EZBuck™ 1.8A High Efficiency
Constant Current Regulator for LEDs
AOZ1081
General Description
The AOZ1081 is a high efficiency, simple to use, 1.8A
buck regulator for White LED. The AOZ1081 works from
a 4.5V to 16V input voltage range, and provides up to
1.8A of continuous output current with an output voltage
adjustable down to 0.25V.
The AOZ1081 comes in an SO-8 package and is rated
over a -40°C to +85°C ambient temperature range.
Features
●
●
4.5V to 16V operating input voltage range
100 m
Ω
internal PFET switch for high efficiency:
up to 95%
Internal Schottky Diode
Internal soft start
0.25V internal reference with ±5% accuracy over
temperature
1.8A continuous output current
Fixed 1MHz 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
●
●
●
●
Buck regulator for white LEDs
Landscape lighting
Flashlights
Battery powered backlight applications
Typical Application
VIN
C1
22µF
VIN
4.7µH
EN
COMP
R1
C2
AOZ1081
LX
FB
VOUT
HB
LED
C3
22µF
RFB
AGND
PGND
Figure 1.
Rev. 1.1 April 2009
www.aosmd.com
Page 1 of 16
AOZ1081
VIN
C1
22µF
VIN
4.7µH
EN
COMP
R1
C2
AOZ1081
LX
FB
VOUT
AGND
PGND
C3
22µF
R
FB
R2
R3
R4
R5
R6
R7
R8
Figure 2.
Ordering Information
Part Number
AOZ1081AI
Ambient Temperature Range
-40°C to +85°C
Package
SO-8
Environmental
RoHS
All AOS products are offered in packages with Pb-free plating and compliant to RoHS standards.
Please visit
www.aosmd.com/web/quality/rohs_compliant.jsp
for additional information.
Rev. 1.1 April 2009
www.aosmd.com
Page 2 of 16
AOZ1081
Pin Configuration
PGND
VIN
AGND
FB
1
2
3
4
8
7
6
5
LX
LX
EN
COMP
SO-8
(Top View)
Pin Description
Pin
Number
1
2
3
4
5
6
7,8
Pin Name
PGND
VIN
AGND
FB
COMP
EN
LX
Pin Function
Power ground. Electrically needs to be connected to AGND.
Supply voltage input. When V
IN
rises above the UVLO threshold the device starts up.
Reference connection for controller section. Also used as thermal connection for controller
section. Electrically needs to be connected to PGND.
LED Current Feedback Input. The FB voltage is regulated at 250mV in normal operation. The FB
sense resistor sets the nominal LED current
External loop compensation pin.
The enable pin is active high. Connect EN pin to V
IN
if not used. Do not leave the EN pin floating.
PWM output connection to inductor. Thermal connection for output stage.
Rev. 1.1 April 2009
www.aosmd.com
Page 3 of 16
AOZ1081
Block Diagram
VIN
EN
UVLO
& POR
5V LDO
Regulator
Internal
+5V
OTP
+
ISen
Reference
& Bias
Softstart
ILimit
–
Q1
+
0.25V
+
EAmp
–
+
FB
–
PWM
Comp
PWM
Control
Logic
Level
Shifter
+
FET
Driver
LX
COMP
Frequency
Foldback
Comparator
1000kHz / 76kHz
Oscillator
+
0.15V
–
0.33V
+
–
Over Voltage
Protection
Comparator
AGND
PGND
Absolute Maximum Ratings
Exceeding the Absolute Maximum Ratings may damage the
device.
Recommend Operating Ratings
The device is not guaranteed to operate beyond the Maximum
Operating Ratings.
Parameter
Supply Voltage (V
IN
)
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)
Note:
Rating
18V
-0.7V to V
IN
+0.3V
-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
2kV
Parameter
Supply Voltage (V
IN
)
Output Voltage Range
Ambient Temperature (T
A
)
Package Thermal Resistance SO-8
(Θ
JA
)
(2)
Rating
4.5V to 16V
0.25V to V
IN
-40°C to +85°C
87°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 spe-
cific board design.
1. Devices are inherently ESD sensitive, handling precautions are required.
Human body model rating: 1.5k
Ω
in series with 100pF.
Rev. 1.1 April 2009
www.aosmd.com
Page 4 of 16
AOZ1081
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
V
IN
Rising
V
IN
Falling
Conditions
Min.
4.5
Typ.
4.0
3.7
2
1
Max.
16
Units
V
V
I
OUT
= 0, V
COMP
= 0.1V, V
EN
>1.2V
V
EN
= 0V
0.2375
3
10
0.2625
mA
µA
V
%
%
0.25
0.5
0.5
I
FB
V
EN
V
HYS
f
O
D
MAX
D
MIN
Feedback Voltage Input Current
EN Input Threshold
EN Input Hysteresis
Frequency
Maximum Duty Cycle
Minimum Duty Cycle
Error Amplifier Voltage Gain
Error Amplifier Transconductance
500
200
2.5
Off Threshold
On Threshold
330
240
150
400
V
IN
= 12V
V
IN
= 5V
97
166
850
100
Off Threshold
On Threshold
2.0
100
1000
200
0.6
nA
V
mV
MODULATOR
1150
12
kHz
%
%
V/ V
µA / V
4.0
A
mV
°C
µs
130
200
PROTECTION
I
LIM
V
PR
T
J
t
SS
Current Limit
Output Over-Voltage Protection
Threshold
Over-Temperature Shutdown Limit
Soft Start Interval
High-Side Switch On-Resistance
OUTPUT STAGE
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 April 2009
www.aosmd.com
Page 5 of 16
Power technology
京公网安备 11010802033920号
EEWORLD
