AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
4900.2009.10.1.4 1
www.analogictech.com
General Description
The AAT4900 FastSwitch is a member of AnalogicTech’s
Application Specific Power MOSFET™ (ASPM™) product
family. It is a buffered power half-bridge, consisting of
low on resistance power MOSFETs with integrated control
logic. This device operates with inputs ranging from 2.0V
to 5.5V, making it ideal for 2.5V, 3V, and 5V systems.
The device is protected from shoot-through current with
its own control circuitry. The AAT4900 is capable of very
fast switching times and is ideal for use in high frequen-
cy DC/DC converters. The quiescent supply current is a
low 4mA at 1MHz CLK frequency. In shutdown mode, the
supply current decreases to less than 1μA max.
The AAT4900 is available in a Pb-free 5-pin SOT23 or
8-pin SC70JW package and is specified over the -40°C to
+85°C temperature range.
Features
• 2.0V to 5.5V Input Voltage Range
• 105mΩ (typ) Low Side Switch RDS(ON)
• 130mΩ (typ) High Side Switch RDS(ON)
• Low Quiescent Current:
▪ 1μA (max) DC
▪ 4mA at 1MHz
• Only 2.5V Needed for Control Signal Input
• Break-Before-Make Shoot-Through Protection
• Temperature Range: -40°C to +85°C
• 5-Pin SOT23 or 8-Pin SC70JW Package
Applications
• DC Motor Drive
• High Frequency DC/DC Converters
• MOSFET Driver
Typical Application
AAT4900
EN
IN
LX
CLK
GND
ENABLE
2.0V to 5.5V Input
OUTPUT
Control Circuit
(PWM Output)
SOT23
DC/DC Converter Output Stage
AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
2 4900.2009.10.1.4
www.analogictech.com
Pin Descriptions
Pin #
Symbol Function
SOT23-5 SC70JW-8
1 2, 3 LX Inductor connection. LX output is controlled by CLK and EN (see Control Logic Table).
2 6, 7, 8 GND Ground connection.
34EN
Active-high enable input. A logic low signal puts the LX output pin in high impedance
mode.
4 5 CLK Logic input signal determines the state of LX output.
5 1 IN Supply voltage input. Input voltage range from 2.0V to 5.5V.
Pin Configuration
SOT23-5 SC70JW-8
(Top View) (Top View)
1
2
3
EN
LX
4
5
GND
IN
CLK
LX
LX
EN
1 2
GND
GND
GND
CLK
IN
1
2
3
4
8
7
6
5
AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
4900.2009.10.1.4 3
www.analogictech.com
1. 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.
2. Human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.
3. Mounted on a demo board.
Control Logic Table
Inputs Output
CLK EN LX
0 0 High Impedance
01 V
IN
1 0 High Impedance
1 1 Ground
Absolute Maximum Ratings1
TA = 25°C, unless otherwise noted.
Symbol Description Value Units
VIN IN to GND -0.3 to 6 V
VEN, VCLK EN, CLK to GND -0.3 to 6 V
VOUT OUT to GND -0.3 to VIN+0.3 V
IMAX Maximum Continuous Switch Current 2 A
TJOperating Junction Temperature Range -40 to 150 °C
VESD ESD Rating2 - HBM 4000 V
TLEAD Maximum Soldering Temperature (at Leads) 300 °C
Thermal Information3
Symbol Description Value Units
ΘJA Thermal Resistance (SOT23-5, SC70JW-8) 190 °C/W
PDPower Dissipation (SOT23-5, SC70JW-8) 526 mW
AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
4 4900.2009.10.1.4
www.analogictech.com
Electrical Characteristics
VIN = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C.
