SwitchReg™
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
1151.2005.11.1.4 1
General Description
The AAT1151 SwitchReg™ is a member of
AnalogicTech's Total Power Management IC™
(TPMIC™) product family. The step-down switching
converter is ideal for applications where high effi-
ciency is required over the full range of output load
conditions. The 2.7V to 5.5V input voltage range
makes the AAT1151 ideal for single-cell lithium-
ion/polymer battery applications. Capable of more
than 700mA with internal MOSFETs, the current-
mode controlled IC provides high efficiency using
synchronous rectification. Fully integrated compen-
sation simplifies system design and lowers external
parts count.
The device operates at a fixed 850kHz switching fre-
quency and enters PFM mode for light load current
to maintain high ef ficiency across all load conditions.
The AAT1 151 is available in MSOP-8 and QFN33-16
packages and is rated over the -40°C to +85°C tem-
perature range.
Features
•V
IN Range: 2.7V to 5.5V
• Up to 95% Efficiency
• High Initial Accuracy ±1%
• 110mΩRDS(ON) Internal Switches
• <1µA Shutdown Current
• 850kHz Switching Frequency
• Fixed VOUT or Adjust able VOUT ≥1.0V
• Integrated Power Switches
• Synchronous Rectification
• Current Mode Operation
• Internal Compensation
• Stable with Ceramic Capacitors
• PWM and PFM for Optimum Efficiency for All
Load Conditions
• Internal Soft Start
• Over-Temperature Protection
• Current Limit Protection
• MSOP-8 and QFN33-16 Packages
• -40°C to +85°C Temperature Range
Applications
• Cellular Phones
• Digital Cameras
• MP3 Players
• Notebook Computers
• PDAs
• USB-Powered Equipment
• Wireless Notebook Adapters
Typical Application
OUTPUT
3.0µH
2x 22µF
10µF
0.1µF
100Ω
LX
VP
INPUT
FB
SGND
AAT1151
ENABLE
VCC
PGND
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
21151.2005.11.1.4
Pin Descriptions
Pin Configuration
MSOP-8 QFN33-16
(Top view) (Top view)
VP
VP
VP
NC
P
GND
P
GND
P
GND
1
2
3
4
SGND
SGND
EN
16
15
14
13
5
6
7
8
12
11
10
9
NC
VCC
LX
LX
LX
FB
1 2
LX
PGND
LX
VP
FB
SGND
EN
VCC
1
2
3
4
8
7
6
5
Pin #
MSOP-8 QFN33-16 Symbol Function
1 4 FB Feedback input pin. This pin is connected to the converter output. It
is used to set the output of the converter to regulate to the desired
value via an internal resistive divider. For an adjustable output, an
external resistive divider is connected to this pin on the 1V model.
2 5, 6 SGND Signal ground. Connect the return of all small signal components to
this pin. (See board layout rules.)
3 7 EN Enable input pin. A logic high enables the converter; a logic low
forces the AAT1151 into shutdown mode reducing the supply current
to less than 1µA. The pin should not be left floating.
4 9 VCC Bias supply. Supplies power for the internal circuitry. Connect to input
power via low pass filter with decoupling to SGND.
5 10, 11, 12 VP Input supply voltage for the converter power stage. Must be closely
decoupled to PGND.
6, 7 13, 14, 15 LX Connect inductor to these pins. Switching node internally connected
to the drain of both high- and low-side MOSFETs.
8 1, 2, 3 PGND Main power ground return pin. Connect to the output and input
capacitor return. (See board layout rules.)
8, 16 NC Not internally connected.
EP Exposed paddle (bottom); connect to PGND directly beneath package.
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
1151.2005.11.1.4 3
Absolute Maximum Ratings1
Thermal Characteristics3
Recommended Operating Conditions
Symbol Description Value Units
T Ambient Temperature Range -40 to 85 °C
Symbol Description Value Units
ΘJA Thermal Resistance (MSOP-8) 150 °C/W
PDMaximum Power Dissipation (MSOP-8) (TA= 25°C)4667 mW
ΘJA Thermal Resistance (QFN33-16) 50 °C/W
PDMaximum Power Dissipation (QFN33-16) (TA= 25°C)52.0 W
Symbol Description Value Units
VCC, VPVCC, VPto GND 6 V
VLX LX to GND -0.3 to VP+0.3 V
VFB FB to GND -0.3 to VCC+0.3 V
VEN EN to GND -0.3 to 6 V
TJOperating Junction Temperature Range -40 to 150 °C
VESD ESD Rating2- HBM 3000 V
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at condi-
tions 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 1.5kΩresistor into each pin.
