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PDF AOZ1284 Data sheet ( Hoja de datos )
| Número de pieza | AOZ1284 | |
| Descripción | 4A Simple Buck Regulator | |
| Fabricantes | Alpha & Omega Semiconductors | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AOZ1284 (archivo pdf) en la parte inferior de esta página. Total 14 Páginas | ||
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AOZ1284
EZBuck™ 4A Simple Buck Regulator
General Description
The AOZ1284 is a high voltage, high efficiency,
simple to use, 4A buck regulator optimized for a
variety of applications. The AOZ1284 works from a
3.0V to 36V input voltage range, and provides up to
4A of continuous output current. The output voltage
is adjustable from 30V down to 0.8V.
The AOZ1284 integrates an N-channel high-side
power MOSFET. The switching frequency can set
from 200kHz to 2MHz with an external resistor. The
soft-start time can be set with an external capacitor.
Features
3.0V to 36V operating input voltage range
50mΩ internal NMOS
Efficiency up to 95%
Adjustable soft-start
Output voltage adjustable from 0.8V to 30V
4A continuous output current
Adjustable switching frequency from 200kHz to
2MHz
Cycle-by-cycle current limit
Short-circuit protection
Over-voltage protection
Over-temperature protection
EPAD SO-8 package
Applications
Point of load DC/DC conversion
Set top boxes and cable modems
Automotive applications
DVD drives and HDDs
LCD Monitors & TVs
Telecom/Networking/Datacom equipment
Typical Application
Rev. 0.5 March 2012
Figure 1. 36V/4A Buck Regulator
www.aosmd.com
Page 1 of 14
1 page  
Typical Performance Characteristics
TA = 25°C, VIN = 24V, VEN = 5V, VOUT = 5V, unless otherwise specified.
AOZ1284
Rev. 0.5 March 2012
www.aosmd.com
Page 5 of 14
5 Page 
AOZ1284
Equation above can also be simplified to:
CC
CO RL
RC
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 AOZ1284 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
GND pin of the AOZ1284, to the LX pins of the
AOZ1284. 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 GND pin of the
AOZ1284.
In the AOZ1284 buck regulator circuit, the three major
power dissipating components are the AOZ1284,
external diode and 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 power dissipation of diode is
Pdiode _ loss
IO
VF
1
VO
VIN
The actual AOZ1284 junction temperature can be
calculated with power dissipation in the AOZ1284 and
thermal impedance from junction to ambient.
T junction
Ptotal _ loss Pinductor _ loss Pdiode _ loss
JA Tambient
The maximum junction temperature of AOZ1284 is
145ºC, which limits the maximum load current
capability.
The thermal performance of the AOZ1284 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. The Figure 3 (a)
and (b) give the example of layout for AOZ1284A and
AOZ1284D respectively.
1. Do not use thermal relief connection to the VIN
and the GND pin. Pour a maximized copper area
to the GND pin and the VIN pin to help thermal
dissipation.
2. Input capacitor should be connected to the VIN
pin and the GND pin as close as possible.
3. Make the current trace from LX pins to L to Co to
the GND as short as possible.
4. Pour copper plane on all unused board area and
connect it to stable DC nodes, like VIN, GND or
VOUT.
5. Keep sensitive signal trace such as trace
connected with FB pin and COMP pin far away
from the LX pins.
Rev. 0.5 March 2012
www.aosmd.com
Page 11 of 14
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet AOZ1284.PDF ] | |
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