AOZ1051PI

EZBuck™ 3 A Synchronous Buck Regulator

Not Recommended For New Designs

General Description Features

The AOZ1051PI is a high efficiency, easy to use, 3 A z 4.5 V to 18 V operating input voltage range
synchronous buck regulator. The AOZ1051PI works from z Synchronous Buck: 70 mΩ internal high-side switch
4.5 V to 18 V input voltage range, and provides up to 3 A and 40 mΩ internal low-side switch (at 12 V)
of continuous output current with an output voltage

ns
z Up to 95 % efficiency
adjustable down to 0.8 V.
z External soft start

ig
The AOZ1051PI comes in an exposed pad SO-8 z Output voltage adjustable to 0.8 V
package and is rated over a -40 °C to +85 °C operating
z 3 A continuous output current

es
ambient temperature range.
z 500 kHz PWM operation

D
z Cycle-by-cycle current limit
Replacement Parts:
z Pre-bias start-up
AOZ6663DI

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z Short-circuit protection
AOZ6683CI z Thermal shutdown

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z Exposed pad SO-8 package

r Applications
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z Point of load DC/DC converters
z LCD TV
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z Set top boxes

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z DVD and Blu-ray players/recorders

z Cable modems
en
m
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Typical Application

VIN
ec

C1 CSS
10µF
R

VIN SS
L1 4.7µH
ot

EN VOUT
AOZ1051PI LX
N

COMP R1
C2, C3
RC FB 22µF

CC AGND PGND R2

Figure 1. 3.3 V 3 A Synchronous Buck Regulator, Fs = 500 kHz

Rev. 1.0 June 2011 www.aosmd.com Page 1 of 14

 AOZ1051PI

Ordering Information
Part Number Ambient Temperature Range Package Environmental
AOZ1051PI -40 °C to +85 °C EPAD SO-8 Green Product

AOS Green Products use reduced levels of Halogens, and are also RoHS compliant.
Please visit www.aosmd.com/web/quality/rohs_compliant.jsp for additional information.

Pin Configuration

ns
PGND 1 8 NC

ig
es
VIN 2 7 SS
PAD
AGND (LX) EN

D
3 6

FB 4 5 COMP

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Exposed Pad SO-8

N
(Top View)

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Fo

Pin Description
d
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Pin Number Pin Name Pin Function

1 PGND Power ground. PGND needs to be electrically connected to AGND.
en

2 VIN Supply voltage input. When VIN rises above the UVLO threshold and EN is logic high,
the device starts up.
m

3 AGND Analog ground. AGND is the reference point for controller section. AGND needs to be
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electrically connected to PGND.

4 FB Feedback input. The FB pin is used to set the output voltage via a resistive voltage divider
between the output and AGND.
ec

5 COMP External loop compensation pin. Connect a RC network between COMP and AGND to
compensate the control loop.
R

6 EN Enable pin. Pull EN to logic high to enable the device. Pull EN to logic low to disable the
device. If on/off control in not needed, connect EN to VIN and do not leave it open.
ot

7 SS Soft-start pin. 5 µA current charging current.

8 NC No Connect Pin. Pin 8 is not internally connected. Connect this pin externally to LX and
N

use it for better thermal performance.

Exposed pad LX Switching node. LX is the drain of the internal PFET. LX is used as the thermal pad of the
power stage.

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 AOZ1051PI

Block Diagram

VIN

EN UVLO 5V LDO Internal OTP

& POR Regulator +5V

Reference ISen

ns
Softstart –
& Bias
Q1
ILimit

ig
SS
SS
5µA

es
+
+ PWM Level
0.8V PWM Shifter
EAmp – Control

D
FB – Comp +
Logic
+ FET LX
Driver

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Q2
COMP

N
500kHz
Oscillator r
Fo
d
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AGND PGND
en

Absolute Maximum Ratings Recommended Operating Conditions

m

Exceeding the Absolute Maximum Ratings may damage the The device is not guaranteed to operate beyond the Maximum
device. Recommended Operating Conditions.
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Parameter Rating Parameter Rating

