AX3051/A
2.8A,Wide-Input Sensorless CC/CV Step-Down
DC/DC Converter
GENERAL DESCRIPTION
AX3051/A is a wide input voltage, high efficiency Active CC step-down DC/DC
converter that operates in either CV (Constant Output Voltage) mode or CC (Constant
Output Current) mode.
AX3051/A consists of step-down switching regulator with PWM control. The device
includes a reference voltage source, oscillation circuit, error amplifier and etc.
AX3051/A provides low-ripple power, high efficiency, and excellent transient
characteristics. The PWM control circuit is able to the duty ratio linearly forms 0 up to 90%.
An over current protection function is built outside that it can set by a resistance. An
external compensation is easily to system stable; the low ESR output capacitor can be
used.
With the addition of an internal N-channel Power MOS, a coil, capacitors, and a
diode connected externally, these ICs can function as step-down switching regulators.
They serve as ideal power supply units for portable devices when coupled with the
SOP-8L-EP packages, providing such outstanding features as low current consumption.
Since this converter can accommodate an input voltage up to 34V.
1/15
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.9 May. 06, 2015
AX3051/A
FEATURES
-
Input Voltage：8V to 34V
-
-
-
-
-
-
Vout Accuracy (V
FB
=1V) ±1% /±2%
CC/CV mode(Constant Current and Constant Voltage)
Up to 2.8A output current
±5%/±15% Current limit Accuracy
Duty ratio：0% to 90% PWM control
Oscillation frequency：
AX3051: 100KHz
-
-
-
-
-
-
-
-
AX3051A: 250KHz
Thermal Shutdown function.
Short Circuit Protect (SCP).
Built-in internal LX N-channel MOS.
Current mode non-synchronous PWM converter
External current limit setting.
Over Voltage Protection 5.8V.
Built in adjustable line-compensation.
SOP-8L-EP Pb-Free packages
APPLICATIONS
-
Car charger
-
Portable charger Device.
BLOCK DIAGRAM
CURRENT
SENSE
AMPLIFIER
OSCILLATOR
FB
100KHz/250KHz
BS
RAMP
CLK
IN
+
-
5V
+
-
1V
S
R
Q
Q
M1
0.15Ω
+
ERROR
AMPLIFIER
-
OVP
CURRENT
COMPARATOR
M2
5Ω
LX
COMP
IN
CURRENT
Limit
AMPLIFIER
INTERNAL
REGULATORS
SHUTDOWN
COMPARATOR
5V
GND
+
7V
Zener
1.5V
+
-
SENSE1
-
SENSE2
2/15
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.9 May. 06, 2015
AX3051/A
PIN ASSIGNMENT
The package of AX3051/A is SOP-8L-EP; the pin assignment is given by:
Name
Description
Bootstrap Pin. This provides
power to the internal
high-side MOSFET gate
BS
driver.
Connect a 0.1uF capacitor
( Top View )
from BS pin to LX pin.
Power Switching Output to
LX
BS 1
8 GND
External Inductor.
SENSE1
Current Sense input1
LX 2
7 VIN
GND
SENSE1
SENSE2
3
4
SOP-8L-EP
6
COMP
5 FB
SENSE2
FB
COMP
VIN
GND
Current Sense input2
Output voltage feedback
control
Error Amplifier Output. This
pin is used to compensate
the converter.
Power Supply Input. Bypass
this pin with a 0.1uF ceramic
capacitor to GND, placed as
close to the IC as possible.
GND pin
ORDER/MARKING INFORMATION
Order Information
Top Marking
Logo
AX3051 X XX X
Blank:100KHz Package Type Packing
A:250KHz ES: SOP-8L-EP Blank : Tube
A : Taping
AX
3 0 5
AX3051A
1
A Y Y W WX
Part number
ID code: internal
WW: 01~52
Year: 11=2011
12=2012
:
:
19=2019
Note:
Bin 2: ±5%, Bin 3: ±15% (Sense Voltage)
3/15
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.9 May. 06, 2015
AX3051/A
ABSOLUTE MAXIMUM RATINGS
(at T
A
= 25°C)
Characteristics
Symbol
Rating
Unit
IN to GND
LX to GND
BS to GND
FB, SENSE1, SENSE2, COMP to GND
Operating Junction Temperature
Storage Junction Temperature
Lead Temperature (Soldering 10 sec.)
