GS1085
Vishay
formerly General Semiconductor
3A Low Dropout Positive Adjustable Regulator
New Product
Document Number 74821
www.vishay.com
24-May-02
1
Description
The GS1085 is a low dropout three terminal regulator with
3A output current capability. The output voltage is
adjustable with the use of a resistor divider. For fixed output
voltage versions, the output voltage is internally set at
1.8V, 2.5V, or 3.3V. Dropout is guaranteed at a maximum
of 1.4V at maximum output current. Its low dropout voltage
and fast transient response make it ideal for low voltage
microprocessor applications. Internal current and thermal
limiting provides protection against any overload condition
that would create excessive junction temperatures.
Applications
Post Regulator for Switching Supply
Microprocessor Power Supplies
Constant-Current Regulators
Motherboard I/O Power Supplies
Mechanical Data
Case: TO-220AB, TO-263AB (D
2
PAK),
TO-252 (DPAK)
High temperature soldering guaranteed:
260C/10 seconds at terminals
Case outlines are on the back page
+
+
--
For
fixed
voltage
device
Thermal
Limit
Current
Amp
Current
Limit
GM
V
OUT
V
IN
ADJ
GND
V
REF
1.25V
55
A
Functional Block Diagram
Features
Dropout Voltage 1.3V at 3A Output Current
Fast Transient Response
Line Regulation typically at 0.015%
Load Regulation typically at 0.1%
Internal thermal and current limiting
Adjustable Output Voltage or Fixed 1.8V, 2.5V, 3.3V
Standard 3-Pin Power Packages
TO-220AB
TO-263AB
(D
2
Pak)
GS1085CT
GS1085CM
GS1085CE
TO-252
(DPak)
1
2
3
1
2
3
1
2
3
Pin Definition
1. Adjust/Gnd.
2. V
out (tab)
3. V
in
GS1085
Vishay
formerly General Semiconductor
www.vishay.com
Document Number 74821
2
24-May-02
Maximum Ratings and Thermal Characteristics
(T
A
= 25C unless otherwise noted)
Parameter
Symbol
Value
Unit
Vin Pin to ADJ/GND Pin
Vin
7
V
Thermal Resistance Junction to Case
TO-220AB
3.0
TO-252
R
JC
8.0
C/W
TO-263AB
3.0
Operating Junction Temperature Range
T
J
0 to +125
C
Storage Temperature Range
T
stg
65 to 150
C
Electrical Characteristics
(1)
T
J
= 25C
(2)
, V
IN
= 5V, I
o
= 10mA unless otherwise noted.
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
T
J
= 25C
1.238
1.250
1.262
Reference Voltage
V
REF
0C
T
J
125C 1.225
1.250
1.275
V
2.65V
V
IN
7V
10mA
I
o
3A
GS1085-1.8
V
IN
= 5V
1.78
1.8
1.82
GS1085-2.5 V
IN
= 5V
2.47
2.5
2.53
Output Voltage
V
OUT
GS1085-3.3 V
IN
= 7V
3.26
3.3
3.33
V
GS1085
0.98V
N
V
N
1.02V
N
0C
T
J
125C
2.65V
V
IN
5V
10mA
I
o
3A
2.65V
V
IN
7V
Line Regulation
REG
line
T
J
= 25C
0.015
0.2
% V
O
0C
T
J
125C
0.035
0.2
10mA
I
o
3A
Load Regulation
REG
load
T
J
= 25C
0.1
0.3
% V
O
0C
T
J
125C
0.2
0.4
0C
T
J
125C
Dropout Voltage
V
DROP
I
o
= 3A
1.3
1.4
V
I
o
= 2A
1.28
1.37
I
o
= 1A
1.25
1.34
Output Current
I
o
0C
T
J
125C
3.0
4.0
A
2.65
Vin
7V
Adjust Pin Current
I
adj
10mA
I
o
3A
55
120
A
0C
T
J
125C
2.65
Vin
7V
Adjust Pin Current Change
I
adj
10mA
I
o
3A
0.2
5
A
0C
T
J
125C
Temperature Stability
T
S
I
o
= 0.5A
0.5
%V
O
0C
T
J
125C
Minimum Load Current
I
LMIN
0C
T
J
125C
5
10
mA
Adjustable Version
Document Number 74821
www.vishay.com
24-May-02
3
GS1085
Vishay
formerly General Semiconductor
Electrical Characteristics
(con't.)
(1)
T
J
= 25C
(2)
, V
IN
= 5V, I
o
= 10mA unless otherwise noted.
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Quiescent Current
I
Q
0C
T
J
125C
10
14
mA
Fixed Voltage Version
RMS Output Noise
N
10H
Z
f
10 kH
Z
0.003
%V
O
Ripple Rejection Ratio
RR
f = 120 H
Z
, C
O
= 25
F
60
68
dB
C
adj
= 25
F
Thermal Regulation
R
TH
T
A
= 25C, 30ms Pulse
0.02
0.05
%/W
Long Term Stability
T
A
= 125C, 1000 Hrs
0.3
%V
O
Notes:
(1) All parameters, except nominal output voltage are specified for the variable voltage version, allowing a wider V
in
Range.
The specified limits also apply for the fixed voltage versions over the allowable input voltage range: GS1085-1.8 (3.2V - 7.0V), GS1085-2.5 (3.9V - 7.0V),
GS1085-3.3 (4.75V - 7.0V).
(2) To maintain the specified junction temperatures, low duty cycle pulse testing is required for most parameters.
Notes:
V
REF
= V
OUT
V
ADJ
= 1.25V (typ.)
V
OUT
= V
REF
x (1+R2/R1) + I
ADJ
x R2
I
ADJ
= 55
A (typ.)
(1) C1 needed if device is far away from filter capacitors
(2) C2 required for stability
Typical Application Circuit
V
IN
5V
V
OUT
3.3V
C1
10
F
C2
10
F
ADJ
V
REF
1
3
2
R1
125
1%
R2
205
1%
GS1085
Adjustable Voltage Regulator
+
+
V
IN
5V
V
OUT
C1
10
F
C2
10
F
1
3
2
GS1085-1.8
GS1085-2.5
GS1085-3.3
Fixed Voltage Regulator
+
+
GS1085
Vishay
formerly General Semiconductor
www.vishay.com
Document Number 74821
4
24-May-02
--0.10
0.10
--0.05
0.05
0
--0.15
--0.20
20
40
60
80
100
120
Fig. 2 Load Regulation
vs. Temperature
Output V
oltage Deviation (%)
Temperature (
C)
0
20
40
60
80
100
--50
--25
0
25
50
75
100
125
Fig. 4 Adjust Pin Current
Adjust Pin Current (
A)
Temperature (
C)
0
--1.0
--0.75
--0.5
--0.25
0.25
0.5
0.0
0.75
1.0
--20
0
20
40
60
80
100
120
140
Fig. 5 Temperature Stability
Output V
oltage Deviation (%)
Temperature (
C)
I
out
= 0.5A
I
OUT
= 3A
0.5
1.0
2
2.5
3.0
1.5
Minimum Dif
ferential V
oltage (V)
Output Current (A)
1.20
1.18
1.16
1.14
1.12
1.10
1.08
1.06
1.22
0
100
1K
100K
10K
1M
Fig. 6 Ripple Rejection
(with Cadj 25
F)
Ripple Rejection (dB)
Frequency (Hz)
20
30
40
50
60
70
80
10
1
2
4
5
6
3
Fig. 3 Minimum Load Current
(Adjustable Version)
Minimum Operating Current (mA)
Input / Output Differential Voltage (V)
2
4
6
8
10
0
T
J
= 0
C
T
J
= 25
C
T
J
= 125
C
Fig. 1 Dropout Voltage
vs. Output Current
C
OUT
=
25
F
C
OUT
=
25
F
C
OUT
=
10
F
C
OUT
= 10
F
Ratings and
Characteristic Curves
(T
A
= 25C unless otherwise noted)
Document Number 74821
www.vishay.com
24-May-02
5
GS1085
Vishay
formerly General Semiconductor
Ratings and
Characteristic Curves
(T
A
= 25C unless otherwise noted)
--0.1
1.5A
0.1A
--0.05
0
0.05
0.1
40
80
120
160
200
Fig. 7 Load Transient Response
Load Current
Output V
oltage
(V
, AC)
Time (
s)
0
V
IN
=
5V
C
IN
= 1
F
C
OUT
= 10
F (Tantalum)
V
OUT
= 3.3V
--100
7.0
6.0
--50
0
50
10
20
30
40
50
Fig. 8 Line Transient Response
Input V
oltage (V)
Output V
oltage
(mV
, AC)
Time (
s)
0
C
OUT
= 10
F (Tantalum)
V
OUT
= 3.3V
GS1085Cxx xxx
Package Type
T: TO-220
M: TO-263
E: TO-252
Output Voltage
Default: Adj.
1.8: 1.8V
2.5: 2.5V
3.3: 3.3V
Ordering Information
GS1085
Vishay
formerly General Semiconductor
www.vishay.com
Document Number 74821
6
24-May-02
9.65
10.29
8.63
9.66
14.60
15.88
1
2
3
4.06
4.83
1.14
1.40
0.7 (max.)
2.28
2.80
0.50
1.00
1.14
1.40
2.54 (TYP.)
1.40 (max.)
TO-263
TO-252 (DPAK)
5.59
5.33
10.42
9.40
5.46
5.21
6.73
6.35
0.58
0.46
2.38
2.19
2.28 (TYP.)
0.88
0.64
1
3
2
1.27
1.02
0.51 (min.)
Dimensions in millimeters
10.66
9.66
6.35 Max.
3.42
2.54
4.08
3.54
6.85
5.85
16.51
14.23
14.73
12.70
1.77
1.15
1.01
0.38
2.79
2.29
(with plating)
4.82
3.56
1.39
0.51
1.14
0.31
2.92
2.04
(with plating)
TO-220
Case Outlines
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