AOZ2366QI
28V/20A Synchronous EZBuckTM Regulator
General Description
Features
The AOZ2366QI is a high-efficiency, easy-to-use DC/DC
synchronous buck regulator that operates over a wide
4.5V to 28V voltage range.The device is capable of
supplying 20A of continuous output current with an
output voltage adjustable down to 0.6V (±1.0%).
Wide input voltage range
A proprietary constant on-time PWM control with input
feed-forward results in ultra-fast transient response while
maintaining relatively constant switching frequency over
the entire input voltage range. A low 80ns minimum ontime enables very low output voltages at ultra-high
operating frequencies.
Integrated AC ripple injection enables all-ceramic low
ESR output filter capacitors and smaller PCB footprint
with no external components needed.
– 4.5V to 28V
20A continuous output current
Output voltage adjustable down to 0.6V (±1.0%)
Low RDS(ON) internal NFETs
– 5m high-side
– 1.6m low-side
Constant On-Time with input feed-forward
Programmable on-time up to 2.6µs and down to 80ns
Programmable switching frequency range: 32kHz to
1MHz (for 12VIN to 1VOUT)
Selectable PFM or forced PWM light load operation
Ceramic capacitor stable
Selectable PFM mode optimizes light load efficiency
while forced PWM mode maintains constant frequency
for lower harmonic noise.
Adjustable soft start
The device features multiple protection functions such as
VCC under-voltage lockout, cycle-by-cycle current limit,
output over-voltage protection, short-circuit protection,
and thermal shutdown.
Cycle-by-cycle current limit
The AOZ2366QI is available in a 5mm×5mm QFN_28L
package and is rated over a -40°C to +85°C ambient
temperature range.
Power Good output
Integrated bootstrap diode
Short-circuit protection
Thermal shutdown
Thermally enhanced 5mm x 5mm QFN_28L package
Applications
Compact PCs and gaming systems
Set-top boxes and LCD TVs
Server and storage systems
Datacom and networking
Embedded computing
Point-of load DC/DC converters
Rev. 1.2 June 2021
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Page 1 of 18
AOZ2366QI
Typical Application
R TON
TON
5V
R3
100k
C4
4.7µF
Power Good
IN
BST
VCC
EN
LX
SS
L1
0.47µH
Output
1.2V, 20A
R2
FB
PFM
CSS
C5
0.1µF
Input
4.5V to 28V
C2
22µF
AOZ2366QI
PGOOD
Off On
C2
22µF
R1
C3
220µF
AGND
PGND
Power Ground
Analog Ground
Rev. 1.2 June 2021
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Page 2 of 18
AOZ2366QI
Ordering Information
Part Number
Ambient Temperature Range
Package
Environmental
AOZ2366QI
-40°C to +85°C
28-Pin 5mm x 5mm QFN
Green Product
AOS Green Products use reduced levels of Halogens, and are also RoHS compliant.
Please visit www.aosmd.com/media/AOSGreenPolicy.pdf for additional information.
Pin Configuration
PGND
22
26
PGND 23
27
GL 24
BST
PGND 25
VCC
NC 28
SS
1
PGOOD
2
EN
3
19 LX
PFM
4
18 LX
AGND
5
21 LX
29
GL
20 LX
PGND
17 LX
16 LX
15 LX
PGND 13
PGND 12
PGND 11
IN 10
14 LX
9
7
IN
TON
IN
8
6
IN
FB
28-Pin 5mm x 5mm QFN
(Top View)
Rev. 1.2 June 2021
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Page 3 of 18
AOZ2366QI
Pin Description
Pin Number
Pin Name
Pin Function
1
SS
Soft-Start Time Setting Pin. Connect a capacitor between SS and AGND to set the softstart time.
2
PGOOD
Power Good Signal Output. PGOOD is an open-drain output used to indicate the status
of the output voltage. It is internally pulled low when the output voltage is 15% lower than
the nominal regulation voltage for or 20% higher than the nominal regulation voltage.
