Datasheet

AOZ1024D
EZBuck™ 4A Synchronous Buck Regulator
Not Recommended For New Designs
Features
The AOZ1024D is a synchronous high efficiency, simple
to use, 4A buck regulator. The AOZ1024D works from a
4.5V to 16V input voltage range, and provides up to 4A
of continuous output current with an output voltage
adjustable down to 0.8V.
●
4.5V to 16V operating input voltage range
●
Synchronous rectification: 100mΩ internal high-side
switch and 20mΩ internal low-side switch
●
High efficiency: up to 95%
●
Internal soft start
The AOZ1024D comes in a DFN 5 x 4 package and is
rated over a -40°C to +85°C ambient temperature range.
●
1.5% initial output accuracy
●
Output voltage adjustable to 0.8V
Replacement Part: AOZ1034DI
●
4A continuous output current
●
Fixed 500kHz PWM operation
●
Cycle-by-cycle current limit
●
Pre-bias start-up
●
Short-circuit protection
●
Thermal shutdown
●
Small size DFN 5 x 4 packages
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General Description
Applications
Point of load DC/DC conversion
●
PCIe graphics cards
●
Set top boxes
●
DVD drives and HDD
●
LCD panels
●
Cable modems
●
Telecom/networking/datacom equipment
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●
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Typical Application
C1
22µF
Ceramic
VIN
L1 4.7µH
N
ot
VIN
EN
AOZ1024D
VOUT
LX
R1
COMP
RC
CC
FB
AGND
PGND
C2, C3
22µF
Ceramic
R2
Figure 1. 3.3V/4A Synchronous Buck Regulator
Rev. 1.3 September 2009
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Page 1 of 16
AOZ1024D
Ordering Information
Part Number
Ambient Temperature Range
Package
Environmental
AOZ1024DI
-40°C to +85°C
DFN-8
Green
All AOS products are offered in packages with Pb-free plating and compliant to RoHS standards.
Please visit www.aosmd.com/web/quality/rohs_compliant.jsp for additional information.
PGND
1
8
LX
7
LX
6
EN
5
COMP
ns
Pin Configuration
2
AGND
3
es
VIN
ig
LX
FB
4
D
GND
5 x 4 DFN
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(Top Thru View)
Pin Description
Pin Name
Pin Function
1
PGND
2
VIN
3
AGND
Reference connection for controller section. Also used as thermal connection for controller
section. Electrically needs to be connected to PGND.
4
FB
The FB pin is used to determine the output voltage via a resistor divider between the output
and GND.
5
COMP
6
EN
7, 8
LX
d
Pin Number
de
Power ground. Electrically needs to be connected to AGND.
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en
Supply voltage input. When VIN rises above the UVLO threshold the device starts up.
External loop compensation pin.
The enable pin is active high. Connect in to VIN if not used and do not leave it open.
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PWM output connection to inductor.
Rev. 1.3 September 2009
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Page 2 of 16
AOZ1024D
Block Diagram
VIN
UVLO
& POR
EN
Internal
+5V
5V LDO
Regulator
OTP
+
ISen
Softstart
Q1
ig
ILimit
FB
–
–
Level
Shifter
+
FET
Driver
PWM
Control
Logic
PWM
Comp
+
500kHz/68kHz
Oscillator
–
Fo
r
0.2V
Frequency
Foldback
Comparator
N
COMP
LX
Q2
ew
+
D
EAmp
es
+
+
0.8V
ns
–
Reference
& Bias
PGND
de
d
AGND
Absolute Maximum Ratings
en
Exceeding the Absolute Maximum ratings may damage the
device.
Supply Voltage (VIN)
LX to AGND
PGND to AGND
ot
PGOOD to AGND
4.5V to 16V
-0.7V to VIN+0.3V
Output Voltage Range
0.8V to VIN
-0.3V to VIN+0.3V
Ambient Temperature (TA)
-40°C to +85°C
-0.3V to 6V
Package Thermal Resistance DFN-8
(ΘJA)(2)
50°C/W
-0.3V to 6V
Storage Temperature (TS)
-65°C to +150°C
N
+150°C
ESD Rating
Note:
2. The value of ΘJA is measured with the device mounted on 1-in2 FR-4
board with 2oz. Copper, in a still air environment with TA = 25°C. The
value in any given application depends on the user's specific board
design.
