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PDF AOZ1075 Data sheet ( Hoja de datos )
| Número de pieza | AOZ1075 | |
| Descripción | 1.2A Simple Buck Regulator | |
| Fabricantes | Alpha & Omega Semiconductors | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AOZ1075 (archivo pdf) en la parte inferior de esta página. Total 15 Páginas | ||
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AOZ1075
EZBuck™ 1.2A Simple Buck Regulator
General Description
The AOZ1075 is a high efficiency, simple to use, 1.2A
buck regulator. The AOZ1075 works from a 4.75V to
16V input voltage range, and provides up to 1.2A of
continuous output current with an output voltage
adjustable down to 0.8V.
The AOZ1075 comes in an SO-8 package and is rated
over a -40°C to +85°C ambient temperature range.
Features
● 4.75V to 16V operating input voltage range
● 130mΩ internal PFET switch for high efficiency:
up to 95%
● Internal Schottky diode
● Internal soft start
● Output voltage adjustable to 0.8V
● 1.2A continuous output current
● Fixed 500kHz PWM operation
● Cycle-by-cycle current limit
● Short-circuit protection
● Under voltage lockout
● Output over voltage protection
● Thermal shutdown
● Small size SO-8 package
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
Typical Application
VIN
C1
22µF Ceramic
VIN
From µPC
R1
C5
EN
AOZ1075
COMP
C2
LX
FB
AGND PGND
L1
4.7µH
VOUT
R2
C4, C6
22µF Ceramic
R3
Rev. 1.0 June 2008
Figure 1. 3.3V/1.2A Buck Regulator
www.aosmd.com
Page 1 of 15
1 page  
AOZ1075
Typical Performance Characteristics
Circuit of Figure 1. TA = 25°C, VIN = VEN = 12V, VOUT = 3.3V unless otherwise specified.
Light Load (DCM) Operation
Full Load (CCM) Operation
Vin ripple
0.1V/div
Vo ripple
20mV/div
IL
1A/div
VLX
10V/div
1µs/div
1µs/div
Startup to Full Load
Vin
10V/div
Short Circuit Protection
Vo
1V/div
lin
0.2A/div
400µs/div
10% to 100% Load Transient
100µs/div
Short Circuit Recovery
Vin ripple
0.1V/div
Vo ripple
20mV/div
IL
1A/div
VLX
10V/div
Vo
2V/div
IL
1A/div
100µs/div
Vo Ripple
50mV/div
lo
1A/div
1ms/div
Vo
2V/div
IL
1A/div
Rev. 1.0 June 2008
www.aosmd.com
Page 5 of 15
5 Page 
AOZ1075
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
=
f
C
×
--V-----O----
V FB
×
-----2---π-----×-----C-----O------
GEA × GCS
where;
fC is desired crossover frequency,
VFB is 0.8V,
GEA is the error amplifier transconductance, which is 200x10-6
A/V, and
GCS is the current sense circuit transconductance, which is
5.64 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 × f p1
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 AOZ1075 buck regulator circuit, high pulsing cur-
rent 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 PGND pin of the AOZ1075, to the LX
pins of the AZO1015. 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 recommended to connect input capacitor, output
capacitor, and PGND pin of the AOZ1075.
In the AOZ1075 buck regulator circuit, the two major
power dissipating components are the AOZ1075 and
output inductor. The total power dissipation of 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.
P inductor _loss = IO 2 × R inductor × 1.1
The actual AOZ1075 junction temperature can be calcu-
lated with power dissipation in the AOZ1075 and thermal
impedance from junction to ambient.
T junction =
(P total _loss–P inductor _loss) × ΘJA + T ambient
The maximum junction temperature of AOZ1075 is
150°C, which limits the maximum load current capability.
Please see the thermal de-rating curves for the maximum
load current of the AOZ1075 under different ambient
temperature.
The thermal performance of the AOZ1075 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.
Several layout tips are listed below for the best electric
and thermal performance. Figure 3 below illustrates a
single layer PCB layout example as reference.
1. 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.
2. Input capacitor should be connected to the VIN pin
and the PGND pin as close as possible.
3. 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. In this case, a decoupling
capacitor should be connected between VIN pin and
AGND pin.
4. Make the current trace from LX pins to L to Co to the
PGND as short as possible.
5. Pour copper plane on all unused board area and
connect it to stable DC nodes, like VIN, GND or VOUT.
Rev. 1.0 June 2008
www.aosmd.com
Page 11 of 15
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet AOZ1075.PDF ] | |
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