Supply Voltage (VIN) 20 V Supply Voltage (VIN) 4.5 V to 18 V
ec

LX to AGND -0.7 V to VIN +0.3 V Output Voltage Range 0.8 V to 0.85 • VIN
LX to AGND (20 ns) -5 V to 22 V Ambient Temperature (TA) -40 °C to +85 °C
R

EN to AGND -0.3 V to VIN +0.3 V Package Thermal Resistance

Exposed Pad SO-8 (ΘJA)(2) 50 °C/W
ot

FB, SS, COMP to AGND -0.3 V to 6.0 V

PGND to AGND -0.3 V to +0.3 V Note:
2. The value of ΘJA is measured with the device mounted on a 1-in2
N

Junction Temperature (TJ) +150 °C

FR-4 board with 2 oz. Copper, in a still air environment with
Storage Temperature (TS) -65 °C to +150 °C TA = 25 °C. The value in any given application depends on the
ESD Rating(1) 2.0 kV user’s specific board design.

Note:
1. Devices are inherently ESD sensitive, handling precautions are
required. Human body model rating: 1.5 kΩ in series with 100 pF.

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 AOZ1051PI

Electrical Characteristics
TA = 25 °C, VIN = VEN = 12 V, VOUT = 3.3 V unless otherwise specified(3)

Symbol Parameter Conditions Min. Typ. Max. Units

VIN Supply Voltage 4.5 18 V
VUVLO Input Under-Voltage Lockout VIN Rising 4.1
Threshold V
VIN Falling 3.7
IIN Supply Current (Quiescent) IOUT = 0, VFB = 1.2 V, VEN > 1.2 V 1.6 2.5 mA
IOFF Shutdown Supply Current VEN = 0 V 1 10 µA
VFB Feedback Voltage TA = 25 °C 0.788 0.8 0.812 V

ns
Load Regulation 0.5 %
Line Regulation 1 %

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IFB Feedback Voltage Input Current 200 nA

es
VEN EN Input Threshold Off Threshold 0.6
V
On Threshold 2

D
VHYS EN Input Hysteresis 100 mV

ew
EN Leakage Current 1 µA
SS Time CSS = 10 nF 2 ms
MODULATOR

N
fO Frequency 400 500 600 kHz
DMAX Maximum Duty Cycle r 85 %
Fo
TMIN Controllable Minimum On Time 150 ns
Current Sense Transconductance 8 A/ V
d

Error Amplifier Transconductance 200 µA / V

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PROTECTION
ILIM Current Limit 3.5 4.5 A
en

Over-Temperature Shutdown Limit TJ Rising 150

°C
TJ Falling 100
m

OUTPUT STAGE
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High-Side Switch On-Resistance VIN = 12 V 70

mΩ
VIN = 5 V 110
Low-Side Switch On-Resistance VIN = 12 V 40
ec

mΩ
VIN = 5 V 50
R

Note:
3. Specification in BOLD indicate an ambient temperature range of -40 °C to +85 °C. These specifications are guaranteed by design.
ot
N

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 AOZ1051PI

Typical Performance Characteristics

Circuit of Figure 1. TA = 25 °C, VIN = VEN = 12 V, VOUT = 3.3 V unless otherwise specified.

Light Load Operation Full Load Operation

Vin ripple
0.5V/div
Vin ripple
0.1V/div
Vo ripple
Vo ripple
0.1V/div
0.1V/div

ns
IL
IL
2A/div
2A/div

ig
VLX
VLX
10V/div

es
10V/div

D
2µs/div 2µs/div

ew
Start Up to Full Load Short Circuit Protection

N
Vin LVX
5V/div 10V/div
r
Fo
Vo
Vo
d

2V/div
2V/div
de

IL
en

lin 2A/div
2A/div
m

2ms/div 20ms/div
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50% to 100% Load Transient Short Circuit Recovery

ec

VLX
R

10V/div

Vo
ot

0.1V/div
Vo
N

2V/div

Io
2A/div IL
2A/div

100µs/div 20ms/div

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 AOZ1051PI

Efficiency

Efficiency (VIN = 12V) vs. Load Current

100

95

90

85
Efficiency (%)

ns
80

ig
5V OUTPUT
75 3.3V OUTPUT

es
1.8V OUTPUT
1.2V OUTPUT
70

D
65

ew
60
0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0

N
Load Current (A)

