datasheet for AOZ1232QI-01 by Alpha and Omega Semiconductor

datasheet for AOZ1232QI-01 by Alpha and Omega Semiconductor
AOZ1232-01
28V/6A Synchronous EZBuckTM Regulator
General Description
Features
The AOZ1232-01 is a high-efficiency, easy-to-use DC/DC
synchronous buck regulator that operates up to 28V.
The device is capable of supplying 6A of continuous
output current with an output voltage adjustable down to
0.8V (±1.0%).
 Wide input voltage range
The AOZ1232-01 integrates an internal linear regulator
to generate 5.3V VCC from input. If input voltage is lower
than 5.3V, the linear regulator operates at low dropoutput mode, which allows the VCC voltage is equal to
input voltage minus the drop-output voltage of the
internal linear regulator.
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. The switching frequency
can be externally programmed up to 1MHz.
– 2.7V to 28V
 6A continuous output current
 Output voltage adjustable down to 0.8V (±1.0%)
 Low RDS(ON) internal NFETs
– 35m high-side
– 12m low-side SRFET™
 Constant On-Time with input feed-forward
 Programmable frequency up to 1MHz
 Internal 5.3V/20mA linear regulator
 Ceramic capacitor stable
 Adjustable soft start
 Power Good output
 Integrated bootstrap diode
 Cycle-by-cycle current limit
The device features multiple protection functions such as
VCC under-voltage lockout, cycle-by-current limit, output
over-voltage protection, short-circuit protection, as well
as thermal shutdown.
 Short-circuit protection
The AOZ1232-01 is available in a 5mm x 5mm QFN-30L
package and is rated over a -40°C to +85°C ambient
temperature range.
Applications
 Thermal shutdown
 Thermally enhanced 5mm x 5mm QFN-30L package
 Portable computers
 Compact desktop PCs
 Servers
 Graphics cards
 Set-top boxes
 LCD TVs
 Cable modems
 Point-of-load DC/DC converters
 Telecom/Networking/Datacom equipment
Rev. 1.3 October 2012
www.aosmd.com
Page 1 of 18
AOZ1232-01
Typical Application for VIN = 12V or above
Input = 12V or above
IN
C2
22μF
RTON
AIN
TON
BST
VCC
R3
100kΩ
Power Good
C4
1μF
AOZ1232-01
Output
LX
PGOOD
Off On
C5
0.1μF
L1
R1
EN
FB
R2
CSS
C3
100μF
AGND
SS
PGND
Analog Ground
Power Ground
Typical Application for VIN = 5V
Input = 5V
IN
C2
22μF
RTON
AIN
TON
BST
VCC
R3
100kΩ
Power Good
C4
1μF
AOZ1232-01
Output
LX
PGOOD
Off On
C5
0.1μF
L1
R1
EN
FB
R2
CSS
SS
C3
100μF
AGND
PGND
Analog Ground
Power Ground
Rev. 1.3 October 2012
www.aosmd.com
Page 2 of 18
AOZ1232-01
Typical Application for High Light Load Efficiency Requirement or VIN = 2.7V ~ 6.5V
Input
IN
C2
22μF
5V
R3
100kΩ
Power Good
RTON
AIN
TON
BST
VCC
C4
1μF
AOZ1232-01
Output
LX
PGOOD
Off On
C5
0.1μF
L1
R1
EN
FB
R2
CSS
C3
100μF
AGND
SS
PGND
Analog Ground
Power Ground
Ordering Information
Part Number
Ambient Temperature Range
AOZ1232QI-01
-40°C to +85°C
Package
30-Pin 5mm x 5mm QFN
Environmental
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.
Rev. 1.3 October 2012
www.aosmd.com
Page 3 of 18
AOZ1232-01
SS
AGND
VCC
BST
PGND
LX
LX
LX
Pin Configuration
30
29
28
27
26
25
24
23
PGOOD
1
22
LX
EN
2
21
LX
PFM
3
20
LX
AGND
4
19
PGND
FB
5
18
PGND
17
PGND
16
PGND
15
PGND
10
11
12
13
14
PGND
9
PGND
IN
8
PGND
7
IN
AIN
IN
IN
6
LX
IN
TON
AGND
30-pin 5mm x 5mm QFN
(Top View)
Pin Description
Pin Number
Pin Name
Pin Function
1
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 10% lower than
the nominal regulation voltage for 50µs (typical time) or 15% higher than the nominal
regulation voltage. PGOOD is pulled low during soft-start and shut down.