Symbol Description Conditions Min Typ Max Units
VIN Operation Voltage 2.0 5.5 V
IQAC AC Quiescent Current IN = 5V, EN = IN, CLK = 1MHz, ILX = 0 4 9 mA
IQDC DC Quiescent Current IN = 5V, EN = IN, CLK = GND, ILX = 0 1 μA
IQ(OFF) Off-Supply Current EN = CLK = GND, IN = LX = 5.5V 1 μA
ISD(OFF) Off-Switch Current EN = GND, IN = 5.5V, VOUT = 0 or LX = IN 0.03 1 μA
RDS(ON)H High Side MOSFET On Resistance
IN = 5V, TA = 25°C 130 165
mΩIN = 3V, TA = 25°C 165 195
IN = 2V, TA = 25°C 235
RDS(ON)L Low Side MOSFET On Resistance
IN = 5V, TA = 25°C 105 145
mΩIN = 3V, TA = 25°C 135 175
IN = 2V, TA = 25°C 200
VONL CLK, EN Input Low Voltage IN = 2V to 5.5V 0.4 V
VONH CLK, EN Input High Voltage IN = 2V to 5.5V 1.5 V
ISINK CLK, EN Input Leakage CLK, EN = 5.5V 0.01 1 μA
TBBM Break-Before-Make Time CLK Rising 5 ns
CLK Falling 5
TON-DLY CLK to LX Delay CLK Rising 30 ns
CLK Falling 40
THIZ EN to OUT HiZ Delay CLK = GND 40 ns
CLK = IN 40
AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
4900.2009.10.1.4 5
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Typical Characteristics
Operating Current vs. Input Voltage
(FS = 1MHz)
0
1
2
3
4
5
6
7
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Input Voltage (V)
Operating Current (mA)
Operating Current vs. Switching Frequency
0.000
0.001
0.010
0.100
1.000
10.000
0.0 0.1 1 10 100 1000 10000
Frequency (kHz)
Operating Current (mA)
VIN = 5V
VIN = 3V
Operating Current vs. Temperature
(FS = 1MHz)
0
2
4
6
8
10
12
-40 -20 0 20 40 60 80 100 120
Temperature (
°
C)
Operating Current (mA)
VIN = 5.5V
VIN = 4.3V
Operating Current vs. Temperature
(FS = 1MHz)
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
-40 -20 0 20 40 60 80 100 120
Temperature (
°
C)
Operating Current (mA)
VIN = 3.1V
VIN = 2.7V
High Side RDS(ON) vs. Output Current
0.10
0.11
0.12
0.13
0.14
0.15
0.16
0.17
0.18
0.19
0.20
0.21
0.22
0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.2
0
Output Current (A)
RDS(ON) (
Ω
)
VIN = 2.7V
VIN = 5.5V
Low Side RDS(ON) vs. Output Current
0.08
0.09
0.10
0.11
0.12
0.13
0.14
0.15
0.16
0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2
Output Current (A)
RDS(ON) (
)
VIN = 2.7V
VIN = 5.5V
AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
6 4900.2009.10.1.4
www.analogictech.com
Typical Characteristics
High Side RDS(ON)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
-40 -20 0 20 40 60 80 100 120
Temperature (
°
C)
RDS(ON)
(
Ω
)
VIN = 2.7V,
ID = 2.2A
VIN = 5.5V,
ID = 0.2A to 2.2A
VIN = 2.7V,
ID = 0.2A
Low Side RDS(ON)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
-40 -20 0 20 40 60 80 100 120
Temperature (
°
C)
RDS(ON) (
Ω
)
VIN = 2.7V,
ID = 2.2A
VIN = 5.5V,
ID = 0.2A to 2.2A
VIN = 2.7V,
ID = 0.2A
Propagation Delay vs. Input Voltage
(CL = 1000pF)
Input Voltage (V)
Delay Time (ns)
20
40
60
80
100
120
1.5 2.5 3.523454.5 5.5
tPLH
tPHL
CLK/Enable Threshold vs. Input Voltage
Input Voltage (V)
Threshold Voltage (V)
1.5 2 2.5 3 3.5 4 4.5 5 5.5
0.2
0.4
0.6
0.8
1.0
1.2
1.4
VONH
VONL
RDS(ON) vs. Input Voltage
Input Voltage (V)
RDS(ON)
(Ω
Ω
)
0.10
0.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
1.5 2 2.5 3 3.5 4 4.5 5 5.5
High Side
Low Side
AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
4900.2009.10.1.4 7
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Typical Applications
DC/DC Converter
The most common AAT4900 applications include a DC/
DC converter output power stage and a MOSFET gate
drive buffer.
Figure 1 shows a common configuration when used as a
DC/DC converter power stage with synchronous rectifica-
tion. The enable pin can be used to force the LX output to
a high impedance state under light load conditions. This
enables the output inductor to operate in discontinuous
conduction mode (DCM), improving efficiency under light
load conditions. The body diode associated with the low
side switching device gives the AAT4900 inductive switch-
ing capability, clamping the LX node at a diode drop below
GND during the break-before-make time.