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Fo
Detailed Description
d

The AOZ1051PI is a current-mode step down regulator Steady-State Operation

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with an integrated high-side PMOS switch and a low-side Under heavy load steady-state conditions, the converter
NMOS switch. The AOZ1051PI operates from a 4.5 V to operates in fixed frequency and Continuous-Conduction
18 V input voltage range and supplies up to 3 A of load
en

Mode (CCM).
current. Features include enable control, power-on reset,
input under voltage lockout, output over voltage The AOZ1051PI integrates an internal P-MOSFET as the
m

protection, external soft-start and thermal shut down. high-side switch. Inductor current is sensed by amplifying
the voltage drop across the drain to source of the high
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The AOZ1051PI is available in an exposed pad SO-8 side power MOSFET. Output voltage is divided down by
package. the external voltage divider at the FB pin. The difference
of the FB pin voltage and reference voltage is amplified
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Enable and Soft Start

by the internal transconductance error amplifier. The
The AOZ1051PI has an external soft start feature to limit error voltage, which shows on the COMP pin, is
R

in-rush current and ensure the output voltage ramps up compared against the current signal, which is the sum of
smoothly to regulation voltage. The soft start process inductor current signal and ramp compensation signal, at
ot

begins when the input voltage rises to 4.1 V and voltage the PWM comparator input. If the current signal is less
on the EN pin is HIGH. In the soft start process, the than the error voltage, the internal high-side switch is on.
N

FB voltage is ramped to follow the voltage of the soft start The inductor current flows from the input through the
pin until it reaches 0.8 V. The voltage of the soft-start pin inductor to the output. When the current signal exceeds
is charged by an internal 5 µA current. the error voltage, the high-side switch is off. The inductor
current is freewheeling through the internal low-side
The EN pin of the AOZ1051PI is active high. Connect the N-MOSFET switch to output. The internal adaptive FET
EN pin to VIN if the enable function is not used. Pulling driver guarantees no turn on overlap of both the
EN to ground will disable the AOZ1051PI. Do not leave high-side and the low-side switch.
EN open. The voltage on the EN pin must be above 2 V
to enable the AOZ1051PI. When the EN pin voltage falls
below 0.6 V, the AOZ1051PI is disabled.

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 AOZ1051PI

Compared with regulators using freewheeling Schottky Since the switch duty cycle can be as high as 100 %, the
diodes, the AOZ1051PI uses a freewheeling NMOSFET maximum output voltage can be set as high as the input
to realize synchronous rectification. This greatly voltage minus the voltage drop on the upper PMOS and
improves the converter efficiency and reduces power the inductor.
loss in the low-side switch.
Protection Features
The AOZ1051PI uses a P-Channel MOSFET as the
high-side switch. This saves the bootstrap capacitor The AOZ1051PI has multiple protection features to
normally seen in a circuit using an NMOS switch. It also prevent system circuit damage under abnormal
allows 100 % turn-on of the high-side switch to achieve conditions.
linear regulation mode of operation. The minimum
Over Current Protection (OCP)
voltage drop from VIN to VO is the load current times DC

ns
resistance of the MOSFET plus DC resistance of the The sensed inductor current signal is also used for over
buck inductor. It can be calculated by equation below: current protection. Since the AOZ1051PI employs peak

ig
current mode control, the COMP pin voltage is
V O_MAX = V IN – I O × R DS ( ON ) proportional to the peak inductor current. The COMP pin

es
voltage is limited to be between 0.4 V and 2.5 V internally.
where; The peak inductor current is automatically limited

D
VO_MAX is the maximum output voltage, cycle-by-cycle.
VIN is the input voltage from 4.5 V to 18 V,

ew
When the output is shorted to ground under fault
IO is the output current from 0 A to 3 A, and
conditions, the inductor current slowly decays during a
RDS(ON) is the on resistance of the internal MOSFET. switching cycle because the output voltage is 0 V.

