1° 9° 1° 9°

SC70JW-8

Θ1

D

A

A2

b

E

eee

L

E1

Θ

A1

c

0.048REF

AAT4250

Slew Rate Controlled Load Switch

12 4250.2001.12.0.94

Advanced Analogic Technologies, Inc.

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

Dim

Millimeters Inches

Min Max Min Max

E 2.10 BSC 0.083 BSC

E1 1.75 2.00 0.069 0.079

L 0.23 0.40 0.009 0.016

A 1.10 0.043
A1 0 0.10 0.004
A2 0.70 1.00 0.028 0.039

D 2.00 BSC 0.079 BSC

e 0.50 BSC 0.020 BSC

b 0.15 0.30 0.006 0.012

c 0.10 0.20 0.004 0.008

Θ 08º08º

Θ1 4º 10º 4º 10º