-0.3V to +0.3V
Junction Temperature (TJ)
(1)
Rating
Supply Voltage (VIN)
-0.3V to 6V
R
COMP to AGND
Parameter
18V
ec
EN to AGND
FB to AGND
The device is not guaranteed to operate beyond the Maximum
Operating Ratings.
Rating
om
m
Parameter
Recommend Operating Ratings
2.0kV
Note:
1. Devices are inherently ESD sensitive, handling precautions are
required. Human body model rating: 1.5kΩ in series with 100pF.
Rev. 1.3 September 2009
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Page 3 of 16
AOZ1024D
Electrical Characteristics
TA = 25°C, VIN = VEN = 12V, VOUT = 3.3V unless otherwise specified(3)
Symbol
VIN
VUVLO
Parameter
Conditions
Min.
Supply Voltage
4.5
2.5
mA
3
20
µA
0.8
VFB
Feedback Voltage
0.812
V
Load Regulation
0.5
%
Line Regulation
1
%
200
nA
Feedback Voltage Input Current
EN Input Threshold
es
IFB
VEN
ig
0.788
V
ns
VEN = 0V
Off Threshold
On Threshold
D
EN Input Hysteresis
ew
Maximum Duty Cycle
DMIN
Minimum Duty Cycle
Fo
r
Error Amplifier Voltage Gain
Error Amplifier Transconductance
PROTECTION
en
om
m
High-Side Switch On-Resistance
Low-Side Switch On-Resistance
500
600
kHz
%
%
500
V/ V
200
µA / V
5.0
6.0
150
100
3
V
mV
6
TJ Rising
TJ Falling
de
Soft Start Interval
100
100
d
Current Limit
Over-Temperature Shutdown Limit
OUTPUT STAGE
350
N
Frequency
DMAX
0.6
2
MODULATOR
tSS
V
1.6
IOUT = 0, VFB = 1.2V, VEN > 1.2V
ILIM
16
4.1
3.7
Shutdown Supply Current
fO
Units
VIN Rising
VIN Falling
Supply Current (Quiescent)
VHYS
Max.
Input Under-Voltage Lockout Threshold
IOFF
IIN
Typ.
A
°C
5
6.5
ms
VIN = 12V
VIN = 5V
97
166
130
200
mΩ
VIN = 12V
VIN = 5V
18
30
23
36
mΩ
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Note:
3. Specification in BOLD indicate an ambient temperature range of -40°C to +85°C. These specifications are guaranteed by design.
Rev. 1.3 September 2009
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Page 4 of 16
AOZ1024D
Typical Performance Characteristics
Circuit of Figure 1. TA = 25°C, VIN = VEN = 12V, VOUT = 3.3V unless otherwise specified.
Light Load Operation
Full Load (CCM) Operation
Vin ripple
0.1V/div
Vin ripple
0.1V/div
Vo ripple
20mV/div
ns
Vo ripple
20mV/div
IL
1A/div
ig
IL
1A/div
VLX
10V/div
D
es
VLX
10V/div
1μs/div
Startup to Full Load
Short Circuit Protection
N
ew
1μs/div
d
Vo
2V/div
de
Vo
2V/div
LX
10V/div
Fo
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VIN
10V/div
lL
5A/div
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lin
1A/div
1ms/div
100μs/div
Short Circuit Recovery
Vo Ripple
200mV/div
Vo
2V/div
lo
2A/div
IL
5A/div
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50% to 100% Load Transient
100μs/div
Rev. 1.3 September 2009
2ms/div
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Page 5 of 16
AOZ1024D
Efficiency
AOZ1024D Efficiency
Efficiency (VIN = 12V) vs. Load Current
95
5V OUTPUT
90
3.3V OUTPUT
ns
1.8V OUTPUT
85
ig
1.2V OUTPUT
80
es
Efficieny (%)
100
D
75
65
0.5
1
1.5
2
2.5
3.5
4
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Load Current (A)
3
N
0
ew
70
Thermal Derating Curves
1.2V OUTPUT
4
4.4
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5
4.2
3.3V
OUTPUT
ec
3
R
2
Output Current (IO)
1.8V
ot
Output Current (IO)
Derating Curve at 12 Input
en
Derating Curve at 5V/6V Input
de
d
For DFN package part under typical line and output voltage condition. Circuit of Figure 1. 25°C ambient temperature
and natural convection (air speed<50LFM) unless otherwise specified.