Synchronous Buck
DC/DC Converter Application
The losses associated with the AAT4900 high side switch-
ing MOSFET are due to switching losses and conduction
losses. The conduction losses are associated with the
RDS(ON) characteristics of the output switching device. At
the full load condition, assuming continuous conduction
mode (CCM), the on losses can be derived from the fol-
lowing equations.
Eq. 1: D = O
IN
V
V
D is the duty cycle.
Eq. 2: 1ΔI = ⎛⎞
-
⎝⎠
VO
VIN
VO
L · FS
ΔI is the peak-to-peak inductor ripple current.
Functional Block Diagram
Control Logic
and
Shoot-Through
Protection
CLK
EN
IN
LX
GND
AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
8 4900.2009.10.1.4
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High Side Switch RMS Current
Eq. 3:
2
2
12
O
I
I
⎛⎞
Δ
= + · D
⎝⎠
IRMS(HS)
Low Side Switch RMS Current
The low side RMS current is estimated by the following
equation.
Eq. 4:
2
2
12
O
I
I
⎛⎞
Δ
= + · (1 - D)
⎝⎠
IRMS(LS)
Total Losses
A simplified form of the above results (where the above
descriptions of IRMS has been approximated with Io) is
given by:
Eq. 5: PLOSS
+ (tsw • FS • IO + IQ) • VIN
IO2 • (RDS(ON)H • VO + RDS(ON)L • (VIN -VO))
VIN
=
Substitution of the IRMS equations with IO results in very
little error when the inductor ripple current is 20% to
40% of the full load current. The equation also includes
switching and quiescent current losses where tSW is
approximated at 18 nsec and IQ is the no load quiescent
current of the AAT4900. Quiescent current losses are
associated with the gate drive of the output stage and
biasing. Since the gate drive current varies with fre-
quency and voltage, the bias current must be checked at
the frequency, voltage, and temperature of operation
with no load attached to the LX node. Once the above
losses have been determined, the maximum junction
temperature can be calculated.
Eq. 6: TJ(MAX) = PLOSS • ΘJC = TAM
B
Using the above equations, the graph below shows the
current capability for some typical applications with
maximum junction temperatures of 150°C and 120°C.
The increase in RDS(ON) vs. temperature is estimated at
3.75mΩ for a 10°C increase in junction temperature.
Step-Down Converter Limits
(FS = 1MHz)
0.5
0.75
1
1.25
1.5
1.75
25 35 45 55 65 75 85
Ambient Temperature (°C)
Output Current (A)
TJMAX = 150
°
C
VIN = 4.2V, VO = 2.5V
VIN = 5.0V, VO = 3.3V
VIN = 4.2V, VO = 2.5V
VIN = 5.0V, VO = 3.3V
TJMAX = 120
°
C
DC / DC
Controller
EN
CLK
GND
IN
LXAAT4900
V
IN
= 2.0 to 5.5V
V
OUT
= 0 to V
IN
I
OUT
= 0 to 1A
+
-
GND
Figure 1: AAT4900 DC/DC Converter Power Stage.
AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
4900.2009.10.1.4 9
www.analogictech.com
Gate Drive
When used as a MOSFET gate driver, the break-before-
make shoot-through protection significantly reduces
losses associated with the driver at high frequencies.
(See Figure 2.)
The low RDS(ON) of the output stage allows for a high peak
gate current and fast switching speeds. A small package
size facilitates close placement to the power device for
optimum switching performance. The logic level inputs
(CLK and EN) are high impedance inputs.
Gate Drive Current Ratings
An estimate of the maximum gate drive capability with
no external series resistor can be derived from Equation
7. Note that the quiescent current varies with the ambi-
ent temperature, frequency of operation, and input volt-
age. The graphs below display the quiescent current and
maximum gate charge drive capability at 85°C ambient
vs. frequency for various input voltages.
Eq. 7: QG(MAX) = · - IQ
⎛
⎝⎞
⎠
1
FS
TJ(MAX) - TAMB
θJA · VIN(MAX)
= · - 3.2mA
⎛
⎝⎞
⎠
1
1MHz
120°C - 85°C
190°C/W · 4.2V
= 40nC
The quiescent current was first measured over tempera-
ture for various input voltages with no load attached.
Equation 7 was then used to derive the maximum gate
charge capability for the desired maximum junction tem-
perature. QG is the gate charge required to raise the
gate of the load MOSFET to the input voltage. This value
is taken from the MOSFET manufacturer’s gate charge
curve.
No Load Operating Current at 85
°
C Ambient
0.1
1
10
100
100 1000 10000
Frequency (kHz)
Operating Current (mA)
VIN = 2.7V
VIN = 5.5V
VIN = 5.0V
VIN = 4.2V
Maximum Gate Charge Load @ 85
°
C
(Ambient TJ(MAX) = 120
°
C)
1
10
100
1000
100 1000 10000
Frequency (kHz)
Gate Charge (nC)
VIN = 5.0V
VIN = 5.5V
VIN = 4.2V
VIN = 2.7V
EN
CLK
GND
IN
LXAAT4900
+5V
Load
Circuit
Clock
Enable
Ground
Figure 2: AAT4900 Gate Drive Configuration.
AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
10 4900.2009.10.1.4
www.analogictech.com
Motor Drive
The AAT4900 is also ideally suited for use as an efficient
output driver for DC brushless motor con trol. The induc-
tive load switching capability of the AAT4900 eliminates
the need for external diodes. A typical motor control
circuit is illustrated in Figure 3.
Recommended Decoupling
Layout Pattern
Because of the extremely fast switching speed and the
high switching currents, optimum placement of the input
capacitor is critical. It is recommended that a 0.1μF to
10μF 0805 or 1206 ceramic capacitor be placed as close
as possible to the IC, as shown in Figure 4. This helps to
decouple the switching transients from the stray induc-
tance present in the PC board.
EN
CLK
GND
IN
LX
AAT4900 LX
IN
GND
AAT4900
EN
CLK
DC Brushless
Motor
Clock
Enable
Ground
+5V
Figure 3: Typical Motor Control Block Diagram.
5 V+
2 GND
1 LX
3 EN
4 CLK
AAT4900
CAP
Figure 4: Recommended Decoupling Layout Pattern.
AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
4900.2009.10.1.4 11
www.analogictech.com
CLK
LX
Figure 5: Timing Diagram.
CLK
LX
tPLH tPHL
50%
10%
50%
90%
tf
Figure 6: Switching Time Waveforms.
IN
VIN
EN
CLK
LX
GND
1000pF
10μF
Figure 7: Propagation Delay Test Circuit.
AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
12 4900.2009.10.1.4
www.analogictech.com
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
Ordering Information
Package Marking1Part Number (Tape and Reel)2
SOT23-5 ABXYY AAT4900IGV-T1
SC70JW-8 ABXYY AAT4900IJS-T1
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means semiconductor
products that are in compliance with current RoHS standards, including the requirement that lead not
exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at
http://www.analogictech.com/aboutus/quality.php.
Package Information
SOT23-5
4
°
±
4
°
0.15
±
0.07
0.45
±
0.15 0.10 BSC
1.20
±
0.25
1.575
±
0.125
2.80
±
0.20
0.40
±
0.10
0.60 REF
2.85
±
0.15
1.90 BSC
0.95
BSC
1.10
±
0.20
10
°
±
5
°
GAUGE PLANE
0.075
±
0.075
0.60 REF
All dimensions in millimeters.
AAT4900
Buffered Power Half-BridgeFastSwitchTM
PRODUCT DATASHEET
4900.2009.10.1.4 13
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Advanced Analogic Technologies, Inc.
3230 Scott Boulevard, Santa Clara, CA 95054
Phone (408) 737-4600
Fax (408) 737-4611
© Advanced Analogic Technologies, Inc.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual
property rights are implied. AnalogicTech reserves the right to make changes to their products or specifi cations or to discontinue any product or service without notice. Except as provided in AnalogicTech’s terms and
conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties
relating to fi tness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate
design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to
support this warranty. Specifi c testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other
brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
SC70JW-8
0.225
±
0.075
0.45
±
0.10
0.05
±
0.05
2.10
±
0.30
2.00
±
0.20
7
°
±
3
°
4
°
±
4
°
1.75
±
0.10
0.85
±
0.15
0.15
±
0.05
1.10 MAX
0.100
2.20
±
0.20
0.048REF
0.50 BSC 0.50 BSC 0.50 BSC
All dimensions in millimeters.