2
EN
3
PFM
4, 29
AGND
5
FB
6
TON
On-Time Setting Input. Connect a resistor between VIN and TON to set the on time.
7
AIN
Supply Input for analog functions.
8, 9, 10, 11
IN
12, 13, 14, 15, 16,
17, 18, 19, 26
PGND
Power Ground.
20, 21, 22, 23,
24, 25
LX
Switching Node.
27
BST
Bootstrap Capacitor Connection. The AOZ1232-01 includes an internal bootstrap diode.
Connect an external capacitor between BST and LX as shown in the Typical Application
diagrams.
28
VCC
Output for internal linear regulator. Bypass VCC to AGND with a 1µF ceramic capacitor.
Place the capacitor close to VCC pin.
30
SS
Rev. 1.3 October 2012
Enable Input. The AOZ1232-01 is enabled when EN is pulled high. The device shuts
down when EN is pulled low.
PFM Selection Input. Connect PFM pin to VCC/VIN for forced PWM operation. Connect
PFM pin to ground for PFM operation to improve light load efficiency.
Analog Ground.
Feedback Input. Adjust the output voltage with a resistive voltage-divider between the
regulator’s output and AGND.
Supply Input. IN is the regulator input. All IN pins must be connected together.
Soft-Start Time Setting Pin. Connect a capacitor between SS and AGND to set the
soft-start time.
www.aosmd.com
Page 4 of 18
AOZ1232-01
Absolute Maximum Ratings
Maximum Operating Ratings
Exceeding the Absolute Maximum Ratings may damage the
device.
Parameter
The device is not guaranteed to operate beyond the
Maximum Operating ratings.
Rating
IN, AIN, TON, PFM to AGND
Parameter
-0.3V to 30V
LX to AGND
-2V to 30V
BST to AGND
-0.3V to 36V
SS, PGOOD, FB, EN to AGND
-0.3V to 6V
PGND to AGND
-0.3V to +0.3V
Junction Temperature (TJ)
+150°C
Storage Temperature (TS)
-65°C to +150°C
ESD Rating(1)
2kV
Note:
1. Devices are inherently ESD sensitive, handling precautions are
required. Human body model rating: 1.5k in series with 100pF.
Rating
2.7V(1) to 28V
Supply Voltage (VIN)
Output Voltage Range
0.8V to 0.85*VIN
Ambient Temperature (TA)
-40°C to +85°C
Package Thermal Resistance
HS MOSFET
25°C/W
LS MOSFET
20°C/W
PWM Controller
50°C/W
Note:
1. Connect VCC and AIN to external 5V for VIN = 2.7V ~ 6.5V
application.
2. LX to PGND Transient (t<20ns) ------ -7V to VIN + 7V.
Electrical Characteristics
TA = 25°C, V IN = 12V, EN = 5V, unless otherwise specified. Specifications in BOLD indicate a temperature range of -40°C to +85°C.
Symbol
VIN
VUVLO
Iq
IOFF
VFB
IFB
Parameter
Conditions
IN Supply Voltage
Min.
Typ.
Max
Units
28
V
4.0
3.7
4.4
2
3
mA
1
20
A
0.800
0.800
0.808
0.812
V
2.7
Under-Voltage Lockout Threshold of Vcc
Vcc rising
Vcc falling
Quiescent Supply Current of Vcc
IOUT = 0, VFB = 1.0V, VEN > 2V
Shutdown Supply Current
VEN = 0V
Feedback Voltage
TA = 25°C
TA = 0°C to 85°C
3.2
0.792
0.788
Load Regulation
0.5
Line Regulation
1
FB Input Bias Current
V
%
%
200
nA
Enable
VEN
EN Input Threshold
VEN_HYS
EN Input Hysteresis
Off threshold
On threshold
0.5
2.5
100
V
mV
PFM Control
VPFM
PFM Input Threshold
VPFMHYS
PFM Input Hysteresis
PFM Mode threshold
Force PWM threshold
0.5
2.5
100
V
mV
Modulator
TON
On Time
RTON = 100k, VIN = 12V
RTON = 100k, VIN = 24V
200
250
150
300
ns
TON_MIN
Minimum On Time
100
ns
TOFF_MIN
Minimum Off Time
250
ns
Rev. 1.3 October 2012
www.aosmd.com
Page 5 of 18
AOZ1232-01
Symbol
Parameter
Conditions
Min.