PGOOD is pulled low during soft-start and shut down.
3
EN
Enable Input. The AOZ2366QI is enabled when EN is pulled high. The device shuts down
when EN is pulled low. Assert EN to high for power-up after IN and VCC are well
supplied. Power-off the device by EN off is suggested.
4
PFM
PFM Selection Input. Connect PFM pin to VCC for forced PWM operation. Connect PFM
pin to ground for PFM operation to improve light load efficiency.
5
AGND
6
FB
Analog Ground.
Feedback Input. Adjust the output voltage with a resistive voltage-divider between the
regulator’s output and AGND.
7
TON
8, 9, 10
IN
11, 12, 13,
22, 23, 25
PGND
Power Ground.
14, 15, 16, 17,
18, 19, 20, 21
LX
Switching Node.
24, 29
GL
Low-Side MOSFET Gate connection. This is for test purposes only.
26
BST
Bootstrap Capacitor Connection. The AOZ2366QI includes an internal bootstrap diode.
Connect an external capacitor between BST and LX as shown in the Typical Application
diagram.
27
VCC
Supply Input for analog functions. Bypass VCC to AGND with a 4.7µF~10µF ceramic
capacitor. Place the capacitor close to VCC pin.
28
NC
Rev. 1.2 June 2021
On-Time Setting Input. Connect a resistor between VIN and TON to set the on time.
Supply Input. IN is the regulator input. All IN pins must be connected together.
No Connect.
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Page 4 of 18
AOZ2366QI
Absolute Maximum Ratings
Maximum Operating Ratings
Exceeding the Absolute Maximum Ratings may damage the
device.
Parameter
Rating
IN, TON to AGND
Parameter
-0.3V to 30V
LX to AGND(1)
-1V to 30V
BST to AGND
-0.3V to 36V
SS, PGOOD, FB, EN, VCC, PFM to AGND
+150°C
Storage Temperature (TS)
-65°C to +150°C
(2)
4.5V to 28V
Output Voltage Range
0.6V to 0.85*VIN
Ambient Temperature (TA)
-40°C to +85°C
Package Thermal Resistance
(θJA)
-0.3V to +0.3V
Junction Temperature (TJ)
Rating
Supply Voltage (VIN)
-0.3V to 6V
PGND to AGND
ESD Rating
The device is not guaranteed to operate beyond the
Maximum Operating Ratings.
20°C/W
2kV
Notes:
1. LX to PGND Transient (t 2V, PFM
mode
150
µA
Shutdown Supply Current
VEN = 0V
Reference Voltage
TA = 25°C
TA = 0°C to 85°C
594
591
1
20
µA
600
600
606
609
mV
200
nA
FB Input Bias Current
Enable
VEN
EN Input Threshold
VEN_HYS
EN Input Hysteresis
Off threshold
On threshold
0.5
1.6
100
V
mV
PFM Control
VPFM
PFM Input Threshold
VPFM_HYS
PFM Input Hysteresis
PFM Mode threshold
Force PWM threshold
0.5
2.5
V
100
mV
200
ns
Modulator
TON
On Time
RTON = 100k, VIN = 12V
TON_MIN
Minimum On Time
80
ns
TON_MAX
Maximum On Time
2.6
µs
TOFF_MIN
Minimum Off Time
300
ns
Soft-Start
ISS_OUT
SS Source Current
Rev. 1.2 June 2021
VSS = 0V
CSS = 0.001µF to 0.1µF
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7
11
15
µA
Page 5 of 18
AOZ2366QI
Electrical Characteristics (Continued)
TA = 25°C, VIN = 12V, VCC = 5V, EN = 5V, unless otherwise specified. Specifications in BOLD indicate a temperature range of
-40°C to +85°C.
Symbol
Parameter
Conditions
Min.
Typ.