N
To prevent catastrophic failure, a secondary current limit
Output Voltage Programming
is designed inside the AOZ1051PI. The measured
Output voltage can be set by feeding back the output to r
inductor current is compared against a preset voltage
Fo
the FB pin using a resistor divider network as shown in which represents the current limit, between 3.5 A and 5.0
Figure 1. The resistor divider network includes R1 and A. When the output current is greater than the current
R2. Usually, a design is started by picking a fixed R2 limit, the high side switch will be turned off. The converter
d

value and calculating the required R1 with the equation will initiate a soft start once the over-current condition is
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below: resolved.
⎛ R ⎞
V O = 0.8 × ⎜ 1 + ------1-⎟ Power-On Reset (POR)
en

⎝ R 2⎠ A power-on reset circuit monitors the input voltage. When

the input voltage exceeds 4.1 V, the converter starts
m

Some standard value of R1 and R2 for the most common operation. When input voltage falls below 3.7 V, the
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output voltages are listed in Table 1. converter will be shut down.

Table 1. Thermal Protection

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An internal temperature sensor monitors the junction

VO (V) R1 (kΩ) R2 (kΩ) temperature. The sensor shuts down the internal control
circuit and high side PMOS if the junction temperature
R

0.8 1.0 Open

exceeds 150 ºC. The regulator will restart automatically
1.2 4.99 10
under the control of the soft-start circuit when the junction
ot

1.5 10 11.5 temperature decreases to 100 ºC.

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1.8 12.7 10.2

2.5 21.5 10
3.3 31.1 10
5.0 52.3 10

The combination of R1 and R2 should be large enough to

avoid drawing excessive current from the output, which
will cause power loss.

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 AOZ1051PI

Application Information For reliable operation and best performance, the input
capacitors must have a current rating higher than
The basic AOZ1051PI application circuit is show in
ICIN_RMS at the worst operating conditions. Ceramic
Figure 1. Component selection is explained below.
capacitors are preferred for input capacitors because of
Input Capacitor their low ESR and high current rating. Depending on the
application circuits, other low ESR tantalum capacitors
The input capacitor must be connected to the VIN pin and
may be used. When selecting ceramic capacitors, X5R or
the PGND pin of AOZ1051PI to maintain steady input
X7R type dielectric ceramic capacitors should be used
voltage and filter out the pulsing input current. The
for their better temperature and voltage characteristics.
voltage rating of input capacitor must be greater than
Note that the ripple current rating from capacitor
maximum input voltage plus ripple voltage.
manufactures are based on a certain operating life time.

ns
The input ripple voltage can be approximated by Further de-rating may need to be considered for long
equation below: term reliability.

ig
IO ⎛ VO ⎞ VO Inductor
ΔV IN = ----------------- × ⎜ 1 – --------
-⎟ × ---------

es
The inductor is used to supply constant current to output
f × C IN ⎝ V IN⎠ V IN when it is driven by a switching voltage. For a given input
and output voltage, inductance and switching frequency

D
Since the input current is discontinuous in a buck together decide the inductor ripple current, which is:
converter, the current stress on the input capacitor is

ew
another concern when selecting the capacitor. For a buck VO ⎛ VO ⎞
circuit, the RMS value of input capacitor current can be ΔI L = ----------- × ⎜ 1 – --------
-⎟
f×L ⎝ V ⎠
calculated by: IN

N
VO ⎛ VO ⎞ The peak inductor current is:
I CIN_RMS = I O × --------
- ⎜ 1 – --------
-⎟ r
V IN ⎝ V IN⎠
Fo
ΔI
I Lpeak = I O + -------L-
if we let m equal the conversion ratio:
2
d

VO
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High inductance gives low inductor ripple current but

- = m
-------- requires larger size inductor to avoid saturation. Low
V IN
ripple current reduces inductor core losses. It also
en

reduces RMS current through inductor and switches,

The relationship between the input capacitor RMS which results in less conduction loss. Usually, peak to
m

current and voltage conversion ratio is calculated and peak ripple current on the inductor is designed to be
shown in Figure 2 below. It can be seen that when VO is 20 % to 40 % of output current.
om

half of VIN, CIN is under the worst current stress. The

worst current stress on CIN is 0.5 x IO. When selecting the inductor, confirm it is able to handle
the peak current without saturation at the highest
0.5
ec

operating temperature.
0.4
R

The inductor takes the highest current in a buck circuit.

