AAT4250IGV-T1 [ANALOGICTECH]
Slew Rate Controlled Load Switch; 压摆率受控负载开关
| 型号： | AAT4250IGV-T1 |
| 厂家： | 
ADVANCED ANALOGIC TECHNOLOGIES |
| 描述： | Slew Rate Controlled Load Switch |
| 文件： | 总12页 (文件大小：194K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
AAT4250
Slew Rate Controlled Load Switch
™
SmartSwitch
General Description
Features
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 volt-
age 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.
•
•
•
1.8V to 5.5V Input voltage range
120mΩ (5V) typical RDS(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
The AAT4250 is available in a 5-pin SOT23 and 8-
pin SC70JW specified over -40 to 85°C.
•
•
•
Hot swap supplies
Notebook computers
Personal communication devices
Typical Application
INPUT
OUTPUT
IN
OUT
AAT4250
SOT23
ON
ON/OFF
CIN
COUT
1µF
0.1µF
GND
GND
GND
4250.2001.12.0.94
1
AAT4250
Slew Rate Controlled Load Switch
Pin Descriptions
Pin #
SOT23-5
SC70JW
Symbol
OUT
Function
1
2
3
4
5
1
2, 3, 4, 5
n/a
P-channel MOSFET drain
GND
NC
Ground connection
Not internally connected
6
ON/OFF
IN
Active-High Enable Input (Logic high turns the switch on)
P-channel MOSFET source
7, 8
Pin Configuration
SOT23-5
(Top View)
1
2
3
5
4
OUT
IN
GND
NC
ON/OFF
SC70JW-8
(Top View)
1
8
IN
IN
ON/OFF
GND
OUT
2
3
4
7
6
5
GND
GND
GND
2
4250.2001.12.0.94
AAT4250
Slew Rate Controlled Load Switch
Absolute Maximum Ratings (TA=25°C unless otherwise noted)
Symbol
Description
Value
Units
VIN
VON
VOUT
IMAX
IN to GND
-0.3 to 6
V
V
ON/OFF to GND
-0.3 to 6
OUT to GND
-0.3 to VIN+0.3
V
Maximum Continuous Switch Current
1.7
A
IN ≥ 2.5V
IN < 2.5V
4
2
A
IDM
Maximum Pulsed Current
A
TJ
Operating Junction Temperature Range
Maximum Soldering Temperature (at Leads)
ESD Rating1 - HBM
-40 to 150
300
°C
°C
V
TLEAD
VESD
5000
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.
Note 1: Human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.
Thermal Characteristics
Symbol
Description
Thermal Resistance (SOT23-5 or SC70JW-8)2
Power Dissipation (SOT23-5 or SC70JW-8)2
Value
Units
ΘJA
PD
150
667
°C/W
mW
Note 2: Mounted on an AAT4250 demo board in still 25ºC air.
Electrical Characteristics (VIN = 5V, TA = -40 to 85°C unless otherwise noted. Typical values
are at TA=25°C)
Symbol Description
Conditions
Min Typ
Max Units
VIN
IQ
Operation Voltage
Quiescent Current
Off Supply Current
Off Switch Current
Undervoltage Lockout
1.8
5.5
4
V
µA
VIN = 5V, ON/OFF = VIN, IOUT = 0
ON/OFF = GND, VIN = 5V, OUT open
ON/OFF = GND, VIN = 5V, VOUT = 0
VIN falling
2
IQ(OFF)
ISD(OFF)
VUVLO
1
µA
0.1
1.5
1
µA
V
VUVLO(hys) Undervoltage Lockout hysteresis
250
120
135
165
2800
mV
mΩ
mΩ
mΩ
ppm/ºC
V
VIN = 5V
VIN = 3V
VIN =1.8V
175
200
RDS(ON)
On-Resistance
TCRDS
VIL
On-Resistance Temp-Co
ON/OFF Input Logic Low Voltage
VIN = 2.7V to 5.5V3
VIN = 2.7V to ≤ 4.2V
VIN = > 4.2V to 5.5V
VON = 5V
0.8
1
2.0
VIH
ON/OFF Input Logic High Voltage
V
2.4
ISINK
TD
ON Input leakage
0.01
300
µA
µs
µs
µs
µs
µs
µs
Output Turn-On Delay Time
Turn-Off Fall Time
Turn-Off Fall Time
Turn-On Rise Time
Turn-On Rise Time
Turn-On Rise Time
TOFF
TOFF
TON
TON
TON
VIN=5V, RLOAD=10Ω
VIN=3V, RLOAD=5Ω
VIN=5V, RLOAD=16.5Ω , TA=0 to 50º C
VIN=5V, RLOAD=10Ω , COUT=0.1µF
VIN=3V, RLOAD=5Ω , COUT=0.1µF
10
10
1000
1500
1500
Note 3: For VIN outside this range consult typical ON/OFF threshold curve.