Max
Units
0.5
V
±1
µA
Power Good Signal
VPG_LOW
PGOOD Low Voltage
IOL = 1mA
PGOOD Leakage Current
VPGH
PGOOD Threshold
(Low Level to High Level)
FB rising
90
%
VPGL
PGOOD Threshold
(High Level to Low Level)
FB rising
FB falling
120
85
%
5
%
70
%
32
µs
120
%
5
m
PGOOD Threshold Hysteresis
Under Voltage and Over Voltage Protection
VPL
Under Voltage Threshold
TPL
Under Voltage Delay Time
VPH
Over Voltage Threshold
FB falling
FB rising
Power Stage Output
RDS(ON)
RDS(ON)
High-Side NFET On-Resistance
VIN = 12V, VCC = 5V
High-Side NFET Leakage
VEN = 0V, VLX = 0V
Low-Side NFET On-Resistance
VLX = 12V, VCC = 5V
Low-Side NFET Leakage
VEN = 0V
10
1.6
µA
m
10
µA
Over-current and Thermal Protection
ILIM
Current Limit
VCC = 5V
Thermal Shutdown Threshold
TJ rising
TJ falling
Rev. 1.2 June 2021
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30
A
150
125
°C
Page 6 of 18
AOZ2366QI
Functional Block Diagram
BST
IN
PGood
VCC
EN
UVLO
Reference
& Bias
TOFF_MIN
Q
Timer
Error Comp
0.6V
SS
ISENSE
(AC)
FB
PG Logic
S
Q
R
FB
Decode
LX
ILIM Comp
ILIM
Current
Information
Processing
ISENSE
OTP
ISENSE
ISENSE (AC)
Vcc
TON
Q
Timer
PFM
TON
EN
TON
Generator
Light Load
Threshold
Light Load
Comp
ISENSE
PGND
Rev. 1.2 June 2021
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AGND
Page 7 of 18
AOZ2366QI
Typical Performance Characteristics
Circuit of Typical Application. TA = 25°C, VIN = 12V, VOUT = 1V, fsw = 500kHz unless otherwise specified.
Output Voltage vs. Input Voltage
Output Voltage vs. Output Current
1.025
1.020
1.015
1.020
Output Voltage (V)
Output Voltage (V)
1.010
1.015
1.010
1.005
1.005
1.000
0.995
0.990
PFM 0A
1.000
FPWM 0A
0.995
10.8
11.2
11.6
12
12.4
FPWM
PFM
0.985
FPWM 20A
12.8
0.980
13.2
0
5
10
Input Voltage (V)
15
20
Output Current (A)
Switching Frequency vs. Output Current
Switching Frequency vs. Input Voltage
560
450
440
540
430
520
410
FSW (KHz)
FSW (KHz)
420
400
390
380
480
460
370
FPWM 0A
10.8
11.2
11.6
12
12.4
12.8
VOUT = 1V
VOUT = 1.8V
440
360
350
500
420
7.5
13.2
10.5
13.5
16.5
19.5
Output Current (A)
Input Voltage (V)
Thermal Derating with 12Vin
30
1VO
3.3VO
Io_max (A)
25
5VO
20
15
10
25.0
45.0
65.0
85.0
Ta (C)
Rev. 1.2 June 2021
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Page 8 of 18
AOZ2366QI
Typical Performance Characteristics
Circuit of Typical Application. TA = 25°C, VIN = 20V, VOUT = 1.2V, fsw = 500kHz unless otherwise specified.
Normal Operation
Load Transient 0% to 100%
VLX
(20V/div)
V O ripple
(50mV/div)
V O ripple
(50mV/div)
ILX
(10A/div)
ILX
(10A/div)
10µs/div
1ms/div
Full Load Start-up
Load Transient 50% to 100%
VLX
(20V/div)
V O ripple
(50mV/div)
EN
(5V/div)
ILX
(10A/div)
ILX
(20A/div)
VO
(1V/div)
1ms/div
1ms/div
Efficiency vs. Load Current
100
90
80
VOUT = 1.2V
Efficiency (%)
70
60
50
Vin = 6.5V
40
Vin = 12V
30
Vin = 19V
20
Vin = 24V
10
0
0.0
Rev. 1.2 June 2021
5.0
10.0
Output Current (A)
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15.0
20.0
Page 9 of 18
AOZ2366QI
Detailed Description
The AOZ2366QI is a high-efficiency, easy-to-use,
synchronous buck regulator. The regulator is capable of
supplying 20A of continuous output current with an
output voltage adjustable down to 0.6V. The
programmable on-time from 80ns to 2.6μs enables
optimizing the configuration for PCB area and efficiency.
The input voltage of AOZ2366QI can be as low as 4.5V.
The highest input voltage of AOZ2366QI can be 28V.
Constant on-time PWM with input feed-forward control
scheme results in ultra-fast transient response while
maintaining relatively constant switching frequency over
the entire input range. True AC current mode control
scheme guarantees the regulator can be stable with
ceramics output capacitor. The switching frequency can
be externally programmed. Protection features include
VCC under-voltage lockout, current limit, output over
voltage and under voltage protection, short-circuit
protection, and thermal shutdown.
The AOZ2366QI is available in 28-pin 5mm×5mm QFN
package.
Enable and Soft Start
The AOZ2366QI has external soft start feature to limit inrush current and ensure the output voltage ramps up
smoothly to regulate voltage. A soft start process begins
when VCC rises to 4.5V and voltage on EN pin is HIGH.
An internal current source charges the external soft-start
capacitor; the FB voltage follows the voltage of soft-start
pin (VSS) when it is lower than 0.6V. When VSS is higher
than 0.6V, the FB voltage is regulated by internal precise
band-gap voltage (0.6V). When VSS is higher than 3.3V,
the PGOOD signal is high. The soft-start time for
PGOOD can be calculated by the following formula:
TSS(µs) = 330 x CSS(nF)
If CSS is 1nF, the soft start time will be 330µs; if CSS is
10nF, the soft start time will be 3.3ms.
Constant-On-Time PWM Control with Input
Feed-Forward
The control algorithm of AOZ2366QI is constant-on-time
PWM control with input feed-forward.
The simplified control schematic is shown in Figure 2.
IN
PWM
–
Programmable
One-Shot
VSS
Comp
+
0.6V
Figure 2. Simplified Control Schematic
The high-side switch on-time is determined solely by a
one-shot whose pulse width can be programmed by one
external resistor and is inversely proportional to input
voltage (IN). The one-shot is triggered when the internal
0.6V is higher than the combined information of FB
voltage and the AC current information of inductor, which
is processed and obtained through the sensed lower-side
MOSFET current once it turns-on. The added AC current
information can help the stability of constant-on time
control even with pure ceramic output capacitors, which
have very low ESR. The AC current information has no
DC offset, which does not cause offset with output load
change, which is fundamentally different from other V2
constant-on time control schemes.
The constant-on-time PWM control architecture is a
pseudo-fixed frequency with input voltage feed-forward.
The internal circuit of AOZ2366QI sets the on-time of
high-side switch inversely proportional to the IN.
R TON
T ON ------------------------V IN V
(1)
To achieve the flux balance of inductor, the buck
converter has the equation:
V OUT
F SW = -------------------------V IN T ON
VOUT
FB Voltage/
AC Current
Information
(2)
Once the product of VIN x TON is constant, the switching
frequency keeps constant and is independent with input
voltage.
VSS=3.3V
An external resistor between the IN and TON pin sets the
switching on-time according to the following curves:
VSS=0.6V
Figure 1. Soft Start Sequence
Rev. 1.2 June 2021
PGOOD
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Page 10 of 18
AOZ2366QI
A further simplified equation will be:
Ton v.s. Ron @ Vin=5V~15V
1130
V OUT V
6
F SW kHz = ------------------------------------------------ 10
V IN V T ON ns
Vin=5V
Vin=7V
Vin=9V
Vin=11V
Vin=13V
Vin=15V
1064
998
932
866
(3)
800
Ton (nS)
734
If Vo is 1.05V, Vin is 19V, and set Fs=500kHz. According
to eq.(3), Ton=110nS is needed. Finally, use the Ton to
RTon curve, we can find out RTon is 82k.
668
602
536
470
404
338
272
206
140
60
74
88
102
116
130
144
158
172
186
200
Ron (Kohm)
True Current Mode Control
Ton v.s. Ron @ Vin=17V~28V
315
299
283
267
251
AOS constant-on-time (COT) control scheme uses a
patented current-injection technique to provide stable
performance using an all-ceramic output capacitors. The
constant-on-time control scheme is intrinsically unstable
if output capacitor’s ESR is not large enough as an
effective current-sense resistor. Ceramic capacitors
usually cannot be used as output capacitor.
Vin=17V
Vin=19V
Vin=21V
Vin=24V
Vin=26V
Vin=28V
235
219
Ton (nS)
This algorithm results in a nearly constant switching
frequency despite the lack of a fixed-frequency clock
generator.
203
187
171
155
139
123
The AOZ2366QI senses the low-side MOSFET current
and processes it into DC current and AC current
information using AOS proprietary technique. The AC
current information is decoded and added on the FB pin
on phase. With AC current information, the stability of
constant-on-time control is significantly improved even
without the help of output capacitor’s ESR; and thus the
pure ceramic capacitor solution can be applicant. The
pure ceramic capacitor solution can significantly reduce
the output ripple (no ESR caused overshoot and
undershoot) and less board area design.
107
91
75
60
74
88
102
116
130
144
158
172
186
200
Ron (Kohm)
Ton v.s. Ron @ Vin=5V~15V
2600
2477
2354
2231
2108
1985
1862
Vin=5V
Vin=7V
Vin=9V
Vin=11V
Vin=13V
Vin=15V
1739
Ton (nS)
1616
1493
1370
1247
1124
1001
Current-Limit Protection
878
755
632
509
386
263
140
60
156
252
348
444
540
636
732
828
924
1020
1116
1212
1308
1404
1500
1336
1452
1568
1684
1800
Ron (Kohm)
Ton v.s. Ron @ Vin=17V~28V
2600
2473
2346
2219
2092
1965
1838
Vin=17V
Vin=19V
Vin=21V
Vin=24V
Vin=26V
Vin=28V
1711
Ton (nS)
1584
1457
1330
1203
1076
949
822
695
568
441
314
The AOZ2366QI has the current-limit protection by using
RDS(ON) of the low-side MOSFET to be as current
sensing. To detect real current information, a minimum
constant off-time (300nS typical) is implemented after a
constant-on time. If the current exceeds the current-limit
threshold, the PWM controller is not allowed to initiate a
new cycle. The actual peak current is greater than the
current-limit threshold by an amount equal to the inductor
ripple current. Therefore, the exact current-limit
characteristic and maximum load capability are a function
of the inductor value and input and output voltages. The
current limit will keep the low-side MOSFET on and will
not allow another high-side on-time, until the current in
the low-side MOSFET reduces below the current limit.
187
60
60
176
292
408
524
640
756
872
988
1104
1220
Ron (Kohm)
Figure 3. TON vs. RTON Curves
Rev. 1.2 June 2021
After 64 switching cycles, the AOZ2366QI considers this
is a true failed condition and thus turns-off both high-side
and low-side MOSFET and latches off. Only when
triggered, the enable can restart the AOZ2366QI again.
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Page 11 of 18
AOZ2366QI
Output Voltage Under-Voltage Protection
Power Good Output
If the output voltage is lower than 70% by over-current or
short circuit, the AOZ2366QI will wait for 32µs (typical)
and turns-off both high-side and low-side MOSFETs and
latches off. Only when triggered, the enable can restart
the AOZ2366QI again.
The power good (PGOOD) output, which is an open
drain output, requires the pull-up resistor. When the
output voltage is 15% below than the nominal regulation
voltage for, the PGOOD is pulled low. When the output
voltage is 20% higher than the nominal regulation
voltage, the PGOOD is also pull low.
Output Voltage Over-Voltage Protection
The threshold of OVP is set 20% higher than 0.6V. When
the VFB voltage exceeds the OVP threshold, high-side
MOSFET is turned-off and low-side MOSFET is turnedon 1μs, then latch-off.
Rev. 1.2 June 2021
When combined with the under-voltage-protection circuit,
this current-limit method is effective in almost every
circumstance.
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Page 12 of 18
AOZ2366QI
Application Information
The basic AOZ2366QI application circuit is shown in
Typical Application section. Component selection is
explained below.
Input Capacitor
The input capacitor must be connected to the IN pins and
PGND pin of the AOZ2366QI to maintain steady input
voltage and filter out the pulsing input current. A small
decoupling capacitor, usually 4.7μF, should be connected
to the VCC pin and AGND pin for stable operation of the
AOZ2366QI. 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:
IO
VO VO
V IN = ----------------- 1 – -------- --------f C IN
V IN V IN
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:
VO
VO
I CIN_RMS = I O --------- 1 – --------
V IN
V IN
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 ripple current rating. Depending on the
application circuits, other low ESR tantalum capacitor or
aluminum electrolytic capacitor may also be used. When
selecting ceramic capacitors, X5R or X7R type dielectric
ceramic capacitors are preferred for their better
temperature and voltage characteristics. Note that the
ripple current rating from capacitor manufactures is
based on certain amount of life time. Further de-rating
may be necessary for practical design requirement.
Inductor
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:
VO
VO
I L = ----------- 1 – --------
V IN
fL
The peak inductor current is:
I
I Lpeak = I O + -------L2
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 30% to
50% of output current.
if 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 4. 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.
0.5
When selecting the inductor, make sure it is able to
handle the peak current without saturation even at the
highest operating temperature.
The inductor takes the highest current in a buck circuit.
The conduction loss on the inductor needs to be checked
for thermal and efficiency requirements.
Surface mount inductors in different shapes and styles
are available from Coilcraft, Elytone and Murata.
Shielded inductors are small and radiate less EMI noise,
but they do cost more than unshielded inductors. The
choice depends on EMI requirement, price and size.
0.4
ICIN_RMS(m) 0.3
IO
0.2
0.1
0
0
0.5
m
1
Figure 4. ICIN vs. Voltage Conversion Ratio
Rev. 1.2 June 2021
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Page 13 of 18
AOZ2366QI
Output Capacitor
The output capacitor is selected based on the DC output
voltage rating, output ripple voltage specification and
ripple current rating.
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:
1
V O = I L ESR CO + ------------------------
8 f C O
where, CO is output capacitor value, and ESRCO is the
Equivalent Series Resistor of output capacitor.
When a low ESR ceramic capacitor is used as 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:
1
V O = I L ------------------------8fC
O
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:
V O = I 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 are recommended
to be used as output capacitors.
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:
I L
I CO_RMS = ---------12
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, the output capacitor could
be overstressed.
Rev. 1.2 June 2021
Thermal Management and Layout
Consideration
In the AOZ2366QI 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 returns to the input capacitor through
ground. Current flows in the first loop when the high side
switch is on. The second loop starts from the inductor, to
the output capacitors and load, to the low side switch.
Current flows in the second loop when the low side
switch is on.
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 the input
capacitor, output capacitor and PGND pin of the
AOZ2366QI.
In the AOZ2366QI buck regulator circuit, the major power
dissipating components are the AOZ2366QI and output
inductor. The total power dissipation of the converter circuit can be measured by input power minus output
power.
P total_loss = V IN I IN – V O I O
The power dissipation of inductor can be approximately
calculated by output current and DCR of inductor and
output current.
P inductor_loss = IO2 R inductor 1.1
The actual junction temperature can be calculated with
power dissipation in the AOZ2366QI and thermal
impedance from junction to ambient.