The conduction loss on the inductor needs to be checked
ICIN_RMS(m) 0.3 for thermal and efficiency requirements.
ot

IO
Surface mount inductors in different shape and styles are
N

0.2
available from Coilcraft, Elytone and Murata. Shielded
0.1 inductors are small and radiate less EMI noise. However,
they cost more than unshielded inductors. The choice
0 depends on EMI requirement, price and size.
0 0.5 1
m

Figure 2. ICIN vs. Voltage Conversion Ratio

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 AOZ1051PI

Output Capacitor Usually, the ripple current rating of the output capacitor is
The output capacitor is selected based on the DC output a smaller issue because of the low current stress. When
voltage rating, output ripple voltage specification and the buck inductor is selected to be very small and
ripple current rating. inductor ripple current is high, the output capacitor could
be overstressed.
The selected output capacitor must have a higher rated
voltage specification than the maximum desired output Loop Compensation
voltage including ripple. De-rating needs to be The AOZ1051PI employs peak current mode control for
considered for long term reliability. ease of use and fast transient response. Peak current
mode control eliminates the double pole effect of the
Output ripple voltage specification is another important output L&C filter. It also greatly simplifies the
factor for selecting the output capacitor. In a buck

ns
compensation loop design.
converter circuit, output ripple voltage is determined by
inductor value, switching frequency, output capacitor With peak current mode control, the buck power stage

ig
value and ESR. It can be calculated by the equation can be simplified to be a one-pole and one-zero system

es
below: in frequency domain. The pole is dominant pole can be
calculated by:
ΔV O = ΔI L × ⎛ ESR CO + -------------------------⎞
1
⎝ 8 × f × C O⎠

D
1
f P1 = -----------------------------------
2π × C O × R L

ew
where,
CO is output capacitor value, and The zero is a ESR zero due to the output capacitor and
its ESR. It is can be calculated by:

N
ESRCO is the equivalent series resistance of the output
capacitor.
1
f Z1 = ------------------------------------------------
r 2π × C O × ESR CO
Fo
When a low ESR ceramic capacitor is used as the output
capacitor, the impedance of the capacitor at the switching
where;
frequency dominates. Output ripple is mainly caused by
capacitor value and inductor ripple current. The output CO is the output filter capacitor,
d

ripple voltage calculation can be simplified to: RL is load resistor value, and
de

1 ESRCO is the equivalent series resistance of output capacitor.

ΔV O = ΔI L × -------------------------
8×f×C
en

O The compensation design shapes the converter control

loop transfer function for the desired gain and phase.
If the impedance of ESR at switching frequency
m

Several different types of compensation networks can be

dominates, the output ripple voltage is mainly decided by used with the AOZ1051PI. For most cases, a series
om

capacitor ESR and inductor ripple current. The output capacitor and resistor network connected to the
ripple voltage calculation can be further simplified to: COMP pin sets the pole-zero and is adequate for a stable
ΔV O = ΔI L × ESR CO high-bandwidth control loop.
ec

In the AOZ1051PI, FB and COMP are the inverting input

R

For lower output ripple voltage across the entire and the output of the internal error amplifier. A series
operating temperature range, X5R or X7R dielectric type R and C compensation network connected to COMP
ot

of ceramic, or other low ESR tantalum capacitors are provides one pole and one zero. The pole is:
recommended as output capacitors.
G EA
N

In a buck converter, output capacitor current is f P2 = ------------------------------------------

-
2π × C C × G VEA
continuous. The RMS current of output capacitor is
decided by the peak to peak inductor ripple current. It can
where;
be calculated by:
GEA is the error amplifier transconductance, which is 200 x 10-6
ΔI L A/V,
I CO_RMS = ----------
12 GVEA is the error amplifier voltage gain, which is 500 V/V, and
CC is the compensation capacitor in Figure 1.