4250.2001.12.0.94
3
AAT4250
Slew Rate Controlled Load Switch
Typical Characteristics
(Unless otherwise noted, VIN = 5V, TA = 25°C)
Quiescent Current vs. Temperature
Quiescent Current vs. VIN
4
4
3.5
3
3.5
3
VIN=5V
2.5
2
2.5
2
1.5
1.5
1
VIN=3V
1
0.5
0
0.5
0
0
1
2
3
4
5
6
-40
-20
0
20
40
60
80
100
100
100
Temperature (°C)
VIN
Off-Supply Current vs. Temperature
Off-Switch Current vs. Temperature
1000
10000
1000
100
10
100
10
1
1
-40
-40
-20
0
20
40
60
80
-20
0
20
40
60
80
100
Temperature (°C)
Temperature (°C)
Turn-On Time vs. Temperature
Turn-OFF Time vs. Temperature
CIN=1µF, COUT=0.1µF
CIN=1µF, COUT=0.1µF
3.0
2.5
2.0
1.5
1.0
0.5
10
9
VIN=5V
RLOAD=10Ω
8
VIN=5V
RLOAD=10Ω
VIN=3V
RLOAD=5Ω
7
VIN=3V
RLOAD=5Ω
6
5
-40
-20
0
20
40
60
80
100
-40
-20
0
20
40
60
80
Temperature (°C)
Temperature (°C)
4
4250.2001.12.0.94
AAT4250
Slew Rate Controlled Load Switch
(Unless otherwise noted, VIN = 5V, TA = 25°C)
Turn On Waveforms
CIN=1µF,COUT=0.1µF,VIN=3V
Turn On Waveforms
CIN=1µF,COUT=0.1µF,VIN=5V
2
1.2
1
4
6
5
V(ON/OFF)
V(ON/OFF)
3
2
1.5
1
V(out)
0.8
0.6
0.4
0.2
0
4
V(out)
3
2
1
0
0.5
0
I(in)
1
I(in)
0
-1
0
1
2
3
4
-1
0
1
2
3
4
Time (ms)
Time (ms)
Turn On Waveforms
CIN=1µF,COUT=10µF,VIN=3V
Turn On Waveforms
CIN=1µF,COUT=10µF,VIN=5V
2
1.2
1
4
6
V(ON/OFF)
V(ON/OFF)
5
4
3
2
1.5
1
0.8
0.6
0.4
0.2
0
V(out)
V(out)
3
2
I(in)
0.5
0
1
0
1
0
I(in)
-1
0
1
2
3
4
-1
0
1
2
3
4
Time (ms)
Time (ms)
Turn Off Waveforms
CIN=1µF,COUT=1µF,VIN=3V
Turn Off Waveforms
CIN=1µF,COUT=1µF,VIN=5V
4
3
2
5
3
V(out)
V(out)
1
0
1
V(ON/OFF)
V(ON/OFF)
-1
-1
-1
1
3
5
7
9
11
13
15
-1
1
3
5
7
9
11
13
15
Time (µs)
Time (µs)
4250.2001.12.0.94
5
AAT4250
Slew Rate Controlled Load Switch
(Unless otherwise noted, VIN = 5V, TA = 25°C)
RDS(ON) vs. VIN
RDS(ON) vs. Temperature
190
180
160
170
IOUT = 100mA
160
150
140
130
120
110
VIN=3V
120
VIN=5V
80
1.5
2
2.5
3
3.5
4
4.5
5
5.5
-40
-20
0
20
40
60
80
100
VIN
Temperature (°C)
Typical ON/OFF Threshold vs. VIN
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
VIH
VIL
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VIN
6
4250.2001.12.0.94
AAT4250
Slew Rate Controlled Load Switch
Functional Block Diagram
OUT
IN
Slew Rate
Control
Under-
voltage
Lockout
Level
Shift
ON/OFF
GND
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 slew-
ing, 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 quick-
ly 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 RDS(ON) is minimized.