3. Mounted on a demo board.
4. Derate 6.7mW/°C above 25°C.
5. Derate 20mW/°C above 25°C.
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
41151.2005.11.1.4
Electrical Characteristics1
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 + 0.2 to 5.5V, -3.0 +3.0 %
IOUT = 0 to 700mA
VUVLO Under-Voltage Lockout VIN Rising 2.5 V
VIN Falling 1.2
VUVLO(HYS) Under-Voltage Lockout Hysteresis 250 mV
IIL Input Low Current VIN = VFB = 5.5V 1.0 µA
IIH Input High Current VIN = VFB = 0 V 1.0 µA
IQQuiescent Supply Current No Load, VFB = 0 V, VIN = 4.2V 210 300 µA
TA= 25°C
ISHDN Shutdown Current VEN = 0 V, VIN = 5.5V 1.0 µA
ILIM Current Limit TA= 25°C 1.2 A
RDS(ON)H High Side Switch On Resistance TA= 25°C 110 150 mΩ
RDS(ON)L Low Side Switch On Resistance TA= 25°C 100 150 mΩ
ηEfficiency IOUT = 300mA, VIN = 3.5V 92 %
∆VOUT (VOUT*∆VIN) Load Regulation VIN = 4.2V, ILOAD = 0 to 700mA ±0.9 %
∆VOUT/VOUT Line Regulation VIN = 2.7V to 5.5V ±0.1 %/V
FOSC Oscillator Frequency TA= 25°C 600 850 1200 KHz
VEN(L) Enable Threshold Low 0.6 V
VEN(H) Enable Threshold High 1.4 V
TSD Over-Temperature Shutdown 140 °C
Threshold
THYS Over-Temperature Shutdown 15 °C
Hysteresis
1. The AAT1151 is guaranteed to meet performance specifications over the -40°C to +85°C operating range and is assured by design,
characterization, and correlation with statistical process controls.
Typical Characteristics
AAT1151 Efficiency
(VOUT = 2.5V; L = 4.2µ
µ
H)
Output Current (mA)
Efficiency (%)
50
55
60
65
70
75
80
85
90
95
100
1 10 100 1000 10000
Switching Frequency vs. Temperature
0
200
400
600
800
1000
1200
-40 -20 0 20 40 60 80 100
Temperature (°
°
C)
Frequency (kHz)
Load and Line Regulation
Load Current (mA)
VOUT Error (%)
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
1 10 100 1000
VIN = 3.6V
VIN = 4.2V
VIN = 2.7V
Output Voltage vs. Temperature
1.78
1.782
1.784
1.786
1.788
1.79
1.792
1.794
-40 -20 0 20 40 60 80 100
Temperature (°
°
C)
Output Voltage (V)
Frequency vs. Input Voltage
850
860
870
880
890
2.5 3 3.5 4 4.5 5 5.5
Input Voltage (V)
Frequency (kHz)
No Load Supply Current vs. Input Voltage
2.5 3 3.5 4 4.5 5 5.5
Input Voltage (V)
Supply Current (µ
µ
A)
0
50
100
150
200
250
300
T = 85°C
T = -40°CT = 25°C
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
1151.2005.11.1.4 5
Typical Characteristics
Soft Start 1.8V, 0.7A, VIN = 3.6V
Circuit of Figure 1
Time (200µ
µ
s/div)
Enable (top)
Output (middle) (V)
Inductor Current
(bottom) (A)
-4
-3
-2
-1
0
1
2
3
4
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
Load Transient Response 50mA to 0.7A
VIN = 3.6V −
−
Circuit of Figure 1
Time (200µs/div)
Output Voltage (top) (mV)
(AC coupled)
Inductor Current
(bottom) (A)
-120
-100
-80
-60
-40
-20
0
20
40
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
Line Transient Response 1.8V, 0.7A
Circuit of Figure 1
2.8
3
3.2
3.4
3.6
3.8
4
4.2
4.4
Time (20µ
µ
s/div)
Input Voltage
(top) (V)
-40
-20
0
20
40
60
80
100
120
Output Voltage
(bottom) (mV)
Output Ripple 1.8V, 0.7A, VIN = 3.6V
Circuit of Figure 1
Time (2µ
µ
s/div)
Output Voltage
(AC coupled) (top) (mV)
Inductor Current
(bottom) (A)
-60
-50
-40
-30
-20
-10
0
10
20
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
Line Transient Response 1.8V, 50mA
Circuit of Figure 1
2.8
3
3.2
3.4
3.6
3.8
4
4.2
4.4
Time (20µ
µ
s/div)
Input Voltage
(top) (V)
-40
-20
0
20
40
60
80
100
120
Output Voltage
(bottom) (mV)
Output Ripple 1.8V, 50mA, VIN = 3.6V
Circuit of Figure 1
Time (2µ
µ
s/div)
Output Voltage
(AC coupled) (top) (mV)
Inductor Current
(bottom) (A)
-60
-50
-40
-30
-20
-10
0
10
20
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
61151.2005.11.1.4
Typical Characteristics