Typ.
Max
Units
VSS = 0, CSS = 0.001F to 0.1F
7
10
15
A
0.5
V
±1
A
18
-8
%
Soft-Start
ISS_OUT
SS Source Current
Power Good Signal
VPG_LOW
PGOOD Low Voltage
IOL = 1mA
PGOOD Leakage Current
VPGH
VPGL
TPG_L
PGOOD Threshold
FB rising
FB falling
12
-12
15
-10
PGOOD Threshold Hysteresis
3
%
PGOOD Fault Delay Time (FB falling)
50
s
Under Voltage and Over Voltage Protection
VPL
Under Voltage Threshold
TPL
Under Voltage Delay Time
VPH
Over Voltage Threshold
FB rising
Under Voltage Shutdown Blanking Time
VIN = 12V, VEN = 0V, VCC = 5V
20
VIN = 12V, VCC = 5V
35
TUV_LX
FB falling
-30
-25
-20
s
128
12
15
%
18
%
mS
Power Stage Output
RDS(ON)
High-Side NFET On-Resistance
High-Side NFET Leakage
VEN = 0V, VLX = 0V
RDS(ON)
Low-Side NFET On-Resistance
VLX = 12V, VCC = 5V
Low-Side NFET Leakage
VEN = 0V
12
45
m
10
A
15
m
10
A
Over-current and Thermal Protection
ILIM
Valley Current Limit
Thermal Shutdown Threshold
Rev. 1.3 October 2012
6
TJ rising
TJ falling
www.aosmd.com
A
145
100
°C
Page 6 of 18
AOZ1232-01
Functional Block Diagram
BST AIN
IN
PGood
LDO
VCC
EN
UVLO
Reference
& Bias
TOFF_MIN
Q
Timer
Error Comp
0.8V
SS
FB
ISENSE
(AC)
PG Logic
S
Q
R
FB
Decode
LX
ILIM Comp
ILIM_VALLEY
Current
Information
Processing
ISENSE
OTP
ISENSE (DC)
ISENSE (AC)
Vcc
TON
Q
Timer
PFM
TON
TON
Generator
Light Load
Threshold
Light Load
Comp
ISENSE
PGND
Rev. 1.3 October 2012
www.aosmd.com
AGND
Page 7 of 18
AOZ1232-01
Typical Performance Characteristics
Circuit of Typical Application. TA = 25°C, V IN = 12V, VOUT = 1.5V, fs = 300kHz unless otherwise specified.
Normal Operation
Load transient 1.2A (20%) to 4.8A (80%)
VLX
10V/div
VLX
10V/div
ILX
5A/div
ILX
2A/div
VO Ripple
100mV/div
VO Ripple
20mV/div
5μs/div
500μs/div
Full Load (6A) Start-UP
Full Load Short
VLX
10V/div
EN
5V/div
ILX
2A/div
VLX
10V/div
IO
5A/div
VO
1V/div
1ms/div
Rev. 1.3 October 2012
VO
500mV/div
1ms/div
www.aosmd.com
Page 8 of 18
AOZ1232-01
Detailed Description
The AOZ1232-01 is a high-efficiency, easy-to-use,
synchronous buck regulator optimized for notebook
computers. The regulator is capable of supplying 6A of
continuous output current with an output voltage
adjustable down to 0.8V. The programmable operating
frequency range of 100kHz to 1MHz enables optimizing
the configuration for PCB area and efficiency.
The input voltage of AOZ1232-01 can be as low as 2.7V.
The highest input voltage of AOZ1232-01 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 a
ceramic output capacitor. The switching frequency can
be externally programmed up to 1MHz. Protection
features include VCC under-voltage lockout, valley
current limit, output over voltage and under voltage
protection, short-circuit protection, and thermal
shutdown.
The AOZ1232-01 is available in 30-pin 5mm x 5mm QFN
package.
Input Power Architecture
The AOZ1232-01 integrates an internal linear regulator
to generate 5.3V VCC from input. If input voltage is lower
than 5.3V, the linear regulator operates at low dropoutput mode; the VCC voltage is equal to input voltage
minus the drop-output voltage of internal linear regulator.
Enable and Soft Start
Constant-On-Time PWM Control with Input
Feed-Forward
The control algorithm of AOZ1232-01 is constant-on-time
PWM Control with input feed-forward.
The simplified control schematic is shown in Figure 1.