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 AOZ1051PI

The zero given by the external compensation network, Thermal Management and Layout
capacitor CC and resistor RC, is located at: Considerations
1 In the AOZ1051PI buck regulator circuit, high pulsing
f Z2 = ----------------------------------- current flows through two circuit loops. The first loop
2π × C C × R C
starts from the input capacitors, to the VIN pin, to the
LX pad, to the filter inductor, to the output capacitor and
To design the compensation circuit, a target crossover
load, and then returns to the input capacitor through
frequency fC to close the loop must be selected. The
ground. Current flows in the first loop when the high side
system crossover frequency is where the control loop
switch is on. The second loop starts from the inductor,
has unity gain. The crossover is the also called the
to the output capacitors and load, to the low side
converter bandwidth. Generally a higher bandwidth
NMOSFET. Current flows in the second loop when the

ns
means faster response to load transients. However, the
low side NMOSFET is on.
bandwidth should not be too high because of system
stability concern. When designing the compensation

ig
In PCB layout, minimizing the area of the two loops will
loop, converter stability under all line and load condition reduce the noise of the circuit and improves efficiency.

es
must be considered. A ground plane is strongly recommended to connect the
input capacitor, the output capacitor, and the PGND pin
Usually, it is recommended to set the bandwidth to be

D
of the AOZ1051PI.
equal or less than 1/10 of the switching frequency.

ew
In the AOZ1051PI buck regulator circuit, the major power
The strategy for choosing RC and CC is to set the cross
dissipating components are the AOZ1051PI and the
over frequency with RC and set the compensator zero
output inductor. The total power dissipation of converter
with CC. Using selected crossover frequency, fC, to

N
circuit can be measured by input power minus output
calculate RC:
power:
VO 2π × C C r
P total_loss = V IN × I IN – V O × I O
Fo
R C = f C × ---------- × -----------------------------
-
V G ×G
FB EA CS
The power dissipation of the inductor can be
d

where; approximately calculated by the output current and DCR

de

fC is the desired crossover frequency. For best performance, value of the inductor:
fC is set to be about 1/10 of the switching frequency;
P inductor_loss = IO2 × R inductor × 1.1
en

VFB is 0.8V,
GEA is the error amplifier transconductance, which is The actual junction temperature can be calculated by the
200 x 10-6 A/V, and
m

power dissipation in the AOZ1051PI and the thermal

GCS is the current sense circuit transconductance, which is impedance from junction to ambient:
om

8 A/V
T junction = ( P total_loss – P inductor_loss ) × Θ JA
The compensation capacitor CC and resistor RC together
ec

make a zero. This zero is put somewhere close to the The maximum junction temperature of the AOZ1051PI is
dominate pole fp1 but lower than 1/5 of the selected 150 ºC, which limits the maximum load current capability.
crossover frequency. CC can is selected by:
R

The thermal performance of the AOZ1051PI is strongly

1.5 affected by the PCB layout. Care should be taken during
ot

C C = -----------------------------------
2π × R C × f P1 the design process to ensure that the IC will operate
under the recommended environmental conditions.
N

The above equation can be simplified to:

CO × RL
C C = ---------------------
RC

An easy-to-use application software which helps to

design and simulate the compensation loop can be found
at www.aosmd.com.

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 AOZ1051PI

Layout Considerations
The AOZ1051PI is an exposed pad SO-8 package.
Several layout tips are listed for the best electric and
thermal performance.

1. The exposed pad (LX) is connected to the internal

PFET and NFET drains. Connected a large copper
plane to the LX pin to help thermal dissipation.
2. Do not use a thermal relief connection to the VIN pin
or the PGND pin. Pour a maximized copper area to
the PGND pin and the VIN pin to help thermal

ns
dissipation.
3. The input capacitor should be connected as close as

ig
possible to the VIN pin and the PGND pin.

es
4. A ground plane is preferred. If a ground plane is not
used, separate PGND from AGND and only connect

D
them at one point to avoid the PGND pin noise
coupling to the AGND pin.

ew
5. Make the current trace from the LX pad to L to Co to
the PGND as short as possible.

