AX995 Datasheet. Www.s Manuals.com. R1.1 Axelite
User Manual: Datasheets AX995, AX995SA.
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Rev.1.1 Aug.25, 2010
AX995
1.6X Linear Fan Driver with VO Fully On
Control
GENERAL DESCRIPTION
The AX995 is a low dropout linear regulator which is designed to power a DC fan
and delivers up to 600mA output current. The output voltage follows the 1.6 times of
VSET voltage and typical dropout voltage is only 150mV (typical) at 600mA output
current. The VSET voltage must be larger than 1V to guarantee VO 1.6 times of VSET. A
FON
pin turns VO output fully on when given low. The features of current limit (with fold
back current) and over temperature protection protect the device against current
over-loads and over temperature. The AX995 is available in a SOP-8 package.
FEATURES
- Low Dropout Voltage: 150mV@0.6A
- VO Follows 1.6 times of VSET
-
FON
Pin to Turn VO Fully On
- Stable with Low ESR Ceramic Capacitors
- Current-Limit and Thermal Shutdown Protection
- SOP-8 Pb-Free Package
BLOCK DIAGRAM
Current Limit and
Short Protection
-
+
VIN VO
GND
Error
Amp
Thermal
Shutdown
VO Fully On
Logic
VSET
FON
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Rev.1.1 Aug.25, 2010
AX995
PIN ASSIGNMENT
The package of AX995 is SOP-8L; the pin assignment is given by:
( Top View
)
1
2
3
4
8
7
6
5
VO
VSET
SOP-8L
AX995
FON
VIN
GND
GND
GND
GND
Name
Description
GND
GND pin
VIN
IC power supply pin
VO
Output Pin. Its voltage is 1.6 times of
VSET
VSET
This pin sets the output voltage. Its
voltage must be larger than 1V to
guarantee VO 1.6 times of VSET
FON
FON
Input. Pulling this pin below 0.4V
turns the regulator fully on. Internally
pulled high.
ORDER/MARKING INFORMATION
Order Information
Top Marking
Package Type
S: SOP-8L
AX995
X X
Packing
Blank : Tube
A : Taping
Logo
Y
AX Part number
ID code:internal
WW: 01~52
Year: 10=2010
11=2011
99 5
YWWX
ABSOLUTE MAXIMUM RATINGS (at TA=25°C)
Characteristics
Symbol
Rating
Unit
VIN Supply Voltage
VIN
-0.3 to 6.5
V
FON
Input Voltage
VFON
-0.3 to VIN
V
VSET Voltage
VSET
-0.3 to VIN
V
Power Dissipation
PD
Internally limited
W
Storage Temperature Range
TST
-65 to +150
°C
Junction Temperature Range
TJ
-40 to 125
°C
Operating Temperature Range
TOP
-40 to +85
°C
Thermal Resistance from Junction to case
θJC
20
°C/W
Thermal Resistance from Junction to ambient
θJA
60
°C/W
Note: θJA is measured with the PCB copper area approximately 1.5 in2 (Multi-layer)
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Rev.1.1 Aug.25, 2010
AX995
ELECTRICAL CHARACTERISTICS
(VSET=2V, VIN=5V, IOUT= 0.5A, CIN=COUT=2.2uF, TA=25°C unless otherwise specified)
Characteristics
Symbol
Conditions
Min
Typ
Max
Units
VIN Supply Voltage Range
VIN
4.5
-
5.5
V
Quiescent Current
ICCQ
VO=5V, No Load
-
70
-
uA
Output Voltage/VSET Voltage
VO/VSET
VIN=5.5V,
VSET=1V~3.2V
1.552
1.6
1.648
V/V
Line Regulation
VIN=4.5V to 5.5V
-
0.2
0.5
%
Load Regulation
IOUT =10mA ~ 0.6A
-
0.2
0.5
%
Output Resistance
RDS(ON)
IOUT=0.6A,
VSET=3.4V
-
240
320
mΩ
Current Limit
ILimt
-
1
-
A
Short Circuit Current
IShort
Vo<0.6V
-
0.5
-
A
Minimum VSET Voltage
VSET
-
1
-
V
VSET Pin Current
ISET
-
80
200
nA
FON
Pin Logic Threshold Voltage
VFON-H
Normal Operating
2.0
-
-
V
VFON-L
Regulator Fully On
-
-
0.8
FON
Pin Bias Current
IFON
FON
=0V
-
1
5
uA
Thermal shutdown Temp
TSD
-
140
-
°C
Thermal Shutdown Hysteresis
-
30
-
°C
APPLICATION CIRCUIT
C1
2.2uF
Vo=1.6 X VSET
VIN=5V U1
AX995
2
5,6,7,8
1
4
3
VIN
GND
VSET
FON
VO
C2
2.2uF
FON
VSET
FAN
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Rev.1.1 Aug.25, 2010
AX995
FUNCTION DESCRIPTIONS
Output Voltage Regulation
The Output Voltage is set by VSET voltage. VO output voltage follows the 1.6
times of VSET voltage until it reaches VIN voltage.
Fully-On Control
If the
FON
pin logic level smaller than 0.8V, the output voltage can be
promoted near to VIN voltage. Otherwise, VOUT is normal operating by
FON
larger
than 2.0V.
