AOZ1037
EZBuck™ 5A Synchronous Buck Regulator
General Description
The AOZ1037 is a high efficiency, simple to use, 5A
synchronous buck regulator. The AOZ1037 works from a
4.5V to 18V input voltage range, and provides up to 5A
of continuous output current with an output voltage
adjustable down to 0.8V.
The AOZ1037 comes in an exposed pad SO-8 packages
and is rated over a -40°C to +85°C ambient temperature
range.
Features
4.5 to 18V operating input voltage range
Synchronous rectification: 55m
Ω
internal high-side
switch and 19m
Ω
Internal low-side switch
High efficiency: up to 95%
Internal soft start
Active high power good state
Output voltage adjustable to 0.8V
5A continuous output current
Fixed 500kHz PWM operation
Cycle-by-cycle current limit
Pre-bias start-up
Short-circuit protection
Thermal shutdown
Exposed pad SO-8 package
Applications
Point of load DC/DC conversion
LCD TVs
Set top boxes
DVD / Blu-ray players/recorders
Cable modems
PCIe graphics cards
Telecom/Networking/Datacom equipment
Typical Application
VIN
C1
22µF
5V
R3
VIN
EN
COMP
R
C
C
C
PGOOD
L1 4.7µH
AOZ1037
LX
R1
VOUT
FB
AGND
PGND
R2
C2, C3
22µF
Figure 1. 3.3V/5A Synchronous Buck Regulator
Rev. 1.1 September 2010
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Page 1 of 14
AOZ1037
Ordering Information
Part Number
AOZ1037PI
Ambient Temperature Range
-40°C to +85°C
Package
EPAD SO-8
Environmental
Green Product
AOS Green Products use reduced levels of Halogens, and are also RoHS compliant.
Please visit
www.aosmd.com/web/quality/rohs_compliant.jsp
for additional information.
Pin Configuration
PGND
VIN
AGND
FB
1
2
3
4
8
NC
PGOOD
EN
COMP
PAD
(LX)
7
6
5
Exposed Pad SO-8
(Top View)
Pin Description
Pin Number
1
2
3
4
5
6
7
8
Pad
Pin Name
PGND
V
IN
AGND
FB
COMP
EN
PGOOD
NC
LX
Pin Function
Power ground. PGND needs to be electrically connected to AGND.
Supply voltage input. When V
IN
rises above the UVLO threshold and EN is logic high, the device
starts up.
Analog ground. AGND is the reference point for controller section. AGND needs to be electrically
connected to PGND.
Feedback input. The FB pin is used to set the output voltage via a resistor divider between the out-
put and AGND.
External loop compensation pin. Connect a RC network between COMP and AGND to compen-
sate the control loop.
Enable pin. Pull EN to logic high to enable the device. Pull EN to logic low to disable the device. if
on/off control is not needed, connect it to V
IN
and do not leave it open.
Power Good Output. PGOOD is an open-drain output that indicates the status of output voltage.
PGOOD is pulled low when output is below 90% of the normal regulation.
No Connect. Pin 8 is not internally connected.
Switching node. LX is the drain of the internal PFET. LX is used as the thermal pad of the power
stage.
Rev. 1.1 September 2010
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Page 2 of 14
AOZ1037
Block Diagram
VIN
EN
UVLO
& POR
5V LDO
Regulator
Internal
+5V
OTP
+
ISen
Reference
& Bias
–
Softstart
ILimit
Q1
+
0.8V
+
EAmp
–
FB
PWM
–
Comp
+
PWM
Control
Logic
Level
Shifter
+
FET
Driver
Q2
LX
COMP
+
0.2V
–
Short Circuit
Detection
Comparator
500kHz
Oscillator
PGOOD
–
0.72V
+
AGND
PGND
Absolute Maximum Ratings
Exceeding the Absolute Maximum ratings may damage the
device.
Recommended Operating Conditions
The device is not guaranteed to operate beyond the Maximum
Recommended Operating Conditions.