Thermal Resistance from Junction to case
Thermal Resistance from Junction to ambient
θ
JC
θ
JA
-0.3 to 40
-1 to V
IN
+ 1
V
LX
- 0.3 to V
LX
+ 7
-0.3 to + 6
-40 to 150
-65 to 150
300
15
75
V
V
V
V
°C
°C
°C
°C/W
°C/W
Note : θ
JA
is measured with the PCB copper are (need connect to Exposed pad) of approximately 1
in
2
(Multi-layer).
ELECTRICAL CHARACTERISTICS
(V
IN
=12V, T
A
=25°C, unless otherwise specified)
Characteristics
Symbol
Conditions
Input Voltage
OVP detect voltage
V
OVP
Internal define
OVP Hysteresis
Quiescent Current
I
CCQ
V
FB
= 1.5V, force driver off.
Standby Supply Current
V0 = 5V, No Load
Line compensation Current
I
FB
V
SENSE1
-V
SENSE2
=100mV
Feedback Voltage(Bin2)
AX3051ES
Feedback Voltage(Bin2)
AX3051AES
Feedback Voltage(Bin3)
AX3051ES/AX3051AES
High-Side Switch On
R
DSON
V
IN
=12V, I
OUT
= 1A
Resistance
Low-Side Switch On
R
DSON
V
IN
=12V
Resistance
AX3051; I
OUT
=200mA
Switching Frequency
F
OSC
AX3051A; I
OUT
=200mA
AX3051
Maximum Duty Cycle
AX3051A
Minimum On-Time
Secondary Cycle-by-Cycle
Minimum Duty Cycle, no CC
Current Limit
Reference Voltage of the
Short Circuit Fold back
V
SCP
Comparator
Sense Voltage (Bin2)
V
SENSE
V
SENSE1
-V
SENSE2
Sense Voltage (Bin3)
V
SENSE
V
SENSE1
-V
SENSE2
Thermal shutdown Temp
T
SD
Thermal Shutdown
T
SH
Hysteresis
Min Typ Max
8
-
34
-
5.8
-
-
0.3
-
-
2
-
-
10 15
3.5
5
6.5
0.99 1 1.01
0.98 1 1.02
0.98 1 1.02
-
-
80
200
90
87
-
-
-
95
85
-
-
150
5
100
250
93
90
150
3.5
0.4
100
100
140
30
Units
V
V
V
mA
mA
uA
V
V
V
200 mΩ
-
Ω
120 KHz
300 KHz
-
%
-
%
-
ns
-
0.45
A
V
105 mV
115 mV
-
°C
-
°C
4/15
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.9 May. 06, 2015
AX3051/A
APPLICATION CIRCUIT
AL CAPACITOR
(1)
Frequency=100KHz
V
IN
=8~34V
C1
100μF/35V
C8
2.2μF
~10μF
C3
0.1μF
IN
R2
8.2KΩ
C2
2.2nF
C7
Option
COMP
GND
BS
LX
SENSE1
SENSE2
FB
R4
1KΩ
D1
40V/3A
L1
68μH
C4
470μF
R1
37mΩ
R3
4kΩ
C5
2.2nF
C6
10μF
Vout=5V/2.5A
(2)
Frequency=250KHz
V
IN
=8~34V
C1
100μF/35V
C8
2.2μF
~10μF
IN
R2
10KΩ
C2
4.7nF
C7
39pF
COMP
GND
D2
1N4148
L1
22μH
C4
47uF~
220uF
R1
37mΩ
C3
0.1μF
BS
LX
SENSE1
SENSE2
FB
R4
1KΩ
D1
40V/3A
R3
4kΩ
C5
Option
C6
Option
Vout=5V/2.5A
5/15
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.9 May. 06, 2015
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