Current-Limit
The AX995 monitors the current via the output PMOS and limits the maximum
current to prevent load and AX995 from damages during overload or short circuit
conditions.
Short Current Protection
When the output voltage drops below 0.6V (typical), which is caused by over load
or short circuit, the fold back current limit circuitry limits the output current to 500mA.
The fold back current limit is used to reduce the power dissipation during short circuit
condition.
Thermal Shutdown
A thermal shutdown circuit limits the junction temperature of AX995. When the
junction temperature exceeds +140°C, a thermal sensor turns off the output PMOS,
allowing the device to cool down. The regulator regulates the output again through
initiation of a new soft-start cycle after the junction temperature cools by 30°C, resulting
in a pulsed output during continuous thermal overload conditions.
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Rev.1.1 Aug.25, 2010
AX995
APPLICATION INFORMATION
Capacitor Selection
Normally, use a 2.2µF capacitor on the input and a 2.2µF capacitor on the output
of the AX995. In order to insure the circuit stability, the proper output capacitor value
should be larger than 1uF. With X5R and X7R dielectrics, 2.2uF is sufficient at all
operating temperatures.
Thermal Considerations
The AX995 series can deliver a current of up to 500mA over the full operating
junction temperature range. However, the maximum output current must be dated at
higher ambient temperature to ensure the junction temperature does not exceed 125°C.
With all possible conditions, the junction temperature must be within the range specified
under operating conditions. Power dissipation can be calculated based on the output
current and the voltage drop across regulator.
PD = (VIN - VO) IO
The final operating junction temperature for any set of conditions can be
estimated by the following thermal equation:
PD (MAX) = (TJ (MAX) - TA) / θJA
Where TJ (MAX) is the maximum junction temperature of the die (125°C) and TA is
the maximum ambient temperature. The junction to ambient thermal resistance (θJA) for
SOP-8L package at recommended minimum footprint is 60°C/W. Visit our website in
which “Recommended Footprints for Soldering Surface Mount Packages” for detail.
PCB Layout
1. Please place the input capacitors close to the VIN
2. Ceramic capacitors for load must be placed near the load as close as possible
3. To place AX995 and output capacitors near the load is good for performance.
4. Large current paths that VIN and Output lines must have wide tracks.
5. GND connect large copper area can reduced IC temperature.
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Rev.1.1 Aug.25, 2010
AX995
TYPICAL CHARACTERISTICS
0
20
40
60
80
100
120
140
160
180
200
3 3.5 4 4.5 5 5.5 6
VIN VS ICCQ
VIN (V)
ICCQ (uA)
IOUT=0A
0
20
40
60
80
100
120
140
160
180
200
0 0.5 1 1.5 2 2.5 3 3.5 4
VSET VS ICCQ
VSET (V)
ICCQ (uA)
IOUT=0A
0
1
2
3
4
5
6
0 0.5 1 1.5 2 2.5 3 3.5 4
VSET VS VOUT
VSET (V)
VOUT (V)
IOUT=100A
VIN=5.5
1.50
1.52
1.54
1.56
1.58
1.60
1.62
1.64
1.66
1.68
1.70
-40℃ -25℃ 0℃ 25℃ 50℃ 75℃ 100℃ 125℃
Temperaute VS VOUT
Temperature(℃)
VOUT (V)
VSET=1V
IOUT=200mA
0
50
100
150
200
250
300
350
400
450
500
-40℃ -25℃ 0℃ 25℃ 50℃ 75℃ 100℃ 125℃
Temperaute VS Output Resistance
Temperature(℃)
Output Resistance (mΩ)
VIN=5V
VSET=3.5V
IOUT=500mA
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
-40℃ -25℃ 0℃ 25℃ 50℃ 75℃ 100℃ 125℃
Temperaute VS FON Voltage
Temperature(℃)
FON Voltage (V)
VFON-H
VFON-L
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Rev.1.1 Aug.25, 2010
AX995
TYPICAL CHARACTERISTICS (CONTINUOUS)
Power ON
Power ON
Fully-On
Fully-On(VIN Drop)
Load Transient
Load Transient (VIN Drop)
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Rev.1.1 Aug.25, 2010
AX995
PACKAGE OUTLINES
DETAIL A
L
H
E
A
A2
A1
e
D
7(4X)
b
y
C
DETAIL A
θ
Symbol
Dimensions in Millimeters
Dimensions in Inches
Min.
Nom.
Max.
Min.
Nom.
Max.
A
-
-
1.75
-
-
0.069
A1
0.1
-
0.25
0.04
-
0.1
A2
1.25
-
-
0.049
-
-
C
0.1
0.2
0.25
0.0075
0.008
0.01
D
4.7
4.9
5.1
0.185
0.193
0.2
E
3.7
3.9
4.1
0.146
0.154
0.161
H
5.8
6
6.2
0.228
0.236
0.244
L
0.4
-
1.27
0.015
-
0.05
b
0.31
0.41
0.51
0.012
0.016
0.02
e
1.27 BSC
0.050 BSC
y
-
-
0.1
-
-
0.004
θ
0O
-
8O
0O
-
8O
Mold flash shall not exceed 0.25mm per side
JEDEC outline: MS-012 AA