Output Ripple
Circuit of Figure 1
0
5
10
15
20
1 10 100 1000
Output Current (mA)
Ripple (mV)
VIN = 2.7V
VIN = 3.6V
VIN = 4.2V
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
1151.2005.11.1.4 7
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
81151.2005.11.1.4
Functional Block Diagram
VP = 2.7V- 5.5VVCC
ENSGND PGND
LOGIC
1.0V REF
Temp.
Sensing
OSC
OP. AMP
LX
FB DH
DL
CMP
1MΩ
Operation
Control Loop
The AAT1151 is a peak current mode buck con-
verter. 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-cir-
cuit and overload protection. A fixed slope com-
pensation signal is added to the sensed current to
maintain stability. The loop appears as a voltage
programmed current source in parallel with the out-
put capacitor.
The voltage error amplifier output programs the cur-
rent loop for the necessary inductor current to force
a constant output voltage for all load and line condi-
tions. The volt age feedback resistive divider is inter-
nal, dividing the output voltage to the error amplifier
reference voltage of 1.0V. The voltage error amplifi-
er does not have the large DC gain typical of most
error amplifiers. This eliminates the need for exter-
nal compensation components, while still providing
sufficient DC loop gain for load regulation. The volt-
age loop crossover frequency and phase margin are
set by the output capacitor value only.
PFM/PWM Operation
Light load efficiency is maintained by way of Pulse
Frequency Modulation (PFM) control. The AAT1151
PFM control forces the peak inductor current to a
minimum level regardless of load demand. At medi-
um to high load demand, this has no effect on circuit
operation and normal PWM controls take over. PFM
reduces the switching frequency at light loads, thus
reducing the associated switching losses.
Soft Start/Enable
Soft st art 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.
When pulled low, the enable input forces the
AAT1151 into a low-power , non-switching state. The
total input current during shut down is less than 1µA.
Power and Signal Source
Separate small signal ground and power supply pins
isolate the internal control circuitry from the noise
associated with the output MOSFET switching. The
low pass filter R1 and C2 in schematic Figure 1 fil-
ters the noise associated with the power switching.
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
1151.2005.11.1.4 9
Current Limit and Over-Temperature
Protection
For overload conditions, the peak input current is
limited. As load impedance decreases and the
output voltage falls closer to zero, more power is
dissipated internally, raising the device tempera-
ture. Thermal protection completely disables
switching when internal dissipation becomes
excessive, protecting the device from damage.
The junction over-temperature threshold is 140°C
with 10°C of hysteresis.
Inductor
The output inductor is selected to limit the ripple cur-
rent 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 limita-
tion, and the peak current rating, which is deter-
mined by the saturation characteristics. The inductor
should not show any appreciable saturation under
normal load conditions. During overload and tran-
sient conditions, the average current in the inductor
can meet or exceed the current limit point of the
AAT1151. These conditions can tolerate greater sat-
uration in the inductor without degradation in con-
verter performance. Some inductors may meet the
peak and average current ratings yet result in exces-
sive losses due to a high DCR. Always consider the
losses associated with the DCR and its ef fect on the
total converter ef ficiency when selecting an inductor.