N
6. Pour copper plane on all unused board area and
connect it to stable DC nodes, like VIN, GND or
VOUT. r
Fo
7. Keep sensitive signal trace away from the LX pad.
d
de
en
m
om
ec
R
ot
N

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 AOZ1051PI

Package Dimensions, SO-8 EP1

Gauge plane
D0 0.2500
C

L1

E2 E3 E1 E

ns
ig
es
D
D1 L1'
Note 5
D
θ

ew
7 (4x)

N
A2 A

r
Fo
B e
A1

Dimensions in millimeters Dimensions in inches

d

Symbols Min. Nom. Max. Symbols Min. Nom. Max.

de

RECOMMENDED LAND PATTERN A 1.40 1.55 1.70 A 0.055 0.061 0.067

A1 0.00 0.05 0.10 A1 0.000 0.002 0.004
en

3.70
A2 1.40 1.50 1.60 A2 0.055 0.059 0.063
B 0.31 0.406 0.51 B 0.012 0.016 0.020
m

C 0.17 — 0.25 C 0.007 — 0.010

2.20 D 4.80 4.96 5.00 D 0.189 0.195 0.197
om

D0 3.20 3.40 3.60 D0 0.126 0.134 0.142

5.74 D1 3.10 3.30 3.50 D1 0.122 0.130 0.138
E 5.80 6.00 6.20 E 0.228 0.236 0.244
ec

2.71
e — 1.27 — e — 0.050 —
2.87 E1 3.80 3.90 4.00 E1 0.150 0.153 0.157
R

E2 2.21 2.41 2.61 E2 0.087 0.095 0.103

E3 0.40 REF E3 0.016 REF
ot

L 0.40 0.95 1.27 L 0.016 0.037 0.050

N

0.80 y — — 0.10 y — — 0.004

1.27 θ 0° 3° 8° θ 0° 3° 8°
0.635
UNIT: mm | L1–L1' | — 0.04 0.12 | L1–L1' | — 0.002 0.005
L1 1.04 REF L1 0.041 REF
Notes:
1. Package body sizes exclude mold flash and gate burrs.
2. Dimension L is measured in gauge plane.
3. Tolerance 0.10mm unless otherwise specified.
4. Controlling dimension is millimeter, converted inch dimensions are not necessarily exact.
5. Die pad exposure size is according to lead frame design.
6. Followed from JEDEC MS-012

Rev. 1.0 June 2011 www.aosmd.com Page 12 of 14

 AOZ1051PI

Tape and Reel Dimensions, SO-8 EP1

Carrier Tape P1
D1
P2
T

E1

E2 E

ns
B0

ig
K0 D0
A0 P0 Feeding Direction

es
UNIT: mm
Package A0 B0 K0 D0 D1 E E1 E2 P0 P1 P2 T

D
SO-8 6.40 5.20 2.10 1.60 1.50 12.00 1.75 5.50 8.00 4.00 2.00 0.25
(12mm) ±0.10 ±0.10 ±0.10 ±0.10 ±0.10 ±0.10 ±0.10 ±0.10 ±0.10 ±0.10 ±0.10 ±0.10

ew
N
Reel
W1
r
Fo
S
G
d
de

N
M K
V
en

R
m

H
om

W
UNIT: mm
Tape Size Reel Size M N W W1 H K S G R V
ec

12mm ø330 ø330.00 ø97.00 13.00 17.40 ø13.00 10.60 2.00 — — —

±0.50 ±0.10 ±0.30 ±1.00 +0.50/-0.20 ±0.50
R
ot

Leader/Trailer and Orientation

N

Trailer Tape Components Tape Leader Tape

300mm min. or Orientation in Pocket 500mm min. or
75 empty pockets 125 empty pockets

Rev. 1.0 June 2011 www.aosmd.com Page 13 of 14

 AOZ1051PI

Part Marking

Z1051PI
Part Number Code
FAYWLT

ns
ig
Fab & Assembly Location Assembly Lot Code

es
Year & Week Code

D
ew
r N
Fo
d
de
en
m
om
ec

This data sheet contains preliminary data; supplementary data may be published at a later date.
Alpha & Omega Semiconductor reserves the right to make changes at any time without notice.
R

LIFE SUPPORT POLICY

ot

ALPHA & OMEGA SEMICONDUCTOR PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL
COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS.
N

As used herein:

1. Life support devices or systems are devices or 2. A critical component in any component of a life
systems which, (a) are intended for surgical implant into support, device, or system whose failure to perform can
the body or (b) support or sustain life, and (c) whose be reasonably expected to cause the failure of the life
failure to perform when properly used in accordance support device or system, or to affect its safety or
with instructions for use provided in the labeling, can be effectiveness.
reasonably expected to result in a significant injury of
the user.

Rev. 1.0 June 2011 www.aosmd.com Page 14 of 14