0
25
3.3V
3.8
5V
OUTPUT
3.6
N
1
1.2V, 1.8V OUTPUT
4.0
3.4
35
45
55
65
75
85
Ambient Temperature (TA)
Rev. 1.3 September 2009
25
35
45
55
65
75
85
Ambient Temperature (TA)
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Page 6 of 16
AOZ1024D
Detailed Description
freewheeling through the internal low-side N-MOSFET
switch to output. The internal adaptive FET driver guarantees no turn on overlap of both high-side and low-side
switch.
Compared with regulators using freewheeling Schottky
diodes, the AOZ1024D uses freewheeling NMOSFET to
realize synchronous rectification. It greatly improves the
converter efficiency and reduces power loss in the
low-side switch.
ns
The AOZ1024D is a current-mode step down regulator
with integrated high-side PMOS switch and a low-side
NMOS switch. It operates from a 4.5V to 16V input voltage range and supplies up to 4A of load current. The
duty cycle can be adjusted from 6% to 100% allowing a
wide range of output voltage. Features include enable
control, Power-On Reset, input under voltage lockout,
output over voltage protection, active high power good
state, fixed internal soft-start, and thermal shut down.
The AOZ1024D is available in a DFN 5x4 package.
D
ew
where;
VO_MAX is the maximum output voltage,
VIN is the input voltage from 4.5V to 16V,
IO is the output current from 0A to 2A, and
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Steady-State Operation
en
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d
The EN pin of the AOZ1024D is active HIGH. Connect
the EN pin to VIN if enable function is not used. Pulling
EN to ground will disable the AOZ1024D. Do not leave it
open. The voltage on EN pin must be above 2V to enable
the AOZ1024D. When voltage on the EN pin falls below
0.6V, the AOZ1024D is disabled. If an application circuit
requires the AOZ1024D to be disabled, an open drain or
open collector circuit should be used to interface to the
EN pin.
V O_MAX = V IN – I O × R DSON
N
The AOZ1024D has internal soft start feature to limit
in-rush current and ensure the output voltage ramps up
smoothly to regulation voltage. A soft start process
begins when the input voltage rises to 4.1V and voltage
on the EN pin is HIGH. In the soft start process, the
output voltage is typically ramped to regulation voltage in
4ms. The 4ms soft start time is set internally.
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Enable and Soft Start
es
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The AOZ1024D uses a P-Channel MOSFET as the
high-side switch. It saves the bootstrap capacitor
normally seen in a circuit which is using an NMOS
switch. It allows 100% turn-on of the high-side switch to
achieve linear regulation mode of operation. The minimum voltage drop from VIN to VO is the load current x
DC resistance of MOSFET + DC resistance of buck
inductor. It can be calculated by equation below:
ec
Under steady-state conditions, the converter operates in
fixed frequency and Continuous-Conduction Mode
(CCM).
N
ot
R
The AOZ1024D integrates an internal P-MOSFET as the
high-side switch. Inductor current is sensed by amplifying
the voltage drop across the drain to source of the high
side power MOSFET. Output voltage is divided down by
the external voltage divider at the FB pin. The difference
of the FB pin voltage and reference is amplified by the
internal transconductance error amplifier. The error voltage, which shows on the COMP pin, is compared against
the current signal, which is sum of inductor current signal
and ramp compensation signal, at PWM comparator
input. If the current signal is less than the error voltage,
the internal high-side switch is on. The inductor current
flows from the input through the inductor to the output.