For a 1.0 Amp load and the ripple set to 40% at the
maximum input voltage, the maximum peak-to-
peak ripple current is 280mA. The inductance
value required is 2.84µH.
The factor "k" is the fraction of full load selected for
the ripple current at the maximum input voltage. For
ripple current at 40% of the full load current, the
peak current will be 120% of full load. Selecting a
standard value of 3.0µH gives 38% ripple current. A
3.0µH inductor selected from the Sumida
CDRH5D28 series has a 24mΩDCR and a 2.4ADC
current rating. At full load, the inductor DC loss is
24mW, which amounts to a 1.6% loss in efficiency.
L = · 1 -
VOUT VOUT
IO · k · F VIN
= · 1 -
1.5V 1.5V
1A · 0.4 · 850kHz 4.2V
⎛⎞
⎝⎠
⎛⎞
⎛⎞
⎝⎠
⎝⎠
= 2.84µH
Figure 1: AAT1151 Evaluation Board.
Efficiency vs. Load Current
(VOUT = 1.8V)
50
60
70
80
90
100
1 10 100 1000
Load Current (mA)
Efficiency (%)
2.7V
3.6V 4.2V
L1
3.3µH
C3, C4
2x22µF
C1
10µF
R1
100
C2
0.1µF
C1 Murata 10µF 6.3V X5R GRM42-6X5R106K6.3
R2
100k
C3-C4 MuRata 22µF 6.3V GRM21BR60J226ME39L X5R 0805
1.8
2.7V-4.2V
Out 4
gnd
5
EN
7
Vcc
9
Vp
10
LX 13
LX 14
Pgnd 3
Vp
11
gnd
6
Pgnd 2
LX 15
n/c
16
Pgnd 1
n/c 8
Vp
12
U1
AAT1151-QFN
R6
100k
L1 Sumida CDRH3D16-4R7NC or CDRH3D16-3R3NC
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
10 1151.2005.11.1.4
Input Capacitor
The primary function of the input capacitor is to pro-
vide a low impedance loop for the edges of pulsed
current drawn by the AAT1151. A low ESR/ESL
ceramic capacitor is ideal for this function. To mini-
mize stray inductance, the capacitor should be
placed as close as possible to the IC. This keep s the
high frequency content of the input current localized,
minimizing radiated and conducted EMI while facili-
tating optimum performance of the AAT1151.
Ceramic X5R or X7R capacitors are ideal for this
function. The size required will vary depending on the
load, output voltage, and input volt age source imped-
ance 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:
The input capacitor RMS ripple current reaches a
maximum when VIN is two times the output voltage
where it is approximately one half of the load cur-
rent. 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 layout in Figures 2 and 4.
Output Capacitor
Since there are no external compensation compo-
nents, the output capacitor has a strong effect on
loop stability. Lager output capacitance will reduce
the crossover frequency with greater phase mar-
gin. For the 1.5V 1A design using the 4.1µH induc-
tor, two 22µF capacitors provide a stable output. In
addition to assisting stability, the output capacitor
limits the output ripple and provides holdup during
large load transitions. The output capacitor RMS
ripple current is given by:
For a ceramic capacitor, the ESR is so low that dis-
sipation due to the RMS current of the capacitor is
not a concern. Tantalum capacitors with sufficiently
low ESR to meet output voltage ripple require-
ments also have an RMS current rating well
beyond that actually seen in this application.
Layout
Figures 2 through 5 display the suggested PCB
layout for the AAT1151. The following guidelines
should be used to help ensure a proper layout.
• The input capacitor (C1) should connect as
closely as possible to VPOWER (Pin 5) and
PGND (Pin 8).
• C2 and L1 should be connected as closely as
possible. The connection L1 to the LX node
should be as short as possible.
• The feedback trace (Pin 1) should be sepa-
rate from any power trace and connect as
closely as possible to the load point. Sensing
along a high-current load trace will degrade
DC load regulation.