Functional Description
The AAT4250 is a slew rate controlled P-channel
MOSFET power switch designed for high-side load-
switching applications. It operates with input volt-
ages 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 MOS-
FET 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-
4250.2001.12.0.94
7
AAT4250
Slew Rate Controlled Load Switch
In applications where there is a possibility of VOUT
exceeding VIN for brief periods of time during nor-
mal operation, the use of a larger value CIN capaci-
tor is highly recommended. A larger value of CIN
with respect to COUT will effect a slower CIN decay
rate during shutdown, thus preventing VOUT from
exceeding VIN. In applications where there is a
greater danger of VOUT exceeding VIN for extended
periods of time, it is recommended to place a schot-
tky diode from VIN to VOUT (connecting the cathode
to VIN and anode to VOUT). The Schottky diode for-
ward voltage should be less then 0.45 volts.
Applications Information
Input Capacitor
Typically a 1µF or larger capacitor is recommend-
ed for CIN in most applications. A CIN capacitor is
not required for basic operation, however, it is use-
ful in preventing load transients from affecting up
stream circuits. CIN should be located as close to
the device VIN pin 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 cur-
rent operation, ceramic capacitors are recom-
mended for CIN due to their inherent capability over
tantalum capacitors to withstand input current
surges from low impedance sources such as bat-
teries in portable devices.
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.
Output Capacitor
For proper slew operation, a 0.1µF capacitor or
greater between VOUT and GND is required.
The following discussions will assume the load
switch is mounted on a printed circuit board utiliz-
ing the minimum recommended footprint as stated
in the layout considerations section.
Likewise, with the output capacitor, there is no spe-
cific capacitor ESR requirement. If desired, COUT
maybe increased without limit to accommodate any
load transient condition without adversely affecting
the slew rate.
At any given ambient temperature (TA) the maxi-
mum package power dissipation can be deter-
mined by the following equation:
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 cur-
rent drops to leakage levels below 1µA.
PD(MAX) = [TJ(MAX) - TA] / ΘJA
Constants for the AAT4250 are maximum junction
temperature, TJ(MAX) = 125°C, and package thermal
resistance, ΘJA = 150°C/W. Worst case conditions
are calculated at the maximum operating tempera-
ture where TA = 85°C. Typical conditions are cal-
culated under normal ambient conditions where TA
= 25°C. At TA = 85°C, PD(MAX) = 267mW. At TA =
25°C, PD(MAX) = 667mW.
Reverse Output to Input Voltage
Conditions and Protection
The maximum continuous output current for the
AAT4250 is a function of the package power dissi-
pation and the RDS of the MOSFET at TJ(MAX). The
maximum RDS of the MOSFET at TJ(MAX) is calcu-
lated by increasing the maximum room tempera-
ture RDS by the RDS temperature coefficient. The
temperature coefficient (TC) is 2800ppm/°C.
Therefore, at 125°C
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 main-
taining a reverse bias on the internal parasitic
diode. Conditions where VOUT might exceed VIN
should be avoided since this would forward bias
the internal parasitic diode and allow excessive
current flow into the VOUT pin and possibly damage
the load switch.
RDS(MAX) = RDS(25°C) × (1 + TC × ∆T)
RDS(MAX) = 175mΩ × (1 + .002800 × (125°C - 25°C))
RDS(MAX) = 224mΩ
8
4250.2001.12.0.94
AAT4250
Slew Rate Controlled Load Switch
For maximum current, refer to the following equation:
by consulting the chart of RDSON vs. VIN. The Rds
reported for 5 volt RDS can be scaled by the ratio
seen in the chart to derive the Rds for 4 volt VIN:
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:
1/2
IOUT(MAX) < ( PD(MAX) / RDS
)
For example, if VIN = 5V, RDS(MAX)=224mΩ and TA
= 25°C, IOUT(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.