IN
PWM
–
Programmable
One-Shot
FB Voltage/
AC Current
Information
Comp
+
0.8V
Figure 1. Simplified Control Schematic of AOZ1232-01
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
0.8V is lower 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 AOZ1232-01 sets the on-time of
high-side switch inversely proportional to the IN.
The AOZ1232-01 has external 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 VCC rises to 4.0V 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 0.8V. When VSS
is higher than 0.8V, the FB voltage is regulated by
internal precise band-gap voltage (0.8V). The soft-start
time can be calculated by the following formula:
26.3  10
 R TON   
T ON = ---------------------------------------------------------------V IN  V 
TSS(s) = 330 x CSS(nF)
V OUT
F SW = --------------------------V IN  T ON
– 12
(1)
To achieve the flux balance of inductor, the buck
converter has the equation:
(2)
If CSS is 1nF, the soft-start time will be 330µs; if CSS is
10nF, the soft-start time will be 3.3ms.
Rev. 1.3 October 2012
www.aosmd.com
Page 9 of 18
AOZ1232-01
Once the product of VIN x TON is constant, the switching
frequency keeps constant and is independent with input
voltage.
An external resistor between the IN and TON pin sets the
switching frequency according to the following equation:
function of the inductor value as well as input and output
voltages. The current limit will keep the low-side
MOSFET ON and will not allow another high-side ontime, until the current in the low-side MOSFET reduces
below the current limit. Figure 2 shows the inductor
current during the current limit.
12
V OUT  10
F SW = --------------------------------26.3  R TON
(3)
Inductor
Current
A further simplified equation will be:
38000  V OUT  V 
F SW  kHz  = ----------------------------------------------R TON  k 
Ilim
(4)
Time
Figure 2. Inductor Current
If VOUT is 1.8V, RTON is 137k, the switching frequency
will be 500kHz.
This algorithm results in a nearly constant switching
frequency despite the lack of a fixed-frequency clock
generator.
After 128s (typical), the AOZ1232-01 considers this is a
true failed condition and therefore, turns-off both highside and low-side MOSFETs and latches off. When
triggered, only the enable can restart the AOZ1232-01
again.
True Current Mode Control
Output Voltage Under-Voltage Protection
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.
If the output voltage is lower than 25% by over-current or
short circuit, the AOZ1232-01 will wait for 128s (typical)
and turns-off both high-side and low-side MOSFETs and
latches off. When triggered, only the enable can restart
the AOZ1232-01 again.
The AOZ1232-01 senses the low-side MOSFET current
and processes it into DC 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 applicable. The
pure ceramic capacitor solution can significantly reduce
the output ripple (no ESR caused overshoot and
undershoot) and less board area design.
Valley Current-Limit Protection
The AOZ1232-01 uses the valley current-limit protection
by using RDSON of the lower MOSFET current sensing.
To detect real current information, a minimum constantoff (150ns typical) is implemented after a constant-on
time. If the current exceeds the valley current-limit
threshold, the PWM controller is not allowed to initiate a
new cycle. The actual peak current is greater than the
valley current-limit threshold by an amount equal to the
inductor ripple current. Therefore, the exact current-limit
characteristic and maximum load capability are a
Rev. 1.3 October 2012
Output Voltage Over-Voltage Protection
The threshold of OVP is set 15% higher than 800mV.
When the VFB voltage exceeds the OVP threshold, highside MOSFET is turned-off and low-side MOSFETs is
turned-on until VFB voltage is lower than 800mV.
Power Good Output
The power good (PGOOD) output, which is an open
drain output, requires the pull-up resistor. When the
output voltage is 10% below than the nominal regulation
voltage for 50s (typical), the PGOOD is pulled low.
When the output voltage is 15% higher than the nominal
regulation voltage, the PGOOD is also pulled low.
When combined with the under-voltage-protection circuit,
this current limit method is effective in almost every
circumstance. In forced-PWM mode, the AOZ1232-01
also implements a negative current limit to prevent
excessive reverse inductor currents when VOUT is
sinking current.
www.aosmd.com
Page 10 of 18
AOZ1232-01
Application Information
The basic AOZ1232-01 application circuit is shown in
pages 2 and 3. Component selection is explained below.