• The resistance of the trace from the load
return to the PGND (Pin 8) should be kept to
a minimum. This will help to minimize any
error in DC regulation due to differences in
the potential of the internal signal ground
and the power ground.
• Low pass filter R1 and C3 provide a cleaner
bias source for the AAT1151 active circuitry.
C3 should be placed as closely as possible
to SGND (Pin 2) and VCC (Pin 4). See
Figures 2 and 7.
1
23
VOUT · (VIN - VOUT)
RMS
IN
ILFV
=· ··
·
⎛⎞
IRMS = IO · · 1 -
⎝⎠
VO
VIN
VO
VIN
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
1151.2005.11.1.4 11
Figure 2: MSOP Evaluation Figure 3: MSOP Evaluation
Board Top Layer. Board Bottom Layer.
Figure 4: QFN Evaluation Board Figure 5: QFN Evaluation Board
Top Side. Bottom Side.
Figure 6: R3 vs. VOUT for Adjustable Output Figure 7: Adjustable Output Schematic.
Using the AAT1151-1.0V.
L1
3.3µHC2, C4
2x 22µF
C1
10µF
R1 100
C3
0.1 µF
C1 Murata 10µF 6.3V X5R GRM42-6X5R106K6.3
L1 Sumida CDRH3D16-3R3 NC
R2
100k
C2, C4 MuRata 22µF 6.3V GRM21BR60J226ME39L X5R 0805
Vo+ 1.25V 0.7A
2.7V-5.5V
V-
FB 1
gnd
2
EN
3
Vcc
4
Vp
5
LX 6
LX 7
Pgnd 8
AAT1151-1.0 R3
2.55k 1%
R4
10kΩ 1%
0
5
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
Output Voltage (V)
R3 (kΩ)
R4=10kΩ
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
12 1151.2005.11.1.4
Thermal Calculations
There are two types of losses associated with the
AAT1151 output switching MOSFET: switching loss-
es and conduction losses. Conduction losses are
associated with the RDS(ON) characteristics of the
output switching device. At the full load condition,
assuming continuous conduction mode (CCM), a
simplified form of the total losses is given by:
where Iqis the AAT1151 quiescent current.
Once the total losses have been determined, the
junction temperature can be derived from the θJA
for the MSOP-8 package.
Adjustable Output
For applications requiring an output other than the
fixed available, the 1V version can be programmed
externally. Resistors R3 and R4 of Figure 7 force
the output to regulate higher than 1 volt. R4 should
be 100 times less than the 1MΩinternal resistance
of the FB pin (recommended 10kΩ). Once R4 is
selected, R3 can be calculated. For a 1.25 volt out-
put with R4 set to 10.0kΩ, R3 is 2.55kΩ.
R3 = (VO - 1) · R4 = 0.25 · 10kΩ = 2.55kΩ
TJ = P · θJA + TAMB
SW O IN
IN
IO2 · (RDSON(HS) · VO + RDSON(LS) · (VIN · VO))
P =
FI V
V
+ IQ) · VIN
·· ·
+ (t
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
1151.2005.11.1.4 13
Design Example
Specifications
IOUT 0.7A
IRIPPLE 40% of Full Load at Max VIN
VOUT 1.5V
VIN 2.7V to 4.2V (3.6V nominal)
FS850kHz
TAMB 85°C
Maximum Input Capacitor Ripple:
Inductor Selection:
Select Sumida inductor CDRH3D16 3.3µH 63mΩ1.8mm height.