PD(MAX) = I2OUT x RDS
PD(100mA) = (100mA)2 x 235mΩ
PD(100mA) = 2.35mW
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.
PD(87.5%D/C) = %DC x PD(100mA)
PD(87.5%D/C) = 0.875 x 2.35mW
PD(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 cal-
culated:
High Peak Output Current Applications
Some applications require the load switch to oper-
ate at a continuous nominal current level with short
duration high current peaks. Refer to the IDM spec-
ification in the Absolute Maximum table to ensure
the AAT 4250’s maximum pulsed current rating is
not exceeded. The duty cycle for both output cur-
rent 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 addi-
tional power dissipation due to the short duration
high current peak scaled by the duty factor.
PD(MAX) = I2OUT x RDS
PD(2A) = (2A)2 x 235mΩ
PD(2A) = 940mW
PD(12.5%D/C) = %DC x PD(2A)
PD(12.5%D/C) = 0.125 x 940mW
PD(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 dissipa-
tion under the varied load.
For example, a 4V system using an AAT4250 oper-
ates at a continuous 100mA load current level and
has short 2A current peaks, as in a GSM applica-
tion. The current peak occurs for 576µs out of a
4.61ms period.
PD(total) = PD(100mA) + PD(2A)
PD(total) = 2.1mW + 117.5mW
PD(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 ambi-
ent temperatures the duty cycle can be further
increased.
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 RDS MAX for 4
volts operation, it must be calculated approximated
4250.2001.12.0.94
9
AAT4250
Slew Rate Controlled Load Switch
Printed Circuit Board Layout
Recommendations
Evaluation Board Layout
The AAT4250 evaluation layout follows the printed
circuit board layout recommendations, and can be
used for good applications layout.
For proper thermal management, and to take
advantage of the low RDSON 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, CIN and COUT should
be placed close to the package pins.
Note: Board layout shown is not to scale.
Figure 1: Evaluation board
top side silk screen layout /
assembly drawing
Figure 2: Evaluation board
component side layout
Figure 3: Evaluation board
solder side layout
10
4250.2001.12.0.94
AAT4250
Slew Rate Controlled Load Switch
Ordering Information
Part Number
Package
Marking
Bulk
Tape and Reel
AAT4250IGV-T1
AAT4250IJS-T1
SOT23-5
N/A
N/A
SC70JW-8
Package Information
SOT23-5
e
Millimeters
Inches
Dim
Min
1.00
0.00
0.70
0.35
0.10
2.70
Max
1.30
0.10
0.90
0.50
0.25
3.10
Min
Max
S1
A
A1
A2
b
c
D
0.039
0.000
0.028
0.014
0.004
0.106
0.051
0.004
0.035
0.020
0.010
0.122
H
E
E1.40
e
H
L
S
S1
Θ
1.80
1.90
0.055
0.071
0.075
2.60
0.37
0.45
0.85
1°
3.00
0.102
0.118
D
0.015
0.018
0.033
1°
0.55
1.05
9°
0.022
0.041
9°
A
A2
c
Θ
S
b
L
4250.2001.12.0.94
11
AAT4250
Slew Rate Controlled Load Switch
SC70JW-8
e
e
e
Millimeters
Min Max
BSC
Inches
Min Max
0.083
0.069
Dim
E2.10
E1
L
BSC
1.75
0.23
2.00
0.40
1.10
0.10
1.00
0.079
0.016
0.043
0.004
0.039
0.009
E
A
A1
A2
D
e
b
c
Θ
Θ1
0
0.70
0.028
0.079 BSC
0.020 BSC
2.00 BSC
0.50 BSC
b
D
0.15
0.10
0
0.30
0.20
8º
0.006
0.004
0
0.012
0.008
8º
0.048REF
c
A2
A
4º
10º
4º
10º
A1
L
Θ
Θ1
E1
Advanced Analogic Technologies, Inc.
1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086
Phone (408) 524-9684
Fax (408) 524-9689
12
4250.2001.12.0.94
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