AOZ1073

EZBuck™ 3A Synchronous Buck Regulator

General Description Features

The AOZ1073 is a synchronous high efficiency, simple ● 4.5V to 16V operating input voltage range
to use, 3A buck regulator. The AOZ1073 works from a ● Synchronous rectification: 85mΩ internal high-side
4.5V to 16V input voltage range, and provides up to 3A switch and 30mΩ Internal low-side switch
of continuous output current with an output voltage
● High efficiency: up to 95%
adjustable down to 0.8V.
● Internal soft start
The AOZ1073 comes in an SO-8 packages and is rated ● Output voltage adjustable to 0.8V
over a -40°C to +85°C ambient temperature range. ● 3A continuous output current
● Fixed 500kHz PWM operation
● Cycle-by-cycle current limit
● Pre-bias start-up
● Short-circuit protection
● Thermal shutdown
● Output over voltage protection
● 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
L1 4.7µH
EN VOUT
AOZ1073 LX

COMP R1
C2, C3
RC FB 22µF Ceramic

CC AGND PGND R2

Figure 1. 3.3V/3A Buck Regulator

Rev. 1.1 September 2008 www.aosmd.com Page 1 of 15

 AOZ1073

Ordering Information
Part Number Ambient Temperature Range Package Environmental
AOZ1073AIL -40°C to +85°C SO-8 Green (Halogen Free)

• All AOS products are offered in packages with Pb-free plating and compliant to RoHS standards.
• Parts marked as Green Products (with “L” suffix) 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 1 8 LX

VIN 2 7 LX

AGND 3 6 EN

FB 4 5 COMP

SO-8
(Top View)

Pin Description
Pin Number Pin Name Pin Function
1 PGND Power ground. Electrically needs to be connected to AGND.
2 VIN Supply voltage input. When VIN rises above the UVLO threshold the device starts up.
3 AGND Reference connection for controller section. Also used as thermal connection for controller section.
Electrically needs to be connected to PGND.
4 FB The FB pin is used to determine the output voltage via a resistor divider between the output and
GND.
5 COMP External loop compensation pin.
6 EN The enable pin is active HIGH. Connect it to VIN if not used and do not leave it open.
7, 8 LX PWM outputs connection to inductor.

Rev. 1.1 September 2008 www.aosmd.com Page 2 of 15

 AOZ1073

Block Diagram
VIN

EN UVLO 5V LDO Internal OTP

& POR Regulator +5V

+
ISen
–
Reference Softstart
& Bias Q1
ILimit

+
+ PWM Level
0.8V PWM Shifter
EAmp – Control
FB – Comp +
Logic
+ FET LX
Driver
Q2
COMP

Frequency 500kHz/68kHz
Foldback Oscillator
Comparator
+
0.2V –

OVP
Comparator
+
0.96V –

AGND PGND

Absolute Maximum Ratings Recommend Operating Ratings

Exceeding the Absolute Maximum Ratings may damage the The device is not guaranteed to operate beyond the Maximum
device. Operating Ratings.
Parameter Rating Parameter Rating
Supply Voltage (VIN) 18V Supply Voltage (VIN) 4.5V to 16V
LX to AGND -0.7V to VIN+0.3V Output Voltage Range 0.8V to VIN
EN to AGND -0.3V to VIN+0.3V Ambient Temperature (TA) -40°C to +85°C
FB to AGND -0.3V to 6V Package Thermal Resistance (ΘJA )(2)
COMP to AGND -0.3V to 6V SO-8 87°C/W
PGND to AGND -0.3V to 0.3V Package Thermal Resistance (ΘJC)
Junction Temperature (TJ) +150°C SO-8 30°C/W
Storage Temperature (TS) -65°C to +150°C Package Power Dissipation (PD)
ESD Rating(1) 2.0kV @ 25°C Ambient
SO-8 1.15W
Note:
1. Devices are inherently ESD sensitive, handling precautions are Note:
required. Human body model rating: 1.5kΩ in series with 100pF. 2. The value of ΘJA is measured with the device mounted on 1-in2
FR-4 board with 2oz. Copper, in a still air environment with
TA = 25°C. The value in any given application depends on the
user's specific board design.

Rev. 1.1 September 2008 www.aosmd.com Page 3 of 15

 AOZ1073

Electrical Characteristics
TA = 25°C, VIN = VEN = 12V, VOUT = 3.3V unless otherwise specified.(3)

Symbol Parameter Conditions Min. Typ. Max. Units

VIN Supply Voltage 4.5 16 V
VUVLO Input Under-Voltage Lockout Threshold VIN Rising 4.1
V
VIN Falling 3.7
IIN Supply Current (Quiescent) IOUT = 0, VFB = 1.2V, VEN > 1.2V 1.6 2.5 mA
IOFF Shutdown Supply Current VEN = 0V 3 20 µA
VFB Feedback Voltage TA = 25°C 0.788 0.8 0.812 V
Load Regulation 0.5 %
Line Regulation 1 %
IFB Feedback Voltage Input Current 200 nA
ENABLE
VEN EN Input Threshold Off Threshold 0.6
V
On Threshold 2
VHYS EN Input Hysteresis 100 mV
MODULATOR
fO Frequency 350 500 600 kHz
DMAX Maximum Duty Cycle 100 %
DMIN Minimum Duty Cycle 6 %
GVEA Error Amplifier Voltage Gain 500 V/V
GEA Error Amplifier Transconductance 200 µA / V
PROTECTION
ILIM Current Limit 3.5 5.0 A
VPR Output Over-Voltage Protection Threshold Off Threshold 960
mV
On Threshold 940
Over-Temperature Shutdown Limit TJ Rising 150
°C
TJ Falling 100
tSS Soft Start Interval 3 5 6.5 ms
PWM OUTPUT STAGE
High-Side Switch On-Resistance VIN = 12V 85 115
mΩ
VIN = 5V 120 170
Low-Side Switch On-Resistance VIN = 12V 30 36
mΩ
VIN = 5V 50 60
Note:
3. Specifications in BOLD indicate an ambient temperature range of -40°C to +85°C. These specifications are guaranteed by design.

Rev. 1.1 September 2008 www.aosmd.com Page 4 of 15