T junction = P total_loss – P inductor_loss JA + T A
The maximum junction temperature of AOZ2366QI is
150ºC, which limits the maximum load current capability.
The thermal performance of the AOZ2366QI 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.
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Page 14 of 18
AOZ2366QI
Layout Considerations
Several layout tips are listed below for the best electric
and thermal performance.
7. Voltage divider R1 and R2 should be placed as close
as possible to FB and AGND. Place R1 and R2 on
the same layer with IC.
1. The LX pins and pad are connected to internal low
side switch drain. They are low resistance thermal
conduction path and most noisy switching node.
Connected a copper plane to LX pin to help thermal
dissipation. The inductor need to be placed as close
to LX pin as possible.
8. RTON should be connected as close as possible to
Pin 7 (TON pin). Place RTON on the same layer with
IC.
2. The IN pins and pad are connected to internal high
side switch drain. They are also low resistance thermal conduction path. Connected a large copper
plane to IN pins to help thermal dissipation.
9. A ground plane is preferred; Pin 22, 23, 25 (PGND)
must be connected to the ground plane through VIAs
as shown in figure below.
10. Sensitive signal traces such as feedback trace must
be shielded from all noise sources, especially the LX
node.
3. Connect a large PGND copper plane to PGND pin.
Thick and short PGND trace could keep power path
impedance low.
11. The feedback trace should be taken directly from output capacitor pad and use thin trace. FB trace goes
through other layer and shielded by GND layer is
acceptable.
4. Input decoupling capacitors should be connected to
the IN pin and the PGND pin as close as possible to
reduce the switching spikes.
5. Decoupling capacitor CVCC should be connected to
VCC and GND as close as possible. Connect this
GND to GND layer with vias as shown in below figure. Place CVCC on the same layer with IC.
12. No signal should run on nearby layer under the Lx
trace or under the inductor.
13. Pour copper plane on all unused board area and
connect it to stable DC nodes, like VIN, GND or
VOUT.
6. Connect AGND to GND layer with vias close to
AGND pin as shown in figure below.
14. Insert at least two inner layers (or planes) connected
to the power ground, in order to shield and isolate
the small signal traces from noisy power lines.
GND
9
GL 24
PGND 23
PGND 22
BST 26
VCC 27
NC 28
AGND
PGND 25
5
29
GL
21 LX
SS
1
PGOOD
2
EN
3
19 LX
6 PFM 4
18 LX
AGND
5
FB
6
TON
7
20 LX
17 LX
PGND
1
VOUT
LX
16 LX
PGND 13
9
PGND 12
4
PGND 11
8
IN 10
2
IN
8
VIN
15 LX
14 LX
IN
7
IN
11
3
PGND
10
Rev. 1.2 June 2021
VOUT trace
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Page 15 of 18
AOZ2366QI
Package Dimensions, QFN5x5-28L
Rev. 1.2 June 2021
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Page 16 of 18
AOZ2366QI
Tape and Reel Dimensions, QFN5x5-28L
Rev. 1.2 June 2021
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Page 17 of 18
AOZ2366QI
Part Marking
AOZ2366QI
(QFN 5x5)
CX00
Part Number Code
YWLT
Year & Week Code
Assembly Lot Code
LEGAL DISCLAIMER
Applications or uses as critical components in life support devices or systems are not authorized. AOS does not
assume any liability arising out of such applications or uses of its products. AOS reserves the right to make changes
to product specifications without notice. It is the responsibility of the customer to evaluate suitability of the product for
their intended application. Customer shall comply with applicable legal requirements, including all applicable export
control rules, regulations and limitations.
AOS' products are provided subject to AOS' terms and conditions of sale which are set forth at:
http://www.aosmd.com/terms_and_conditions_of_sale
LIFE SUPPORT POLICY
ALPHA AND 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. 1.2 June 2021
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.
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Page 18 of 18
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