Input Capacitor
The input capacitor must be connected to the IN pins and
PGND pin of the AOZ1232-01 to maintain steady input
voltage and filter out the pulsing input current. A small
decoupling capacitor, usually 1F, should be connected
to the VCC pin and AGND pin for stable operation of the
AOZ1232-01. 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:
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
IO

-  ------------------------   1 – -------V IN V IN
f  C 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 L = -----------   1 – ---------
V IN
fL 
The peak inductor current is:
I L
I Lpeak = I O + -------2
VO 
VO 
I CIN_RMS = I O  ---------  1 – ---------
V IN 
V IN
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 3. It can be seen that when VO is half of VIN, CIN it
is under the worst current stress. The worst current
stress on CIN is 0.5 x IO.
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.
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.
0.5
0.4
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.
ICIN_RMS(m) 0.3
IO
0.2
0.1
0
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.
0
0.5
m
1
Figure 3. ICIN vs. Voltage Conversion Ratio
Rev. 1.3 October 2012
www.aosmd.com
Page 11 of 18
AOZ1232-01
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  ------------------------8fC
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
Thermal Management and Layout
Consideration
In the AOZ1232-01 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
AOZ1232-01.
In the AOZ1232-01 buck regulator circuit, the major
power dissipating components are the AOZ1232-01 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 AOZ1232-01 and thermal
impedance from junction to ambient.
T junction =  P total_loss – P inductor_loss    JA
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:
The maximum junction temperature of AOZ1232-01 is
150ºC, which limits the maximum load current capability.
The thermal performance of the AOZ1232-01 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.
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. 1.3 October 2012
www.aosmd.com
Page 12 of 18
AOZ1232-01
Several layout tips are listed below for the best electric
and thermal performance.
5. Decoupling capacitor CVCC should be connected to
VCC and AGND as close as possible.
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.
Connect a large copper plane to LX pin to help thermal dissipation.
6. Voltage divider R1 and R2 should be placed as close
as possible to FB and AGND.
7. RTON should be connected as close as possible to
Pin 6 (TON pin).
2. The IN pins and pad are connected to internal high
side switch drain. They are also low resistance thermal conduction path. Connect a large copper plane
to IN pins to help thermal dissipation.
8. A ground plane is preferred; Pin 26 (PGND) is connected to the ground plane through via.
9. Keep sensitive signal traces such as feedback trace
far away from the LX pins.
3. Do not use thermal relief connection on the PGND
pin. Pour a maximized copper area on the PGND pin
to help thermal dissipation.
10. Pour copper plane on all unused board area and
connect it to stable DC nodes, like VIN, GND or
VOUT.
4. Input capacitors should be connected to the IN pin
and the PGND pin as close as possible to reduce the
switching spikes.
Vo
R2
R1
Rton
FB
ND
AGN
D
PFM
EN
PGOOD
5
4
3
2
1
7
6
AIN
TON
30
IN
9
D
29 AGND
IN
10
IN
11
IN
D
AGND
AGN
8
IN
Cin
SS
Cvcc
28 VCC
Vcc
27 BST
26
PGND
GND
Cb
25 LX
12
PGND
13
24 LX
PGND
14
23 LX
LX
PGND
15
16
17
18
19
20
21
22
PGND
PGND
PGND
PGND
PGND
LX
LX
LX
Cout
LX
Vo
Vo
Rev. 1.3 October 2012
www.aosmd.com
Page 13 of 18
AOZ1232-01
Package Dimensions, QFN 5x5, 30 Lead EP3_S
D
A
D/2
22
B
15
23
2
14
INDEX AREA
E/2
(D/2xE/2)
A3/2
2x
aaa C
E
e
30
8
1
7
2x
aaa C
A3
TOP VIEW
A3/2
ccc C
A3
C
A
SEATING
PLANE
A1
4
3
30 x b
ddd C
bbb M C A B
SIDE VIEW
PIN#1 DIA
C0.35x45˚
D1
1
e
e/2
L5
7
30
8
E1
E1
D2
L3
L1
L1
L4
L2
E2
2e
e/2
L5
23
14
L
22
15
L5
D3/2
D3
L5
Notes:
1. All dimensions are in millimeters.
2. The location of the terminal #1 identifier and terminal numbering convention conforms to JEDEC publication 95 SPP-002.
3. Dimension b applies to metallized terminal and is measured between 0.20mm and 0.35mm 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.