Parameter
Supply Voltage (V
IN
)
LX to AGND
LX to AGND
EN to AGND
FB to AGND
COMP to AGND
PGND to AGND
Junction Temperature (T
J
)
Storage Temperature (T
S
)
ESD Rating
(1)
Rating
20V
-0.7V to V
IN
+0.3V
23V (<50ns)
-0.3V to V
IN
+0.3V
-0.3V to 6V
-0.3V to 6V
-0.3V to +0.3V
+150°C
-65°C to +150°C
2.0kV
Parameter
Supply Voltage (V
IN
)
Output Voltage Range
Ambient Temperature (T
A
)
Package Thermal Resistance
Exposed Pad SO-8 (Θ
JA
)
(2
)
Rating
4.5V to 18V
0.8V to V
IN
-40°C to +85°C
50°C/W
Note:
2. The value of
Θ
JA
is measured with the device mounted on 1-in
2
FR-4
board with 2oz. Copper, in a still air environment with T
A
= 25°C. The
value in any given application depends on the user's specific board
design.
Note:
1. Devices are inherently ESD sensitive, handling precautions are
required. Human body model rating: 1.5k
Ω
in series with 100pF.
Rev. 1.1 September 2010
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Page 3 of 14
AOZ1037
Electrical Characteristics
Symbol
V
IN
V
UVLO
I
IN
I
OFF
V
FB
T
A
= 25°C, V
IN
= V
EN
= 12V, V
OUT
= 3.3V unless otherwise specified
(3
)
Parameter
Supply Voltage
Input Under-Voltage Lockout Threshold
Supply Current (Quiescent)
Shutdown Supply Current
Feedback Voltage
Load Regulation
Line Regulation
Conditions
V
IN
Rising
V
IN
Falling
I
OUT
= 0, VFB = 1.2V, V
EN
> 1.2V
V
EN
= 0V
T
A
= 25°C
Min.
4.5
Typ.
4.1
3.7
1.6
1.0
Max.
18
Units
V
V
2.5
10
0.812
mA
µA
V
%
%
0.788
0.8
0.5
1.0
I
FB
ENABLE
V
EN
V
HYS
f
O
D
MAX
T
on_min
G
VEA
G
EA
I
LIM
Feedback Voltage Input Current
EN Input Threshold
EN Input Hysteresis
Frequency
Maximum Duty Cycle
Minimum On Time
Error Amplifier Voltage Gain
Error Amplifier Transconductance
Current Limit
Over-Temperature Shutdown Limit
T
J
Rising
T
J
Falling
5.8
400
100
150
500
200
6.5
150
100
3
I
OL
= 1mA
87
90
3
128
V
IN
= 12V
V
IN
= 5V
V
IN
= 12V
V
IN
= 5V
55
75
19
23
Off Threshold
On Threshold
200
0.6
2
100
500
600
nA
V
mV
kHz
%
ns
V/ V
µA / V
A
°C
ms
MODULATOR
PROTECTION
t
SS
V
OLPG
V
PGL
t
PG
Soft Start Interval
PG LOW Voltage
PG Leakage
PG Threshold Voltage
PG Threshold Voltage Hysteresis
PG Delay Time
High-Side Switch On-Resistance
Low-Side Switch On-Resistance
POWER GOOD
0.6
1
92
V
µA
%Vo
%
µs
PWM OUTPUT STAGE
m
Ω
m
Ω
Note:
3. Specification in
BOLD
indicate an ambient temperature range of -40°C to +85°C. These specifications are guaranteed by design.
Rev. 1.1 September 2010
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Page 4 of 14
AOZ1037
Typical Performance Characteristics
Circuit of Figure 1. T
A
= 25°C, V
IN
= V
EN
= 12V, V
OUT
= 3.3V unless otherwise specified.
Light Load Operation
Full Load (CCM) Operation
Vin ripple
0.1V/div
Vo ripple
20mV/div
Vin ripple
0.1V/div
Vo ripple
20mV/div
IL
1A/div
IL
1A/div
VLX
10V/div
VLX
10V/div
2ms/div
1µs/div
Start Up to Full Load
Short Circuit Protection
Vin
10V/div
LX
10V/div
Vo
2V/div
Vo
2V/div
lin
1A/div
IL
2A/div
1ms/div
Short Circuit Recovery
50µs/div
LX
10V/div
Vo
2V/div
IL
2A/div
1ms/div
Rev. 1.1 September 2010
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Page 5 of 14
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