Output Capacitor Ripple Current:
1
23
1 1.5V · (4.2V - 1.5V)
3.3µH · 850kHz · 4.2V
23
RMS
IN
ILFV
=·
··
·
· = 99mArms
·
VOUT · (VIN - VOUT)=
Pesr = esr · IRMS2 = 5mΩ · 992 mA = 50µW
V
O
V
O
1.5
V
1.5V
∆I = ⋅ 1 - = ⋅ 1- = 340mA
L ⋅ F
V
IN
3.3µH ⋅ 850kHz
4.2V
I
PK
= I
OUT
+ ∆I = 0.7A + 0.17A = 0.87A
2
P = I
O2
⋅ DCR = (0.7)
2
⋅ 63mΩ = 31mW
⎛
⎝⎞
⎠
⎛
⎝⎞
⎠
V
OUT
V
OUT
1.5
V
1.5V
L = ⋅ 1 - = ⋅ 1 - = 4.05µH
I
O
⋅ k ⋅ F
V
IN
0.7A ⋅ 0.4 ⋅ 850kHz
4.2V
⎛
⎝⎞
⎠⎛
⎝⎞
⎠
1 0.35Arms, VIN = 2
×
VO
OO
RMS O
IN IN
VV
II
VV
⎛⎞
=· · -=
⎝⎠
P = esr · IRMS
2 = 5mΩ · 0.352 A = 0.6mW
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
14 1151.2005.11.1.4
AAT1151 Dissipation:
Surface Mount Inductors
Surface Mount Capacitors
Manufacturer Part Number Value Voltage Temp. Co. Case
MuRata GRM40 X5R 106K 6.3 10µF 6.3V X5R 0805
MuRata GRM42-6 X5R 106K 6.3 10µF 6.3V X5R 1206
MuRata GRM21BR60J226ME39L 22µF 6.3V X5R 0805
MuRata GRM21BR60J106ME39L 10µF 6.3V X5R 0805
Max DC Size (mm)
Manufacturer Part Number Value Current DCR (ΩΩ)L
××W ××H Type
TaiyoYuden 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 Shielded
Sumida CDRH5D28-3R0 3.0µH 2.4A 0.024 5.7 x 5.7 x 3.0 Shielded
Sumida CDRH5D28-4R2 4.2µH 2.2A 0.031 5.7 x 5.7 x 3.0 Shielded
Sumida CDRH5D18-4R1 4.1µH 1.95A 0.057 5.7 x 5.7 x 2.0 Shielded
MuRata LQH55DN4R7M03 4.7µH 2.7A 0.041 5.0 x 5.0 x 4.7 Non-Shielded
MuRata LQH66SN4R7M03 4.7µH 2.2A 0.025 6.3 x 6.3 x 4.7 Shielded
MuRata CDRH3D16-3R3 3.3µH 1.1A 0.063 3.8 x 3.8 x 1.8 Shielded
TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + 150°C/W · 0.145W = 107°C (MSOP-8)
= 85°C + 50°C/W · 0.145W = 92°C (QFN33-16)
PTOTAL + (tsw · F · IO + IQ) · VIN
IO2 · (RDSON(H) · VO + RDSON(L) · (VIN -VO))
VIN
=
=+ (20nsec · 850kHz · 0.7A + 0.3mA) · 4.2V = 0.145W
(0.7A)2 · (0.2Ω · 1.5V + 0.187Ω · (4.2V - 1.5V))
4.2V
Ordering Information
Package Information
MSOP-8
All dimensions in millimeters.
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
Output Voltage1Package Marking2Part Number (Tape and Reel)3
1.0V (Adj VOUT ≥1.0V) MSOP-8 JHXYY AAT1151IKS-1.0-T1
1.0V (Adj VOUT ≥1.0V) QFN33-16 JHXYY AAT1151IVN-1.0-T1
1.8V MSOP-8 JIXYY AAT1151IKS-1.8-T1
1.8V QFN33-16 JIXYY AAT1151IVN-1.8-T1
2.5V MSOP-8 JJXYY AAT1151IKS-2.5-T1
2.5V QFN33-16 JJXYY AAT1151IVN-2.5-T1
3.3V MSOP-8 NKXYY AAT1151IKS-3.3-T1
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
1151.2005.11.1.4 15
1. Contact local sales office for custom options.
2. XYY = assembly and date code.
3. Sample stock is generally held on part numbers listed in BOLD.
AAT1151
850kHz 700mA Synchronous Buck DC/DC Converter
16 1151.2005.11.1.4
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
QFN33-16
All dimensions in millimeters.
3.000 ± 0.05
Pin 1 Dot By Marking
1.55 ± 0.15
0.400 ± 0.05
3.000 ± 0.05 0.500 ± 0.05
0.850 ± 0.05
Pin 1 Identification
0.025 ± 0.025
0.203 ± 0.0254
0.230 ± 0.05
Top View Bottom View
Side View
1
13
5
9
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