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PDF AOZ1034 Data sheet ( Hoja de datos )
| Número de pieza | AOZ1034 | |
| Descripción | 4A Synchronous Buck Regulator | |
| Fabricantes | Alpha & Omega Semiconductors | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AOZ1034 (archivo pdf) en la parte inferior de esta página. Total 18 Páginas | ||
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AOZ1034
EZBuck™ 4A Synchronous Buck Regulator
General Description
The AOZ1034 is a synchronous high efficiency, simple to
use, 4A buck regulator. The AOZ1034 works from a 4.5V
to 18V input voltage range, and provides up to 4A of
continuous output current with an output voltage
adjustable down to 0.8V.
The AOZ1034 comes in both a 5x4 DFN-8 and an
exposed pad SO-8 package and is rated over a
-40°C to +85°C ambient temperature range.
Features
z 4.5V to 18V operating input voltage range
z Synchronous rectification: 60mΩ internal high-side
switch and 20mΩ Internal low-side switch
z High efficiency: up to 95%
z Internal soft start
z Output voltage adjustable to 0.8V
z 4A continuous output current
z Fixed 500kHz PWM operation
z Cycle-by-cycle current limit
z Pre-bias start-up
z Short-circuit protection
z Thermal shutdown
z Thermally enhanced 5x4 DFN-8 and exposed pad
SO-8 packages
Applications
z Point of load DC/DC conversion
z PCIe graphics cards
z Set top boxes
z DVD drives and HDD
z LCD panels
z Cable modems
z Telecom/Networking/Datacom equipment
Typical Application
VIN
C1
22µF
Ceramic
RC
CC
VIN
EN AOZ1034 LX
COMP
AGND
FB
PGND
L1
4.7µH
VOUT
R1
C2, C3
22µF
Ceramic
R2
Rev. 1.1 September 2010
Figure 1. 3.3V 4A Synchronous Buck Regulator
www.aosmd.com
Page 1 of 18
Free Datasheet http://www.datasheet4u.com/
1 page  
AOZ1034
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
2ms/div
Start Up to Full Load
Vin ripple
0.1V/div
Vo ripple
20mV/div
IL
1A/div
VLX
10V/div
Vin
10V/div
1µs/div
Short Circuit Protection
Vin ripple
0.1V/div
Vo ripple
20mV/div
IL
5A/div
VLX
10V/div
LX
10V/div
1ms/div
Vo
2V/div
lin
1A/div
Short Circuit Recovery
50µs/div
LX
10V/div
Vo
2V/div
IL
2A/div
Vo
2V/div
IL
2A/div
1ms/div
Rev. 1.1 September 2010
www.aosmd.com
Page 5 of 18
Free Datasheet http://www.datasheet4u.com/
5 Page 
AOZ1034
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.
Usually, it is recommended to set the bandwidth to be
equal or less than 1/10 of switching frequency. The
AOZ1034 operates at a frequency range from 400kHz to
600kHz. It is recommended to choose a crossover
frequency equal or less than 40kHz.
fC = 40kHz
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 RC:
RC
=
fC
×
--V----O----
VFB
×
-----2----π----×-----C-----C------
GEA × GCS
where;
fC is desired crossover frequency. For best performance,
fC is set to be about 1/10 of 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
dominate pole fp1 but lower than 1/5 of selected
crossover frequency. CC can is selected by:
CC
=
--------------1----.-5----------------
2π × RC × fP1
The equation above can also be simplified to:
CC
=
C-----O-----×-----R-----L-
RC
An easy-to-use application software which helps to
design and simulate the compensation loop can be found
at www.aosmd.com.
Thermal Management and Layout
Consideration
In the AOZ1034 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 anode of the Schottky
diode, to the cathode of the Schottky diode. Current flows
in the second loop when the low side diode 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 input
capacitor, output capacitor, and PGND pin of the
AOZ1034.
In the AOZ1034 buck regulator circuit, the major power
dissipating components are the AOZ1034 and the output
inductor. The total power dissipation of converter circuit
can be measured by input power minus output power.
Ptotal_loss = VIN × IIN – VO × IO
The power dissipation of inductor can be approximately
calculated by output current and DCR of inductor.
Pinductor_loss = IO2 × Rinductor × 1.1
The actual junction temperature can be calculated with
power dissipation in the AOZ1034 and thermal
impedance from junction to ambient.
Tjunction = (Ptotal_loss–Pinductor_loss) × ΘJA
The maximum junction temperature of AOZ1034 is
150ºC, which limits the maximum load current capability.
Please see the thermal de-rating curves for maximum
load current of the AOZ1034 under different ambient
temperature.
The thermal performance of the AOZ1034 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.
Rev. 1.1 September 2010
www.aosmd.com
Page 11 of 18
Free Datasheet http://www.datasheet4u.com/
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet AOZ1034.PDF ] | |
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