When the current signal exceeds the error voltage,
the high-side switch is off. The inductor current is
Rev. 1.3 September 2009
RDS(ON) is the on resistance of internal MOSFET, the value is
between 97mΩ and 200mΩ depending on input voltage and
junction temperature.
Switching Frequency
The AOZ1024D switching frequency is fixed and set by
an internal oscillator. The practical switching frequency
could range from 350kHz to 600kHz due to device
variation.
Output Voltage Programming
Output voltage can be set by feeding back the output
to the FB pin by using a resistor divider network (see
Figure 1). The resistor divider network includes R1 and
R2. Usually, a design is started by picking a fixed R2
value and calculating the required R1 with equation
below:
R 1⎞
⎛
V O = 0.8 × ⎜ 1 + -------⎟
R 2⎠
⎝
Some standard values of R1 and R2 for the most
commonly used output voltage values are listed in
Table 1.
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Page 7 of 16
AOZ1024D
Table 1.
Thermal Protection
VO (V)
R1 (kΩ)
R2 (kΩ)
0.8
1.0
Open
An internal temperature sensor monitors the junction
temperature. It shuts down the internal control circuit and
high side PMOS if the junction temperature exceeds
150°C. The regulator will restart automatically under the
control of soft-start circuit when the junction temperature
decreases to 100ºC.
4.99
10
10
11.5
1.8
12.7
10.2
2.5
21.5
10
Application Information
3.3
31.6
10
5.0
52.3
10
The basic AOZ1024 application circuit is show in
Figure 1. Component selection is explained below.
ig
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The input capacitor must be connected to the VIN pin and
PGND pin of AOZ1024D to maintain steady input voltage
and filter out the pulsing input current. The voltage rating
of input capacitor must be greater than maximum input
voltage plus ripple voltage.
The input ripple voltage can be approximated by equation below:
N
Since the switch duty cycle can be as high as 100%, the
maximum output voltage can be set as high as the input
voltage minus the voltage drop on upper PMOS and
inductor.
Input capacitor
ew
The combination of R1 and R2 should be large enough to
avoid drawing excessive current from the output, which
will cause power loss.
ns
1.2
1.5
Protection Features
Over Current Protection (OCP)
Since the input current is discontinuous in a buck
converter, the current stress on the input capacitor is
another concern when selecting the capacitor. For a buck
circuit, the RMS value of input capacitor current can be
calculated by:
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The sensed inductor current signal is also used for over
current protection. Since the AOZ1024D employs peak
current mode control, the COMP pin voltage is proportional to the peak inductor current. The COMP pin voltage is limited to be between 0.4V and 2.5V internally.
The peak inductor current is automatically limited cycle
by cycle.
IO
VO ⎞ VO
⎛
ΔV IN = ----------------- × ⎜ 1 – ---------⎟ × --------f × C IN ⎝
V IN⎠ V IN
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The AOZ1024D has multiple protection features to prevent system circuit damage under abnormal conditions.
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When the output is shorted to ground under fault
conditions, the inductor current decays very slowly during
a switching cycle because of VO = 0V. To prevent catastrophic failure, a secondary current limit is designed
inside the AOZ1024D. The measured inductor current is
compared against a preset voltage which represents the
current limit, between 5.0A and 6.0A. When the output
current is more than current limit, the high side switch will
be turned off. The converter will initiate a soft start once
the over-current condition is resolved.
VO ⎛
VO ⎞
- ⎜ 1 – --------⎟
I CIN_RMS = I O × -------V IN ⎝
V IN⎠
if we let m equal the conversion ratio:
VO
-------- = m
V IN
The relation between the input capacitor RMS current
and voltage conversion ratio is calculated and shown in
Figure 2 on the next page. It can be seen that when VO is
half of VIN, CIN is under the worst current stress. The
worst current stress on CIN is 0.5 x IO.
Power-On Reset (POR)
A power-on reset circuit monitors the input voltage.
When the input voltage exceeds 4.1V, the converter
starts operation. When input voltage falls below 3.7V,
the converter will be shut down.
Rev. 1.3 September 2009
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Page 8 of 16
AOZ1024D
The inductor takes the highest current in a buck circuit.
The conduction loss on inductor need to be checked for
thermal and efficiency requirements.
0.5
0.4
Surface mount inductors in different shape and styles are
available from Coilcraft, Elytone and Murata. Shielded
inductors are small and radiate less EMI noise, but they
cost more than unshielded inductors. The choice
depends on EMI requirement, price, and size.
ICIN_RMS(m) 0.3
IO
0.2
0.1
Output Capacitor
The output capacitor is selected based on the DC output
voltage rating, output ripple voltage specification and
ripple current rating.
ns
1
ig
0.5
m
D
es
The selected output capacitor must have a higher rated
voltage specification than the maximum desired output
voltage including ripple. De-rating needs to be considered for long term reliability.
Output ripple voltage specification is another important
factor for selecting the output capacitor. In a buck
converter circuit, output ripple voltage is determined by
inductor value, switching frequency, output capacitor
value and ESR. It can be calculated by the equation
below:
d
For reliable operation and best performance, the input
capacitors must have current rating higher than ICIN_RMS
at worst operating conditions. Ceramic capacitors are
preferred for input capacitors because of their low ESR
and high current rating. Depending on the application
circuits, other low ESR tantalum capacitor may also be
used. When selecting ceramic capacitors, X5R or X7R
type dielectric ceramic capacitors should be used for
their better temperature and voltage characteristics. Note
that the ripple current rating from capacitor manufactures
are based on certain amount of life time. Further
de-rating may be necessary in practical design.
ew
Figure 2. ICIN vs. Voltage Conversion Ratio
N
0
Fo
r
0
de
Inductor
om
m
VO ⎛
VO ⎞
-⎟
ΔI L = ----------- × ⎜ 1 – -------f×L ⎝
V IN⎠
en
The inductor is used to supply constant current to output
when it is driven by a switching voltage. For given input
and output voltage, inductance and switching frequency
together decide the inductor ripple current, which is:
where,
CO is output capacitor value, and
ESRCO is the equivalent series resistance of the output
capacitor.
ec
R
1
ΔV O = ΔI L × ------------------------8×f×C
ot
O
N
High inductance gives low inductor ripple current but
requires a larger size inductor to avoid saturation. Low
ripple current reduces inductor core losses. It also
reduces RMS current through inductor and switches,
which results in less conduction loss. Usually, peak to
peak ripple current on inductor is designed to be 20–30%
of output current.
When selecting the inductor, make sure it is able to
handle the peak current without saturation even at the
highest operating temperature.
Rev. 1.3 September 2009
O
When a low ESR ceramic capacitor is used as the output
capacitor, the impedance of the capacitor at the switching
frequency dominates. Output ripple is mainly caused by
capacitor value and inductor ripple current. The output
ripple voltage calculation can be simplified to:
The peak inductor current is:
ΔI L
I Lpeak = I O + -------2
1
ΔV O = ΔI L × ⎛ ESR CO + -------------------------⎞
⎝
8×f×C ⎠
If the impedance of ESR at switching frequency
dominates, the output ripple voltage is mainly decided
by capacitor ESR and inductor ripple current. The output
ripple voltage calculation can be further simplified to:
ΔV O = ΔI L × ESR CO
For lower output ripple voltage across the entire operating temperature range, X5R or X7R dielectric type of
ceramic, or other low ESR tantalum capacitors are
recommended to be used as output capacitors.
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Page 9 of 16
AOZ1024D
In a buck converter, output capacitor current is continuous. The RMS current of output capacitor is decided by
the peak to peak inductor ripple current. It can be
calculated by:
ΔI L
I CO_RMS = ---------12
R and C compensation network connected to COMP
provides one pole and one zero. The pole is:
G EA
f P2 = -----------------------------------------2π × C 2 × G VEA
where;
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es
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To design the compensation circuit, a target crossover
frequency fC for close loop must be selected. The system
crossover frequency is where control loop has unity gain.
The crossover is the also called the converter bandwidth.
Generally a higher bandwidth means faster response to
load transient. However, the bandwidth should not be too
high because of system stability concern. When designing the compensation loop, converter stability under all
line and load condition must be considered.
de
d
1
f P1 = ----------------------------------2π × C O × R L
1
f Z2 = ----------------------------------2π × C C × R C
ew
With peak current mode control, the buck power stage
can be simplified to be a one-pole and one-zero system
in frequency domain. The pole is dominant pole can be
calculated by:
om
m
1
f Z1 = -----------------------------------------------2π × C O × ESR CO
en
The zero is a ESR zero due to output capacitor and its
ESR. It is can be calculated by:
CO is the output filter capacitor,
The zero given by the external compensation network,
capacitor C2 and resistor R3, is located at:
N
The AOZ1024D employs peak current mode control for
easy use and fast transient response. Peak current mode
control eliminates the double pole effect of the output
L&C filter. It greatly simplifies the compensation loop
design.
Usually, it is recommended to set the bandwidth to be
equal or less than 1/10 of switching frequency. The
AOZ1024D operates at a frequency range from 350kHz
to 600kHz. It is recommended to choose a crossover
frequency equal or less than 40kHz.
f C = 40kHz
ec
RL is load resistor value, and
C2 is compensation capacitor in Figure 1.
Fo
r
Loop Compensation
where;
GVEA is the error amplifier voltage gain, which is 500 V/V, and
ig
Usually, the ripple current rating of the output capacitor is
a smaller issue because of the low current stress. When
the buck inductor is selected to be very small and inductor ripple current is high, output capacitor could be overstressed.
GEA is the error amplifier transconductance, which is 200 x 10-6
A/V,
R
ESRCO is the equivalent series resistance of output capacitor.
N
ot
The compensation design is actually to shape the
converter control loop transfer function to get desired
gain and phase. Several different types of compensation
network can be used for the AOZ1024D. For most cases,
a series capacitor and resistor network connected to the
COMP pin sets the pole-zero and is adequate for a stable
high-bandwidth control loop.
In the AOZ1024D, FB pin and COMP pin are the inverting input and the output of internal error amplifier. A
series
The strategy for choosing RC and CC is to set the cross
over frequency with RC and set the compensator zero
with CC. Using selected crossover frequency, fC , to
calculate R3:
VO
2π × C 2
R C = f C × ---------- × ----------------------------G ×G
V
FB
EA
CS
where;
fC is the desired crossover frequency. For best performance, fC
is set to be about 1/10 of the switching frequency;
VFB is 0.8V,
GEA is the error amplifier transconductance, which is 200 x 10-6
A/V, and
GCS is the current sense circuit transconductance, which is 6.68
A/V.
The compensation capacitor CC and resistor RC together
make a zero. This zero is put somewhere close to the
Rev. 1.3 September 2009
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Page 10 of 16
AOZ1024D
dominate pole fp1 but lower than 1/5 of selected crossover frequency. C2 can is selected by:
1.5
C C = ----------------------------------2π × R C × f P1
The actual junction temperature can be calculated with
power dissipation in the AOZ1024D and thermal
impedance from junction to ambient.
T junction = ( P total – P inductor_loss ) × Θ JA
The thermal performance of the AOZ1024D is strongly
affected by the PCB layout. Extra care should be taken
by users during design process to ensure that the IC
will operate under the recommended environmental
conditions.
N
ew
The AOZ1024D is standard DFN5*4 package. Several
layout tips are listed below for the best electric and
thermal performance. Figure 3 on the next page
illustrates a PCB layout example of AOZ1024D.
1. The LX pins are connected to internal PFET and
NFET drains. They are low resistance thermal
conduction path and most noisy switching node.
Connected a large copper plane to LX pin to help
thermal dissipation. For full load (4A) application,
also connect the LX pads to the bottom layer by
thermal vias to enhance the thermal dissipation.
de
d
In the AOZ1024D buck regulator circuit, high pulsing
current flows through two circuit loops. The first loop
starts from the input capacitors, to the VIN pin, to the
LX pins, to the filter inductor, to the output capacitor
and load, and then return to the input capacitor through
ground. Current flows in the first loop when the high side
switch is on. The second loop starts from inductor, to the
output capacitors and load, to the low-side NMOSFET.
Current flows in the second loop when the low-side
NMOSFET is on.
Fo
r
Thermal Management and Layout
Consideration
D
es
An easy-to-use application software which helps to
design and simulate the compensation loop can be found
at www.aosmd.com.
ig
CO × RL
C C = --------------------RC
ns
The maximum junction temperature of AOZ1024D is
150°C, which limits the maximum load current capability.
Please see the thermal de-rating curves for maximum
load current of the AOZ1024D under different ambient
temperature.
The previous equation can also be simplified to:
om
m
en
In PCB layout, minimizing the two loops area reduces the
noise of this circuit and improves efficiency. A ground
plane is strongly recommended to connect input capacitor, output capacitor, and PGND pin of the AOZ1024D.
In the AOZ1024D buck regulator circuit, the major power
dissipating components are the AOZ1024D and the
output inductor. The total power dissipation of converter
circuit can be measured by input power – output power.
R
ec
P total = V IN × I IN – V O × I O
ot
The power dissipation of the inductor can be
approximately calculated by output current and DCR
of inductor.
N
P inductor = IO2 × R inductor × 1.1
2. Do not use thermal relief connection to the VIN and
the PGND pin. Pour a maximized copper area to
the PGND pin and the VIN pin to help thermal
dissipation.
3. Input capacitor should be connected to the VIN pin
and the PGND pin as close as possible.
4. A ground plane is preferred. If a ground plane is
not used, separate PGND from AGND and connect
them only at one point to avoid the PGND pin noise
coupling to the AGND pin.
5. Make the current trace from LX pins to L to CO to the
PGND as short as possible.
6. Pour copper plane on all unused board area and
connect it to stable DC nodes, like VIN, GND or VOUT.
7. Keep sensitive signal trace far away form the LX
pins.
Rev. 1.3 September 2009
www.aosmd.com
Page 11 of 16
AOZ1024D
Bottom Layer
Thermal Dissipation
de
d
Fo
r
N
ew
D
es
ig
ns
Thermal Vias
N
ot
R
ec
om
m
en
Figure 3. AOZ1024D (DFN 5x4) PCB Layout
Rev. 1.3 September 2009
www.aosmd.com
Page 12 of 16
AOZ1024D
Package Dimensions, DFN 5x4
D
A
Pin #1 IDA
D/2
e
B
1
L
E/2
R
aaa C
E
E3
E2
es
A3
Seating C
Plane
A1
b
CAB
N
bbb
ew
A
ddd C
Fo
r
Dimensions in millimeters
Recommended Land Pattern
1.775
en
0.5
0.95
A1
A3
0.00
b
D
Nom.
0.90
Dimensions in inches
Symbols
A
Min.
0.031
0.02
0.05
0.20 REF
A1
A3
0.000
0.001 0.002
0.008 REF
0.35
0.40
0.45
5.00 BSC
b
D
0.014
0.016 0.018
0.197 BSC
D2
D3
E
1.975
1.625
2.125 2.225
1.775 1.875
4.00 BSC
D2
D3
E
0.078
0.064
0.084 0.088
0.070 0.074
0.157 BSC
E2
E3
2.500
2.050
2.750
2.300
E2
E3
0.098
0.081
e
L
L1
R
0.600
0.400
0.95 BSC
0.700 0.800
0.500 0.600
0.30 REF
e
L
L1
R
0.024
0.016
aaa
bbb
ccc
ddd
–
–
–
–
aaa
bbb
ccc
ddd
–
–
–
–
2.650
2.200
0.15
0.10
0.10
0.08
Max.
1.00
–
–
–
–
Nom.
0.035
0.104
0.087
Max.
0.039
0.108
0.091
0.037 BSC
0.028 0.031
0.020 0.024
0.012 REF
0.006
0.004
0.004
0.003
–
–
–
–
N
Notes:
ot
R
ec
Unit: mm
om
m
2.2
0.8
Min.
0.80
de
0.6
2.7
Symbols
A
d
2.125
L1
D
ccc C
D3
ig
D2
aaa C
ns
Index Area
(D/2 x E/2)
1. Dimensions and tolerancing conform to ASME Y14.5M-1994.
2. All dimensions are in millimeters.
3. The location of the terminal #1 identifier and terminal numbering convention conforms to JEDEC publication 95 SP-002.
4. Dimension b applies to metallized terminal and is measured between 0.15mm and 0.30mm from the terminal tip. If the terminal has the
optional radius on the other end of the terminal, the dimension b should not be measured in that radius area.
5. Coplanarity applies to the terminals and all other bottom surface metallization.
6. Drawing shown are for illustration only.
Rev. 1.3 September 2009
www.aosmd.com
Page 13 of 16
AOZ1024D
Tape Dimensions, DFN 5x4
Tape
R0
20
0.
.40
T
D1
ig
ns
E1
E2
D0
es
E
K0
Feeding
Direction
ew
D
B0
A0
N
P0
Unit: mm
A0
B0
K0
D0
D1
DFN 5x4
(12 mm)
5.30
±0.10
4.30
±0.10
1.20
±0.10
1.50
Min.
Typ.
+0.10 / –0
E1
E2
P0
P1
P2
T
12.00
±0.30
1.75
±0.10
5.50
±0.10
8.00
±0.10
4.00
±0.20
2.00
±0.10
0.30
±0.05
om
m
en
de
d
1.50
E
Fo
r
Package
ot
R
ec
Leader/Trailer and Orientation
N
Trailer Tape
(300mm Min.)
Rev. 1.3 September 2009
Components Tape
Orientation in Pocket
www.aosmd.com
Leader Tape
(500mm Min.)
Page 14 of 16
AOZ1024D
II
R1
59
Reel Dimensions, DFN 5x4
I
R1
6.0±1
21
M
R1
I
27
Zoom In
ig
R6
ns
R1
R5
D
5
es
P
B
III
ew
W1
Zoom In
3-1.8
Fo
r
N
0.05
II
d
"
/4
ø1
.0
om
m
en
5
A A
N=ø100±2
ø9
6±
0.2
±0
3-
.9
de
A
ø2
3-ø1
3-
/8"
Zoom In
1.8
6.0
1.8
6.45±0.05
8.00
6.2
ø2
1.
0
R
5.0
ø13.0
ø17.0
ot
R1.10
R3.10
C
1.8
12 REF
.0±0
10°
41.5 REF
43.00
44.5±0.1
44.5±0.1
.95
R3
4.0
6.10
VIEW: C
3-
8.0±0.1
ø3
6"
ø3
/1
3-
38°
40°
10.0
EF
8R
R4
46.0±0.1
R0.5
.1
3.3
6.50
A
R1
2.00
ø9
20
ø86
N
11.90
0.00
ec
8.9±0.1
14 REF
2.20
0.00
-0.05
/1
2.00
6.50
0.80
3.00
2.5
1.80
+0.05
6"
8.000.00
10.71
6°
Rev. 1.3 September 2009
www.aosmd.com
Page 15 of 16
AOZ1024D
AOZ1024D Package Marking
Z1024DI
FAYWLT
ig
ns
Part Number Code
es
Assembly Lot Code
Fab & Assembly Location
ec
om
m
en
de
d
Fo
r
N
ew
D
Year & Week Code
R
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.
ot
LIFE SUPPORT POLICY
N
ALPHA & OMEGA SEMICONDUCTOR PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL
COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS.
As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant into
the body or (b) support or sustain life, and (c) whose
failure to perform when properly used in accordance
with instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of
the user.
Rev. 1.3 September 2009
2. A critical component in any component of a life
support, device, or system whose failure to perform can
be reasonably expected to cause the failure of the life
support device or system, or to affect its safety or
effectiveness.
www.aosmd.com
Page 16 of 16