Rev. 1.3 October 2012
www.aosmd.com
Page 14 of 18
AOZ1232-01
Package Dimensions, QFN 5x5, 30 Lead EP3_S (Continued)
3.76
0.22
0.80
0.25
0.75
0.116
1.996
14
0.44
30
2.50
0.71
8
0.30X45°
7
1.25
1
0.500 REF
0.25
0.22
2.32
0.22
1.494
0.386
23
0.25
15
22
2.50
0.22
1.88
UNIT: MM
1.17
2.50
2.50
RECOMMENDED STENCIL DESIGN
1.04
0.22
0.27
0.27
0.80
0.14
0.27
0.52
15
22
0.15
2.50
0.81
2.50
0.116
0.75
0.873
0.622
0.436
0.39
0.25
14
23
8
0.30X45°
1
0.27
7
0.25
Rev. 1.3 October 2012
0.37
0.27
0.975
2.50
0.500 REF
0.27
0.15
30
1.07
UNIT: MM
2.50
www.aosmd.com
Page 15 of 18
AOZ1232-01
Package Dimensions, QFN 5x5, 30 Lead EP3_S (Continued)
Dimensions in millimeters
Symbols
Min.
A
A1
A3
b
D
D1
0.80
0.00
2.12
2.22
D2
0.97
1.07
D3
3.56
3.66
0.20
E
E1
E2
e
L
L1
L2
L3
L4
L5
aaa
bbb
ccc
ddd
Rev. 1.3 October 2012
Typ.
0.90
0.02
0.20 REF
0.25
5.00 BSC
Max.
Symbols
Min.
1.00
0.05
0.031
0.000
0.008
2.32
A
A1
A3
b
D
D1
0.083
0.087
0.091
1.17
D2
0.038
0.042
0.046
3.76
D3
0.140
0.144
0.148
0.35
E
5.00 BSC
1.294
1.796
0.30
0.336
—
0.29
0.66
0.17
1.394
1.896
0.50 BSC
0.40
0.436
0.066
0.39
0.76
0.27
0.15
0.10
0.10
0.08
Dimensions in inches
1.494
1.996
0.50
0.536
0.166
0.49
0.86
0.37
E1
E2
e
L
L1
L2
L3
L4
L5
aaa
bbb
ccc
ddd
www.aosmd.com
0.051
0.110
0.012
0.013
—
0.011
0.026
0.007
Typ.
0.035
0.001
0.008 REF
0.010
0.197 BSC
0.197 BSC
0.055
0.114
0.020 BSC
0.016
0.017
0.003
0.015
0.030
0.011
0.006
Max.
0.039
0.002
0.014
0.059
0.118
0.020
0.021
0.007
0.019
0.034
0.015
0.004
0.004
0.003
Page 16 of 18
AOZ1232-01
Tape and Reel Dimensions, QFN 5x5, 30 Lead EP3_S
Carrier Tape
P1
P2
D1
T
E1
E2
E
B0
K0
D0
P0
A0
Feeding Direction
UNIT: mm
Package
A0
B0
K0
D0
QFN 5x5
(12mm)
5.25
±0.10
5.25
±0.10
1.10
±0.10
1.50
Min.
D1
1.50
+0.10/-0
E
E1
E2
P0
P1
P2
T
12.00
+0.3
1.75
±0.10
5.50
±0.05
8.00
±0.10
4.00
±0.10
2.00
±0.05
0.30
±0.05
Reel
W1
S
G
N
M
K
V
R
H
W
UNIT: mm
Tape Size Reel Size
12mm
ø330
M
ø330.0
±2.0
N
ø79.0
±1.0
W
12.4
+2.0/-0.0
W1
17.0
+2.6/-1.2
H
ø13.0
±0.5
K
10.5
±0.2
S
2.0
±0.5
G
—
R
—
V
—
Leader/Trailer and Orientation
Trailer Tape
300mm min.
75 Empty Pockets
Rev. 1.3 October 2012
Components Tape
Orientation in Pocket
www.aosmd.com
Leader Tape
500mm min.
125 Empty Pockets
Page 17 of 18
AOZ1232-01
Part Marking
Z1232QI1
Part Number Code
FAYWLT
Assembly Lot Code
Fab & Assembly Location
Year & Week Code
LEGAL DISCLAIMER
Alpha and Omega Semiconductor makes no representations or warranties with respect to the accuracy or
completeness of the information provided herein and takes no liabilities for the consequences of use of such
information or any product described herein. Alpha and Omega Semiconductor reserves the right to make changes
to such information at any time without further notice. This document does not constitute the grant of any intellectual
property rights or representation of non-infringement of any third party’s intellectual property rights.
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. 1.3 October 2012
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 18 of 18
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement