S3U1085
3A
Low Dropout
Positive
Elektronische Bauelemente
RoHS Compliant Product
Adjustable or
Fixed-Mode Regulator
Description
The S3U1085 is a low dropout at positive adjustable or fixed-mode
regulator with min. of
3A
output current capability. The product is
specifically designed to provide well-regulated supply for low voltage
IC applications such as high-speed bus termination and low current
3.3V logic supply. S3U1085 is also well suited for other applications
such as VGA cards. S3U1085 is guaranteed to have lower than 1.4V
dropout at full load current making it ideal to provide well regulated
outputs of 1.25V to
5V with 4.7 to 12V input supply by different
output voltage.
Features
*
1.4V Max. Dropout Full Load Current
REF.
A
b
L4
c
L3
L1
E
* 3-Terminal Adjustable or Fixed 1.5V,1.8V,2.5V,3.3V,5.0V
* Output Current Limiting
* Fast Transient Response
* Built-in Thermal Shutdown
Millimeter
REF.
Min.
Max.
4.40
4.80
c2
0.76
1.00
b2
0.00
0.30
B D
0.36
0.5
e
1.50 REF.
L
2.29
2.79
9.80
10.4
L2
Millimeter
Min.
Max.
1.25
1.45
1.17
1.47
8.6
9.0
2.54 REF.
14.6
15.8
0˚
8˚
1.27 REF.
Block Diagram
Typical Circuit
3.3V/3A
2.5V/3A
http://www.SeCoSGmbH.com/
Any changing of specification will not be informed individual
01-Jun-2002 Rev. A
Page 1 of
4
S3U1085
Elektronische Bauelemente
3A
Low Dropout
Positive
Adjustable or
Fixed-Mode Regulator
Pin Descriptions
Name
Adj (GND)
Vout
O
I/O
PIN#
1
2
Adjustable (Ground only for fixed mode)
The output of the regulator. A minimum of 10uF
capacitor must be connected from this pin to
ground to insure stability.
The input pin of regulator .Typically a large storage capacitor is connected from this pin to ground
to insure that the input voltage does not sag below the minimum dropout voltage during the load
s
sag below the minimum dropout voltage during the load
V higher than Vout
order for the device to
transient response .This pin must always be 1.4V higher than Vout in
in order for the device to
regulate properly.
FUNCTION
Vin
I
3
Absolute Maximum Ratings
Parameter
DC Supply Voltage
Power Dissipation
Storage Temperature Range
Operating Juction Temperature Range
Symbol
V
IN
P
D
T
ST
T
OP
Ratings
-0.3 to 12
Internally Limited
-65~+150
0~+150
Unit
V
o
o
C
C
Electrical Characteristics
Parameter
Reference Voltage
S3U1085ADJ
S3U1085-1.5
S3U1085-1.8
Output Voltage
S3U1085-2.5
S3U1085-3.3
S3U1085-5.0
Line Regulator
S3U1085-XXX
S3U1085ADJ
S3U1085-1.5
Load Regulation
S3U1085-1.8
S3U1085-2.5
S3U1085-3.3
S3U1085-5.0
Dropout Voltage
(Vin-Vout)
Current Limit
Minimum Load Current
Thermal Regulation
Ripple Rejection
Temperature Stability
Thermal Resistance
Junction–to-Ambient
Thermal Resistance
Junction-to-Case
S3U1085-XXX
S3U1085-XXX
S3U1085-XXX
T
A
=25 , 30ms pulse
F=120Hz, C
OUT
=25uF, Tantalum, Io=3A
S3U1085-XXX
Io=10mA
Vin=Vout+3V
-
-
Control Circuitry/Power Transistor
-
-
60
0.5
91
10
70
-
-
-
dB
%
/W
Conditions
Io=10mA, T
J
=25 , (Vin-Vout )=1.5V
Io=10mA, T
J
=25 , 3V Vin 12V
Io=10mA, T
J
=25 , 3.3V Vin 12V
Io=10mA, T
J
=25 , 4V Vin 12V
Io=10mA, T
J
=25 , 4.8V Vin 12V
Io=10mA, T
J
=25 , 6.5V Vin 12V
Io=10mA, Vout+1.5<Vin<12
Vin=3.3V, 0mA<Io<3A, T
J
=25
Vin=3.0V, 0mA<Io<3A, T
J
=25
Vin=3.3V, 0mA<Io<3A, T
J
=25
Vin=4.0V, 0mA<Io<3A, T
J
=25
Vin=5.0V, 0mA<Io<3A, T
J
=25
Vin=8.0V, 0mA<Io<3A, T
J
=25
Io=3A( Vout=1% Vout)
Vin-Vout=5V
0
T
J
125
-
(Note 1,2)
(Note 1,2)
(Note 1,2)
(Note 1,2)
(Note 1,2)
(Note 1,2)
MIN
1.225
1.470
1.764
2.450
3.235
4.900
-
-
-
-
-
-
-
-
3.1
-
TYP
1.250
1.500
1.800
2.500
3.300
5.000
-
-
12
15
20
26
40
1.3
-
5
0.008
MAX
1.275
1.530
1.836
2.550
3.365
5.100
0.2
1
15
18
25
33
50
1.4
-
10
0.04
UNIT
V
V
V
V
V
V
%
%
mV
mV
mV
mV
mV
V
A
mA
%/W
(No heat sink ;No air flow)
/W
Note 1: See thermal regulation specifications for changes in output voltage due to heating effects. Line and load regulation are measured
at a constant junction Temperature by low duty cycle pulse testing. Load regulation is measured at the output lead =1/18” from the
package.
Note 2: Line and load regulation are guaranteed up to the maximum power dissipation of 15W. Power dissipation is determined by the
difference in input and output and the output current. Guaranteed maximum power dissipation will not be available over the full
input/output range.
Note 3: Quiescent current is defined as the minimum output current required in maintaining regulation. At 12V input/output differential the
device is guaranteed to regulate if the output current is greater than 10mA.
http://www.SeCoSGmbH.com/
Any changing of specification will not be informed individual
01-Jun-2002 Rev. A
Page
2
of
4
S3U1085
Elektronische Bauelemente
3A
Low Dropout
Positive
Adjustable or
Fixed-Mode Regulator
Functional Description
Introduction
The
S3U1085
adjustable or fixed-mode Low Dropout (LDO) regulator is a 3 terminal device which can easily be
programmed by internal mask change to any voltage within the range of 1.25 to Vin-1.4V. The
S3U1085
only needs 1.4V
differential between Vin and Vout to maintain output regulation, in addition, the output voltage tolerances are also extremely
tight and they include the transient response as port of the specification. For example, Intel VRE specification calls for a
total of +/-100mV including initial tolerance, load regulation and 0 to 3A load step. The
S3U1085
is specifically designed to
meet the fast current transient needs as well as providing an accurate initial voltage, reducing the overall system cost with
the need for fewer output capacitors.
Load Regulation
Since the
S3U1085
is only a 3 terminal device, it is not possible to provide true remote sensing of the output voltage at the
load. But it can supply good load regulation by internal feedback bypass the external loss such as adjustable mode.
Stability
The
S3U1085
requires the use of an output capacitor as part of the frequency compensation in order to make the regulator
stable .For most applications a minimum of 10uF aluminum electrolytic capacitor insures both stability and good transient
response.
Thermal Design
The
S3U1085
incorporates an internal shutdown that protects the device when the junction temperature exceeds the
maximum allowable junction temperatures. Although this device can operate with junction temperatures in the range of
150 :
,
it is recommended that the selected heat sink be chosen such that during maximum continuous load operation the
junction temperature is kept below the temperature.
Layout Consideration
The output capacitors must be located as close to the Vout terminal of the device as possible .It is recommended to use a
section of a layer of the PC board as a plane to connect the Vout pin to the output capacitors to prevent any high frequency
oscillation that may result due to excessive trace inductance.
h tp://www.SeCoSGmbH.com/
Any changing of specification will not be informed individual
01-Jun-2002 Rev. A
Page
3
of
4
S3U1085
Elektronische Bauelemente
3A
Low Dropout
Positive
Adjustable or
Fixed-Mode Regulator
Typical Performance Characteristics
3A
h tp://www.SeCoSGmbH.com/
Any changing of specification will not be informed individual
01-Jun-2002 Rev. A
Page
4
of
4
Microcontroller MCU
京公网安备 11010802033920号
EEWORLD
