AOSMD AOZ1020AI-EVB Ezbuckâ ¢ 2a synchronous buck regulator evaluation board note Datasheet

AOZ1020AI-EVB
EZBuck™ 2A Synchronous Buck Regulator
Evaluation Board Note
General Description
Features
The AOZ1020AI evaluation board is a fully assembled
and tested circuit board built with the AOZ1020AI buck
regulator IC. It outputs an adjustable voltage up to 2A of
continuous current. The evaluation board requires an
input voltage from 4.5 to 16V. The output voltage is preset
at 3.3V and can be adjusted down to 0.8V.
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The AOZ1020AI-EVB circuit has features like current
limit, short circuit protection, input under voltage lock out,
internal soft start and thermal shut down. It operates at a
fixed 500kHz switching frequency. The integrated
internal MOSFETs minimize component count, board
area and total cost.
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The AOZ1020AI-EVB demonstrates the simple buck
converter design. Only one resistor value change is
needed for different output voltage designs. The
AOZ1020AI-EVB also supports single layer board
design.
4.5V to 16V operating input voltage range
Output voltage preset to 3.3V, adjustable to as low as
0.8V
2A continuous output current
Fixed 500kHz PWM operation
Internal soft start
Open-drain Power Good output
Cycle-by-cycle current limit
Short-circuit protection
Thermal shutdown
Enables single layer board design
Applications
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Point of load DC/DC conversion
PCIe graphics cards
Set top boxes
DVD drives and HDD
LCD panels
Cable modems
Telecom/Networking/Datacom equipment
Evaluation Board Schematic
Rg
PG
10k
Cp
open
Cc
C6
EN
R3
0
Vin
Vin
C4
104
GND
20k
102
R4
EN
Rc
U1
5
3
AGND
6
EN
2
C1
226
VIN
C5
open
8
R2
10k
PG
GND
COMP
GND
GND
PGND
PG5V
FB
LX
1
GND
R1
4
31.6k
7
1
L
4R7
2
VO
C2
226
C3
226
GND
GND
Rev. 1.1 July 2009
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AOZ1020AI-EVB
Table 1. Component List
Ref Designation
Part Number
Description
Manufacturer
C1, C2, C3
GRM32ER61E226KE15L
Cap, 22µF/25V, 1210, X5R, 10%
muRata
C4
GRM188R71H104KA01D
Cap, 0.1µF/50V, 0603, X7R, 10%
muRata
C5, Cp
Open
Cap, 0603
TDK, muRata
C1608C0G1H102J
Cap, 1nF/50V, 0603, X7R 10%
C6, Cc
GRM188R71H102KA01D
TDK
muRata
L
VLF10040T-4R7N5R4
Inductor, 4.7µH, 5.4A
R1
31.6k
Res, 31.6k, 0603, 1%
R2
20k
Res, 20k, 0603, 1%
R3
0
Res, 0, 0603
R4
Open
Res, 0603, 5%
R5, Rc
10k
Res, 10k, 0603, 5%
U1
AOZ1020AI
IC, MAX 2A, SO8
TDK
AOS
Output voltage is set by R1: R1= R2 • (Vout – 0.8) / 0.8. Table 2 below shows the value of R1 at typical output
voltages.
Table 2.
Vout (V)
R1 (kΩ)
R2 (kΩ)
0.8
1
Open
1
2.49
10
1.2
4.99
10
1.5
8.66
10
1.8
12.7
10
2.5
21.5
10
3.3
31.6
10
5
52.3
10
Rev. 1.1 July 2009
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Page 2 of 4
AOZ1020AI-EVB
PCB Layout
Figure 1. Top Silk Screen
Figure 2. Top Layer
Figure 3. Bottom Layer
Rev. 1.1 July 2009
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Page 3 of 4
AOZ1020AI-EVB
Quick Start Guide
1. Connect the terminals of load to Vout and GND port.
2. Connect the DC power supply to Vin and GND port. Set DC power supply voltage to between 4.5V and 16V.
3. EN pin is connected to Vin via a 0Ohm resistor in the demo board. If a separate enable signal is desired, connect
EN pin to any voltage source between 2.0V and 16V.
4. Measure input voltage at the Vin and GND ports to eliminate the effect of voltage drop on the wire between DC
power supply and evaluation board.
5. Measure output voltage at the Vout and GND ports to eliminate the effect of voltage drop on the wire between load
and evaluation board.
6. Use an oscilloscope to monitor the input ripple voltage across input capacitor C1.
7. Use an oscilloscope to monitor the output ripple voltage across output capacitor C2.
Note:
When testing the ripple voltage, remove the cap of the voltage probe and touch the probe tip directly across the Vin or
Vout and GND terminals, as shown in Figure 4.
V
GND
Figure 4. Voltage Ripple Test
Alpha &Omega Semiconductor reserves the right to make changes at any time without notice.
LIFE SUPPORT POLICY
ALPHA & 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. 1.1 July 2009
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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