1
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
Typical Application
VOUT : 1.0V - 4.2V
VIN : 2.7V - 5.5V
SGND
ENABLE
VCC
VP LX
PGND
AAT1150
LX
FB
100Ω
10
μ
F0.1
μ
F
4.1
μ
H
3x22
μ
F
6.3V
General Description
The AAT1150 is a step-down, SwitchReg™, switching
converter ideal for applications where high efficiency,
small size, and low ripple are critical. Able to deliver 1A
with internal power MOSFETs, the current-mode con-
trolled IC provides high efficiency using synchronous
rectification. Fully internally compensated, the AAT1150
simplifies system design and lowers external parts
count.
The AAT1150 is available in a Pb-free, MSOP-8 package
and is rated over the -40°C to +85°C temperature
range.
Features
• VIN Range: 2.7V to 5.5V
• Up to 95% Efficiency
• 110m RDS(ON) MOSFET Switch
• <1.0μA of Shutdown Current
• 1MHz Switching Frequency
• Adjustable VOUT: 1.0V to 4.2V
• High Initial Accuracy: ±1%
• 1.0A Peak Current
• Integrated Power Switches
• Synchronous Rectification
• Internally Compensated Current Mode Control
• Constant PWM Mode for Low Output Ripple
• Internal Soft Start
• Current Limit Protection
• Over-Temperature Protection
• MSOP-8 package
• -40°C to +85°C Temperature Range
Applications
• Cable/DSL Modems
• Computer Peripherals
• High Efficiency Conversion From 5V or 3.3V Supply
• Network Cards
• Set-Top Boxes
2
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
Pin Descriptions
Pin # Symbol Function
1 FB Feedback input pin. This pin is connected to an external resistive divider for an adjustable output.
2 SGND Signal ground.
3EN
Enable input pin. When connected high, the AAT1150 is in normal operation. When connected low, it is
powered down. This pin should not be left fl oating.
4 VCC Power supply. It supplies power for the internal circuitry.
5 VP Input supply voltage for converter power stage.
6, 7 LX Inductor connection pins. These pins should be connected to the output inductor. Internally, Pins 6 and 7
are connected to the drains of the P-channel switch and N-channel synchronous rectifi er.
8 PGND Power ground return for the output stage.
Pin Configuration
MSOP-8
(Top View)
1 2
LX
PGND
LX
VP
FB
SGND
EN
VCC
1
2
3
4
8
7
6
5
3
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
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.
2. Human body model is a 100pF capacitor discharged through a 1.5kW resistor into each pin.
3. Mounted on a demo board.
4. Derate 6.7mW/°C above 25°C.
Absolute Maximum Ratings1
Symbol Description Value Units
VCC, VPVCC, VP to GND 6
V
VLX LX to GND -0.3 to VP + 0.3
VFB FB to GND -0.3 to VCC + 0.3
VEN EN to GND -0.3 to 6
TJOperating Junction Temperature Range -40 to 150 °C
VESD ESD Rating2 - HBM 3000 V
Thermal Characteristics3
Symbol Description Value Units
JA Maximum Thermal Resistance 150 °C/W
PDMaximum Power Dissipation (TA = 25°C)4667 mW
Recommended Operating Conditions
Symbol Description Rating Units
T Ambient Temperature Range -40 to +85 °C
4
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
Electrical Characteristics
VIN = VCC = VP = 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 Input Voltage Range 2.7 5.5 V
VOUT Output Voltage Tolerance VIN = VOUT + 0.3 to 5.5V, IOUT = 0 to 1A -4.0 4.0
%
VOUT
(VOUT*VIN)Load Regulation VIN = 4.2V, ILOAD = 0 to 1A 3.0
VOUT/VOUT Line Regulation VIN = 2.7V to 5.5V 0.2 %/V
VUVLO Under-Voltage Lockout VIN Rising 2.5 V
VIN Falling 1.2
VUVLO(HYS) Under-Voltage Lockout Hysteresis 250 mV
IQQuiescent Supply Current No Load, VFB = 0 160 300 μA
ISHDN Shutdown Current VEN = 0V, VIN = 5.5V 1.0
ILIM Current Limit
TA = 25°C
1.2 A
RDS(ON)H High Side Switch On Resistance 110 150 m
RDS(ON)L Low Side Switch On Resistance 100 150
Effi ciency VIN = 5V, VOUT = 3.3V, IOUT = 600mA 93 %
VEN(L) Enable Low Voltage VIN = 2.7V to 5.5V 0.6 V
VEN(H) Enable High Voltage 1.4
IEN Enable Pin Leakage Current VEN = 5.5V 1.0 μA
FOSC Oscillator Frequency TA = 25°C 700 1000 1200 kHz
TSD Over-Temperature Shutdown Threshold 140 °C
THYS Over-Temperature Shutdown Hysteresis 15
5
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
Typical Characteristics
Efficiency vs. Output Current
(VOUT = 1.5V)
0
20
40
60
80
100
10 100 1000
Output Current (mA)
Efficiency (%)
2.7V
3.6V
4.2V
Efficiency vs. Output Current
(VOUT = 3.3V)
0
10
20
30
40
50
60
70
80
90
100
10 100 1000
Output Current (mA)
Efficiency (%)
VIN = 5.0V
High Side RDS(ON) vs. Temperature
70
90
110
130
150
170
-20 0 20 40 60 80 100 120
Temperature (°C)
RDS(ON) (mΩ)
2.7V
3.6V
4.2V 5.5V
Low Side RDS(ON) vs. Temperature
70
90
110
130
150
170
-20 0 20 40 60 80 100 12
0
Temperature (°C)
RDS(ON) (mΩ)
2.7V
3.6V
4.2V
5.5V
RDS(ON) vs. Input Voltage
80
90
100
110
120
130
2.5 3 3.5 4 4.5 5 5.5
Input Voltage (V)
RDS(ON) (mΩ)
High Side
Low Side
Enable Threshold vs. Input Voltage
0.7
0.8
0.9
1
1.1
1.2
2.5 3 3.5 4 4.5 5 5.5
Input Voltage (V)
Enable Threshold (V)
VEN(H)
VEN(L)
6
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
Typical Characteristics
Oscillator Frequency Variation vs.
Supply Voltage
-1.5
-0.5
0.5
1.5
2.5
3.5
2.5 3 3.5 4 4.5 5 5.5
Supply Voltage (V)
Variation (%)
Oscillator Frequency Variation vs. Temperature
(VIN = 3.6V)
-10
-6
-2
2
6
10
-20 0 20 40 60 80 100
Temperature (°C)
Variation (%)
Output Voltage vs. Temperature
(IOUT = 900mA; VOUT = 1.5V)
-1.0
-0.6
-0.2
0.2
0.6
1.0
-20 0 20 40 60 80 100
Temperature (°C)
Output Voltage Error (%)
VIN = 2.7V
VIN = 3.6V
Line Regulation
(VOUT = 1.5V)
-0.25
-0.15
-0.05
0.05
0.15
0.25
2.5 3 3.5 4 4.5
5
5
Input Voltage (V)
Accuracy (%)
IOUT = 0.4A
IOUT = 1.0A
Load Regulation
(VOUT = 1.5V; VIN = 3.6V)
-5
-4
-3
-2
-1
0
0 150 300 450 600 750 900
IOUT (mA)
Error (%)
Load Regulation
(VOUT = 3.3V; VIN = 5.0V)
-5
-4
-3
-2
-1
0
0 150 300 450 600 750 900 1050
Output Current (mA)
VOUT Error (%)
7
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
Typical Characteristics
Efficiency vs. Input Voltage
(VOUT = 1.5V)
50
60
70
80
90
100
2.5 3 3.5 4 4.5 5 5.5
Input Voltage (V)
Efficiency (%)
IO = 1A
IO = 0.4A
AAT1150 Loop Gain and Phase
(CO = 22μF; VO = 1.5V; VIN = 3.6V; IO = 1A)
Frequency (kHz)
Gain (dB)
Phase (degrees)
-20
-16
-12
-8
-4
0
4
8
12
16
20
10 100 1000
-200
-160
-120
-80
-40
0
40
80
120
160
200
Gain
Phase
3 x 22mF
5 x 22mF
4 x 22mF
No Load Input Current vs. Temperature
(VCC = VP)
0
2
4
6
8
10
12
-20 -5 10 25 40 55 70 8
Temperature (°C)
Input Current (mA)
VCC = 5.0V
VCC = 2.7VVCC = 3.6VVCC = 4.2V
VCC = 5.5V
Non-Switching IQ vs. Temperature
(FB = 0V; VP = VCC)
100
110
120
130
140
150
160
170
180
190
200
-20-5102540 557085
Temperature (°C)
Operating Current (μA)
VCC = 5.0V
VCC = 2.7V
VCC = 3.6V
VCC = 4.2V
VCC = 5.5V
Switching Waveform
(V
IN
= 3.6V; V
OUT
= 1.5V; I
OUT
= 1.2A)
Time (500ns/div)
V
(LX)
2V/div
I
L
500mA/div
Transient Response
(V
IN
= 3.6V; V
OUT
= 1.5V; I
LOAD
= 0.25 to 1.2A)
Time (20μs/div)
V
OUT
50mV/div
Inductor Current
500mA/div
8
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
Typical Characteristics
Output Ripple
(VIN = 3.6V; VOUT = 1.5V; IOUT = 0A)
Time (500ns/div)
VOUT
5mV/div
BW = 20MHz
LX
2V/div
Output Ripple
(VIN = 3.6V; VOUT = 1.5V; IOUT = 1A)
Time (500ns/div)
VOUT
5mV/div
BW = 20MHz
LX
2V/div
Output Ripple
(VIN = 5.0V; VOUT = 3.3V; IOUT = 0A)
Time (500ns/div)
VOUT
5mV/div
BW = 20MHz
LX
2V/div
Output Ripple
(VIN = 5.0V; VOUT = 3.3V; IOUT = 1A)
Time (500ns/div)
VOUT
5mV/div
BW = 20MHz
LX
2V/div
Time (200μs/div)
VOUT
1V/div
IL
0.5A/div
Enable
2V/div
Inrush Limit
(VIN = 3.6V; VOUT = 1.5V; IL = 1A)
9
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
Functional Block Diagram
VP = 2.7V- 5.5VVCC
ENSGND PGND
LOGIC
1.0V REF
Temp.
Sensing
OSC
OP. AMP
LX
FB
DH
DL
CMP
Applications Information
Control Loop
The AAT1150 is a peak current mode buck converter.
The inner wide bandwidth loop controls the peak current
of the output inductor. The output inductor current is
sensed through the P-channel MOSFET (high side) and is
also used for short-circuit and overload protection. A
fixed slope compensation signal is added to the sensed
current to maintain stability. The loop appears as a
voltage-programmed current source in parallel with the
output capacitor.
The voltage error amplifier output programs the current
loop for the necessary inductor current to force a con-
stant output voltage for all load and line conditions. The
feedback resistive divider is external, dividing the output
voltage to the error amplifier reference voltage of 1.0V.
The error amplifier does not have a large DC gain typical
of most error amplifiers. This eliminates the need for
external compensation components while still providing
sufficient DC loop gain for load regulation. The crossover
frequency and phase margin are set by the output
capacitor value only.
Soft Start/Enable
Soft start increases the inductor current limit point in
discrete steps when the input voltage or enable input is
applied. It limits the current surge seen at the input and
eliminates output voltage overshoot. The enable input,
when pulled low, forces the AAT1150 into a low power,
non-switching state. The total input current during shut-
down is less than 1μA.
10
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
C1 Murata 10μF 6.3V X 5R GRM 42-6X 5R106K 6.3
C2,C3,C4 Murata 22uF 6.3V GRM 21BR60J226ME 39L 0805 X 5R
V
IN
: 2.7V - 5.5V
L 1 Sumida CDRH 5D18-4R1μH
SGND
ENABLE
VCC
VP LX
PGND
LX
FB
R1 100Ω
C1
10μF
C7
0.1μF
L1
4.1μH
C2,C3,C4
3x22μF
6.3V
R4
10k
R3
5k
R2 100k
AAT1150 VOUT : 1.5V 1A
Efficiency vs. Output Current
(VOUT = 1.5V)
0
20
40
60
80
100
10 100 1000
Output Current (mA)
Efficiency (%)
2.7V
3.6V
4.2V
Figure 1: Lithium-Ion to 1.5V Converter.
C1 Murata 10μF 6.3V X 5R GRM 42-6X 5R106K 6.3
C2,C3,C4 Murata 22μF 6.3V GRM 21BR 60J226ME 39L 0805 X 5R
VOUT : 3.3V 1A
VIN : 3.5V -5.5V
L 1 Sumida CDRH 5D18-4R1μH
SGND
ENABLE
VCC
VP LX
PGND
LX
FB
R1 100Ω
C1
10μF
C7
0.1μF
L1
4.1μH
C2,C3,C4
3x22μF
6.3V
R4
10k
R3
23k
R2 100 k
AAT1150
Figure 2: 5V Input to 3.3V Output Converter.
Power and Signal Source
Separate small signal ground and power supply pins iso-
late the internal control circuitry from the noise associ-
ated with the output MOSFET switching. The low pass
filter R1 and C7 in schematic Figures 1 and 2 filters the
noise associated with the power switching.
Current Limit and
Over-Temperature Protection
For overload conditions, the peak input current is limit-
ed. Figure 3 displays the current limit characteristics. As
load impedance decreases and the output voltage falls
closer to zero, more power is dissipated internally, rais-
ing the device temperature. Thermal protection com-
pletely disables switching when internal dissipation
becomes excessive, protecting the device from damage.
The junction over-temperature threshold is 140°C with
15°C of hysteresis.
Efficiency vs. Output Current
(V
OUT
= 3.3V)
0
10
20
30
40
50
60
70
80
90
100
10 100 1000
Output Current (mA)
Efficiency (%)
V
IN
= 5.0V
11
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5
Output Current (A)
Output Voltage (V)
VCC = VP = 3.6V
VO = 1.5V
Figure 1 Schematic
VCC = VP = 5.0V
VO = 3.3V
Figure 2 Schematic
Figure 3: Current Limit Characteristics.
Inductor
The output inductor is selected to limit the ripple current
to some predetermined value, typically 20% to 40% of
the full load current at the maximum input voltage.
Manufacturer’s specifications list both the inductor DC
current rating, which is a thermal limitation, and the
peak current rating, which is determined by the satura-
tion characteristics. The inductor should not show any
appreciable saturation under normal load conditions.
During overload and short-circuit conditions, the aver-
age current in the inductor can meet or exceed the ILIMIT
point of the AAT1150 without affecting converter perfor-
mance. Some inductors may have sufficient peak and
average current ratings yet result in excessive losses
due to a high DCR. Always consider the losses associ-
ated with the DCR and its effect on the total converter
efficiency when selecting an inductor.
For a 1.0A load and the ripple set to 30% at the maxi-
mum input voltage, the maximum peak-to-peak ripple
current is 300mA. The inductance value required is
3.9μH.
V
OUT
V
OUT
1.5
V
1.5V
L = ⋅ 1 -
L = 3.9μH
L = ⋅ 1 -
I
O
⋅ k ⋅ F
S
V
IN
1.0A ⋅ 0.3 ⋅ 830kHz
4.2V
⎛
⎝⎞
⎠
⎛
⎝
⎞
⎠
The factor “k” is the fraction of full load selected for the
ripple current at the maximum input voltage. The cor-
responding inductor RMS current is:
∆I
2
12
I
RMS
= ≈ I
O
= 1.0A I
O2
+
I is the peak-to-peak ripple current which is fixed by
the inductor selection above. For a peak-to-peak current
of 30% of the full load current, the peak current at full
load will be 115% of the full load. The 4.1μH inductor
selected from the Sumida CDRH5D18 series has a 57m
DCR and a 1.95A DC current rating. At full load, the
inductor DC loss is 57mW which amounts to a 3.8% loss
in efficiency.
Input Capacitor
The primary function of the input capacitor is to provide
a low impedance loop for the edges of pulsed current
drawn by the AAT1150. A low ESR/ESL ceramic capacitor
is ideal for this function. To minimize stray inductance,
the capacitor should be placed as closely as possible to
the IC. This keeps the high frequency content of the
input current localized, minimizing radiated and con-
ducted EMI while facilitating optimum performance of
the AAT1150. Ceramic X5R or X7R capacitors are ideal
for this function. The size required will vary depending
on the load, output voltage, and input voltage source
impedance characteristics. A typical value is around
10μF. The input capacitor RMS current varies with the
input voltage and the output voltage. The equation for
the RMS current in the input capacitor is:
V
O
⎛
V
O
⎞
I
RMS
= I
O
⋅ ⋅ 1 -
V
IN
⎝ V
IN
⎠
The input capacitor RMS ripple current reaches a maxi-
mum when VIN is two times the output voltage where it
is approximately one half of the load current. Losses
associated with the input ceramic capacitor are typically
minimal and are not an issue. Proper placement of the
input capacitor can be seen in the reference design lay-
out shown in Figures 4 and 5.
12
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
Output Capacitor
Since there are no external compensation components,
the output capacitor has a strong effect on loop stability.
Larger output capacitance will reduce the crossover fre-
quency with greater phase margin. For the 1.5V 1.0A
design using the 4.1μH inductor, three 22μF 6.3V X5R
capacitors provide a stable output. In addition to assist-
ing stability, the output capacitor limits the output ripple
and provides holdup during large load transitions.
The output capacitor RMS ripple current is given by:
V
OUT
⋅
(V
IN
- V
OUT
)
1
I
RMS
=
⋅
L
⋅
F
S
⋅
V
IN
2
⋅
3
For a ceramic capacitor, the dissipation due to the RMS
current of the capacitor is not a concern. Tantalum capac-
itors, with sufficiently low ESR to meet output voltage
ripple requirements, also have an RMS current rating
much greater than that actually seen in this application.
Adjustable Output
For applications requiring an output other than 1V, the
AAT1150 can be externally programmed. Resistors R3
and R4 of Figure 6 force the output to regulate higher
than 1V. R4 should be 100 times less than the internal
1MΩ resistance of the FB pin. Once R4 is selected, R3
can be calculated. For a 1.25V output with R4 set to
10.0kΩ, R3 is 2.55kΩ.
R3 = (VO - 1) · R4 = 0.25 · 10.0kΩ = 2.55kΩ
Layout Considerations
Figures 4 and 5 display the suggested PCB layout for the
AAT1150. The most critical aspect of the layout is the
placement of the input capacitor C1. For proper opera-
tion, C1 must be placed as closely as possible to the
AAT1150.
Thermal Calculations
There are two types of losses associated with the
AAT1150 output switching MOSFET: switching losses and
conduction losses. Conduction losses are associated with
the RDS(ON) characteristics of the output switching device.
At full load, assuming continuous conduction mode
(CCM), a simplified form of the total losses is:
IO2 ⋅ (RDS(ON)H ⋅ VO + RDS(ON)L ⋅ (VIN - VO))
PLOSS =
VIN
+t
sw ⋅ FS ⋅ IO ⋅ VIN + IQ ⋅ VIN
Once the total losses have been determined, the junction
temperature can be derived from the JA for the MSOP-8
package.
13
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
Figure 4: AAT1150 Evaluation Figure 5: AAT1150 Evaluation
Board Layout Top Layer. Board Layout Bottom Layer.
L1
2.7μH C2, C3, C4
3x 22μF
6.3V
C1
10μF
R1 100
C7
0.1μF
C1 Murata 10μF 6.3V X5R GRM42-6X 5R106K6.3
L1 Sumida CDRH4D28-2R7μH
R2
100k
C2, C3, C4 MuRata 22μF 6.3V GRM21BR60J226ME39L X5R 0805
V
O
+ 1.25V 1A
V
IN
+ 3.3V
V-
FB
SGND
EN
VCC
VP
LX
PGND
AAT1150-1.0 R3
2.55k 1%
R4
10k 1%
LX
EN
Figure 6: 3.3V to 1.25V Converter (Adjustable Output).
14
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
Design Example
Specifications
IOUT = 1.0A
IRIPPLE = 30% of Full Load at Max VIN
VOUT = 1.5V
VIN = 2.7V to 4.2V (3.6V nominal)
Fs = 830kHz
Maximum Input Capacitor Ripple
VO
⎛
VO
⎞
IO
IRMS = IO ⋅ ⋅ 1- = = 0.5ARMS, VIN = 2 ⋅ VO
VIN
⎝
VIN
⎠
2
P = ESRCOUT ⋅ IRMS2 = 5mΩ ⋅ 0.52 A = 1.25mW
Inductor Selection
V
OUT
V
OUT
1.5
V
1.5V
L = ⋅ 1 - = ⋅ 1 - = 3.9μH
I
O
⋅ k ⋅ F
S
V
IN
1.0A ⋅ 0.3 ⋅ 830kHz
4.2V
⎛
⎝⎞
⎠⎛
⎝⎞
⎠
Select Sumida inductor CDRH5D18, 4.1μH, 57m, 2.0mm height.
V
O
V
O
1.5
V
1.5V
ΔI = ⋅ 1 - = ⋅ 1- = 280mA
L ⋅ F
S
V
IN
4.1μH ⋅ 830kHz
4.2V
I
PK
= I
OUT
+ ΔI = 1.0A + 0.14A = 1.14A
2
P = I
O2
⋅ DCR = 57mW
⎛
⎝⎞
⎠
⎛
⎝⎞
⎠
Output Capacitor Dissipation
IRMS VOUT ⋅ (VIN - VOUT)1.5V ⋅ (4.2V - 1.5V)
L ⋅ FS ⋅ VIN 4.1μH ⋅ 830kHz ⋅ 4.2V
=⋅⋅= = 82mARMS
⋅⋅
1
23 1
23
PESR = ESRCOUT ⋅ IRMS2 = 5mΩ ⋅ 0.0822A = 33μW
15
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
AAT1150 Dissipation
P + (tsw
⋅
FS
⋅
IO + IQ)
⋅
VIN
IO2
⋅
(RDS(ON)H
⋅
VO + RDS(ON)L
⋅
(VIN -VO))
VIN
=
=+ (20nsec
⋅
830kHz
⋅
1.0A + 0.3mA)
⋅
3.6V = 0.203W
(0.14Ω
⋅
1.5V + 0.145Ω
⋅
(3.6V - 1.5V))
3.6V
TJ(MAX) = TAMB + ΘJA
⋅
PLOSS = 85°C + 150°C/W
⋅
0.203W = 115°C
Manufacturer Part Number Value Max DC Current DCR Size (mm)
L x W x H Type
Taiyo Yuden NPO5DB4R7M 4.7μH 1.4A 0.038 5.9 x 6.1 x 2.8
Shielded
Toko A914BYW-3R5M-D52LC 3.5μH 1.34A 0.073 5.0 x 5.0 x 2.0
Sumida CDRH5D28-4R2 4.2μH 2.2A 0.031 5.7 x 5.7 x 3.0
CDRH5D18-4R1 4.1μH 1.95A 0.057 5.7 x 5.7 x 2.0
Murata LQH55DN4R7M03 4.7μH2.7A 0.041 5.0 x 5.0 x 4.7 Non-Shielded
LQH66SN4R7M03 2.2A 0.025 6.3 x 6.3 x 4.7 Shielded
Table 1: Surface Mount Inductors.
Manufacturer Part Number Value Voltage Temp. Co. Case
Murata
GRM40 X5R 106K 6.3 10μF
6.3V X5R
0805
GRM42-6 X5R 106K 6.3 1206
GRM21BR60J226ME39L 22μF0805
GRM21BR60J106ME39L 10μF
Table 2: Surface Mount Capacitors.
16
AAT1150
1MHz 1A Step-Down DC/DC Converter
DATA SHEET
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201990A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 23, 2012
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a
service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Sky-
works may change its documentation, products, services, specifi cations or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no
responsibility whatsoever for confl icts, incompatibilities, or other diffi culties arising from any future changes.
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THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR
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NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, IN-
CLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM
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Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifi cations as a result of design defects, errors, or operation of products outside of pub-
lished parameters or design specifi cations. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product
design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifi cations or parameters.
Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for
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Ordering Information
Output Voltage Package Marking1Part Number (Tape & Reel)2
1.0V (Adj VOUT ≥ 1.0V) MSOP-8 JZXYY AAT1150IKS-1.0-T1
Skyworks Green™ products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to Skyworks
Definition of Green™, document number
SQ04-0074.
Package Information
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
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is held on part numbers listed in BOLD.
